Tuesday 3 September 2019

 

09:00-10:30 - Plenary Sessions - Amphi Lavoisier

Chairperson: Jean-Louis Coutaz

09:00 Tu-Pl-1

TeraHertz Josephson Plasmonics: Controlling Supercurents in Cuprates

Andrea CAVALLERI, Max Plank Institute, Structure and Dynamics of Matter, Germany

09:45 Tu-Pl-2

Building Blocks And Concepts For THz Remote Sensing And Communications

Daniel DOLFI, Thales Research & Technology, France

10:30-11:00 - Coffee Break

11:00-12:30 Parallel sessions Tu-AM

11:00-12:30 - Tu-AM-1 - Gyrotron 4 - Amphi Lavoisier

Chairperson: Manfred Thumm

11:00 Tu-AM-1-1
Gyro-TWTs With Helically Corrugated Waveguides: Overview Of The Main Principles
Grigory Denisov; Alexander Bogdashov; Igor Gachev; Sergei Samsonov
Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Russian Federation

An overview of the main principles of operation and design for major components of the gyrotron travelling-wave tube (gyro-TWT) based on a helically corrugated waveguide is presented

11:30 Tu-AM-1-2
Recent Progress In K-band Technological Gyrotrons Development
Mikhail Glyavin¹; Mikhail Proyavin¹; Vladimir Manuilov²; et al^1
1Institute of Applied Physics RAS, Russian Federation; ²NNSU, Russian Federation

The overview of recent results and trends of the development of K-band (24-30 GHz) technological gyrotrons are given. The high-efficient second harmonic CW gyrotrons with output power up to 15 kW has been developed and tested. It is shown that promising technologies needs power increasing up to several tens kW. Due to the problem of suppression of high harmonics by fundamental one, the project of powerful CW first harmonic gyrotron is proposed. The reduction of total power consumption is realized by the magnetic system shielded by ferromagnetic screens. The report presented the 28 GHz CW technological gyrotron with the output power 25-30 kW and total (including the power consumption of the main coil) efficiency 35%. The characteristic features of the magnet, electron beam optics and electrodynamics system are described.

11:45 Tu-AM-1-3
Frequency-Tunable Reflective Gyro-BWO
Cheng-Hung Tsai¹; Tsun-Hsu Chang¹; Yoshinori Tatematsu^2
1Department of Physics, National Tsing Hua University, Taiwan; ²Research Center for Development of Far-Infrared Region, University of Fukui, Japan

We design and fabricate a novel electron gun and conduct an experiment using a tapered structure for the reflective gyrotron backward-wave oscillator (gyro-BWO). The electron gun and the interaction structure provide an ideal beam-wave coupling which enhances the interaction efficiency over a broad bandwidth. The cutoff section and mild tapers in the cavity region help to generate the 203 GHz waves operating at TE02 mode with the peak power efficiency of 30% and a wide bandwidth of 8.5 GHz. Preliminary experimental results will be reported.

12:00 Tu-AM-1-4
Broadband Terahertz Frequency Comb Generation From Guided Mode Resonance Excited By Fast Electrons
Tao Zhao; Min Hu; Renbin Zhong; Diwei Liu; Zhunhua Wu; Sen Gong; Shenggang Liu
University of Electric Science and Technolgy of China, China

A physical mechanism of generating tunable terahertz (THz) frequency combs (FCs) with ultra-broad bandwidth of >4 THz and high repetition rate above 20 GHz is presented. An analytical model and diffraction theory demonstrate that the equidistant comb modes are generated from the resonance between the modes of a dielectric waveguide and diffraction waves from a grating adjacent to the waveguide excited by fast electrons. Furthermore, a frequency metrology of the THz FC is developed, and demonstrated to be capable of performing high-precision measurements. This mechanism provides a new way to generate THz FCs with broad bandwidth and large frequency spacing.

12:15 Tu-AM-1-5
Recent Development For THz Vacuum Electronic Devices In IAE
Hongbin Chen; Wenqiang Lei; Guowu Ma; Peng Hu; Yi Jiang; Linlin Hu; Dimin Sun; Yinhu Huang
Institute of Applied Electronics, China Academy of Engineer Physics, China

Institute of Applied Electronics (IAE) of China Academy of Engineer Physics (CAEP) has been developing Grotron and traveling wave tubes operating in the terahertz wave regimes, such as 0.14THz, 0.22THz, 0.34THz. The 0.22THz and 0.34THz pulse folded waveguide TWTs and the CW 0.14THz and 0.22THz folded waveguide TWTs have been measured. By the measurement of 0.22THz pulse TWT, the output power is about 18.2W in 216GHz and 217GHz, the maximum gain is 28.2dB. -3dB bandwidth is about 10GHz at 50% duty cycle. In 0.34THz pulse folded waveguide TWT, the output power is about 1.61W in 338.24GHz, the maximum gain is 23.63dB. -3dB bandwidth is about 1.4GHz at 30% duty cycle. 0.14THz Gyrotron oscillator has been developed and measured at long time pulse work. The output power is about 30kW worked at 60s. 0.67THz and 1THz folded waveguide TWTs is being designed in IAE in this year.

11:00 - 12:30 Tu-AM-2 Supercond. Devices

Chairperson: Masayoshi Tonouchi Petit Amphi

11:00 Tu-AM-2-1
Development Of High-Tc Superconducting THz Emitters
Takanari Kashiwagi¹; Shungo Nakagawa¹; Takayuki Imai¹; Genki Kuwano¹; Youta Kaneko¹; Yukino Ono¹; Shinji Kusunose¹; Takashi Yamamoto²; Hidetoshi Minami¹; Manabu Tsujimoto¹; Kazuo Kadowaki^3
1University of Tsukuba, Japan; ²QuTech, Delft University of Technology, Netherlands; ³Algae Biomass and Energy System R & D Center, University of Tsukuba, Japan

Since the discovery of continuous, coherent THz radiation from intrinsic Josephson junctions (IJJs) constructed in the single crystals of Bi2Sr2CaCu2O8+δ in 2007, various types of device structures have been developed. Thermal management of Joule heat in the IJJ mesa structure is the most important point for the improvement of the radiation characteristics of the IJJ-THz emitters. The radiation frequencies ranging from 0.3 to 2.4 THz, the emission power of ~30 μW and the radiation linewidth of 0.2 GHz at ~0.5 THz were obtained from the thermal managed device structures so far. These characteristics will be discussed in the conference.

11:30 Tu-AM-2-2
Semiconducting Y-Ba-Cu-O Thin Film Detectors At Room Temperature: Front End And Back End Design Issues From Near To Far Infrared
Annick Degardin¹; Vishal Jagtap²; David Alamarguy³; Xavier Galiano²; Alain Kreisler^1
1Sorbonne-University, GeePs, France; ²CentraleSupelec/GeePs, France; ³CNRS/GeePs, France

The Y-Ba-CuO semiconductor material, particularly in its amorphous form (a-YBCO), offers an attractive solution for the easy production of thermal radiation detectors operating at room temperature, because it exhibits a sensitive pyroelectric response. Two aspects must be foreseen, however, for an optimized design of such detectors, in terms of sensitivity and noise level. The front end aspect is related to the optical and thermal coupling of an a-YBCO thin film with the incident radiation. It involves the absorption coefficient, which strongly decreases as wavelength increases. The backend aspect is related to the electrical match between the sensing film and the readout circuitry. It involves the ohmic or Schottky nature of the metal/a-YBCO contacts. We conclude with some design examples and performances, for both planar and trilayer devices. In the near-infrared for instance, noise equivalent power values below 15 pW/√Hz, and detectivity values above 10^9 cm.√Hz/W, could be measured.

11:45 Tu-AM-2-3
Towards Classical Josephson Terahertz Detector
Yuriy Divin; Irina Gundareva; Valery Pavlovskiy
Kotelnikov Institute of Radio Engineering and Electronics, Russian Federation

High-Tc Josephson junctions with Josephson dynamics suppressed by thermal fluctuations were evaluated as detectors of electromagnetic radiation. Classical rectification of THz radiation in the frequency range below 1 THz and in the power range of 4 decades in YBa2Cu3O7-x bicrystal Josephson junctions was experimentally found. As the result of analytical and numerical calculations, the NEP-value of 7x10^(-15) W/Hz^(1/2) and power dynamic range of 3x10^5 at the frequencies up to 1.4 THz were obtained for quasiclassical detection with YBa2Cu3O7-x Josephson junctions operating at the temperature T of 50 K.

12:00 Tu-AM-2-4
Detailed Design Of NbN Based Kinetic Inductance Detectors For Polarimetric Diagnostics
Francesco Mazzocchi¹; Eduard Driessen²; Shibo Shu²; Theo Scherer¹; Dirk Strauss^1
1Karlsruhe Institute Of Technology, Germany; ²IRAM, France

In the following work, we present the detailed design of a polarization sensitive, NbN base Kinetic Inductance Detector to be employed in a low cost, small footprint polarimeter for fusion plasma diagnostics.

12:15 Tu-AM-2-5
Monolithic Terahertz Emitter Of High-temperature Superconductors
Itsuhiro Kakeya¹; Asem Elarabi¹; Keiichiro Maeda¹; Shuma Fujita¹; Manabu Tsujimoto^2
1Kyoto University, Japan; ²University of Tsukuba, Japan

Emission of terahertz electromagnetic (EM) waves from a high critical temperature (Tc) superconductor intrinsic Josephson junction (IJJ) is a new and promising candidate for practical applications of superconducting devices. The emitted EM waves are considered to be coherent because the emission is yielded by synchronization of thousand stacked IJJs consisting of the mesa device. The device has advantages of broad range of frequency tuning and manipulation of polarization with monolithic device structure.

11:00 - 12:30 Tu-AM-3 High Fields 2

Chairperson: Alexander Shkurinov Room 162

11:00 Tu-AM-3-1

Generation Of MV/cm Longitudinal Terahertz Electric Fields From Relativistic Laser-solid Interactions
Abel Hailu Woldegeorgis¹; Takayuki Kurihara²; Mohammed Almassarani¹; Amrutha Gopal^1
1Helmholtz Institute Jena, Helmholtz Institute Jena, Fröbelstieg 3, Germany; ²University of Konstanz, University of Konstanz, Universitatsstr. 10, Germany

We report on the generation and detection of longitudinal terahertz (THz) transient, with field strength of 1.5 MV/cm, at the focus of a radially polarized high-power terahertz beam generated at the rear surface of a thin metal foil irradiated by multi-terawatt laser pulse. An f/1.5 off-axis parabolic mirror was used to focus the collimated THz beam. In addition to the longitudinal field, a transverse field, albeit off-axis, with amplitude in excess of 3 MV/cm was also measured.

11:30 Tu-AM-3-2
Energy Spread And Emittance Control In Segmented High Field Terahertz Driven Electron Accelerators
Dongfang Zhang; Arya Fallahi; Michael Hemmer; Hong Ye; Moein Fakhari; Yi Hua; Huseyin Cankaya; Anne-Laure Calendron; Luis E. Zapata; Nicholas H. Matlis; Franz X. Kärtner
Deutsches Elektronen-Synchrotron (DESY), Germany

Here we use a two-stage segmented-terahertz-electron-accelerator-and-manipulator (STEAM) setup to demonstrate control over the electron beam energy, energy spread and emittance. The first rebunching stage is used to tune the duration of 55 keV electron bunches that enables femtosecond phase control at the second accelerating stage. For optimized parameters, energy spread and emittance are reduced by 4x and 6x, respectively, relative to operation with the first stage off. A record energy gain of ~70 keV was achieved at a peak accelerating field of 200 MV/m, resulting in >100% energy boost in a THz-powered accelerator for the first time.

11:45 Tu-AM-3-3
High Harmonic Generation In Metallic Phase Of 2H-NbSe_2
Kousei Shimomua; Kento Uchida; Kohei Nagai; Satoshi Kusaba; Koichiro Tanaka
Department of Physics, Graduate School of Science, Kyoto University, Japan

High harmonics up to the 9th order have been confirmed in metallic phase of 2H-NbSe2 with intense mid-infrared light. They show the nonperturvative excitation power dependence, and their efficiency are almost independent of the polarization direction to the crystal axis. Our Numerical calculation based on the intraband current model reproduces the experimental results, suggesting that the carrier distribution in k-space plays a crucial role for the high harmonics in metal.

12:00 Tu-AM-3-4
Terahertz Generation By Kerr Effect At Metal Surfaces
Bastien Muller; Maxime Bernier; Emilie Herault; Jean-Louis Coutaz
IMEP-LAHC, France

The emission of terahertz radiation from laser-excited thick metal samples through Kerr effect has been detected for the first time to the authors' knowledge. The observed THz waveforms are generated through nonlinear electronic processes at surfaces (optical rectification) and in the bulk (Kerr effect) of gold samples.

12:15 Tu-AM-3-5

Extremely High Field Single-cycle Terahertz Pulse Sources Based On Echelon Structures
György Tóth¹; László Pálfalvi¹; József András Fülöp²; Gergő Krizsán¹; Priyo S. Nugraha³; Zoltán Tibai¹; Levente Tokodi¹; Gábor Almási¹; János Hebling^1
1University of Pécs, Hungary; ²MTA-PTE High Field Research Group, Hungary; ³Szentágothai Research Centre, Hungary

Three different echelon based structures for the generation of intense THz pulses were suggested and simulated. Their advantages are the energy scalability and the symmetric THz beam profile. Focused single cycle THz pulses up to ~50 MV/cm peak electric field level are predicted with these sources. Such sources can basically promote the realization of THz driven electron and proton accelerators.

11:00 - 12:30 Tu-AM-4 Telecom 1

Chairperson: Tadao Nagatsuma Room 269

11:00 Tu-AM-4-1

Simulation And Automatic Planning Of 300 GHz Backhaul Links
Bo Kum Jung; Nils Dreyer; Johannes Eckhardt; Thomas Kürner
TU Braunschweig, Germany

The IEEE Standard 802.15.3d defines a communication systems allowing wireless solutions for backhaul links operating at 300 GHz with data rates of 100 Gbit/s and beyond. The European Horizon 2020 ThoR project works towards the demonstration of such a solution. One of the goals of ThoR is to develop algorithms for automatic planning of 300 GHz backhaul links and the derivation of planning guidelines. In this paper, an automatic algorithm for the planning of 300 GHz backhaul links using 3D ray tracing taking into account atmospheric effects is presented. The influence of both the applied antennas and the weather conditions are evaluated for an automatically planned network by using a realistic scenario of an ultra-dense network in the city of Hannover.

11:30 Tu-AM-4-2
Bidirectional K-Band Photonic/Wireless Link For 5G Communications
Alvaro Morales; Dimitrios Konstantinou; Simon Rommel; Thiago Roberto Raddo; Ulf Johannsen; Chigo Okonkwo; Idelfonso Tafur Monroy
Eindhoven University of Technology, Netherlands

A bidirectional analogue radio-over-fiber link based on photonic heterodyning and time-division duplex is experimentally demonstrated, successfully transmitting 5G OFDM signals with data rates of 2.4 Gbit/s and 1.2 Gbit/s in down- and uplink directions over 4 m of wireless distance.

11:45 Tu-AM-4-3
Scattering Analysis Of Terahertz Wireless Links By Rough Surfaces
Jianjun Ma¹; Rabi Shrestha²; Wei Zhang²; Lothar Moeller³; Daniel Mittleman^2
1Beijing Institute of Technology, China; ²Brown University, United States; ³New Jersey Institute of Technology, United States

This work presents the diffuse bistatic scattering response of metallic rough surfaces using a data stream at THz frequency range. NLOS links can be established by the form of diffuse scattering rays when a LOS and specular NLOS links are blocked. So non-specular NLOS paths can play a valuable role in future THz wireless systems with a highly directional beam.

12:00 Tu-AM-4-4
Direct Terahertz Communications With Wireless And Fiber Links
Xiongbin Yu¹; Tomoyuki Miyamoto²; Katsunori Obata²; Yasuo Hosoda²; Jae-Young Kim³; Masayuki Fujita¹; Tadao Nagatsuma^1
1Osaka University, Japan; ²Pioneer Corporation, Japan; ³ROHM Co., Ltd, Japan

We have successfully demonstrated a direct THz communications link that employs both a wireless and a fiber portion, for advanced communication systems. Currently, the greatest obstacle is the efficiency of overall link, which we intend to overcome by refining the connection between the photonic-crystal waveguide and THz fiber, in order to achieve a higher data rate. We also aim to employ RTDs as both transmitter and receiver, in order to realize an all-electronic system that does not require laser excitation. Such THz systems may find uses not only in communications, but also in such as remoting sensing, security and medical applications.

12:15 Tu-AM-4-5
Towards Super-heterodyne THz Links Pumped By Photonic Local Oscillators
Iulia Dan¹; Shintaro Hisatake²; Pascal Szriftgiser³; Ralf-Peter Braun⁴; Ingmar Kalfass¹; Guillaume Ducournau^5
1Institute of Robust Power Semiconductor Systems, Univ Stuttgart, Germany; ²Gifu Univ, Japan; ³PhLAM, France; ⁴DEUTSCHE TELEKOM AG, Germany; ⁵IEMN CNRS/Université de Lille, France

We present in this paper wireless data transmission experiments in a superheterodyne wireless system based on millimeterwave monolithic integrated circuits at a center frequency of 300 GHz, driven by photonic local oscillator (LO). Superheterodyne operation is attractive for compliance with the recent IEEE802.15.3d frequency standard. The super-heterodyne transmission with two channels is realized using an AWG and a photonic-based LO. The paper presents initial transmission experiments realized using two channels in the 300 GHz band

11:00 - 12:30 Tu-AM-5 QW

Chairperson: Yanko Todorov Room 101

11:00 Tu-AM-5-1

Quantum Well Infrared Detectors In The Strong Light-matter Coupling Regime
PB Vigneron¹; S Pirotta¹; I Carusotto²; NL Tran¹; G Biasiol³; JM Manceau⁴; A Bousseksou⁴; Raffaele Colombelli^4
1Centre de Nanosciences et Nanotechnologies (C2N), France; ²University of TRENTO, BEC Center, Italy; ³TASC Laboratory, Italy; ⁴Centre de Nanosciences et Nanotechnologies, France

We report quantum well mid-infrared photo-detectors operating in the strong light-matter coupling regime. It is an ideal system to elucidate the elusive problem of the injection of electrons (single-particles) into polaritonic modes (bosonic excitations). We have obtained experimental information on the transfer function between a polaritonic system and an electronic reservoir. This approach opens promising avenues in view of adding previously unavailable functionalities to quantum well detectors and improving their performance.

11:30 Tu-AM-5-2
High Speed Quantum Well Infrared Heterodyne Receivers At 4.9µm
Gregoire Vallet¹; Djamal Gacemi¹; Azzurra Bigioli¹; Angela Vasanelli¹; Yanko Todorov¹; Carlo Sirtori¹; Etienne Rodriguez^2
1Laboratoire de Physique de l'Ecole Normale Superieure, CNRS, France; ²CINTRA CNRS/NTU/THALES, Singapore

We have realized high-speed quantum well infrared photodetectors (QWIPs) for the detection of coherent radiation at 4.9 Ãfâ?sÃ,µm wavelength. Our devices have a detectivity of 4 x 10-10 cm Hz1/2 W-1 at 77 K and a flat response up to 30 GHz.

11:45 Tu-AM-5-3
Far And Mid IR Stimulated Emission In HgCdTe QW Heterostructures
Vladimir Gavrilenko¹; Sergey Morozov¹; Vladimir Rumyantsev¹; Mikhail Fadeev¹; Vladimir Utochkin¹; Nikita Kulikov¹; Alexandre Dubinov¹; Vladimir Aleshkin¹; Nikolay Mikhailov²; Sergey Dvoretskii²; Frederic Teppe³; Carlo Sirtori^4
1Institute for Physics of Microstructures, Russian Federation; ²A.V.Rzhanov Institute of Semiconductor Physics, Russian Federation; ³Laboratoire Charles Coulomb, CNRS & Universite Montpellier, France; ⁴Laboratoire de Physique de l'Ecole Normale Superieure, France

Stimulated emission (SE) at wavelengths up to 24 μm (12.5 THz) and down to 2.8 μm is demonstrated from HgCdTe quantum well (QW) heterostructures. Non-radiative Auger recombination is show to be mitigated due to relativistic energy spectrum. Pump-probe carrier lifetime measurements show that further increase in SE wavelength is feasible up to 60 μm (5 THz). In the short wavelength range SE down to 2.8 μm is demonstrated at temperatures available with Peltier coolers.

12:00 Tu-AM-5-4
Room Temperature THz Intersubband Transitions In Continuously-graded AlxGa1-xAs Parabolic Quantum Wells
Christopher Deimert¹; Paul Goulain²; Jean-Michel Manceau²; Adel Bousseksou²; Raffaele Colombelli²; Zbig Wasilewski^1
1University of Waterloo, Canada; ²centre de nanosciences et naotechnologies, France

We demonstrate room temperature intersubband transitions in the THz range using continuously-graded AlxGa1 xAs parabolic quantum wells. Below 100K, the linewidth of the transition reaches a record-low value of 5.7% of the central frequency.

12:15 Tu-AM-5-5
High Sensitivity 9?m Metamaterial Infrared QC Detectors At 300K
Azzurra Bigioli¹; Giovanni Armaroli¹; Daniele Palaferri²; Yanko Todorov¹; Angela Vasanelli¹; Djamal Gacemi¹; Li Lianhe³; Giles Davies³; Edmund Linfield³; Carlo Sirtori^1
1Laboratoire de Physique de l'Ecole Normale Superieure, France; ²Laboratoire Matériaux et Phénomènes Quantiques, France; ³School of Electronic and Electrical Engineering, Leeds, United Kingdom

Quantum Cascade Detectors are promising devices for high-temperature mid-infrared detection. The responsivity, related to its photovoltaic working principle, still suffers from lower responsivity respect to a photoconductive device such as QWIP. Here, we demonstrate that inserting a QCD detector in a photonic metamaterial made of patch-antenna microcavities, we can boost light-matter interaction reaching responsivity value in the order of 50mA/W at room temperature, the highest value reported in the literature

11:00 - 12:30 Tu-AM-6 Metamaterials 1

Chairperson: Michele Ortolani Room 151

11:00 Tu-AM-6-1

Broadband Achromatic Metalens In Terahertz Regime
Yiming Zhu; Qingqing Cheng; Lin Chen; Yan Peng
University of Shanghai for Science & Technology, China

We demonstrate the achromatic metalens with C-shape units working from 0.3 to 0.8 THz with a bandwidth of approximately 91% over the center wavelength. The achromatic focusing has been observed both experimentally and numerically, with the size of focal spot closed to ?. Meanwhile, the designed metalens possesses high working efficiency of more than 68% at the peak and a relatively high numerical aperture (NA) of NA=0.385 in order to obtain high spatial resolution. We further show the robustness of our C-shape structures, considering lateral shape deformations and deviations of etching depth. Our work successfully demonstrates the THz achromatic metalens, which opens an avenue for the future applications of terahertz meta-devices on spectroscopy, time-of-flight tomography and hyperspectral imaging system.

11:30 Tu-AM-6-2
Terahertz 3D Components Made From Metamaterials
Haruaki Nakao; Takehito Suzuki
Tokyo University of Agriculture and Technology, Japan

A realization of next-generation ultrafast wireless communication (6G) and security imaging in the terahertz waveband is a question of time because of the rapid development of terahertz oscillators. However, terahertz components have yet to be developed whereas components in the optical region and millimeter waveband provide sufficient support for technological and scientific progress. Here we produce a reflectionless metamaterial with an extremely high refractive index of 12.3 in the 0.3-THz band and apply it to a 3D phase delay component for high-performance gradient-index terahertz lenses. We also demonstrate a large-aperture robust polarizer with an extreme sensitivity of high extinction ratios below -50 dB consisting of a metamaterial with a large negative relative permittivity of -97.6. The 3D terahertz components utilizing unprecedented materials would contribute to the development of a future industry based on terahertz applications.

11:45 Tu-AM-6-3
Realizing Sub-diffraction Focusing For Terahertz
Ayato Iba¹; Calvin W. Domier²; Makoto Ikeda¹; Atsushi Mase³; Anh-Vu Pham²; Neville C. Luhmann, Jr^2
1Sensing Technology Department, Asahi-Kasei Corporation, Japan; ²Department of Electrical and Computer Engineering, University of California, Davis, United States; ³Global Innovation Center, Kyushu University, Kasuga-koen, Japan

Measurement resolution is one of the most important elements for industrial applications. However, conventional lenses for terahertz (THz) or millimeter-wave cannot achieve high resolution due to the diffraction limit. Here, we demonstrate that two types of super-oscillatory lenses are very effective for subdiffraction focusing at THz.

12:00 Tu-AM-6-4
All-dielectric Guided-mode Resonance Filters In THz Region
Hyeon Sang Bark¹; In Hyung Baek¹; Kyu-Ha Jang¹; young Uk Jeong¹; Tea-In Jeon^2
1Korea Atomic Energy Research Institute, Republic of Korea; ²Korea Maritime and Ocean University, Republic of Korea

In summary, because the proposed GMR filters have a high Q-factor, tunable filter and good polarizer characteristics, it has potential for THz applications in modulator, band pass filter, reflector, sensor [3] and bio-medical technologies in the future.

12:15 Tu-AM-6-5
Extraordinary THz Absorption In 2D Material-dielectric Integrated Metasurfaces
Sara Arezoomandan; Hugo Condori Quispe; Berardi Sensale-Rodriguez
University of Utah, United States

This work discusses our recent findings on 2D material-dielectric integrated metasurfaces, as an alternative approach to 2D material-metal hybrid metamaterials, for providing efficient control of the electromagnetic beam propagation at THz wavelengths. The analyzed structures consist of a passive dielectric pattern and a reconfigurable 2D material sheet whose THz optical conductivity can be actively tuned. We show that via optimizing the geometric dimensions in the patterns it is possible to attain almost complete absorption by the 2D material at an arbitrary frequency of interest.

11:00 - 12:30 Tu-AM-7 Gas Spectro. & Sensing 2

Chairperson: Gaël Mouret Room 201

11:00 Tu-AM-7-1

High-resolution Fast Terahertz Time-domain Gas Spectroscopy Based On A Fine Comb Spectral Structure Of The NovoFEL
Vitaly Kubarev¹; Yaroslav Getmanov¹; Evgeny Chesnokov²; Pavel Koshlyakov^2
1Budker Institute of Nuclear Physics, Russian Federation; ²Institute of Chemical Kinetics and Combustion, Russian Federation

High coherency and monochromaticity of the terahertz Novosibirsk Free-Electron Laser (NovoFEL) is appeared in very narrow comp spectral structure of its radiation (relative line's width is 2E-8, interval between lines is 5.6 MHz, total width of the comb-structure is 6-12 GHz). Sampling time-domain spectroscopy with resolution of order of the line width (~ 100 kHz) needs measuring time about of 20 µsec per one sampling point and only 56 slow sampling points to overlap the full NovoFEL comb spectrum. Shift of the comb structure will be made by changing of length of the NovoFEL optical resonator. Universal terahertz gas laser (line width ≤0.5E-8) will be used as local oscillator in the heterodyne spectrometer.

11:30 Tu-AM-7-2
Free Induction Decay Signals Stimulated By Photomixing
Fuanki Bavedila¹; Guillaume Ducournau¹; Jean-François Lampin¹; Emilien Peytavit¹; Arnaud Cuisset²; Gaël Mouret²; Cedric Bray³; Robin Bocquet²; Francis Hindle^2
1IEMN CNRS/Université de Lille, France; ²Laboratoire de Physico-chimie de l'Atmosphère ULCO, France; ³Institut des Sciences Moléculaires Université de Bordeaux, France

An optically driven photoconductor device is electrically pulsed to provide a powerful pulse around 206 GHz. The pulsed radiation polarizes the OCS gas which emits a free induction decay signal that is observed after the end of the pulse. This is the first step in the development of a photonic chirped pulsed spectrometer.

11:45 Tu-AM-7-3
Terahertz Differential Absorption Spectroscopy Using Multi-Furcated Nd:YAG Microchip Laser For Gas Sensing
Yuma Takida¹; Toshiyuki Ikeo²; Kouji Nawata¹; Yoshio Wada²; Yasuhiro Higashi²; Hiroaki Minamide^1
1RIKEN, Japan; ²Ricoh Company, Ltd., Japan

We demonstrate a frequency-domain differential absorption spectroscopy in the terahertz (THz) range for gas sensing applications. Our system is based on an injection-seeded THz-wave parametric generator driven by a multi-furcated Nd:YAG microchip laser. Within a single excitation cycle of the laser, the is-TPG generates up to three narrowband THz-wave pulses that are separated in time by 80 µs and in frequency by 11 GHz, which is due to the spatial hole burning effect in the laser cavity. These pulses can be directly used to measure differential absorption signals, and first and second derivative spectra of target gas molecules without measuring reference spectra.

12:00 Tu-AM-7-4
Determining DHO Detection Limits For A Frequency Domain THz Spectrometer Coupled To A Light-weight Multi-pass Sample Cell
Joseph Demers; Elijah Dale
Bakman Technologies, United States

A fringe-free, frequency domain terahertz spectrometer connected to a custom fabricated, light-weight multi-meter multi-pass sample cell was employed to measure the 1.492 THz, 1.507 THz and 1.523 THz molecular transitions of DHO over various pressures. We will report on the detectable concentrations of the DHO achieved with the portable instrument.

12:15 Tu-AM-7-5
THz/Far-IR Astrophysical Studies At The Australian Synchrotron
Dom Appadoo
ANSTO/Australian Synchrotron, Australia

THz synchrotron spectroscopy has become an important tool in the identification and quantification of molecular species of astrophysical interest; it is a routinely used technique as it is well established that synchrotron radiation offers a S/N advantage over conventional thermal sources. The brightness advantage is perfectly suited for high-resolution gas-phase spectroscopy, and at the Australian Synchrotron, this advantage is limited to energies lying below 1500 cm-1; however, a flux advantage is maintained for energies lying only below 350 cm-1 which facilitates the study of homogeneous condensed-phase samples. The THz/Far-IR beamline is equipped with a suite of both gas-phase and condensed-phase techniques to enable research on interstellar molecular species, and in this paper, the beamline capabilities available for the study of molecular species of astrophysical interest will be presented.

12:30-14:00 - Lunch

14:00-16:00 Parallel sessions Tu-PM1

14:00 - 16:00 Tu-PM1-1 Gyrotron 5

Chairperson: Alexander Litvak Amphi Lavoisier

14:00 Tu-PM1-1-1
Characterizing The Accelerating Mode Of A Dielectric-lined Waveguide Designed For Terahertz-driven Manipulation Of Relativistic Electron Beams
Vasileios Georgiadis¹; Morgan Hibberd¹; Alisa Healy²; Daniel Lake²; Graeme Burt²; Steven Jamison²; Darren Graham^1
1The University of Manchester, The University of Manchester, Oxford Road, United Kingdom; ²University of Lancaster, University of Lancaster, Bailrigg, United Kingdom

We report on the generation of a terahertz beam with a quasi-TEM01 mode by exploiting the interferometric recombination of two linearly polarized emitters in a combined spintronic source. The generated THz beam was used to characterize the accelerating mode of a dielectric-lined waveguide (DLW) to inform on the recent demonstration of relativistic electron beam manipulation achieved with this THz-driven DLW at the CLARA research facility at Daresbury Laboratory.

14:30 Tu-PM1-1-2
First Operation Of Ka-band High-current Relativistic Gyrotron
Alexander Leontyev¹; Edward Abubakirov¹; Andrej Denisenko¹; Alexey Fedotov¹; Roman Rozental¹; Vladimir Tarakanov^2
1Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Russian Federation; ²Moscow Engineering Physics Institute, Russian Federation

The results of the first operation of a pulse Ka-band gyrotron with output radiation power more than 110 MW are presented. The gyrotron was excited by electron beam with a current of up to 2 kA and particle energy of up to 500 keV, formed by an explosive emission cathode with subsequent transverse velocities pumping in a non-uniform field produced by a short coil (kicker) to a state with a pitch-ratio of about 1.

14:45 Tu-PM1-1-3
An Experimental Investigation Of A 0.8 THz Gyrotron With An Improved Mode Selection
Mikhail Glyavin¹; Toshitaka Idehara²; Eduard Khutoryan³; Svilen Sabchevski⁴; et al^1
1Institute of Applied Physics RAS, Russian Federation; ²FIR UF, Japan; ³IRE NASU, Ukraine; ⁴IE BAS, Bulgaria

In this paper, we present and discuss the latest experimental results from the investigation of the operational performance of a 0.8 THz double-beam gyrotron, which has been developed and manufactured recently in the framework of an international research project led by IAP-RAS and FIR UF. After the initial tests, the current experiments have been focused not only on the study of the operation at the design mode TE8,5 (at the second harmonic of the cyclotron frequency) but also of several other modes the generated radiation of which could be appropriate for various other applications besides the envisaged 1.2 GHz DNP-NMR spectroscopy. The obtained results give a deeper insight into the specifics of the operation of the double-beam gyrotron and especially on its capability to provide an improved mode selection and therefore a single mode second harmonic operation.

15:00 Tu-PM1-1-4
Observation Of Multi-Peak Frequency Spectrum In A High Power Sub-THz Gyrotron
Teruo Saito¹; Shunsuke Tanaka¹; Ryuji Shinbayashi¹; Yuusuke Yamaguchi¹; Masafumi Fukunari¹; Yoshinori Tatematsu¹; Maria Melnikova²; Nikita Ryskin^2
1University of Fukui, Japan; ²Saratov State University, Russian Federation

Equi-distantly distributed multi-peak frequency spectrum was observed in a high power 300 GHz band gyrotron for the case of strong reflection off the vacuum window. An oscillation mode different from the design mode can oscillate by adjusting the magnetic field in the cavity. However, a large fraction of the output wave is reflected by the vacuum window. A theoretical calculation shows that the multi-peak frequency spectrum stems from periodic amplitude variation that is caused by mode competition between the oscillating co-rotating mode and the counter-rotating mode originating from the reflected wave.

15:15 Tu-PM1-1-5
Demonstration Of A High Power Frequency-Tunable 0.22-THz Gyrotron Operating In High-Order Axial Modes
Xiaotong Guan; Wenjie Fu; Dun Lu; Tongbin Yang; Xuesong Yuan; Yang Yan
University of Electronic Science and Technology, China

To explore the approach for generating high power frequency-tunable sub-THz to THz radiation, a 0.22-THz high-order axial modes (HOAMs) gyrotron is developed and tested in TRC-UESTC. The proof-of-principle experimental results demonstrate that a series of HOAMs in a long gyrotron cavity are excited successfully by an electron beam of high voltage and high current. A frequency tuning range of 0.79 GHz around 219 GHz has been achieved by tuning the operating magnetic field and operating in the first four axial modes. And during the frequency tuning, the out power kept no less than 0.45 kW, while the maximum output power was 3.80 kW. These experimental results of axial mode transition in high power sub-terahertz gyrotron should be conductive to the future development of frequency-tunable gyrotron towards some up-and-coming novel terahertz applications.

15:30 Tu-PM1-1-6
95 GHz Gyrotron With Water Cooled Magnet And High Average Power
Moritz Pilossof
Ariel University, Israel

Abstract-- A 95 GHz gyrotron with water cooled copper magnet delivering high average power was assembled. The cavity interaction mode is TE02 at the second cyclotron harmonic. Internal mode converter is used to convert the interaction mode to quasi-Gaussian mode at the gyrotron output window. A ~1.8T magnetic field is produced by water cooled copper electro-magnet. The magnet and the gyrotron have immediate turn on and off time when the cathode is worm (<1s). Initial results will be presented.

15:45 Tu-PM1-1-7
Multibeam And Multibarrel Gyrotrons
Vladimir Zapevalov; Vladimir Zapevalov
Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Russian Federation

The report analyzes the perspective of multibeam and multibarrel version of gyrotron for possibility of frequency tuning and improved mode selection at gyrotron working on the gyrofrequency harmonics.

14:00 - 16:00 Tu-PM1-2 Solid State 4

Chairperson: Dmitry Khokhlov Petit Amphi

14:00 Tu-PM1-2-1

Infrared/Terahertz Photogalvanic Spectroscopy Of Three And Two Dimensional Topological Insulators
Sergey Ganichev
Terahertz Center, University of Regensburg, Germany

The paper overviews experimental and theoretical studies of photogalvanic and photon drag effects induced in various in three-dimensional (3D) and 2D topological insulators (TI) by polarized infrared/terahertz (IR/THz) radiation. e present the state-of-the-art of this subject, including both recent advances and well-established results. Various physical mechanisms of photogalvanic and photon drag effects in TI systems are described including experimental achievements, phenomenological description, models visualizing physics of nonlinear responses, and microscopic theory of individual effects. Several examples for the characteristics determined by applying photocurrents are: the Fermi velocity, the cyclotron masses as a function of carrier density and temperature, the orientation of surface domains in 3D TIs, and the surface state mobility.

14:30 Tu-PM1-2-2
Terahertz Electron Paramagnetic Resonance Spectroscopy using An Ultrathin Membrane Device
Eiji Ohmichi; Hideyuki Takahashi; Tsubasa Okamoto; Daiki Hachiya; Hitoshi Ohta
Kobe University, Japan

A novel terahertz (THz) electron paramagnetic resonance (EPR) spectroscopy technique is presented. The use of an ultrathin membrane device allows sensitive EPR detection of small volume samples in the frequency region up to 0.65 THz. We show THz EPR spectroscopy results on microliter solution of myoglobin and a tiny single crystal of a magnetically ordered sample.

14:45 Tu-PM1-2-3
Influence Of Cu-doping On Terahertz Conductivity And Temperature-driven Phase Transition In NdNiO3 Thin Films
Mahesh Chandra¹; V. Eswara Phanindra²; S. Prabhu³; Krushna Mavani^1
1Indian Institute of Technology Indore, India; ²Indian Institute of Science Education and Research Bhopal, India; ³Tata Institute of Fundamental Research, India

Perovskite nickelates show the first order metal-insulator transition. Doping of 3d metal ions at Ni-site can drastically change the electronic properties. We have deposited and studied Cu-doped NdNiO3 thin films for structural and electronic properties. Merely 2% Cu-dopingat Ni-site induces a metallic state in otherwise insulating NdNiO3 film at low temperatures. The terahertz conductivity shows Drude behavior and the conductivity is tuned by Cu-doping in these films.

15:00 Tu-PM1-2-4
Calculating The Complex Permittivity Of Powdered Crystalline Materials
Andrew Burnett; Calum Towler; John Kendrick
School of Chemistry, University of Leeds, United Kingdom

Solid-state density functional theory calculations including periodic boundary conditions have become well established for calculating the THz spectra of crystalline materials. Here we compare a range of DFT programs and calculation parameters including a number of van der Waals' dispersive corrections in combination with our post-processing tool, PDielec, to calculate the complex permittivity of a range of powdered crystalline materials.

15:15 Tu-PM1-2-5
Spin And Lattice Dynamics Of Multiferroic SrMn7O12 Studied By THz And Infrared Spectroscopies At Low Temperatures And In Magnetic Field
Filip Kadlec¹; Veronica Goian¹; Dmitry Nuzhnyy¹; Christelle Kadlec¹; Jakub Vít¹; Fedir Borodavka¹; Iana S. Glazkova²; Alexei A. Belik³; Stanislav Kamba^1
1Institute of Physics CAS, Czech Republic; ²Lomonosov Moscow State University, Russian Federation; ³National Institute for Materials Science, Japan

Multiferroic SrMn7O12 crystals are isostructural with CaMn7O12 which is known for its unusual symmetry properties and a record-high spin-induced polarization. We studied SrMn7O12 ceramics by THz time-domain and Fourier-transform infrared spectroscopies upon varying temperature and magnetic field. In the magnetic phases, we observed spin waves gaining strength from phonons; thus, they are assigned to electromagnons. We discuss the observed persistence of several low-temperature vibrational modes above the high-temperature phase transition, and the impact of atomic substitution with regard to CaMn7O12.

15:30 Tu-PM1-2-6
Identification And Characterization Of 'Killer-Modes' In Organic Semiconductors With Terahertz Spectroscopy
Peter Banks; Michael Ruggiero
The University of Vermont, United States

Organic semiconductors are promising modern optoelectric materials, with countless potential applications ranging from flexible displays to photovoltaics. The applicability of these materials is largely driven by their charge carrier mobility, which is strongly influenced by low-frequency vibrations. In this work, the specific low-frequency vibrations that exhibit strong electron-phonon coupling, deemed 'killer-modes', in organic semiconductors are determined using a combination of terahertz time-domain spectroscopy and solid-state density functional theory. The results of this study enable a concerted synthetic effort to rationally design novel materials, utilizing intermolecular forces to stiffen lattice dynamics, to ultimately improve charge carrier mobility.

15:45 Tu-PM1-2-7
Effects Of Low Content Enantiomer Impurity In L-histidine Crystal Observed By Terahertz Spectroscopy
Tetsuo Sasaki¹; Tomoaki Sakamoto²; Makoto Otsuka^3
1Shizuoka University, Japan; ²National Institute of Health Sciences, Japan; ³Musashino University, Japan

Effects of enantiomer impurity molecule at low content on THz spectrum were studied. L-histidine crystal was grown controlled to monoclinic form B from ethanol-rich solvent. D-histidine was added in the range 0.05 to 10.0 % in the solvent before recrystallization. Peak frequency shifts of absorption lines of L-histidine at 10 K on the relation with D-histidine content were evaluated by high frequency accurate THz spectrometer. It was shown that high sensitive detection of enantiomer impurity was possible until DL racemic compound crystal was formed with increasing D-histidine content.

14:00 - 16:00 Tu-PM1-3 THz Devices 1

Chairperson: Stefano Barbieri Room 162

14:00 Tu-PM1-3-1

Free-space Coupling Of Terahertz Whispering-gallery Modes
Dominik Vogt; Angus Jones; Rainer Leonhardt
University of Auckland, New Zealand

We report on free-space coupling of high quality (Q) spherical THz whispering-gallery mode resonators (WGMRs) as a simple alternative to more complex waveguide and prism coupling. Excitation efficiencies up to 50% to WGMs with Q-factors of 1.5x10^4 at 0.7THz are achieved.

14:30 Tu-PM1-3-2
Terahertz Polarization Splitter Based On Parallel-plate Waveguide Technology
Arturo Hernandez-Serrano; Emma Pickwell-MacPherson
University of Warwick, United Kingdom

In this work we present a terahertz polarization splitter based on a parallel-plate waveguide (PPWG). The proposed structure consists of a stacked array of stainless steel plates with 0.8mm spacing. The device is capable of splitting the two orthogonal polarization components (TM and TE) in a frequency range of 250GHz to 500GHz.

14:45 Tu-PM1-3-3
High-Performance Frequency Selective Surface Filters For Terahertz Applications
Sergei Kuznetsov¹; Nazar Nikolaev²; Andrey Arzhannikov^3
1Rzhanov Institute of Semiconductor Physics SB RAS, Russian Federation; ²Institute of Automation and Electrometry SB RAS, Russian Federation; ³Budker Institute of Nuclear Physics SB RAS, Russian Federation

We review the results of extensive R&D activity focused on elaborating high-performance quasi-optical filters using the technology of frequency selective surfaces. The band-pass, low-pass, and high-pass devices operating at subterahertz and terahertz frequencies are described. The issues of design optimization, lithographic fabrication, and spectral characterization of the developed filters alongside with their practical applications are considered.

15:00 Tu-PM1-3-4
Giant Dual-mode Graphene-based THz Modulator
Liang-Hui Du¹; Pei-Ren Tang²; Jiang Li¹; Li-Guo Zhu^1
1Institute of Fluid Physics, China Academy of Engineering Physics, China; ²University of Science and Technology of China, China

We report a high-performance terahertz (THz) modulator with dual-operation mode. For the pulse operation mode, the proposed THz modulator has the advantage of high modulation depth (MD) and can operate in a broadband frequency range. We have experimentally achieved a MD larger than 90% for the fifth-order pulse THz echo at 0.8 THz and the MD stays larger than 75% in a broadband frequency range larger than 1 THz. While, for the coherent operation mode, the Fabry-Perot (F-P) interference effect has been taken into consideration and a MD larger than 75% at 0.76 THz has also been realized.

15:15 Tu-PM1-3-5
Photonic Bandgap Bragg Waveguide-based Terahertz Microfluidic Sensor
Yang Cao; Kathirvel Nallappan; Hichem Guerboukha; Thomas Gervais; Maksim Skorobogatiy
Polytechnique Montreal, Canada

A 3D printed photonic bandgap Bragg waveguide-based resonant microfluidic sensor operating in the THz spectral range is theoretical analyzed and experimental studied. The analytes are injected into a microfluidic channel to a defect layer region which results in a modal anti-crossing phenomenon. By tracking the spectral positions of the induced absorption dips and phase changes of the transmission spectra of various liquids, we measure a sensitivity of 110 GHz/RIU. The proposed sensor features high reliability and can provide a non-contact measurement method for real-time monitoring of the refractive index change of liquid flow in practical applications.

15:30 Tu-PM1-3-6

Efficient Ultrafast THz Modulators Based On Negative Photoconductivity In Controllably Doped Carbon Nanotubes

Burdanova, Maria¹; Tsapenko, Alexey²; Satco, Daria²; Kashtiban, Reza¹; Mosley, Connor³; Monti, Maurizio¹; Staniforth, Michael¹; Sloan, Jeremy¹; Gladush, Yuriy²; Nasibulin, Albert²; Lloyd-Hughes, James^1
1The University of Warwick, United Kingdom ; ²Skolkovo Institute of Science and Technology, Russian Federation

Large diameter single-walled carbon nanotubes films are shown to have a doping level and THz conductivity that can be readily controlled using adsorption doping or electrostatic gating. The giant negative photoconductivity observed upon optical excitation is due to a rapid reduction in mobile carrier density, synchronously to a lowering of the momentum scattering rate. The large modulation depth and tunable recovery time open prospects for carbon nanotube films in ultrafast and THz devices.

15:45 Tu-PM1-3-7
Engineered Silicon For Efficient Mm-Wave And THz Modulators
Lauren Barr¹; Ian Hooper¹; Nicholas Grant²; Samuel Hornett¹; Christopher Lawrence³; John Murphy²; Euan Hendry^1
1University of Exeter, United Kingdom; ²University of Warwick, United Kingdom; ³QinetiQ, United Kingdom

Large diameter single-walled carbon nanotubes films are shown to have a doping level and THz conductivity that can be readily controlled using adsorption doping or electrostatic gating. The giant negative photoconductivity observed upon optical excitation is due to a rapid reduction in mobile carrier density, synchronously to a lowering of the momentum scattering rate. The large modulation depth and tunable recovery time open prospects for carbon nanotube films in ultrafast and THz devices

14:00 - 16:00 Tu-PM1-4 Telecom 2

Chairperson: Guillaume Ducournau Room 269

14:00 Tu-PM1-4-1

12.5-Gbit/s Wireless Link At 720 GHz Based On Photonics
Tadao Nagatsuma¹; Masato Sonoda¹; Taiki Higashimoto¹; Li Yi¹; Jeffrey Hesler^2
1Osaka University, Japan; ²Virginia Diodes, Inc., United States

This paper addresses a development of 600-GHz band wireless links based on photonics technologies. An error-free transmission at a bit rate of >12.5 Gbit/s has been demonstrated for the first time at 720 GHz using a photodiode-based transmitter and a Schottky-barrier-diode mixer receiver.

14:30 Tu-PM1-4-2
The Influence Of RF Front-End Imperfections On Performance Of A 220- 260 GHz Tunable M-QAM Wireless Link In SiGe HBT Technology
Janusz Grzyb¹; Pedro Rodriguez Vazquez¹; Bernd Heinemann²; Ullrich Pfeiffer^1
1University of Wuppertal, Germany; ²IHP- Leibniz-Institut für Innovative Mikroelektronik, Germany

This paper presents system-level characterization and performance evaluation for higher-order M-QAM modulation formats of a fully-electronic 1-m wireless link with two highly-integrated direct-conversion quadrature TX and RX modules in 0.13-υm SiGe HBT technology operating with a tunable 220-260 GHz LO carrier. With the limited baseband bandwidth of 15 GHz, the maximum achieved data rates for 16-/32-/64-QAM modulation are 90 Gbps (EVM of 14.6%), 90 Gbps (EVM of 11.9%) and 81 Gbps (EVM of 8.7%), respectively.

14:45 Tu-PM1-4-3
A Metal Wire Waveguide For Terabit DSL
Rabi Shrestha¹; Kenneth Kerpez²; Chan Soo Hwang²; Mehdi Mohseni²; John Cioffi²; Daniel M. Mittleman^1
1Brown University, United States; ²ASSIA, Inc., United States

We investigate the propagation of terahertz radiation on a complex multi-element metal wire waveguide ensheathed in a metal jacket. Mode mixing due to bends and nonuniformities along the waveguide axis result in a nearly random mode pattern at the output. This stochastic mixing is ideal for a vectored transmission, analogous to the multiple-input, multiple-output (MIMO) concept commonly used in wireless networking and could enable terabit-per-second data rates on the existing cables already in use by DSL systems.

15:00 Tu-PM1-4-4
PIN Photodiode Emitter For 32 GBd 16QAM Wireless Link At 300 GHz
Simon Nellen; Carlos Castro; Lars Liebermeister; Robert B. Kohlhaas; Robert Elschner; Colja Schubert; Martin Schell; Bjoern Globisch; Bjoern Globisch; Ronald Freund
Fraunhofer HHI, Germany

We demonstrate a wireless data link at 300 GHz employing a broadband PIN photodiode as the emitter. With a symbol rate of 32 GBd and QPSK modulation error-free transmission at a gross data rate of 64 Gbit/s is achieved. For 16QAM modulation, forward error correction enables a net data rate of 100 Gbit/s, which is among the highest values reported so far.

15:15 Tu-PM1-4-5
300 GHz Wireless Communication Systems Exploiting The Benefits Of Combining Photonic And Electronic Transceiver Components
Ingmar Kalfass¹; Iulia Dan¹; Pascal Szriftgiser²; Vinay-Kumar Chini³; Mohammed Zaknoune³; Guillaume Ducournau^3
1Institute of Robust Power Semiconductor Systems, Univ Stuttgart, Germany; ²PhLAM, France; ³IEMN CNRS/Université de Lille, France

The contribution presents a wireless data transmission experiment combining photonic and electronic technologies. The photonic transmitter is based on the use of uni-traveling-carrier (UTC) photodiodes. The electronic receiver is based on multi-functional monolithic integrated circuits realized in high electron mobility transistor (HEMT) technology for low-noise pre-amplification as well as integrated I/Q detection. The combination of both is interesting towards the achievement of larger distances and high data-rates for future THz links. In this paper we present an initial experiment where 80 Gbit/s were achieved, carried out in the context of a join French-German research initiative.

15:30 Tu-PM1-4-6
300 GHz-band 50 Gbit/s Dual Channel Link Using Industrial Silicon Photonics Technology
Cybelle Belem¹; Elsa Lacombe²; Vincent Gidel²; Cedric Durand²; Frederic Gianesello²; Daniel Gloria²; Cyril Luxey³; Guillaume Ducournau^1
1IEMN CNRS/Université de Lille, France; ²STMicroelectronics, France; ³Polytech'Lab, Univ Nice Sophia, France

We demonstrate the use of an industrial silicon photonics photodiode towards indoor THz links in the 300 GHz band. The devices are presented and two links are reported: the first one in a single channel operation QPSK-25 Gbit/s signaling and the second one using a dual channel configuration, 260 and 280 GHz, reaching 50 Gbit/s. In each case, the detection is done using a III-V GaAs Schottky-based sub-harmonic mixer.

15:45 Tu-PM1-4-7
Millimeter Wave Vacuum Electronic Amplifiers For High Data Rate Communication
PAN PAN; Zhangxiong Zi; Ji Chen; Shishuo Liu; Qingmei Xie; Ye Tang; Jun Cai; Jinjun Feng
Beijing Vacuum Electronics Research Institute, China

Traveling wave tubes, one kind of vacuum electronic amplifiers, have been widely used in radars and satellite communications. For its capability to provide high output power in millimeter wave regime, traveling wave tubes are an enabling technology for outdoor long-range high data rate communication. Traveling wave tubes operating at E-band, W-band and G-band are being developed and the experimental results of prototypes are presented.

14:00 - 16:00 Tu-PM1-5 Nano-quantum Devices 1

Chairperson: Room 101

14:00 Tu-PM1-5-1

Ultra-Small Mode Volume Three-Dimensional THz LC Metamaterial
Mathieu Jeannin¹; Djamal Gacemi¹; Angela Vasanelli¹; Lianhe Li²; Edmund Linfield²; Carlo Sirtori¹; Yanko Todorov^1
1Ecole Normale Supérieure, France; ²School of Electronics and Electrical Engineering, University of Leeds, United Kingdom

We present a novel architecture for THz metamaterials relying on three-dimensional meta-atoms embedding a semiconductor active region. The meta-atoms behave as inductor-capacitive (LC) resonators with nano-scale capacitive parts, and they have extremely sub-wavelength mode volume (10^-6λ_0) and footprint (10^-3λ_0^2). When the LC resonators are coupled to a two-dimensional electron gas confined inside the capacitive elements the ultra-strong light-matter coupling regime is achieved. We also discuss the potential of such structures for ultra-low dark current THz quantum well photodetectors.

14:30 Tu-PM1-5-2
High Performance Graphene Ballistic Rectifiers For THz Detection
Jiawei Zhang; Joseph Brownless; Aimin Song
University of Manchester, United Kingdom

Although graphene can operate in the ballistic transport regime at room temperature, there are very few devices harnessing this property. Here we present a novel device called the ballistic rectifier which circumvents the problem of opening a bandgap in graphene. Based on the device theory, we proposed four different asymmetric planar structures. All devices are working and showed responsivity higher than 1,000 V/W at room temperature, with noise-equivalent power as low as 4.16 pW/Hz^1/2. These properties make GBRs a suitable candidate for THz detections.

14:45 Tu-PM1-5-3
Ultrastrong Coupling Of Plasmonic Metamaterials And Photons In A Terahertz Photonic Crystal Cavity
Fanqi Meng; Mark D. Thomson; Bernhard Klug; Dovilė Čibiraitė; Qamar ul-Islam; Hartmut G. Roskos
J. W. Goethe-Uni Frankfurt, Germany

Here, we report a new type of strong light-matter interaction of metamaterial 'quasi-particles' with photons in a photonic crystal cavity in the terahertz frequency range. The measured Rabi splitting shows a square-root dependence on the density of metamaterial unit cells, even for unit cells from two spatially separated planar metamaterials, indicating nonlocal collective strong interactions. These findings are of interest for the investigation of fundamental strong-coupling phenomena, but also for applications such as ultra-low-threshold terahertz polariton lasing, voltage-controlled modulators and frequency filters, and ultra-sensitive chemical and biological sensing.

15:00 Tu-PM1-5-4
Towards Millimeter-Wave Based Quantum Networks
Hubert Stokowski¹; Marek Pechal¹; Emma Snively²; Kevin Multani¹; Paul Welander²; Jeremy Witmer¹; Emilio Nanni²; Amir Safavi-Naeini^1
1Stanford University, United States; ²SLAC National Accelerator Laboratory, United States

Realization of quantum networks composed of superconducting microwave circuits acting as qubits recently gained tremendous attention as an effective way of scaling quantum computers. Here we present the first experimental approach to fabricate mm-wave superconducting resonators that could be combined with transmon qubits and used in future ÃfÆ'Ã?â?TÃfâ? Ã¢â,¬â"¢ÃfÆ'ââ,¬Â¦Ãfâ?sÃ,½ÃfÆ'Ã?â?TÃf¢ââ?s¬Ã.¡ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,¼m-mm converters that distribute entanglement at a high rate in low-loss quantum networks. We propose a method that facilitates a long-range spread of quantum information via direct coupling of such a device into W-band (75-110 GHz) waveguide.

15:15 Tu-PM1-5-5
Sliver Nanowire Surface Plasmon Polaritons Enhancement In Terahertz Nanodevices
Shihab Al-Daffaie¹; Oktay Yilmazoglu¹; Matthias Wiecha²; Amin Soltani²; Franko Küppers¹; Thomas Kusserow¹; Hartmut Roskos^2
1Technische Universität Darmstadt, Germany; ²Goethe-Universität, Germany

New types of continuous-wave (CW) THz photomixers were fabricated using a silver nanowire (Ag-NW) as nanocontact on low-temperature-grown (LTG) and nitrogen-ion-implanted GaAs, respectively. The Ag-NW nanoelectrodes produced a large reduction of the device capacitance and a significant enhancement of the photocurrent as compared to conventional photomixers. The combination of very low capacitance and high photocurrent are shown reliable and efficient THz generation in the upper part of the broad spectral THz range. The main enhancement is shown from the wave patterns of surface plasmon polaritons (SPPs) on the Ag-NW which are measured using a scattering-type Scanning Near-field Optical Microscope (s-SNOM).

15:30 Tu-PM1-5-6
Nano-FTIR Spectroscopy Of Intersubband Polaritons In Single Nanoantenna
Oleg Mitrofanov¹; Chih-Feng Wang²; Terefe Habteyes²; Willie Luk³; John Klem³; Hou-Tong Chen⁴; Igal Brener^3
1UCL, United Kingdom; ²University of New Mexico, United States; ³CINT, Sandia NL, United States; ⁴CINT, Los Alamos National Lab, United States

We demonstrate observation of infrared (IR) intersubband (ISB) polaritons in an isolated subwavelength size nanoantenna using near-field Fourier-transform infrared (FTIR) spectroscopy of the evanescent fields on the nanoantenna surface. The near-field approach enables detection of the distinctive polariton splitting of the nanoantenna resonance in the amplitude and phase spectra, as well as mapping of the ISB polariton dispersion. The nano-FTIR spectroscopy approach opens doors for investigations of light-matter interaction in the single subwavelength nanoantenna regime.

15:45 Tu-PM1-5-7
Semiconductor Quantum Plasmonics
Angela Vasanelli¹; Simon Huppert²; Andrew Haky¹; Yanko Todorov¹; Carlo Sirtori^1
1Ecole Normale Supérieure, France; ²Sorbonne Université, France

We investigate the effect of quantum confinement on plasmons in highly doped semiconductor layers. The collective response of the electron gas is constructed from the basis of the confined electronic wavefunctions, accounting for dipole-dipole coupling and non-parabolicity. Our work shows how quantum engineering can be applied to semiconductor plasmonics.

14:00 - 16:00 Tu-PM1-6 Metamarials 2

Chairperson: Aydin Babakhani Room 151

14:00 Tu-PM1-6-1

Spectroscopic Evidence Of Bloch Surface Waves In The Mid Infrared
Michele Ortolani¹; Marialilia Pea²; Agostino Occhicone³; Valeria Giliberti⁴; Alberto Sinibaldi³; Francesco Mattioli²; Sara Cibella²; Raffaella Polito¹; Alessandro Nucara¹; Leonetta Baldassarre¹; Francesco Michelotti^3
1Sapienza University of Rome, Dipartimento di Fisica, Italy; ²Consiglio Nazionale delle Ricerche (CNR), Italy; ³Sapienza University of Rome, Dipartimento SBAI, Italy; ⁴Istituto Italiano di Tecnologia, Center for Life Nanoscience, Italy

Bloch Surface Waves (BSWs) are surface electromagnetic waves with very low intrinsic losses, existing in both in-plane and out-of plane polarizations, supported by a one-dimensional photonic crystal with an in-gap defect. We have developed thin film deposition technology on CaF2 prisms suitable for biosensing applications of BSWs in the mid-infrared. Here we report spectroscopic evidence of BSWs, in perfect agreement with theory, in the wavelength range from 4 to 6 micrometers. In summary, we envisage Surface Plasmon Polarioton-like biosensing applications, in which the mid-IR fingerprints of thin samples located at the interface are detected with high sensitivity by Bloch Surface Waves instead of SPPs.

14:30 Tu-PM1-6-2
High Q-factor Coupled Fabry-Perot Plasmonic Nanoresonator
Baptiste FIX¹; Julien Jaeck¹; Patrick Bouchon¹; Nathalie Bardou²; Sébastien Héron¹; Benjamin Vest¹; Haïdar Riad^1
1ONERA, France; ²C2N-CNRS, France

Fabry-Perot (FP) like resonances have been widely described in nanoantennas. In the case of combination of nanoantennas, it has been reported that each cavity behaves independently. Here, we evidence the interferences between two FP absorbing nanoantennas, which has a strong impact on the optical behavior. While the resonance wavelength is only slightly shifted, the level of absorption reaches nearly 100%. Moreover, the quality factor increases up to factor 7 and can be chosen by geometric design over a range from 11 to 75. We first demonstrate thanks to a simple analytical model that this coupling can be ascribed to a double FP cavity resonance, with the unique feature that each cavity is separately coupled to the outer medium. Based on this principle, we experimentally illustrate the existence of a high-Q factor resonance originating from the interference between two under-coupled ribbon-shaped nano Fabry-Perot.

14:45 Tu-PM1-6-3
Study Of Terahertz High Q-factor All-Dielectric Metamaterials
Xiaoyong He; Jun Peng
Mathematics & Science College, Shanghai Normal University, China

The propagation properties of Si based all-dielectric metamaterials (ADMs) structure have been investigated systematically in the THz regime. The results manifest that ADMs indicate sharp resonant curves with large Q-factors of more than 60, and figure of merit is about 20. Compared with that of metal metamaterials counterparts, the thickness of ADMs (in the range of tens of micrometers) is much larger to excite obvious resonant curves. With the help of a uniform graphene layer, the resonant curves can also be flexible modulated in a wide range, the amplitude modulation depth can reach about 40%. The results are very useful to design high Q-factor dielectric devices in the future, e.g. biosensors, modulators, and filter.

15:00 Tu-PM1-6-4
Modes And Pseudo-modes In TE Extraordinary THz Transmission
Suzanna Freer¹; Miguel Camacho²; Sergei A Kuznetsov³; Eve Shalom¹; Jack Gape¹; Rafael R Boix⁴; Miguel Beruete⁵; Miguel Navarro-Cia^1
1University of Birmingham, United Kingdom; ²University of Exeter, United Kingdom; ³Rzhanov Institute of Semiconductor Physics SB RAS Novosibirsk Branch TDIAM, Russian Federation; ⁴University of Seville, Spain; ⁵Universidad Pública de Navarra, Spain

Transverse electric (TE) transmission through dielectric-backed subwavelength slit arrays is inextricably linked to the grounded-dielectric slab TE1 mode, and thus, it depends highly on the electrical thickness of the substrate. We track the influence of the TE1 mode using both Terahertz time domain spectroscopy (TDS) measurements and the Method of Moments. For electrically thick dielectric samples, the TE1 mode is in propagation, and hence total transmission occurs (in excess of 0 dB, attributed to collimation), whereas in electrically thin samples, the TE1 mode is in cutoff. In this regime, the mode still contributes to transmission, and hence is referred to as a pseudo-mode.

15:15 Tu-PM1-6-5
Fano Resonance In Terahertz Superconducting Tl2Ba2CaCu2O8 Metamaterials
Jingbo Wu¹; Yun Guan¹; Jian Xing²; Lu Ji²; Caihong Zhang¹; Huabing Wang¹; Biaobing Jin¹; Jian Chen¹; Peiheng Wu^1
1Nanjing University, China; ²Nankai University, China

Tl2Ba2CaCu2O8 is layered cuprate superconductor with high anisotropy. Using Tl2Ba2CaCu2O8 film and asymmetric resonator structure, we designed and fabricated a kind of terahertz metamaterials. The tuning of the Fano-type resonance with the change of temperature is experimentally demonstrated.

15:30 Tu-PM1-6-6
Manipulation On Terahertz Slow Light In Symmetry Broken Meta-molecules
Zhenyu Zhao¹; Wei Peng²; Jianbing Zhang^2
1Shanghai Normal University, China; ²Chinese Academy of Sciences, China

We investigate slow light effect owing to the plasmon-induced transparency (PIT) via symmetric breaking in terahertz meta-molecules (MM). A broadband PIT window as well as a localized slow light effect is achieved via conductively coupled dimer and trimer MM.

15:45 Tu-PM1-6-7
Ultrastrong Coupling Experiments With Superradiant Meta-atoms
Moritz Wenclawiak; Benedikt Limbacher; Aaron M. Andrews; Gottfried Strasser; Karl Unterrainer; Juraj Darmo
TU Wien, Austria

In this contribution, we study the effects arising when using a metamaterial surface featuring a dense array of superradiant emitters as cavities for experiments in the ultrastrong coupling regime. We show that an increasing cavity loss does not always lead to the expected transition to the weakly coupled Purcell regime but more that it is still possible to observe polaritons as a feature of the strong coupling between the meta-atoms and the intersubband transition.

15:45-16:15 - Coffee Break

16:30-18:15 Parallel sessions Tu-PM2

16:30 - 18:15 Tu-PM2-1 Films and Coatings

Chairperson: Michael Johnston Amphi Lavoisier

16:30 Tu-PM2-1-1
Investigation Of Multilayered 20th Century Painting By THz Imaging
Kaori Fukunaga¹; Yoshimi Ueno²; Yasunobu Ito^3
1National Institute of Information and Communications Technology, Japan; ²CRS Corporation, Japan; ³Ikea Museum of 20th Century Art, Japan

A masterpiece of Salvador Dali was investigated by using Terahertz time-domain imaging. The experimental results confirmed its multilayered structure and suggested that Dali did not cover the entire canvas because the number of painted layers depends on the area. The painting was supported with a lining layer and a metal plate added in previous intervention, and its structure was compared with that of another 20th century masterpiece painted by Pablo Picasso.

17:00 Tu-PM2-1-2
Mobile Handheld FMCW Terahertz Multilayer Thickness Inspection
Nina Schreiner; Stefan Weber; Andreas Keil; Fabian Friederich
Fraunhofer ITWM, Germany

We present an all-electronic handheld system for the thickness determination of dielectric multilayer structures with submillimeter to several centiÃ,¬meter layer thicknesses, using a frequency-modulated continuous-wave terahertz transceivers. Besides A-scans, an integrated linear position encoder allows to obtain B-scan images. In order to resolve layers below the inherent resolution limit given by the frequency modulation bandwidth, we take advantage of model-based signal processing techniques.

17:15 Tu-PM2-1-3
Ancient Painting On Copper Substrate Inspected By Terahertz Spectroscopy-imaging
Quentin Cassar¹; Corinna Koch-Dandolo²; Jean-Paul Guillet¹; Marie Roux³; Frédéric Fauquet¹; Patrick Mounaix^1
1Laboratoire IMS / Université de Bordeaux / CNRS UMR 5218, France; ²C2MRF / Palais du Louvre, France; ³L'Atelier des Renaissances, France

We used a combination of numerical simulation to find parameters that best describe reflections from a given multi-layered paint sample. The reflected terahertz time domain waveform is simulated where each paint layer is represented by a set of numerical parameters that describe both the thickness and the optical response. We detected numerous sketches under the painting layers.

17:30 Tu-PM2-1-4
Operational Readiness Levels For Terahertz Automotive Paint Inspection
Robert May; Ian Gregory; Daniel Farrell
TeraView Ltd., United Kingdom

The demanding requirements placed on industrial test equipment means that for terahertz sensing to be adopted in quality control sectors, the technology must not only be capable of providing the qualitative and/or quantitative information of interest, but to do so in a robust and reliable manner. Here, we report on some of the developments implemented to bridge this gap for terahertz sensing to be deployed into one such industrial production setting: coating thickness inspection in the automotive paint shop. This has allowed terahertz to provide feedback on paint film thicknesses, and thereby allow for greater control of the paint process. Application Readiness, as defined by key manufacturers, their distributors and integrators, has been achieved.

17:45 Tu-PM2-1-5

Terahertz Non-Destructive Thickness Characterization Of Optically Thin Wu?stite Layers On Steel
David Citrin¹; Alexandre Locquet¹; Roquelet Cyrielle²; Min Zhai^1
1Georgia tech Lorraine, France; ²ArcelorMittal Maizières Research, France

Terahertz (THz) imaging is a relatively new technique for nondestructive evaluation. Compared with the destructive micro-cut technique that provides information along the line of cut only, THz imaging nondestructively provides a global mapping of a sample. Hence, this technique has been applied to characterize coated materials and composite laminates. In this work, we characterize optically thin wüstite layers on steel leveraging signal-processing techniques.

18:00 Tu-PM2-1-6

Learning-Based Shadow Mitigation For Terahertz Multi-Layer Imaging
Pu (Perry) Wang¹; Toshiaki Koike-Akino¹; Arindam Bose²; Rui Ma¹; Phillip Orlik¹; Wataru Tsujita³; Kota Sadamoto³; Hiroyuki Tsutada^3
1Mitsubishi Electric Research Laboratories, United States; ²University of Illinois at Chicago, United States; ³Mitsubishi Electric Corporation Advanced Technology R&D Center, Japan

This paper proposes a learning-based approach to mitigate the shadow effect in the pixel domain for Terahertz Time-Domain Spectroscopy (THz-TDS) multi-layer imaging. Compared with model-based approaches, this learning-based approach requires no prior knowledge of material properties of the sample. Preliminary simulations confirm the effectiveness of the proposed method.

16:30 - 18:30 Tu-PM2-2 Applications 1

Chairperson: René Beigang Petit Amphi

16:30 Tuo-PM2-2-1
Remote Liquid Inspection With Carbon Nanotube Terahertz Detectors
Meiling Sun; Kou Li; Yu Tokumoto; Ryogo Utaki; Yukio Kawano
Tokyo Institute of Technology, Japan

High installation cost, low temperature operation and strict measuring condition have been technical difficulties on terahertz (THz) wave inspections, which severely pulled back the development of THz wave application in real life. Here, to realize much quicker and lower-cost quality inspection in terahertz region, we developed a novel type of compact remote quality inspection system without conventional bulky THz time-domain spectroscopy (THz-TDS) system by utilizing a thermoelectric THz imager based on carbon nanotube (CNT) films. The present scheme enabled us to realize well applicable THz wave inspections.

17:00 Tu-PM2-2-1
Terahertz Diagnostics At Accelerators Using Radio Frequency-driven Frequency Combs Based On Telecommunication Technology
Erik Bruendermann¹; Johannes Leonhard Steinmann¹; Isao Morohashi²; Shinya Nakajima²; Shingo Saito²; Norihiko Sekine²; Anke-Susanne Mueller¹; Iwao Hosako^2
1Karlsruhe Institute of Technology / IBPT, Institute for Beam Physics and Technology, Germany; ²National Institute of Information and Communications Technology, Japan

We report on exploiting information and communications technologies to build reliable and durable terahertz diagnostics for electron accelerator-based light and laser sources. Terahertz and electro-optical diagnostics is an ideal tool to investigate short-bunch electron beams and their emitted photons with the potential to devise methods for controlled and tailored radiation emission. We investigate electro-optical modulators to evaluate their potential for laser-based diagnostics at accelerators, which can serve as building blocks in frequency combs, terahertz generation and detection systems. We built a frequency comb spanning at least 250 GHz with a pulse length of less than 3.7 ps.

17:15 Tu-PM2-2-3
Spoilage Of Salmon Fillets As Observed By THz Waves
Francis Hindle¹; Lotta Kuuliala²; Meriem Mouelhi¹; Arnaud Cuisset³; Mathias Vanwolleghem⁴; Frank Devlieghere⁵; Gael Mouret³; Robin Boquet^3
1Laboratoire de Physico-Chimie de l'Atmosphère, Université du Littoral Côte d'Opale, France; ²Research Unit Food Microbiology and Food Preservation, Department of Food Technology, Ghent University, Belgium; ³Laboratoire de Physico-Chimie de l'Atmosphère, France; ⁴Institute of Electronics, Microelectronics and Nanotechnology, University of Lille, France; ⁵Research Unit Food Microbiology and Food Preservation, Ghent University, France

The minimization of food wastage is an important challenge for today's society. Microbial activity during the storage of foodstuffs packed under a protective atmosphere, will lead to the generation of a complex mixture of trace gases that may be used as food spoilage indicators. THz waves have been used to monitor the generation of hydrogen sulfide in the headspace of a sealed plastic tray containing a salmon fillet portion.

17:30 Tu-PM2-2-4
Towards Detection Of Helical Orientated Cellulose Structures In Wood Using THz Time-Domain Spectroscopy
Jingming Cao¹; Markus Rüggeberg²; Peter Zolliker^3
1Laboratory for Transport at Nanoscale Interfaces/ Empa-Swiss Federal Laboratories for Materials Sci, Switzerland; ²Institute for Building Materials/ETH Zürich-Swiss Federal Institute of Technology, Switzerland; ³Laboratory for Transport at Nanoscale Interfaces/Empa - Swiss Federal Laboratories for Materials Sci, Switzerland

Wood is a fiber-reinforced, orthotropic composite material, which shows complex anisotropic optical characteristics induced by the preferential orientation of the cellulose microfibrils in the THz domain. We hypothesize that in addition to their birefringent properties the helical arrangement of microfibrils could also exhibit optical activity. This would allow determining microfibril angles in wood, a key feature for its mechanical properties. We propose to detect optical activity and birefringence independently using THz time-domain spectroscopy (THz-TDS) despite interference with annual ring structure. Our procedure is based on the Jones calculus formalism. In this report, we demonstrate the ability to detect left- and right-handed chirality of prototype helical structures made of copper wires and birefringence of spruce wood.

17:45 Tu-PM2-2-5
Industrial Applications With Semiconductor-Based CW Terahertz System
Eui Su Lee; Mugeon Kim; Dong Woo Park; Kiwon Moon; Il-Min Lee; Hyun-Soo Kim; Dong Hun Lee; Kyung Hyun Park
ETRI, Republic of Korea

In developing terahertz (THz) technologies that are more suitable for industrial applications, we have focused on research on continuous-wave (CW) THz technologies to develop small, low-cost, and multifunctional THz devices and systems. In this study, we present an example of a practical industrial application of our CW THz system, a nondestructive evaluation (NDE) system: cost-effective high-speed 1-D/2-D reflective imaging system and real-time thickness monitoring system of slurry film. Although further improvements to photonics-based THz technologies are necessary, we believe that efforts in this field will begin an era of THz technologies as a widely-used industrial technique.

18:00 Tu-PM2-2-6
Inspection Of Oils, Caffeine Containing Foods And Consumable Plant Leaves By Time-domain THz Spectroscopy
Mindaugas Karaliūnas¹; Ignas Dapsys²; Andrzej Urbanowicz¹; Gytis Vektaris³; Ausra Vektarienė³; Dalia Brazinskienė¹; Svajus Asadauskas¹; Irmantas Kasalynas¹; Gintaras Valusis^1
1Center for Physical Sciences and Technology, Lithuania; ²Department of Mathematical Modeling, Vilnius Gediminas Technical University, Department of Mathematical Modeling, Lithuania; ³Institute of Theoretical Physics and Astronomy, Vilnius University, Lithuania

Terahertz (THz) spectroscopy is a very promising and practical method for rapid and reliable food quality inspection. However, the issues related to water absorption, scattering of the medium and unambiguous detection of extremely small concentration of contaminants need to be overcome. This work show the capabilities of THz time domain spectroscopy to identify the contaminated and adulterated foods. The performance of this technique is studied on edible oils, caffeine containing foods and consumable plant leaves.

16:30 - 18:15 Tu-PM2-3 THz Devices 2

Chairperson: Iwao Hosako Room 162

16:30 Tu-PM2-3-1

Terahertz Beam Steering Based On Luneburg Lens
Kazuto Sato; Yasuaki Monnai
Keio University, Japan

A novel method of terahertz beam steering using a Luneburg lens is proposed. Based on the nature of the transverse electric wave propagation between parallel plates, we design a Luneburg lens operating around 300 GHz. We experimentally demonstrate the generation of a directional beam from the lens into free-space. We also show that the beam deflection can be changed by tilting the lower plate of the parallel plates.

17:00 Tu-PM2-3-2
Dielectric-Grating In-Lens Polarizer For Beyond 5G Communications
Marta Arias Campo¹; Giorgio Carluccio²; Darwin Blanco³; Simona Bruni⁴; Oliver Litschke⁴; Nuria Llombart^1
1Delft University of Technology, Netherlands; ²NXP Semiconductors, Netherlands; ³Ericsson AB, Sweden; ⁴IMST GmbH, Germany

A high-gain broadband leaky-wave fed lens antenna with an integrated dielectric gratings polarizer covering the whole G-band (140-220GHz) is presented. This work focuses on the polarizer gratings manufacturing and in particular on the selection of plastic materials and the fabrication process refinement. The polarizer geometry has been designed and optimized to be compatible with standard milling techniques. A quasi-analytical method based on an analysis of the lens antenna in reception is used to validate the in-lens polarizer performance. Several prototypes have been fabricated, finally obtaining an excellent match between measurements and quasi-analytical results.

17:15 Tu-PM2-3-3
Low-loss Planar Porous Components For Terahertz Beamforming
Hichem Guerboukha¹; Kathirvel Nallappan¹; Yang Cao¹; Mohamed Seghilani²; Jose Azana²; Maksim Skorobogatiy^1
1Polytechnique Montreal, Canada; ²INRS-EMT, Canada

We develop planar porous components to solve the loss problem of conventional convex optics. We show that by introducing deeply subwavelength pores in a dielectric substrate, we can fabricate a porous lens and an OAM phase plate with lower loss than their all-solid counterparts.

17:30 Tu-PM2-3-4
Characterization Of A Terahertz Isolator Using A 1.5 Port Vector Spectrometer
Fahd Rushd Faridi; Sascha Preu
Technische Universität Darmstadt, Germany

The 1.5 port vector spectrometer combines both transmission and reflection geometry of terahertz time domain spectroscopy (THz TDS) in a single setup. Here we demonstrate its capability for characterizing a non-time invariant device - a terahertz isolator, in terms of isolation level and insertion loss.

17:45 Tu-PM2-3-5
Quasi-Analytical Description Of A Double Slit Planar Dielectric Waveguide As Broadband Dispersion Compensating Element
Mario Méndez Aller; Sascha Preu
Technische Universität Darmstadt, Germany

We demonstrate dispersion compensation of dielectric waveguides by a double slit dielectric structure by a quasi-analytical solution. The concept is then confirmed with a full-wave numerical simulation of realistic rectangular waveguides.

18:00 Tu-PM2-3-6
Device For Broadband THz Spectroscopy Of 1-nL-volume Samples
Sergey Mitryukovskiy; Mélanie Lavancier; Flavie Braud; Théo Hannotte; Emmanuel Dubois; Jean-François Lampin; Romain Peretti
IEMN CNRS/Université de Lille, France

We report on our recent progress in the development of a device for light-matter interaction enhancement in the full terahertz range for precise spectroscopy of minor-volume samples. The efficient confinement of a broadband terahertz pulse to a few-nL-volume was achieved, opening new perspectives for chemical and biological applications. We discuss modifications in the fabrication process leading to the improvement of our technique, following the detailed characterization of the device performances.

16:30 - 18:15 Tu-PM2-4 Biology / Medicine 1

Chairperson: Emma MacPherson Room 269

16:30 Tu-PM2-4-1
Genomic Mechanisms Of THz-Induced Cancer Dysregulation In Human Skin
Cameron Hough¹; David Purschke¹; Chenxi Huang¹; Lyubov Titova²; Olga Kovalchuk³; Brad Warkentin¹; Frank Hegmann^1
1University of Alberta, Canada; ²Worcester Polytechnic Institute, United States; ³University of Lethbridge, Canada

Intense pulses of THz radiation significantly alter gene expression and dysregulate phenotypic endpoints of cancer-related signaling pathways, including activation of an inflammatory response and suppression of pro-mitotic signaling in human skin. Of 1681 potential candidates, the predicted cancer-related dysregulation is nearly entirely localized to a subset of only 42 key driver genes belonging to 7 gene families/superfamilies. The individual and concerted regulatory roles of these genes within the relevant cancer-related pathways are elucidated and discussed in the context of gene-specific response to THz exposure and potential for clinical application.

17:00 Tu-PM2-4-2
Do Humans "shine" In The Sub THz?
Yuri Feldman¹; Ksenia Baksheeva²; Roman Ozhegov²; Gregory Goltsman²; Nikolay Kinev³; Valery Koshelets³; Anna Kochnev¹; Noa Betzalel¹; Alexander Puzenko¹; Paul Ben Ishai^4
1The Hebrew University of Jerusalem, Israel; ²Moscow State University of Education, Russian Federation; ³Kotel'nikov Institute of Radio Engineering and Electronics of RAS, Russian Federation; ⁴Ariel University, Department of Physics, Israel

Radiometry experiments, performed on human subjects, show that in the vicinity of a central frequency 507 GHz the emission of the human skin is substantially non-equilibrium in its nature. The intensity of the radiation registered using a superconducting integrated receiver (SIR) [1], was correlated with the level of the physical and mental stress of subject under examination. This result suggests that human skin may generate sub-THz waves.

17:15 Tu-PM2-4-3
The Study Of The Optical Properties Of Serous And Mucous Tissues Of The Human Stomach
Roman Grigorev¹; Anna Kuzikova¹; Anna Kurasova¹; Petr Demchenko¹; Artyom Senyuk²; Abdo Khamid²; Mikhail Khodzitsky^1
1ITMO University, Russian Federation; ²Pavlova First St. Petersburg State Medical University, Russian Federation

The optical properties of mucous and serous fresh tissues of stomach were obtained using the method THz time-domain spectroscopy in the reflection mode. The difference in the optical properties of the two types of stomach tissue can be explained by their different morphology. The data may be used for intraoperative and endoscopic diagnostics of cancer.

17:30 Tu-PM2-4-4
Measurements Of Effective Porosity Of Pharmaceutical Tablets Using THz TDS
Iliya Tikhomirov¹; Daniel Markl²; Mira Naftaly^1
1National Physical Laboratory, United Kingdom; ²Strathclyde University, United Kingdom

The pharmaceutical industry requires a rapid nondestructive technique for monitoring porosity of tablets. Here porosity of compressed lactose pellets was investigated using THz time-domain spectroscopy (THz TDS) with the aid of index-matching medium.

17:45 Tu-PM2-4-5
Quasi-one-dimensional Terahertz Phononic Band Gap In Phospholipid Tails
Kaicheng Wang¹; Jingchao Tang¹; Jialu Ma¹; Lianghao Guo¹; Yang Yang¹; Wenfei Bo¹; Zhe Wu¹; Zhao Wang¹; Haibo Jiang²; Baoqing Zeng¹; Yubin Gong^1
1University of Electronic Science and Technology of China, China; ²Chengdu Institute of Biology, Chinese Academy of Sciences, China

Terahertz vibrational modes and quasi-one-dimensional terahertz phononic band gap in hydrocarbon tails of phospholipids are revealed through vibration calculation based on the ab initio density functional theory (DFT). We get the correlation between vibrational modes and frequencies. The phononic band gap in linear hydrocarbon chains provides a perspective in the interpretation of biochemical phenomena related to biological membranes, such as the photosynthetic energy transfer pathway and the electron transport chain in the inner mitochondrial membrane.

18:00 Tu-PM2-4-6
Non-Destructive Characterization Of Pharmaceutical Tablets Using Terahertz Frequency Domain Spectroscopy
Anis MoradiKouchi¹; Marin Lindsjö²; Jan Stake¹; Staffan Folestad²; Helena Rodilla^1
1Chalmers University of Technology, Sweden; ²AstraZeneca, Sweden

In this paper, terahertz frequency domain spectroscopy (THz-FDS) technique has been employed to study the impact of porosity in tablets on their optical constants, such as the effective permittivity. Four sets of training tablets with different percentage of active ingredient and compaction force were generated with microcrystalline cellulose (MCC) as the excipient and indomethacin as the active pharmaceutical ingredient. The results show that the extracted effective permittivity is sensitive to the change of porosity in tablets and it is unique for different concentration of indomethacin. Therefore, THz-FDS technique has been revealed to be a promising tool in the quality inspection of pharmaceutical tablets.

16:30 - 18:15 Tu-PM2-5 Materials 2

Chairperson: Patrick Mounaix Room 101

16:30 Tu-PM2-5-1
Can We Observe Vibrational Confinement In Lyophilised Proteins Using Terahertz Spectroscopy?
Talia Shmool; J. Axel Zeitler; Markus Leutzsch; Michael D. Mantle
Department of Chemical Engineering and Biotechnology, University of Cambridge, United Kingdom

Abstract-The purpose of this work was to use terahertz time-domain spectroscopy (THz-TDS) to investigate the vibrational dynamics of freeze-dried protein formulations and the behaviour of these materials below and above the glass transition temperature. In contrast to small organic molecules and polymers which exhibit continuously increasing absorption with temperature, a number of lyophilised formulations examined in this work show a plateau of absorption above 300 K. This plateau suggests that at high temperatures the protein molecules are confined in the surrounding excipient matrix. This vibrational confinement in the solid-state is uniquely observed using THz-TDS, and this work could provide insight into predicting formulation stability.

16:45 Tu-PM2-5-2
Broadband Spectroscopy Of Materials With An Integrated Comb-Based Millimeter-Wave Detector
Babak Jamali; Jiashu Zhou; Aydin Babakhani
University of California, Los Angeles, United States

A miniaturized broadband spectroscopic sensor using a fully integrated millimeter-wave detector is presented. The detector chip generates a frequency comb with a tunable spacing as a reference to downconvert received signals. By tuning the comb spacing, the detector can detect frequency tones from 50 GHz to 155 GHz with a resolution only limited to the line width. A spectroscopy setup including the detector and four sheets made of different materials is implemented to characterize the frequency response of materials in this frequency range.

17:00 Tu-PM2-5-3
THz Absorption And Refraction Of KTA Crystal At Low Temperatures
Zhiming Huang¹; Jingguo Huang¹; Yanqing Gao¹; Gaofang Li¹; Yury Andreev²; Grigory Lanskii²; Valery Losev^3
1Shanghai Institute of Technical Physycs, China; ²Institute of Monitoring of Climatic and Ecological Systems SB RAS, Russian Federation; ³Institute of High Current Electronics SB RAS, Russian Federation

There is a significant interest to determine potential of widely used UV - near IR nonlinear crystals for frequency conversion into the THz range. Potassium titanyl arsenate KTiOAsO4 (KTA) is one of them. Main its advantage in comparison with the other oxide nonlinear crystals such as LBO, BBO or KTP, is significantly higher second-order (d33=16.2 pm/V at 1.064 micronmeter in the mid-IR) nonlinear susceptibility and long (5.3 micronmeter at zero transmittance level) mid-IR cutoff wavelength. As for comparison with semiconductor nonlinear crystals, KTA crystal possesses muchhigher damage threshold. Refractive indices of KTA crystal at THz region were measured before only at room temperature. Here cryogenic THz spectrometer is designed with precision temperature control. Optical properties of KTA crystal (absorption coefficients and refractive indices) are investigated in detail with THz-TDS in the temperature range 5-300 K. Refractive indices can be approximated in the form of dispersion equations for different

17:15 Tu-PM2-5-4
Mechanism Between Material Microstructures And Terahertz Dielectric Properties
Bin Yang
University of Chester, United Kingdom

Significant progress has been made in developing reliable Terahertz (THz) measurement spectroscopy to extract materials' dielectric properties, however, systematic research on exploring intrinsic mechanism between microstructure of ceramics and THz dielectric properties such as loss, permittivity and dispersive characters has barely started. The paper focuses on one dielectric ceramic system (TiO2), its addition with Zn2SiO4 dielectrics and one hexa-ferromagnetic system to expatiate the association.

17:30 Tu-PM2-5-5
Time-resolved THz Spectroscopy Of Conducting Polymers
Jérôme Degert; Frédéric Dutin; Marc Tondusson; Eric Freysz
Université de Bordeaux - LOMA, France

We study, by terahertz time-domain and optical pump-THz probe spectroscopies, the optical and electrical properties of the PEDOT/PSTFSIK polymer. The latter is designed to get reed of some drawbacks of the well-known and widely used conducting polymer: the PEDOT/PSS. The optoelectronic properties in the THz range of both compounds are compared, as well as the relaxation mechanisms taking place after their photoexcitation by ultrashort optical pulses.

17:45 Tu-PM2-5-6
Dynamics Of Hydrogen Bonds And Cross-linked Structures In Polyurethane film Observed By Terahertz Spectroscopy
Hiromichi Hoshina¹; Yuichi Saito²; Takumi Furuhashi³; Tomomi Shimazaki³; Manabu Sawada³; Yasunori Hioki³; Chiko Otani^1
1RIKEN Center for Advanced Photonics, Japan; ²RIKEN, Japan; ³Murata Manufacturing Co., Ltd., Japan

Terahertz (THz) absorption spectra of the cross-linked polyurethane films are observed at the temperature between 30-180 °C. The obtained spectra show characteristic absorption band at 3 THz assigned as hydrogen bonded urethane group. Another band at 7 THz was assigned as intermolecular vibration of cross-linked structures between polymer chains. The temperature dependent spectra were analyzed by the perturbation correlation moving window two-dimensional spectroscopy (PCMW2D) to clarify the slight spectral change. The thermal behavior of the absorption intensities shows the dynamics of hydrogen bonds and cross-linked structures in the polyurethane films.

18:00 Tu-PM2-5-7
Temperature Dependent Giant Birefringence And Dichroism Of A BiFeO3 Single Crystal In The Terahertz Frequency
Zuanming Jin¹; Yuqing Fang¹; Xiumei Liu²; Jiajia Guo²; Yan Peng¹; Yiming Zhu¹; Zhenxiang Cheng³; Guohong Ma^2
1Shanghai Key Lab of Modern Optical System, and Engineering Research Center of Optical Instrument and, China; ²Shanghai University, China; ³University of Wollongong, Australia

THz time-domain spectroscopy (THz-TDS) is used to study the THz-optical properties of a single crystal bismuth ferrite (BiFeO3). The anisotropy of BiFeO3 is strongly dependent on the temperature. A giant birefringence is observed up to around 3.6.

18:30 Tu-PM2-5-8
Competing Interplay Of Photo-thermal And Photo-doping Effect During Light-induced Ultrafast Insulator-to-Metal Transition In VO2 Nanofilms At Terahertz Frequency
Zhaohui Zhai¹; Liang-Hui Du¹; Si-Chao Chen²; Li-Guo Zhu^1
1Institute of Fluid Physics, China Academy of Engineering Physics, China; ²Department of Optics and Optical Engineering, University of Science and Technology of China, China

The competing interplay of photo-thermal and photo-doping effect of VO2 nanofilm under fs laser excitation was studied at terahertz frequency. We find that with photo-thermal effect generated by fs laser pulses, both the character time constant of insulator-to-metal phase transition and the pump fluence threshold of transition were decreased, while the amplitudes of the two photo-response are competing.

16:30 - 18:15 Tu-PM2-6 Metamarials 3

Chairperson: Yiming Zhu Room 151

16:30 Tu-PM2-6-1
THz Resonances With Infinite Lifetime In Array Of Gold Resonators
Niels van Hoof¹; Stan ter Huurne¹; Diego Abujetas²; José Sanchez-gil²; Jaime Gómez Rivas^1
1Eindhoven University of Technology, Netherlands; ²Instituto de Estructura de la Materia Consejo Superior de Investigaciones Científicas, Spain

Metasurfaces consisting of two resonators per unitcell can support resonances with infinitely long lifetime known as bound states in the continuum. We investigate theoretically and experimentally the conditions leading to the formation of these resonances in gold particle arrays.

17:00 Tu-PM2-6-2
Broadband Terahertz Quarter-Wave Plate Design
Xiaolong You; Christophe Fumeaux; Withawat Withayachumnankul
The University of Adelaide, Australia

A broadband terahertz quarter-wave plate design based on an extended analytical approach has been presented and numerically demonstrated. The simulations reveal that this quarter-wave plate enables a linear-to-circular polarization conversion with a 3-dB axial ratio of 53.3%, ranging from 205 to 354 GHz. It is worth of noting that this presented approach has a potential to realize broadband transmissive metasurfaces for other wavefront and phase control functionalities, such as beam focusing, beam deflection, and polarization rotation.

17:15 Tu-PM2-6-3
Broadband And Wide—Angle Terahertz Reflective Half—Wave Mirror
Rajour Tanyi Ako¹; Wendy S. L. Lee²; Madhu Bhaskaran³; Sharath Sriram³; Withawat Withayachumnankul^2
1Functional Materials and Microsystems Research Group and the Micro Nano Research Facility, RMIT Univ, Australia; ²Terahertz Engineering Laboratory, School of Electrical and Electronic Engineering, The University of Adelaide, Australia; ³Functional Materials and Microsystems Research Group and the Micro Nano Research Facility, RMIT University, Australia

Linear—to—linear polarization conversion of electromagnetic wave has application in various fields including communications, imaging, and sensing. Available polarization-control devices enabled by metasurfaces are limited in bandwidth, efficiency and acceptance angle. Herein, a reflective half—wave mirror composed of T—shaped resonators is proposed and experimentally evaluated. Measured results show a bandwidth of 95% and 100% around a center frequency of 0.7 THz for the normal and 45° angle of incidence. The measured results agree well with the simulation. An average polarization conversion ratio (PCR) greater than 80% is observed across 0° to 45° incidence angles.

17:30 Tu-PM2-6-4
Femtosecond Laser Processing And Evaluation Of Broadband THz Anti-Reflection Structures
Haruyuki Sakurai; Natsuki Nemoto; Kuniaki Konishi; Ryota Takaku; Yuki Sakurai; Nobuhiko Katayama; Tomotake Matsumura; Junji Yumoto; Makoto Kuwata-Gonokami
The University of Tokyo, Japan

We fabricate terahertz anti-reflection structures on the surface of high-resistivity silicon via femtosecond laser processing, demonstrating broadband increase in transmissivity over 0.3 - 2.5 THz, and investigate the spectral characteristics by using numerical simulation. We successfully reproduce the observed result, and attribute transmittance drop-off in the higher frequency region to increasing material loss, not structural effects, induced by the laser-ablation fabrication process.

17:45 Tu-PM2-6-5
Free-standing Meta-surface On Ultrathin Si Substrate For High-transmission Phase Shifts In The 3.0-THz Band
Shohei Hayashi¹; Takehito Suzuki²; Kazunori Tanaka¹; Kazuki Horita¹; Hiroyasu Fujiwara¹; Kazuue Fujita^1
1Hamamatsu Photonics K.K., Japan; ²Tokyo University of Agriculture and Technology, Japan

We present a free-standing meta-surface for a high-transmission phase shift in the 3.0-THz band. The structure consists of subwavelength Au patterns with 278,273 units of meta-atoms on both the front and back of an ultrathin (4 µm thick) silicon substrate. The meta-surface for the low terahertz range has been fabricated by etching on a flexible polymer substrate with metal layers. High-precision fabrication of the meta-surface on a silicon substrate by semiconductor processing techniques is powerful and essential for the integration with terahertz semiconductor sources. Measurements by terahertz time-domain spectroscopy (THz-TDS) demonstrate a high transmission of 0.91 and a phase modulation of -0.86π at 2.8 THz agreeing well with simulations. The meta-surface in the high terahertz range can be applied in an ultrathin meta-lens for terahertz quantum cascade laser sources.

18:00 Tu-PM2-6-6
Broadband Terahertz Quarter-wave Plates Via Multipolar-interference-assisted All-dielectric Metamaterials
Da-Cheng Wang; Song Sun; Zheng Feng; Wei Tan
Microsystem and Terahertz Research Center, China

All-dielectric metamaterials with multipolar Mie resonances are proposed and experimentally realized, which operate as a broadband terahertz quarter-wave plate. Composed of elliptically-shaped silicon pillar arrays, the proposed metamaterials support dipole and quadrupole resonance modes. The constructive and destructive interferences among these modes could minimize reflection and maximize transmission. Both numerical and experimental results of the meta-device reveal close to unity transmission and 270 degrees phase delay between two orthogonal directions in a broadband, making the meta-device operate as a terahertz quarter-wave plate. Such multipolar-interference-assisted all-dielectric metamaterials promise a new paradigm for broadband low-loss terahertz devices.

18:15-19:30 - Poster session - Tu-Po 2 - Room 8

Tu-Po2-1
Enhanced Terahertz Emission Bandwidth From Photo-conductive Antenna With Embedded Plasmonic Nano-pillar Array
Arkabrata Bhattacharya; Dipa Ghindani; S. S. Prabhu
Tata Institute of Fundamental Research, India

In this work, we demonstrate a novel photo-conductive antenna (PCA) design, capable of emitting Terahertz radiation with enhanced bandwidth. This device consists of Au electrodes on semi-insulating GaAs substrate. A plasmonic nano-structure array is embedded in the substrate between the two electrodes. The role of this array is two-fold. The plasmonic enhancement of the 800 nm IR light near the nano-structures serves as a rich source of photo-generated charge carriers which are accelerated to generate the THz radiation. Secondly, the nano-structures acts as defect sites which enables fast carrier relaxations, hence, effectively enhancing THz bandwidths. At the same time the terminal currents are highly reduced implying robustness of the device to high applied bias voltages.

Tu-Po2-2
0.4 MW Terahertz Power Generation Through Bias-Free, Telecommunication-Compatible, Photoconductive Nano-Antennas
Deniz Turan; Nezih Tolga Yardimci; Mona Jarrahi
University of California, Los Angeles, United States

We present a bias-free, telecommunication-compatible, photoconductive terahertz source that generates terahertz powers as high as 0.4 mW, enabling time domain terahertz spectroscopy with up to 90 dB dynamic range over a 3.5 THz bandwidth.

Tu-Po2-3
Towards Bandwidth-enhanced GaN-based Terahertz Photoconductive Antennas
Dipa Ghindani¹; Arkabrata Bhattacharya²; Sumayya Samad³; Amit Shah⁴; Arnab Bhattacharya⁴; Shriganesh Prabhu^5
1Tata Institute of Fundamental Research, India; ²Tata Institute of Fundamental Research, Foton Lab, India; ³International School of Photonics, Cochin University of Science and Technology, CUSAT, India; ⁴Tata Institute of Fundamental Research, India; ⁵Tata Institute of Fundamental Research, Foton Lab, India

In this work, we explore a photoconductive antenna for the emission of Terahertz radiation based on Gallium Nitride (GaN) epilayers. Typically, GaN has faster carrier relaxation times as compared to SI-GaAs, which is conventionally used as substrate for conventional photoconductive antennas. Faster carrier lifetime is expected to result into enhanced bandwidth of the emitted THz radiation.

Tu-Po2-4
THz TDS System Driven By A Commercially Available Laser Diode
Jan Balzer¹; Sebastian Tonder¹; Jannik Lehr²; Martin Koch^2
1University Duisburg-Essen, Germany; ²Philipps University Marburg, Germany

We use a commercially available laser diode to drive a standard THz TDS system. The dispersion of the laser diode is compensated by a standard single mode fiber which leads to a pulse duration below 800 fs. The measured THz traces show frequency components up to 1 THz.

Tu-Po2-5
Effect Of Femtosecond Laser Polarization On Terahertz Emission From Cluster Nanoplasma
Nikolay Kuzechkin¹; Alexei Balakin¹; Murat Dzhidzhoev¹; Vyacheslav Gordienko¹; Igor Ivanov¹; Timur Semenov²; Alexander Shkurinov^1
1Lomonosov Moscow State University, Russian Federation; ²FSRC "Crystallography and Photonics" RAS, Russian Federation

We present the results of experimental studies of THz emission from argon cluster nanoplasma switched by the intense femtosecond laser pulses. We have performed measurements of the angular distribution of the THz radiation emitted from the clustered nanoplasma with two polarization states of the linearly polarized laser beam. We have found that polarization state of the laser radiation may influence on the efficiency of THz generation in cluster beam.

Tu-Po2-6
Direct Comparison Of PIN And UTC Photodiodes For Continuous-Wave Terahertz Emission
Simon Nellen¹; Tadao Ishibashi²; Lauri Maximilian Schwenson¹; Robert B. Kohlhaas¹; Lars Liebermeister¹; Steffen Breuer¹; Anselm Deninger³; Martin Schell¹; Bjoern Globisch^1
1Fraunhofer HHI, Germany; ²NTT Electronics Techno Corporation, Japan; ³TOPTICA Photonics AG, Germany

We provide the first-ever direct comparison of the terahertz (THz) output of fiber-coupled UTC- and PIN-based continuous-wave emitters. As both emitters are characterized in the same setup, the observed differences can be traced back to the diode structure itself. We find large differences for frequencies below 350 GHz, where each device excels in a certain spectral range. Between 350 GHz and 1 THz, both emitters achieve a comparable THz output.

Tu-Po2-7
Combined UTC-PD Integrated THz Source And A Leaky Wave Antenna With Complementary Split Ring Resonators Along A Planar Goubau Line
Tahsin Akalin¹; Abdallah Chahadih²; Ibrahim Türer³; Miguel Navarro-Cía⁴; Miguel Beruete⁵; Abbas Ghaddar^2
1Lille University, France; ²Lebanese University, Faculty of Science, section V, Lebanon; ³Airbus Defence and Space, Germany; ⁴University of Birmingham, School of Physics and Astronomy, United Kingdom; ⁵Universidad Pública de Navarra UPNA, Spain

We have fabricated a terahertz source based on the combination of an integrated Uni-Travelling-Carrier Photodiode (UTC-PD) and a leaky wave antenna. The UTC-PD is a broadband source and we have used an efficient transition from CPW to Planar Goubau Line (PGL). In this PGL section, we have included complementary Split Ring Resonators (c-SRR) in order to obtain a leaky wave antenna (LWA). The broadband behavior of the source and of the transition allow us to design systems at a given frequency range by modifying only the c-SRR along the PGL.

Tu-Po2-8
Different Plasmonic Regimes Of Laser-Plasma Terahertz Generation
Vasily Kostin¹; Irina Osovitskaya¹; Nikolay Vvedenskii^2
1University of Nizhny Novgorod, Russian Federation; ²Institute of Applied Physics, Russian Academy of Sciences, Russian Federation

The laser-plasma terahertz generation by one-color ultrashort ionizing pulses is studied using new model allowing the motion of the plasma electrons under forces both linear and quadratic in ionizing optical field. We determine different regimes of generation (with different plasmonic modes excited) and describe how the duration and phase structure of the ionizing pulse can affect not only the terahertz energy, but also the terahertz spectrum due to plasmonic effects.

Tu-Po2-9
A Cavity-coupled Microbolometer Terahertz Detector With A Metamaterial Reflector
Xuecou Tu; Peng Xiao; Zhihao Shao; Chengtao Jiang; Yaqian Wu; Xiaoqing Jia; Lin Kang; Jian Chen; Peiheng Wu
Nanjing University, China

In summary, we demonstrated a tunable Nb5N6 microbolometer with a movable MM reflector for THz detection. Continuous tuning over the free spectral range was achieved. The control of polarization is expected to aid the future implementation of our Nb5N6 microbolometers with broadband metamaterial polarizing reflector tuner structures. In addition, this type of structure has a good prospect in the large array of terahertz devices because of its easy integration and advantage in device packaging.

Tu-Po2-10
Possible Phonon-induced Electronic Bi-stability In VO2 For Ultrafast Memory At Room Temperature
Yong Tan¹; Hang Zhao¹; Liangliang Zhang²; Mostafa Shalaby²; Weber Cedric³; Yan Zhang²; Cunlin Zhang²; Acharya Swagata³; Cunningham Brian⁴; Gruning Myrta⁴; Kai Liu⁵; Mark Schilfgaarde^3
1Beijing Institute of Technology, China; ²Capital Normal University, China; ³King's College London, United Kingdom; ⁴School of Mathematics and Physics, Queen's University Belfast, United Kingdom; ⁵Tsinghua University, China

This concretely addresses a long-standing controversy on the role of phonons in the transition where the M1 phase of VO2 is a band insulator with a gap that is too large for pure many-body effects to stabilize a MIT without nuclear displacements.

Tu-Po2-11
Terahertz Generation In Gallium Nitride Quantum Wells
Abas Roble¹; Morgan Hibberd¹; Menno Kappers²; Rachel Oliver²; Darren Graham^1
1School of Physics and Astronomy & Phtoton Science Institute, The University of Manchester, United Kingdom; ²Department of Material Science and Metallurgy, University of Cambridge, United Kingdom

Terahertz emission spectroscopy was used to characterize InGaN/GaN and GaN/AlGaN quantum well structures grown along the polar c-axis and investigate the role of the built-in electrostatic fields in the generation of terahertz radiation. The fields were first calculated using a self-consistent k•Ã,p solver and compared to the magnitudes of the transient electric fields generated when the structures were excited in reflection geometry with femtosecond laser pulses.

Tu-Po2-12
Generation Of Spontaneous Parametric Down-converted Photons In The Sub-terahertz Frequency Range At 660nm
Bjoern Haase¹; Mirco Kutas¹; Felix Riexinger¹; Patricia Bickert¹; Andreas Keil¹; Daniel Molter¹; Michael Bortz¹; Georg von Freymann^2
1Fraunhofer ITWM, Germany; ²Department of Physics and Research Center OPTIMAS, Universität Kaiserslautern, Germany

There are two crucial steps towards terahertz quantum sensing. First, there is the challenge to deliver a source of entangled photons in the terahertz range. Second, measuring terahertz radiation using photons in a different spectral range has to be possible. As we generated entangled photons in the terahertz range by spontaneous parametric down conversion (SPDC), we received the first milestone. The detected signals matches both for down- and for up-conversion for forward as well as for backward terahertz radiation the calculated frequency angular spectrum both qualitative and quantitative. By observing difference frequency generation of external terahertz radiation with VIS pump photons, we achieved both steps towards terahertz quantum sensing.

Tu-Po2-13
Spatial And Temporal Field Evolution Of Evanescent Single-Cycle THz Pulses
Daniel Lake¹; Edward Snedden²; David Walsh²; Steven Jamison¹; Darren Graham^3
1Lancaster University, United Kingdom; ²Accelerator Science and Technology Centre, United Kingdom; ³The University of Manchester, The Photon Science Institute, United Kingdom

The temporal and spatial evolution of single-cycle THz pulses travelling across a dielectric boundary with effective surface velocity below c has been examined. The resulting subluminal evanescent waves in the near field vacuum region are potential drivers of particle accelerators. The electro-optic temporal and spatial imaging of the THz pulses emitted from the surface were measured in the near field, as a function of distance from the dielectric boundary, and reveal both temporal broadening and field decay that is dependent on the effective velocity of the wave in the plane of the boundary.

Tu-Po2-14
Lensless Infrared Image Processing Method Based On Fresnel Aperture
Dexing Liu; Jiaxin Shi; Yunkui Zhang; Ming Cai; Qingchen Niu; Guanhao Cui; Jun Gou; Jun Wang
University of Electronic Science and Technology of China, China

In this paper, the fringe phase scanning method based on Moire fringe is used to reconstruct the phase information of the target object. And we developed the two algorithms which are named as primary reconstruction and secondary reconstruction for different requirements. Combined with image enhancement technology, we can realize the lensless infrared imaging. This method is also beneficial to the miniaturization and integration of infrared focal plane detectors.

Tu-Po2-15
Low-pump Irradiance To Modulate THz Waves Driven By Photo-generated Carriers In An InAs Slab
Eduardo Alvear¹; Stephane Blin²; Philippe Nouvel²; Fernando Gonzalez-Posada²; Rafik Smaali³; Roland Teissier²; Alexei Baranov²; Thierry Taliercio²; Emmanuel Centeno^3
1Univ. Clermont Auvergne, France; ²IES, France; ³Univ. Clermont Auvergne, France

We theoretically and experimentally study the THz electromagnetic properties of an undoped-InAs slab whose permittivity is optically modified by a photo-generation process. The modulation of the permittivity is calculated by solving the ambipolar rate equation for the free carriers. Experiment results demonstrate that InAs is a promising semiconductor to manufacture fast and efficiently on-chip THz components. We show a high modulation of the THz transmission up to 100% from 0.75 to 1.1THz at very low pump fluence in the continuous wave regime. We also demonstrate a high-speed transmission modulation rate up to the MHz range with a modulated pump.

Tu-Po2-16
High Speed Antenna Enhanced Mid-infrared Quantum Cascade Detector
Gregory Quinchard¹; Alexandre Larrue¹; Alexandre Delga¹; Michel Garcia¹; Colin Mismer¹; Virginie Trinité¹; Axel Evirgen¹; Michael Hakl²; Jean-François Lampin²; Emilien Peytavit²; Stefano Barbieri^2
1III-VLab, France; ²IEMN, France

We demonstrate a λ =10.3 µm Quantum Cascade Detector embedded in a subwavelength optical patch antenna cavity. In this structure, the responsivity is enhanced by the microcavity effect and the dark current is reduced thanks to the antenna effect. The system is used as photo-mixer in a coherent photodetection scheme. It opens the way for high sensitivity and high-speed operation and brings new perspectives for room-temperature photodetection.

Tu-Po2-17
TeraHertz Generation in Semiconductor Microcavities
Hadrien Vergnet¹; Simon Huppert¹; Robson Ferreira¹; Aristide Lemaître²; Jacqueline Bloch²; Sukhdeep Dhillon¹; Emmanuel Baudin¹; Jérôme Tignon^1
1Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Universit, France; ²Centre de Nanosciences et de Nanotechnologies (C2N), CNRS - Université Paris-Sud / Paris-Saclay, France

We explore the potential of engineered exciton-polaritons in monolithic microcavities as compact and tunable THz emitters, by simultaneous THz and NIR spectroscopy

Tu-Po2-18
Numerical Study Of CO Laser Down-conversion In ZnGeP2 Crystal to THz Range
Igor Kinyaevskiy¹; Andrey Ionin¹; Yury Klimachev¹; Yury Andreev^2
1P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Russian Federation; ²Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of Russian Academy, Russian Federation

Difference frequency generation of rotational-vibrational lines of nonselective CO laser in ZnGeP2 crystal was numerically studied. It was shown that the difference frequency spectrum can be tuned at least in the wavelength range of 70--1300 ÃfŽÃ,¼m. The conversion efficiency can be up to 10-2%.

Tu-Po2-19
Room Temperature Silicon Detector For IR Range Coated With Ag2S Quantum Dots
Ivan Tretyakov¹; Alexander Shurakov¹; Alexey Perepelitsa¹; Natalya Kaurova¹; Tatyana Zilberley²; Sergey Ryabchun¹; Mikhail Smirnov³; Oleg Ovchinnikov³; Gregory Goltsman^1
1MSPU, Russian Federation; ²Moscow Institute of Physics and technology, Russian Federation; ³VSU, Russian Federation

For decades silicon has been the chief technological semiconducting material of modern microelectronics and has had a strong influence on all aspects of society. Applications of Si-based optoelectronic devices are limited to the visible and near infrared ranges. For photons with energy less than 1.12 eV silicon is almost transparent. The expansion of the Si absorption to shorter wavelengths of the infrared range is of considerable interest to optoelectronic applications. By creating impurity states in Si it is possible to cause sub-band gap photon absorption. Here, we present an elegant and effective technology of extending the photoresponse of towards the IR range. Our approach is based on the use of Ag2S quantum dots (QDs) planted on the surface of Si to create impurity states in Si band gap. The specific sensitivity of the room temperature zero-bias Si_Ag2S detector is 1011 cmâ^sHzW-1 at 1.55μm. Given the variety of available QDs and

Tu-Po2-20
Polarization Control Of Terahertz Spintronic Emitter Combined With Liquid Crystal By The External Magnetic And Electric Field
Makoto Nakajima¹; Hongsong Qiu¹; Lei Wang²; Zhixiong Shen³; Kosaku Kato¹; Yohei Koike¹; Masashi Yoshimura¹; Wei Hu³; Yanqing Lu^3
1Osaka University, Japan; ²Nanjing University Post and Telecommunications, China; ³Nanjing University, China

We demonstrate a polarization-tunable terahertz emitter that integrates a ferromagnetic heterostructure and large birefringence liquid crystals by the external magnetic and electric field. The direction of the magnetic field can control the emitted THz wave from linear to circular polarization. The phase retardation in liquid crystal layer between ordinary and extraordinary directions is continuously adjustable by the low-voltage electric field.

Tu-Po2-21
Terahertz Pulse Emission From GaInAsBi
Ričardas Norkus; Sandra Stanionytė; Andzej Urbanowicz; Andrius Bičiūnas; Vaidas Pačebutas; Arūnas Krotkus
State research institute Center for Physical Sciences and Technology, Lithuania

The quaternary GaInAsBi alloy epitaxial layers were grown on InP substrates with 6% Bi. It was found that thick layers are strained and has short of the order of few picoseconds carrier lifetimes. The THz emission was investigated using GaInAsBi layer as an unbiased surface emitter and as a substrate for photoconductive antenna. It was observed that fabricated THz emitters were sensitive to the optical pulses with the wavelengths longer than 2 µm. The demonstrated spectral characteristics of THz pulses obtained when using Er-doped fiber laser for the photoexcitation were comparable with those observed in other emitters used for THz-TDS systems

Tu-Po2-22
Synchronous Pumping Terahertz Parametric Oscillator Driven By Amplified Picosecond Mode-locked Laser
Tomohiro Naganawa¹; Heishun Zen²; Toshiteru Kii²; Hideaki Ohgaki^2
1Graduate School of Energy Science, Kyoto University, Japan; ²Institute of Advanced Energy, Kyoto University, Japan

Terahertz parametric oscillator (TPO) is one of the attractive ways to generate THz waves. However this scheme has big problem because of large loss and low conversion efficiency when it is driven by a nano-second pulsed laser. In this study, we propose a novel high-conversion-efficiency TPO, which is called as synchronous pumping Terahertz parametric oscillator (sp-TPO). It uses amplified picosecond mode-locked laser pulses as a pump beam. Design and construction of the device was completed, and the first test will be performed soon. The results will be also presented at the conference.

Tu-Po2-23
+16 DBm High Power And High Linearity Integrated Photoreceiver For W-band Fiber Wireless Communication Applications
Toshimasa Umezawa¹; Atsushi Kanno¹; Atsushi Matsumoto¹; Naokatsu Yamamoto¹; Tetsuya Kawanishi^2
1National Institute of Information and Communications Technology, Japan; ²Waseda University, Japan

We designed and fabricated an 80 GHz range high-power integrated photoreceiver operated using a zero-bias operational broadband uni-traveling carrier photodetector and a high-gain narrow-band amplifier. The results showed that by applying only a single power supply to the amplifier, the integrated photoreceiver could exhibit a higher power output at 1 dB compression (P1dB), i.e., over +16 dBm, and a 3 dB bandwidth of 6.5 GHz at 83 GHz.

Tu-Po2-24
High Efficient Broadband Terahertz Radiation Generated By Photoconductive Antenna Array
Wei Shi; Lei Hou; Cheng Ma; Lei Yang; Shaoqiang Wang; Chengang Dong; Hong Liu
Xi'an University of Technology, China

Coherent combination of radiations from a set of independent sources is an efficient way to obtain high power terahertz (THz) radiation. In this work, we designed and fabricated an antenna array, the THz radiations with opposite phase caused by the reverse bias electrical field existed in the conventional photoconductive antenna arrays was totally eliminated, and the synchronization of THz pulses was realized by precisely adjusting their optical paths. By these designs, we demonstrated, for the first time, the THz pulses with the combination efficiency of near 100% from photoconductive antenna array have been achieved.

Tu-Po2-25
Nonuniformity Study For Silicon-based BIB Terahertz Detectors
Xiaodong Wang; Yulu Chen; Bingbing Wang; Chuansheng Zhang; Haoxing Zhang
The 50th Research Institute of China Electronics Technology Group Corporation, China

In this work, Silicon-based BIB array detector has been fabricated. It is demonstrated that the minimum nonuniformity of 7.6% can be achieved. Additionally, the nonuniformities at the low bias are fundamentally less than those at the high bias, which can be attributed to the increased device temperature caused by the self-heating effect of the chip at the high bias. It can be deduced that the nonuniformity of dark current density will be out of control if the anode bias is larger than 3V due to the occurrence of avalanche randomness.

Tu-Po2-26
Fabrication Of Quarter THz Wavelength Resonant Cavity Using A Multiple spin Coating Process
Xing Zheng; Jingbin Wu; Yunkui Zhang; Ziji Liu; Zhiming Wu; Jun Gou; Tao Wang; Yadong Jiang
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Scien, China

Due to the long terahertz (THz) wavelength, it remains a challenging problem to achieve THz wave absorption through building an effective optical resonant cavity for THz wave with THz focal plane arrays. In this paper, a multiple spin coating (MSC) process was developed for the first time to increase the height of the optical resonant cavity. Four resonant cavities with different heights were fabricated and their abilities to absorb THz waves were tested respectively. The tests suggested that the different THz bands were absorbed effectively by the micro-bridge structure using the proposed MSC process.

Tu-Po2-27
Simulation Of Terahertz Spectrum Generated By Noise-like Pulse
Yu Cheng Hong¹; Cheng Han Lin²; Hsiao Hua Wu²; Ci Ling Pan^2
1Institute of photonics technologies, Taiwan; ²Department of Physics, Taiwan

We simulate the generation of terahertz radiation by using a photoconductive antenna excited by noise-like pulses (NLPs). Our simulation results show that the bandwidth of THz spectrum generated by NLPs is narrower than by mode-locked pulses which is from the same laser system in the low-frequency region. However, the spectrum generated by NLPs exhibits additional components extended to the higher frequency, though the power is relatively low.

Tu-Po2-28
High Efficient THz Time Domain Spectroscopy Using Laser Chaos
Fumiyoshi Kuwashima¹; Takuya Shirao¹; Kazuyuki Iwao¹; Masahiko Tani²; Kazuyoshi Kurihara³; Kohji Yamamoto⁴; Osamu Morikawa⁵; Makoto Nakajima^6
1Fukui Univ. of Tech., Japan; ²Research Center for Development of Far-Infrared Region, University of Fukui, Japan; ³Fac. of Educ., Univ. of Fukui, Japan; ⁴Research Center for Development of Far-Infrared Region, University of Fukui, Japan; ⁵Chair of Liberal Arts, Japan Coast Guard Academy, Japan; ⁶Institute of Laser engineering, Osaka Univ., Japan

Stable and wide range THz waves are obtained from the chaotically oscillated multimode-laser diode excited photoconductive antennas. This system is chap system And. this THz wave is suitable for the spectroscopy. In this paper, it is applied to distinguish water and oil.

Tu-Po2-29
High Sensitivity Heterodyne Electro-Optic Sampling With 1.5-µM Laser Source
Hideaki Kitahara¹; Hiroyuki Kato¹; Masaki Shiihara¹; Akihiro Esaki¹; Kohji Yamamoto¹; Takashi Furuya¹; Elmer Estacio²; Micheal Bakunov³; Masahiko Tani^1
1University of Fukui, Japan; ²University of the Philippines Diliman, Philippines; ³University of Nizhny Novgorod, Russian Federation

A detection module for the heterodyne electro-optic sampling of terahertz pulses composed of a GaAs plate inserted into a tapered parallel plate waveguide has been designed and fabricated. The detector was installed into a standard terahertz time-domain spectrometer with a 1.5-µm femtosecond laser as a light source. The spectral bandwidth of 3.5 THz and dynamic range of 5 orders of magnitude were experimentally demonstrated, even with a photo-conductive antenna designed for 800-nm as an emitter.

Tu-Po2-30
Monolithic Mode-Locked Laser Diode For THz Communication
Alexandra Gerling¹; Kai Tybussek²; Quentin Gaimard³; Kamel Merghem³; Abderrahim Ramdane³; Martin Hofmann¹; Carsten Brenner¹; Jan Balzer^2
1Ruhr University Bochum, Germany; ²Universität Duisburg-Essen,Germany; ³CNRS Centre de Nanoscience et Nanotechnology, France

The need for higher data rates in wireless applications necessitates fast technological development. One option for advancement is the use of higher carrier frequencies, as this technique can incorporate previously established methods of data transfer such as modulation techniques. We show that generation and detection of multiple carrier frequencies in the THz range is possible using standard telecom equipment and a single mode-locked laser diode.

Tu-Po2-31
Generation Of Sub-100-kW Narrow-line Far-infrared Radiation From KTP Off-axis THz Parametric Oscillator Seeded By A Spectrally Filtered Stokes Pulse
Ming-Hsiung Wu; Wei-Che Tsai; Yu-Chung Chiu; Yen-Chieh Huang
National Tsing Hua University, Taiwan

We have reported narrow-line high-power far-infrared radiation with peak power up to 62 kW near 53 µm (~5.7 THz in units of frequency) from a pulse seeded OTPO using KTP. With 63% coupling efficiency of the silicon prism atop the KTP crystal, the measured 62-kW narrow-line far-infrared radiation in our pyrodetector correspond to 98-kW powers emitted from the KTP OTPO.

Tu-Po2-32
On-Chip Harmonically Mode-Locked Lasers In Generic Foundry As Frequency Multiplier For Optoelectronic Terahertz Generation
Mu-Chieh Lo; Robinson Guzmán; Guillermo Carpintero
Universidad Carlos III de Madrid, Spain

We experimentally demonstrated optoelectronic integrated circuits which generate selectable high-order harmonics from optical frequency combs to enable terahertz generation. These two-tone sources based on mode-locked lasers monolithically integrated with frequency multipliers are developed in an InP generic foundry approach.

Tu-Po2-33
Development Of High-speed, Patch-antenna Intersubband Photodetectors At 10.3um
Quyang Lin¹; Michael Hakl¹; Stefano Pirotta²; Raffaele Colombelli²; Wenjian Wan³; Hua Li³; J. C. Cao³; Jean-Francois Lampin¹; Emilien Peytavit¹; Stefano Barbieri^1
1Laboratoire IEMN - CNRS, France; ²Laboratoire C2N - CNRS, France; ³Key Laboratory of Terahertz Solid State Technology, Chinese Academy of Sciences, China

We present our work on the development of high-speed, GaAs-AlGaAs multi-quantum wells photodetectors at 10.3μm, based on two-dimensional arrays of patch-antenna resonators. First, the results of FDTD simulations will be presented that allowed to optimize the patch array geometry and fabricate a first generation of detectors with microwave coplanar access. Next, we will report on our initial results from dc optical characterization, namely reflectivity and photocurrent measurements.

Tu-Po2-34
The Gouy Phase Shift In Terahertz Time-domain Spectroscopy And Its Experimental Estimation, Modelling And Compensation
Pierre Kolejak¹; Kamil Postava¹; Martin Micica¹; Mathias Vanwolleghem²; Jaromir Pistora^1
1VSB-Technical University of Ostrava, Czech Republic; ²Université de Lille, CNRS UMR 8520, France

We propose techniques for compensation of the Gouy phase, which affects transmission time-domain spectroscopy measurements. It is proposed the method to analyze general influence of the Gouy phase. The model simulating the Gouy phase influence compared with measured data is also shown.

Tu-Po2-35
Single-shot Measurement Of THz Pulses With Sub-picosecond Resolution and Megahertz Acquisition Rates
Serge Bielawski¹; Christophe Szwaj¹; Clément Evain¹; Marc Le Parquier¹; Tianwei Jiang²; Cejo Lonappan²; Bahram Jalali^2
1PhLAM, LIlle University, France; ²Department of Electrical and Computer Engineering, University of California, United States

We present a method allowing THz pulses to be recorded in single-shot at tens of MHz repetition rates and long record lengths, using a combination of the time-stretch data acquisition and electro-optic sampling techniques

Tu-Po2-36
Application Of Mosaicity Induced Disorder Controlled Rare Earth Nickelate Thin Films As THz Transmission Modulator
Gulloo LAL PRAJAPATI¹; Sarmistha Das²; Dhanvir Singh Rana^1
1IISER Bhopal, India; ²Physics Department, University of California, United States

Here, we have studied mosaicity induced disorder (a unique type of disorder which is transferred from substrate template to film) controlled properties of rare earth nickelate thin films. While highly oriented film exhibits sharp metal to insulator transition (MIT) and Drude type of terahertz (THz) conductivity behavior, mosaic film exhibit much more subtle and broad transition and Drude-Smith type THz conductivity behavior. On the basis of such contrasting behavior, we propose application of these films as thermally controlled THz transmission modulator: oriented film as digital modulator while mosaic film as analog modulator.

Tu-Po2-37
Profile Control Of One-dimensional Terahertz Moth-eye Structure Fabricated By Femtosecond Laser Processing
Xi Yu; Jongsuck Bae; Shingo Ono
Nagoya Institute of Technology, Japan

To experimentally establishing the profile dependence of antireflective characteristic of moth-eye structure at THz frequencies, one-dimensional tapered moth-eye structures were fabricated on the surface of high-resistivity silicon substrate with different aspect ratio from 1.3 to 3.2 using femtosecond laser processing. A moth-eye structure consists of Klopfentein tapers with aspect ratio of 0.7 was also successfully fabricated by adjusted the scanning pattern while femtosecond laser processing. The antireflective characteristics of these samples were evaluated experimentally by a standard terahertz time domain spectroscopy and simulated by the High Frequency Electromagnetic Field Simulation.

Tu-Po2-38
Application Of Laser Generated Moth-eye Structure For A Periodic Terahertz-wave Generator
Xi Yu; Shingo Ono; Jongsuck Bae
Nagoya Institute of Technology, Japan

To improve the generation efficiency of terahertz wave from periodic terahertz-wave generator, femtosecond laser was employed to fabricated moth-eye structure on the reverse of the antenna substrate (LT-GaAs). The measurement performed by a THz-TDS system showed that The AR structured antennas had a 2.5-4.4 times improvement of the output. the output signals has an overall improvement at the region of 0.1-1.5 THz. At the frequency of 0.342 THz (calculated Ãfâ? Ã¢â,¬â"¢out), 283 THz, 226 THz (experimental Ãfâ? Ã¢â,¬â"¢out of generator without and with moth-eye, the improvement are 3 times, 2.5 times, and 4.4 times, respectively.

Tu-Po2-39
Electromagnetic-field Analysis Of Diagonal-feedhorn Antennas For Terahertz-frequency Quantum-cascade Laser Integration
Esam Zafar¹; Alexander Valavanis¹; Paul Dean¹; Edmund Linfield¹; Giles Davies¹; Yingjun Han¹; Olivier Auriacombe²; Thomas Rawlings²; Brian Ellison²; Nick Brewster²; Matthew Oldfield^2
1University of Leeds, United Kingdom; ²Science and Technology Facilities Council/RAL Space Department, United Kingdom

We present an electromagnetic-field analysis of a terahertz-frequency quantum-cascade laser (THz QCL) integrated with a mechanically micro-machined waveguide cavity and diagonal feedhorn. A hybrid finite-element/Fourier transform approach enables analysis of both the near-field and far-field regions and is shown to agree well with experimental observations. The far-field antenna patterns show enhancement of the beam profile when compared with an unmounted QCL, in terms of beam divergence and side-lobe suppression ratio. Furthermore, we demonstrate integration of the QCL with dual diagonal feedhorns, enabling simultaneous access to both facets of the QCL, underpinning future integration with a satellite-based receiver and frequency-stabilization subsystem

Tu-Po2-40
Open-Source Simulation Software For Quantum Cascade Lasers
Michael Riesch; Christian Jirauschek
Technical University of Munich, Germany

We review the state of the art in open-source simulation and optimization tools for quantum cascade lasers (QCLs) and present the mbsolve project, which is a tool for QCL dynamics simulations.

Tu-Po2-41
High Power THz Quantum Cascade Laser And Its Demonstration In High Resolution Holographic Imaging
Tao Jiang; Changle Shen; Zhiqiang Zhan; Ruijiao Zou; Xuemin Wang; Weidong Wu
Research Center of Laser Fusion CAEP, China

Fabrication of high power terahertz quantum cascade laser (THz QCL) based upon the resonant-phonon active region design and semi-insulating surface-plasmon waveguide with frequency at 4.4 THz and its demonstration in digital holographic imaging are presented. The maximum peak output power is 95mW at 10K in pulsed mode. The maximum working temperature is 80 K. Interestingly, by changing the injection current, the transverse mode of the laser can be switched between TM00 mode and TM01 mode. With such THz QCL as the light source, the lateral resolution of a home-built digital holographic imaging system can reach 80ÃZ¼m.

Tu-Po2-42
Towards A 4.75-THz Local Oscillator Based On A Terahertz Quantum-Cascade Laser With A Back-facet Mirror
Till Hagelschuer¹; Heiko Richter¹; Martin Wienold¹; Xiang Lü²; Benjamin Röben²; Lutz Schrottke²; Klaus Biermann²; Holger T. Grahn²; Heinz-Wilhelm Hübers^1
1German Aerospace Center (DLR), Germany; ²Paul-Drude Institut für Festkörperelektronik, Germany

We report on a compact terahertz (THz) source based on a quantum-cascade laser (QCL). The source is intended for a local oscillator in a THz heterodyne receiver for the detection of the fine structure line of neutral atomic oxygen (OI) at 4.7448 THz. The QCL which is mounted in a small mechanical cryocooler employs a GaAs/AlAs active-region heterostructure and a resonator with an additional back-facet mirror. This allows for low electrical pump powers of less than 1.2 W and high optical output powers of up to 8 mW. The whole setup weighs less than 4 kg. The application of such a system in a spaceborne mission appears to be feasible.

Tu-Po2-43
Optimization Of THz QCLs By Suppressing A Leakage Current Via High Energy States
Tsung-Tse Lin; Ke Wang; Li Wang; Hideki Hihayama
RIKEN, Japan

Terahertz quantum cascade lasers (THz QCLs) are theoretically analyzed based on the non-equilibrium Green's function (NEGF) method. Simulations reveal a carrier leakage channel from upper laser level to the first high energy state in the emitting double-well of the next period. This leakage channel is due to unintentional alignment of the two states, which is distinct from the thermally activated leakage channels. By tuning the energy of this high energy state, such leakage current is clearly suppressed.

Tu-Po2-44
The Material Growth, Device Fabrication And Application Of Terahertz Quantum Cascade Lasers
Weidong Wu; Xuemin Wang; Changle Shen; Tao Jiang; Zhiqiang Zhan
Research Center of Laser Fusion CAEP, China

This talk reviews our recent work on material growth, device fabrication and application of terahertz quantum cascade lasers (THz QCLs).

Tu-Po2-45
Advances In MOEMS-based External Cavity QCLs For Mid-IR Spectroscopy
Yuri Victorovich Flores¹; Marko Haertelt¹; Stefan Hugger¹; Lorenz Butschek¹; Christian Schilling¹; Andre Merten²; Markus Schwarzenberg²; Andre Dreyhaupt²; Jan Grahmann²; Marcel Rattunde¹; Ralf Ostendorf^1
1Fraunhofer Institute of Applied Solid State Physics, Germany; ²Fraunhofer Institute for Photonic Microsystems, Germany

We present miniaturized MOEMS-based external-cavity (EC)-QCLs: A non-resonant, versatile version for setting arbitrary emission wavelengths or wavelength trajectories as a function of time with drive frequencies up to a few tens of Hz and a fast, resonant variant for real time (millisecond resolution) measurements. Both versions are equipped with additional cavity length control for high-resolution mid-IR spectroscopy.

Tu-Po2-46
High Performance Continuous-wave InP-based 2.1 ?m Superluminescent Diode With InGaAsSb Quantum Well
Jinchuan Zhang
Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Science, People's Republic of China, China

Broadband spectrum electrically pumped InP-based superluminescent diodes (SLDs) in continuous-wave (CW) are reported. The optimized active region and high quality of quantum wells are guaranteed for controlling wavelength and acquiring large mode gain. All device spectrums are centered around 2.1 μm and the full width at half maximum (FWHM) of widest spectrum is 99 nm. After the optimization of waveguide structure for higher output power, the maximum CW output power is lifted up to 30 mW. This work is of great importance to pave the way for demonstrating compact and efficient light sources based on InP material systems.

Tu-Po2-47
Resonant Frequency Tuning Of Terahertz Plasmonic Structures Based On Solid Immersion Method
Toshio Sugaya¹; Xiangying Deng¹; Yukio Kawano^2
1Tokyo Institute of Technology, Japan; ²Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Institute of Techn, Japan

We report on a technique for resonant frequency tuning and miniaturization of a terahertz (THz) plasmonic structure. By applying solid immersion method to a nonconcentric plasmonic structure, we achieved resonant frequency tuning of THz plasmon and size reduction by 1/3.41 simultaneously. These results potentially lead to high-resolution THz analysis for bio-medical examination and nano-materials characterization.

Tu-Po2-48
Comparison Of Metallic NW And Evaporated Contact For THz Detector Modules Based On An InGaAs Schottky Diode
Ahid S. Hajo; Oktay Yilmazoglu; Suwei Lu; Franko Küppers; Thomas Kussorow
Technische Universität Darmstadt, Germany

In this paper we report a new Terahertz (THz) Schottky detector module based on vertically contacted highly doped (1 x 1018 cm-3) indium gallium arsenide (InGaAs) by using a small diameter (100 nm) silver nanowire (NW) as air-bridge contact and a standard evaporated contact (SD). These Schottky diodes were placed on a silicon lens and integrated with a pre- amplifier on a printed circuit board (PCB).

Tu-Po2-49
Characterization Of Uncooled Ultra Low-NEP LSMO Bolometers At 3.39 Mm And In The MWIR And LWIR Bands
Bruno Guillet¹; Vanuza Marques Do Nascimento¹; Victor Pierron¹; Laurence Méchin¹; Florent Starecki²; Carolina Adamo³; Darrell Schlom^4
1GREYC - CNRS/ENSICAEN/Université de Caen Normandie, France; ²CIMAP - CNRS/ENSICAEN/CEA/Université de Caen Normandie, France; ³Cornell University, United States; ⁴Kavli Institute at Cornell for Nanoscale Science, United States

La0.7Sr0.3MnO3 (LSMO) uncooled suspended bolometers have been characterized at 3.39 Ã,µm (He-Ne laser) and with a blackbody source at different temperatures. These bolometers could achieve ultra low NEP values below 1 pWÃ,·Hz-1/2 with few microwatts power consumption at 300 K

Tu-Po2-50
A Gap Waveguide Fed Circular Polarization Antenna In The Millimeter- Wave Range
Dayan Pérez; Miguel Beruete; Iñigo Ederra
Public University of Navarra, Spain

In this paper a simple diamond-shaped slot antenna working in the millimeter-wave 5G band of 60 GHz, with circular polarization (CP), high radiation efficiency and broadband performance both in matching and axial ratio (AR) is presented. The antenna is implemented in Gap Waveguide (GW) technology, namely Ridge Gap Waveguide topology. The feeding system is a standard waveguide (WR-15) to RGW transition. The simulation results demonstrate a 14.52% reflection coefficient and AR bandwidth (|S11 < ?10 dB| and AR < 3dB) covering 59- 68 GHz (> 9 GHz) The maximum gain of the system is around 7 dB, with an efficiency close to 98%.

Tu-Po2-51
Investigation Of THz Tapered Parallel Plate Waveguide Integrated With A Metal Slit Array
Dejun Liu¹; Borwen You¹; Ja-Yu Lu²; Toshiaki Hattori^1
1University of Tsukuba, Japan; ²National Cheng Kung University, Taiwan

A metal slit array in a tapered parallel plate waveguide (TPPWG) is experimentally and numerically demonstrated. The metal slit array is embedded in the center of air gaps in tapered regions, realizing multiple narrow Bragg resonances. TPPWG not only enhances the Bragg resonances but also reduces the number of non-Bragg resonances. The induced standing waves at 0.3 THz exhibits enhanced localized field with four antinodes, which originates from the interference between two THz waves divided by the metal slit array.

Tu-Po2-52
Design Of A Compact Cylindrical Micro-lens For Efficient Out-coupling And Collimation Of THz Radiation From A Photoconductive Antenna
Thomas Søndergaard; Christian Sørensen; Esben Skovsen
Aalborg University, Department of Materials and Production, Denmark

A compact cylindrical micro-lens is designed for efficient out-coupling and collimation of THz radiation from a photoconductive THz antenna placed on the backside of a semiconductor substrate. The full radiation pattern of the 3D lens-antenna system is calculated rigorously by using the Green's Function Volume Integral Equation Method in a form that exploits cylindrical symmetry. The lens is designed for an optimum amount of radiation emitted in a useful range of directions relative to the total emission taking into account the Purcell effect and radiation trapped inside the semiconductor substrate

Tu-Po2-53
Tunable Optical Frequency Shifter For Terahertz Communicaiton System
Wei Jiang¹; Shanghong Zhao²; Qinggui Tan¹; Xiaojun Li¹; Zhongbo Zhu^1
1National Key Laboratory of Science and Technology on Space Microwave, China; ²Air Force Engineering University, China

In this paper, a tunable optical frequency shifter for Terahertz (THz) communication system is proposed and demonstrated. The scheme is based on frequency multiplication operation using dual-parallel DPMZM (dual-parallel Mach-Zehnder modulator) and Mach-Zehnder interferometer (MZI). By optimizing the sub-modulators of DPMZMs, the optical carrier suppressed single-side-band signal (SSB-OCS) with adjustable order can be used for tunable optical frequency shifter, and the MZI further suppresses high order intermodulation components. The simulated results show the suppression ratio is above 30 dB, and the maximum range of optical frequency shift is over 150 GHz. The experimental test suppression ratio is over 24 dB.

Tu-Po2-54
Study Of Microstrip-Based Terahertz Phase Shifter Using Liquid Crystal
Yuki Takeda¹; Withawat Withayachumnanku²; Yasuaki Monnai^1
1Keio University, Japan; ²The University of Adelaide, Australia

We propose a microstrip-based terahertz phase shifter using liquid crystal. Voltage-controlled phase shift can be induced by incorporating liquid crystal into the dielectric substrate of the microstrip line (MSL) to cause the refractive index change. DC bias lines running in parallel to the MSL are designed to introduce minimum RF interference. Preliminary experimental results show the proof of concept of the approach.

Tu-Po2-55
Rapid Prototyping Of Simple Optical Elements For The Terahertz Domain
Christian Sørensen¹; Esben Skovsen^2
1Aalborg University, Department of Materials and Production, Denmark; ²Aalborg University, Denmark

This work shows practical details of methodologies for conventional milling of arbitrary spherical lenses from high-density polyethylene as well as the production and polishing of off-axis parabolic mirrors using fused filament fabrication 3D printing. The techniques allow for low-volume, low-cost and fast prototyping of large optical elements for prototype setups.

Tu-Po2-56
THz Gratings Produced By Laser Cutting
Jan Ornik; Yingzhi Zhang; Maximilian Schneider; Mehdi Taherkhani; Hakan Alaboz; Martin Koch
Philipps-Universität Marburg, Germany

We produced terahertz gratings from aluminum and PVC foil by laser cutting. The performance of the produced gratings was simulated and found to be in good agreement with the experimental characterization.

Tu-Po2-57
A Quasi-optical Transmission Line For The ECR Ion Source
jianwei liu¹; junwei guo²; xinjian niu¹; yinghui liu¹; hui wang¹; guo guo¹; Safi Ullah¹; Abdur Rauf¹; xu sun^1
1University of Electronic Science and Technology of China, China; ²Institute of Modern Physics (IMP), Chinese Academy of Science, China

A compact, efficient, 45GHz/20KW quasi-optical transmission line consisting five quasi-optical mirrors for the ECR ion source, which constructed by the Institute of Modern Physics(IMP), Chinese Academy of Science has been proposed. A computer code for vector analysis of the electromagnetic fields in mirror systems has been developed in terms of the vector diffraction theory. Based on Stratton-Chu formula and mirror optimization program, the structure of the five quasi-optical mirrors has been obtained. The simulation results show that the power transmission efficiency from the output of the Matching Optical Unit( MOU) to the vacuum widow which connected with superconducting ECR ion source is 93.53%. The experimental results indicate that a good agreement between measurement and theoretical prediction is obtained.

Tu-Po2-58
Development Of The Planar AlGaN/GaN Bow-tie Diodes For Terahertz Detection
Justinas Jorudas; Justina Malakauskaitė; Liudvikas Subačius; Vytautas Janonis; Vytautas Jakstas; Vitalij Kovalevskij; Irmantas Kasalynas
Center for Physical Sciences and Technology, Lithuania

Completely planar bow-tie (BT) diodes for terahertz (THz) detection were developed on AlGaN/GaN high electron mobility transistor (HEMT) structures employing a shallow ion-implantation for electric isolation. Heating in a two dimensional electron gas (2DEG) layer in the apex zone of geometrically shaped semiconductor was used for THz detection. The diodes were developed with various apex widths varying from 17 µ to 500 nm. The responsivity of the sensor was found to be increasing non-linearly with the decrease of the apex width. In addition, detected signal dependence on frequency was observed with a maximum sensor response at about 150 GHz defined by a THz antenna coupling efficiency and not 2DEG heating effects. These results highlight a potential of the planar AlGaN/GaN BT diodes for the usage upper THz frequency range.

Tu-Po2-59
Concept Of A Prism Spectrograph For Infrared Linear Array Detectors
Ulrich Schade¹; Eglof Ritter²; Ljiljana Puskar¹; Paul Dumas^3
1HZB, Germany; ²HUB, Germany; ³SOLEIL Synchrotron, France

We discuss the concept of an IR spectrograph suitable for linear array detection. The dispersive element of the spectrograph is based on an arrangement of commercially available low-cost prisms. The dispersion is such that the whole spectral bandwidth of interest is distributed along the linear array of detector pixels in such a way to achieve an optimum for the spectral resolution. The concept is exemplarily shown for the design of a spectrograph working in the range between 5000 and 2500 wavenumbers spread onto a linear 128-pixel array detector.

Tu-Po2-60
A Low-Profile Sub-Terahertz Transmit-Array Antenna With High Gain Enhancement
Zhongbo Zhu¹; Weidong Hu²; Xianqi Lin³; Xiaojun Li^1
1The National Key Lab. of Sience and Technology on Space Microwave, China; ²Beijing Institute of Technology, China; ³University of Electronic Science and Technology of China, China

A compact transmit-array (TA) antenna with reduced profile and improved radiation gain is proposed in this paper. The proposed transmitting surface, with a thickness of 0.127 mm (0.042 ?0 @105 GHz), is employed here to adjust the phase distribution across the aperture of a shortened feed horn. The full TA prototype is fabricated and measured. A 3-dB gain bandwidth of 9.52%, from 100 GHz to 110 GHz, is achieved. The measured maximum gain at 105 GHz is 22.76 dBi, which gets an 8-dB enhancement with respect to the primary feed, without expanding the radiation aperture size. This method considerably reduces the complexity of TA and achieves a much more compact structure.

Tu-Po2-61
Detection Performance Of LT-GaAs-on-Silicon Bowtie Photoconductive Antenna Prototype
Jessica Afalla¹; Alexander De Los Reyes²; Maria Angela Faustino²; Victor DC Vistro²; Hannah Bardolaza²; Gerald Angelo Catindig²; Karl Cedric Gonzales²; Elizabeth Ann Prieto²; Joselito Muldera³; Valynn Mag-usara⁴; Neil Irvin Cabello²; Vernalyn Copa²; John Paul Ferrolino²; Garik Torosyan⁵; Takashi Furuya⁴; Hideaki Kitahara⁴; Armando Somintac²; Arnel Salvador²; Masahiko Tani⁴; Elmer Estacio^2
1University of Fukui, Japan; ²University of the Philippines Diliman, Philippines; ³de la Salle University, Philippines; ⁴University of Fukui, Japan; ⁵Photonic Center Kaiserslautern, Germany

We report on the detection characteristics of two bowtie photoconductive antennas which were fabricated on low temperature grown GaAs grown on Silicon substrates. The bowtie structure has a 10-µm antenna gap. The two samples have unique growth recipes, and were epitaxial grown on differently oriented substrates. The sample grown on a Si (100) substrate with a 4° tilt towards the (110) direction, has a longer carrier lifetime (24 ps) and higher detection intensity as a photoconductive antenna. The sample grown on a Si (100) substrate has a carrier lifetime of 13 ps. Its detection intensity was found to be lower, but its bandwidth slightly wider.

Tu-Po2-62
Combined UTC-PD Integrated On-chip THz Near Field Microscopy With Coupled Planar Goubau Lines
Tahsin Akalin¹; Abdallah Chahadih²; Abbas Ghaddar²; Ibrahim Türer^3
1Lille University, France; ²Lebanese University, Faculty of science, Lebanon; ³Airbus Defence and Space, Germany

In most of the cases for terahertz near field microscopy, a free space propagating electromagnetic wave interacts with a small tip placed above the sample. In our original approach, we use a guided way to bring the terahertz wave and to improve the interaction efficiency with the sample. The idea is to take benefit of the confinement around a Planar Goubau Line (PGL). We have fabricated a planar system with an integrated Uni-Travelling-Carrier Photodiode (UTC-PD) as a broadband source. The system can be used to map continuously at discrete frequencies the sample in a wide frequency range.

Tu-Po2-63
Characterization Of Smooth Dielectric Samples With Highly Focused Gaussian Beams In A Scatterometer
Michal Mrnka¹; Per Heighwood Nielsen²; Tonny Rubæk²; Cecilia Cappellin²; Roger Appleby³; Elena Saenz^1
1ESA-ESTEC, Netherlands; ²TICRA, TICRA, Denmark; ³Roger Appleby MMW Consulting Ltd., United Kingdom

This paper describes a numerical validation of the transmission coefficient of a smooth dielectric sample recently measured at ESA-ESTEC during the integration testing of a scatterometer operating in 50-750 GHz frequency range. The aim of the paper is to compare the experimental results of a calibrated measurement with a numerical model in GRASP and describe a numerical method for extracting material parameters.

Tu-Po2-64
Terahertz Near-Field Imaging Using Batch Fabricated Cantilevers With 70 Micrometers Long Tips
Benjamin Walter¹; Estelle Mairiaux¹; Dominique Vignaud²; Sophie Eliet²; Jean-Francois Lampin²; Marc Faucher^2
1Vmicro SAS, France; ²Univ. Lille, CNRS, Centrale Lille, ISEN, Univ. Valenciennes, France

Batch fabricated atomic force microscopy cantilevers with tip longer than 70µm are reported. They are designed to increase terahertz focusing in scattering optical near field imaging. Terahertz SNOM imaging of sub-100nm features on a graphene sample is presented.

Tu-Po2-65
Terahertz Field Enhancement By Bull's Eye Antenna For Force-detected Electron Paramagnetic Resonance Measurements
Ren Fujioka¹; Hideyuki Takahashi²; Kengo Sugahara³; Eiji Ohmichi¹; Hitoshi Ohta^2
1Graduate School of Science, Kobe University, Japan; ²Molecular Photoscience Research Center, Kobe University, Japan; ³School of Science and Engineering, Kindai University, Japan

We designed bull's eye antenna structure working at THz frequencies for use in force-detected EPR measurement, and numerically confirmed that the oscillating magnetic field B1 was focused into the subwavelemgth scale at the aperture with an enhancement by one order.

Tu-Po2-66
Passive Millimeter-wave Microscopy Of Aqueous Protein Solutions at Low Temperatures
Tatsuo Nozokido¹; Yuya Takakura¹; Akio Kishigami^2
1University of Toyama, Japan; ²Gifu Women's University, Japan

Thermal radiation emitted from aqueous solutions of bovine serum albumin (BSA), which is a serum albumin protein derived from cows, was measured and analyzed by passive millimeter-wave microscopy at temperatures below the freezing point of water. The thermal radiation emitted from BSA aqueous solutions with different concentrations was measured at 50 GHz and temperatures ranging from 130 K to 260 K. Two different conformational states of the BSA were observed. The emissivities of the BSA solutions were successfully determined from the measured results.

Tu-Po2-67
Compressed Sensing Image Reconstruction For Millimeter-wave Near-field Scanning Microscopy Using A Metal Slit Probe
Tatsuo Nozokido¹; Hiroki Okano¹; Hiroyuki Kudo^2
1University of Toyama, Japan; ²University of Tsukuba, Japan

We report on the use of a compressed sensing technique for two-dimensional image reconstruction in millimeter-wave near-field scanning microscopy that enables the measurement time required to acquire the projection data sets to be reduced. Experiments performed at 60 GHz to image the electrical response anisotropy of the sample using compressed sensing image reconstruction show that just 1/8th of the full scan data needs to be measured to allow perfect image reconstruction.

Tu-Po2-68
Propagation characteristics of high-throughput terajet beam and its super Resolution THz imaging
Qingshan Qu¹; Bin Cui¹; Zhenwei Zhang²; Yuping Yang¹; Zhichao Yang^1
1Minzu University of China, China; ²Capital Normal University, China

Broad-bandwidth spectral analysis is one of important advantages of terahertz (THz) imaging technology, while low spatial resolution restricts its further applications. In contrast to the contradiction between the high-resolution and the low-throughput as well as narrow-bandwidth in the existing THz near-field imaging technologies, a high-resolution, high- throughput and broad-bandwidth terahertz imaging method is proposed in this work based on the terajet effect produced by a dielectric semi-sphere with appropriate refractive index. The terajet beam can break through the restriction of the diffraction limit on the spatial resolution of the microscopic system without losing the energy and spectral width.

Tu-Po2-69
TeraFET Multi-pixel THz Array For A Confocal Imaging System
Dovilė Čibiraitė¹; Min Wan²; Alvydas Lisauskas³; Adam Rämer⁴; Sergey Chevtchenko⁴; Wolfgang Heinrich⁴; Hartmut G. Roskos¹; John T. Sheridan²; Viktor Krozer¹; Viktor Krozer^4
1Goethe University Frankfurt, Germany; ²University College Dublin, Ireland; ³Vilnius University, Lithuania; ⁴Ferdinand-Braun-Institut, Germany

We present a THz detector based on AlGaN/GaN HEMT technology implemented for a multi-pixel array and tested in a confocal THz imaging system. The multi-pixel array shows good homogeneity where the ratio between the most and the least sensitive pixels is less than two times. The detector has been tested in a confocal system at 300 GHz and the pictures show a good resolution.

Tu-Po2-70
Fabrication And Characterization Of Frequency Selective Terahertz Focal Plane Array And Camera
Hassane Oulachgar; Jacques-Edmond Paultre; Marc Terroux; Francis Provençal; Bruno Fisette; Hélène Spisser; François Berthiaume; Alex Paquet; Michel Doucet; Michel Jacob; Linda Marchese; Francis Généreux; Paul Grenier; Christine Alain; Alain Bergeron
National Optics Institute, Canada

A high performance frequency selective focal plane array (FPA) detector has been developed at INO. The detector array was fabricated using a CMOS compatible microfabrication process. The FPA consists of a 384x288 pixel array, with optimal detection frequency at 515 GHz. The radiometric performance of the detector, at this frequency, was improved by more than five-fold compared to previously reported frequency selective terahertz detector [2].

Tu-Po2-71
Modeling And Simulation Of Dielectric Whispering Gallery Mode Sensor Using Finite Element Method At THz Frequency
Himanshu Gohil¹; Anushree Singh¹; Cijy Mathai²; Niraj Joshi³; Shriganesh Prabhu^1
1Tata Institute of Fundamental Research, India; ²Indian Institute of Technology - Bombay, India; ³SCEM, Mangalore, India

The design and optimization of Whispering Gallery Mode Resonator (WGMR) sensors in the THz regime can be modelled using Finite Element Analysis. In this paper, we have modelled and simulated a rectangular cross section ring WGMR and its response for the biomolecule analyte 'BSA' (Bovine Serum Albumin) at the THz frequencies. We design our resonator model for working frequency of around 0.161 THz using dielectric core with Refractive Index of 1.473, corresponding to HDPE and use the experimentally obtained refractive index of analyte. The simulation results after placing the analyte near the resonator evokes a response in the form of a characteristic peak frequency shift of 80 MHz and line broadening (~3x FWHM). These theoretical results can be used to study and obtain parameters to fabricate optimized devices which can yield results for sensing unlabeled analytes with low concentration and high specificity.

Tu-Po2-72
A GO/FO Tool For Analyzing Quasi-Optical Systems In Reception
Huasheng Zhang; Shahab Oddin Dabironezare; Giorgio Carluccio; Andrea Neto; Nuria Llombart
Delft University of Technology, Netherlands

In this work, a free accessible MATLAB interface is presented to analyze antenna-coupled Quasi-Optical (QO) systems in reception. This goal is achieved by using Fourier Optics (FO) and Geometrical Optics (GO) based methods. Specifically, the FO method represents the field focalized by a QO component on its focal plane as a plane wave spectrum when the component is illuminated by an incident field. This spectrum is related to the field scattered by the QO component which is calculated here using a GO method. By using this spectrum, the tool estimates the power received by an antenna placed at the focal plane of the QO component. Moreover, the performance in reception is evaluated.

Tu-Po2-73
Terahertz Imaging Based On Coherent Detection Of The Fourier-Space Spectrum
Hui Yuan¹; Daniel Voß¹; Min Wan²; Alvydas Lisauskas³; Hartmut G. Roskos¹; John T. Sheridan^2
1Physikalisches Institut/Johann Wolfgang Goethe-Universität, Germany; ²School of Electrical & Electronic Engineering / University College Dublin, Ireland; ³Institute of Applied Electrodynamics & Telecommunications / Vilnius Univ., Germany

A novel continuous-wave THz imaging system based on the coherent recording of the Fourier space spectrum (FSS) with heterodyne detection is described. The system consists of two 300-GHz electrical multiplier-chain sources with a slight frequency offset, and a single narrow-band TeraFET detector working in raster-scanning mode. The complex-valued FSS is recorded in either the focal-plane or in the free space of the optical system in focusing and non-focusing mode, respectively. Two- and three-dimensional (2D and 3D) images are reconstructed numerically with an inverse Fourier transform algorithm. With a 80×80-mm2 detection area and 1-mm2 sampling steps, 1-mm resolution and 76.2×76.2-mm2 image area are achieved.

Tu-Po2-74
Tunable Filter Design For IR Hyperspectral Imaging
Justine Champagne; Samuel Dupont; Joseph Gazalet; Jean-Claude Kastelik
IEMN, France

The use of wide-angle Acousto-Optic Tunable Filter (AOTF) for hyperspectral imaging is considered: the diffraction efficiency is calculated around a usual diffraction plane for two degrees of freedom (azimuthal and transverse angle). The efficiency evolution is also examined over a wide wavelength band. The diffraction efficiency is determined as a function of the incident angles and the results are commented.

Tu-Po2-75
3D Inspection Of Fiber-Reinforced Thermoplastics At THz Frequencies
Matthias Kahl; Jan Boecking; Bernd Engel; Peter Haring Bolívar
University of Siegen, Germany

Utilizing composite materials instead of metals allows to reduce weight while maintaining mechanical strength. Fiber-Reinforced Thermoplastics (FRT) have very competitive mechanical properties and additionally offer the capability for mass production, which makes the material particularly attractive in the automotive and aircraft sectors. Typical defects in FRT are dominated by fiber shifts and cracks. We show that 3D THz imaging using a FMCW approach can resolve such defects and is therefore a suitable tool for nondestructive testing applications, specifically for the quality control in FRT mass production.

Tu-Po2-76
A Convolutional Neural Network For The Non-destructive Testing Of 3Dprinted Samples
Mostafa Elsaadouny; Jan Barowski; Ilona Rolfes
Ruhr University Bochum, Germany

The three dimensional printing is a very important technology that participates in many applications. In this paper we present an approach for the Non-Destructive Testing (NDT) of the three dimensional printed objects. This methodology solves the image classification problem by using the Neural Networks (NN). The network has been trained by large data matrix which contains information about the mean, the variance and the pixel intensity of the input. The proposed solution has been used for testing different data sets for monitoring the performance under different scenarios, and the obtained results show high degree of accuracy regarding defects detection.

Tu-Po2-77
High Responsivity And Low NEP Of Room-Temperature Terahertz Antenna-Coupled Microbolometers With Meander Titanium Thermistor
Norihisa Hiromoto¹; Amit Banerjee²; Durgadevi Elamaran¹; Makoto Aoki³; Catur Apriono⁴; Hiroaki Satoh¹; Erik Bruendermann⁵; Eko Rahardjo⁴; Hiroshi Inokawa^1
1Shizuoka University, Japan; ²National University of Singapore, Singapore; ³National Institute of Information and Communications Technology (NICT), Japan; ⁴Universitas Indonesia, Indonesia; ⁵Karlsruhe Institute of Technology (KIT), Germany

In order to realize room-temperature terahertz (THz) detectors with high-detectivity, we have studied room- temperature THz antenna-coupled bolometers with titanium (Ti) meander-line thermistor fabricated on a high-resistivity silicon (Si) substrate by MEMS structures. In this paper, we report the spectrum of responsivity which spreads in the range of 0.1 THz width around 1 THz and it has high-responsivity bands with the orders of 1000 V/W. Thanks to the high responsivity and low noise of the metal thermistor, we have achieved good noise-equivalent power (NEP) of the order of 10^-11 W/Hz^1/2 and response speed of 5 kHz for the room-temperature antenna-coupled bolometers with Ti meander thermistor 0.1 µm-wide and 90 µm-long.

Tu-Po2-78
Incoherent Power Combining Of THz Source Arrays
Robin Zatta¹; Ritesh Jain²; Daniel Headland³; Ullrich Pfeiffer^1
1Institute for high frequency & communication technology, Germany; ²Bergische Universität Wuppertal, Germany; ³Graduate School of Engeneering Science of Osaka University, Japan

In this paper, we investigate the multi-chip scaling of a previously developed incoherent 4x4-pixel 0.53-THz 1- mW source array, implemented in a 0.13-um SiGe BiCMOS technology. A standalone module under-samples the illumination space due to a large pixel pitch given by the implemented triple-push oscillator topology coupled with narrow pixel beams. Therefore, we present the concept of super-array configurations by arranging multiple source arrays, achieving an increased fill factor, increased radiated power, and wider illumination aperture. Moreover, such super-array configurations can help to reduce the influence of spurious reflections at THz frequencies by providing a diffused radiation. For a 2x1 super-array, the 10-dB fill factor increased from 10.9 to 61.8% while maintaining the illumination aperture; and the net radiated power doubled to 2 mW (3 dBm). For a 2x2 super-array, the illumination aperture quadrupled; the radiated power and the 10-dB fill factor at 0.53 THz were 4 mW (6 dBm).

Tu-Po2-79
Kernel Size Characterization For Deep Learning Terahertz Tomography
Yi-Chun Hung¹; Shang-Hua Yang^2
1National Tsing-Hua University, Taiwan; ²Department of Electrical Engineering, National Tsing Hua University, Taiwan

We present supervised terahertz deep learning models for high-precision terahertz tomography. To investigate the performance of terahertz deep learning models, comprehensive characterization of kernel size in first convolution layers is further studied. By utilizing the length of beam diameter, the optimized kernel size can be designed to deliver the much spatially accurate images, which achieves 2.5% on mean square error (MSE) , 46.8% improvement on MSE than other kernel size.

Tu-Po2-80
340 GHz And 250 GHz Schottky Solid-state Heterodyne Receiver Arrays For Passive Imaging Systems
Yue He¹; Li Wei Hou²; Yao ling Tian¹; Kun Huang¹; Jun Jiang^1
1Microsystem and Terahertz Research Center, China; ²The 50th research institute of china electronics technology group corporation, China

Two four-pixel receiver arrays for operation in 340 and 250 GHz passive imaging system are presented. The millimeter-wave front-end components and THz mixer are achieved by the planar GaAs Schottky-barrier varactor to obtain good performance in room temperature while lowering the cost and difficulty compared to integrated circuit. The discrete 340GHz and 250GHz mixers have the lowest DSB noise temperature of 1020K and 900K respectively within the operation band . A broadband IF bandwidth, 20GHz, is adopted in passive imaging systems for increasing the received human body radiation power. Good detection performance and space resolution is still obtained for object distances 3-8m. Compared to the current sensors operated in cryogenic imaging system, the receiver array is a cheap and feasible method for personal security screening

Tu-Po2-81
Broadband Bendable Terahertz Camera For Built-in Infrastructure Sensor
Daichi Suzuki¹; Koji Ishibashi¹; Yukio Kawano^2
1RIKEN Center for Emergent Matter Science, Japan; ²Tokyo Institute of Technology, Japan

We present a broadband bendable THz camera, composed of a free-standing carbon nanotube film array, which is intended for an built-in infrastructure sensor. As advantages over conventional solid-state THz sensors, our bendable THz camera can be fabricated through simple and low-cost processes and can simplify optical/electrical measurement systems, which enables us to mount the sensor on objects regardless of their shapes, sizes, and locations. We demonstrate the use of our novel THz camera for real-time nondestructive imaging of industrial products, indicating possibilities of one of the powerful components such as built-in/wearable THz sensors for future imaging and remote sensing.

Tu-Po2-82
A Full-wave Analysis Of Lenses For THz Detectors Purposes
Pawel Kopyt¹; Bartlomiej Salski¹; Jerzy Cuper¹; Przemyslaw Zagrajek^2
1Warsaw University of Technology, Poland; ²Military University of Technology, Poland

In this work an analysis of power density inside various types of lenses is presented. Properties of structures commonly used in THz detectors have been verified using a full-wave EM simulations. Two alternative implementations of EM solvers have been considered. Possibility of replacing spherical-based structures with more sophisticated elliptical lenses were considered as well, showing similar properties

Tu-Po2-83
THz Super-Resolution Imaging With Parallel-Pixel Data Acquisition For Rapid Inspection Applications
Rungroj Jintamethasawat; Chayut Thanapirom; Patharakorn Rattanawan; Napat Cota; Natcha Cota; Chia Jia Yi; Kittipong Kasamsook
National Electronics and Computer Technology Center, Thailand

A multi-frame, super-resolution imaging algorithm for a THz array detector with parallel-pixel data acquisition is proposed to overcome both detector resolution limit and prolonged acquisition time. A correction scheme was also implemented to counteract a fixed-pattern noise caused by non-uniform pixel responsivity observed in our experimental results. The proposed technique aims to serve the demands for THz non-destructive testing (NDT) and quality control (QC) applications, which requires a rapid high-resolution THz imaging system.

Tu-Po2-84
A Terahertz Superconducting Single-Pixel Imaging System Using DMD
Yilong Zhang; Yuan Ren; Wei Miao; Hao Gao; Shengcai Shi
Purple Mountain Observatory, Chinese Academy of Sciences, China

We propose a terahertz superconducting single-pixel imaging system with a single hot electron bolometer (HEB) detector combined with a digital-mirror-device (DMD). With the DMD as a programmed coding reflector, the proposed imaging system could acquire coded measurement results of an imaged scene rapidly even with a single detector. Base on compressive sensing (CS) techniques, the imaged scene was reconstructed by fewer coded measurements compared to the image size. We demonstrated that the proposed single-pixel imaging system framework could significantly improve the imaging efficiency and resolution.

Tu-Po2-85
The Design Of W Band Dual Polarization Parabolic High Gain Antenna
Zhengxin Fang; Sen Feng
ECEIEE, China

In this paper, a dual-polarization parabolic high-gain antenna in the W-band is designed. Dual polarized horn is used as feeds in the antenna in the antenna systems. A microstrip reflection array is attached to the parabolic column as a reflective surface. The antenna has dual polarization. In the azimuth direction, phase compensation is performed by the microstrip reflection array applied to the inner surface of the parabolic column, and lobe focusing is achieved together with the dual-polarized horn feed, in the elevation direction, lobe focusing is achieved by means of a parabolic surface on the elevation surface and a dual-polarized horn feed, the W-band far-field pattern is thus obtained. The antenna is 0.6m long and 0.6m wide. After tested, the sidelobe level is â?¤-25dB, the cross polarization is <-30dB, and the gain is >52.5dB in the bandwidth of 93.5GHz-95.5GHz. The antenna has compact structure, small volume, light weight, it is simple feeding, low cost .

Tu-Po2-86
Comparative Study Of Millimeter Wave III/V Semiconductor And Integrated Silicon Based FMCW Radars
Jean-Paul Guillet¹; Frédéric Fauquet²; Jing Shun Goh²; Adrien Chopard²; Jean-Baptiste Perraud²; Marie Roux³; Patrick Mounaix^2
1Laboratoire IMS / Université de Bordeaux / CNRS UMR 5218, France; ²IMS Laboraotry, France; ³Atelier des renaissances, France

In this publication, we present comparative study of the last developments of frequency modulated continuous wave (FMCW) systems in the terahertz frequency range including GaAs based systems and SiGe integrated systems.

Tu-Po2-87
Study Of A THz Hollow-core Fiber For Sample Reflectance Analysis
Mingming Pan¹; Cristiano M. B. Cordeiro²; Frédéric Fauquet¹; Patrick Mounaix¹; Gildo S Rodrigues²; Marcos A. R. Franco³; Jean-Paul Guillet^4
1IMS Laboraotry, France; ²Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Brazil; ³Instituto Tecnológico de Aeronáutica-ITA, Brazil; ⁴Laboratoire IMS / Université de Bordeaux / CNRS UMR 5218, France

We investigated a 3D printed hollow-core THz waveguide with a suitable frequency band to be, in the future, associated with a guided reflectometry system.

Tu-Po2-88
Cooled Silicon-On-Insulator Diode Thermometer: Toward THz Passive Imaging
Jérémy Blond; Jérôme Meilhan; Abdelkader Aliane; Laurent Dussopt
CEA LETI, France

Terahertz passive imaging requires high sensitivity detectors, with Minimum Detectable Power (MDP) under the picowatt range. An antenna-coupled cooled microbolometer, incorporating a lateral PiN-like diode as thermometer, could represent a solution. In a first step, such diode performances have to be investigated, especially the temperature coefficient of current (TCC) and the low frequency noise. Prototypes were fabricated on Silicon-On-Insulator (SOI) 4" wafers with 50-nm active silicon layer. I-V and noise measurements down to 81K were useful to derive the electrical MDP of the future bolometer, already reaching 6.6 pW at 10 frames per second.

Tu-Po2-89
Continuous-wave Terahertz Computed Tomography Based On Bessel Beam
Lu Rong; Bin Li; Dayong Wang; Yunxin Wang; Jie Zhao; Xiaoyu Shi
Beijing University of Technology, China

We report a continuous-wave terahertz computed tomography using Bessel beam generated by the axicon. Two-dimensional cross-sectional images of the internal structure of plastic pipes at different distances are reconstructed by using the filtered back projection algorithm. Compared with conventional Gaussian beam, Bessel beam can extend the depth of field and improve the fidelity of the reconstruction.

Tu-Po2-90
Diffraction Of Terahertz Gaussian And Bessel Beams On 2D Gratings With Wavelength-Scale Openings
Oleg Kameshkov; Boris Knyazev; Igor Kotelnikov; Boris Goldenderg
Budker Institute of Nuclear Physics, Russian Federation

The diffraction of Gaussian and arbitrary-order Bessel wavefronts on the 2D periodic amplitude and phase gratings, including those with holes whose diameters are close to the wavelength, was investigated. When the amplitude grating is illuminated by a Bessel beam, the self-images of the grating in the main and fractional Talbot planes turn into lattices of rings whose radii depend in a complex way on the grating parameters and on the illuminating beam characteristics. The results of the experiments carried out using the wavelength-tunable radiation of the Novosibirsk free electron laser (NovoFEL) are in good agreement with the numerical calculations and the analytical model developed.

Tu-Po2-91
High Resolution Passive THz Imaging Array With Polarization Reusage In 22nm CMOS
Sven van Berkel; Satoshi Malotaux; Bart van den Bogert; Marco Spirito; Daniele Cavallo; Andrea Neto; Nuria Llombart
Delft University of Technology, Netherlands

A 12-pixel THz Focal Plane Array (FPA), integrated in Global Foundries 22nm CMOS technology, enabling high resolution passive THz imaging, is presented. The array efficiently couples blackbody radiation from 200 GHz to 600 GHz to Schottky Barrier Diodes (SBDs) in a differential topology. An antenna-detector co-design results in an average Noise Equivalent Power (NEP) of 0.9 pW/√Hz. An extremely small array periodicity is achieved by using two orthogonal polarizations. Such configuration enables passive imaging with a near-diffraction limited resolution while simultaneously maintaining a high optical efficiency of 42%. The array is currently in tape-out and measurements will be presented at the conference.

Tu-Po2-92
Full-field THz Polarimetric Imaging With THz Quantum Cascade Laser And THz Imager
Takahiko Mizuno¹; Takuya Moriki²; Masatomo Yamagiwa²; Takeo Minamikawa¹; Takeshi Yasui^1
1Institute of Post-LED Photonics, Tokushima University, Japan; ²Faculty of Mechanical Engineering, Tokushima University, Japan

We demonstrate full-field THz polarimetric imaging with THz quantum cascade laser and THz imager. In contrast to point-scanning THz polarization imaging based on THz-TDS, the demonstrated method does not need mechanical stages for time-delay scanning and sample-position scanning. Due to no mechanical scanning, the fill-field polarimetric images are acquired with moderate frame rate.

Tu-Po2-93
Quantum Probability Theory Applied To Improve Terahertz Imaging Quality
Xuling Lin¹; Zhi Zhang¹; Jianbing Zhang²; Zhimin Dai^2
1Beijing Institute of Space Mechanics and Electricity, China; ²Shanghai Institute of Applied Physics, Chinese Academy of Sciences, China

THz imaging plays an important role in astronomy, atmospheric remote sensing and biological identification. Improvement of imaging quality is of great significance to the application of terahertz imaging system. In this paper, on the basis of quantum probability statistics, an image enhancement method for improving terahertz imaging quality is proposed. Experimental results show that this method takes account of both global and local image information, and improves the quality of terahertz image effectively.

Tu-Po2-94
Terahertz Digital Holography Using Field-Effect Transistor Detectors
Yuchen Zhao¹; Dmytro But²; Marc Georges¹; Wojciech Knap^3
1Centre Spatial de Liège, Université de Liège, Belgium; ²Center for Terahertz Research and Applications (CENTERA), Institute for High Pressure Physics,Polish, Poland; ³Laboratory Charles Coulomb, Montpellier University, France

We report on the experimental realization of digital holography at 140 GHz using terahertz detectors based on field-effect transistors. We demonstrate that hologram signal can be efficiently recorded by the FET detector at room temperature. The digital reconstructions of amplitude and phase objects are presented. Owing to the possibility for FET array integration and massive production, potential towards fast scan nondestructive testing application is discussed.

Tu-Po2-95
Genetic Algorithm Based Optimization For Terahertz Time-Domain Adaptive Sampling
Kaidi Li¹; Xuequan Chen¹; Rui Zhang²; Emma Pickwell-MacPherson³; Shuaiqi Shen¹; Kai Liu^1
1The Chinese University of Hong Kong, China; ²Shenzhen Institutes of Advanced Technology, Chines Academy of Science, China; ³The Chinese University of Hong Kong, Hong Kong and Department of Physics, The University of Warwick, the United Kingdom

We propose an approach based on a genetic algorithm (GA) to improve the sampling efficiency in terahertz time-domain spectroscopy (THz-TDS). The experimental results show that our approach can greatly reduce the sampling time whilst maintain a very high accuracy compared to high-resolution step scanning. Moreover, this approach can be easily implemented in most TDS systems equipped with a delay stage without any hardware cost. The accuracy, flexibility and efficiency indicate great potential for this approach to improve the scanning speed in a wide range of applications.

Tu-Po2-96
Hybrid Technique For Gas Sensing Based On Differential Cavity Ring Down Spectroscopy Sensitized With Thermal Lens Effect
Atsushi Yarai
Osaka Sangyo University, Japan

A new gas sensing technique based on a cavity ring down (CRD) spectroscopy is proposed. This technique features the hybrid operation for enhancing the sensitivity by amplifying the optical absorption efficiency with a thermal lens effect. At first, system configuration composed of optical fiber is presented. Then, the observed comb-like differential CRD signal which exhibits its capability definitely is shown. It is confirmed that the detectability is approximately 20 μmol/liter as the limit of detection value with P(13) absorption line of acetylene gas. It is a few-fold higher value compared with our conventional technique.

Tu-Po2-97
Metasurface-Based Anti-Alias Filters For Improved THz-TDS Measurements
Nazar Nikolaev¹; Sergei Kuznetsov²; Alina Rybak³; Shang-Hua Yang^4
1Institute of Automation and Electrometry SB RAS, Russian Federation; ²Rzhanov Institute of Semiconductor Physics SB RAS, Russian Federation; ³Novosibirsk State University, Russian Federation; ⁴Department of Electrical Engineering, National Tsing Hua University, Taiwan

We propose an approach to improve THz-TDS low-frequency measurements accuracy. It is based on applying anti-alias filters to narrow the frequency band of the THz signal that allows increasing the sampling interval in accordance with the Nyquist--Shannon theorem. The concept was verified by studying the transmittance spectra of the reference samples -- band-pass THz filters centered at 156 and 376 GHz. We show a reduction of the spectrometer scanning time by up to 12 times while maintaining the measurement accuracy. The prospects for using this approach to increase the dynamic range and the signal-to-noise ratio of the spectrometer in the subterahertz range are discussed.

Tu-Po2-98
Optical Heterodyne Detection In The Terahertz Region For Accurate Frequency Measurement
Shin'ichiro Hayashi; Shingo Saito; Norihiko Sekine
National Institute of Information and Communications Technology, Japan

We propose an optical heterodyne detection in the terahertz region using parametric up-conversion in a nonlinear LiNbO3 crystal for accurate frequency measurement. Nonlinear wavelength up-conversion techniques based on frequency stabilized infrared pumping beam allow the spectra in the terahertz region to be determine their frequency and intensity. These are very promising for extending applied research into the terahertz region, and we expect that these will open up new research fields such as wireless information communications in the terahertz region.

Tu-Po2-99
Combination Of Adaptive Sampling Terahertz Dual-Comb Spectroscopy With A Free-Running Single-Cavity Dual-Comb Fiber Laser
Jie Chen; Kuzuki Nitta; Xin Zhao; Takahiko Mizuno; Takeo Minamikawa; Zheng Zheng; Takeshi Yasui
Beihang University, China

Mode-resolved adaptive sampling terahertz dual comb spectroscopy is demonstrated using a free-running wavelength-multiplexed dual-comb fiber laser, indicating the capability of such single-cavity dual-comb sources for high-precision THz spectroscopy.

Tu-Po2-100
Frequency Measurement For Terahertz Waves Based On The High Magnetic Field Technology
Xin Qi; Houxiu Xiao; Xiaotao Han; Donghui Xia; Pengbo Wang; Xianfei Chen
Huazhong University of Science and Technology, China

A novel method based on the Zeeman Effect has been proposed for the frequency measurement in the THz range. We convert the frequency measurement into magnetic field measurement. In theory, the measurement range can cover the entire THz range as the magnetic field meets the requirement. Using this method, we demonstrate an accuracy of our measurement system as high as 0.01% for the measurement of a 120GHz source, no matter it work at a continuous regime or a pulse regime.

Tu-Po2-101
Uncertainty Quantization Of Fano Resonance Frequency Shift Measurement
Tuan Anh Pham Tran; Elana Pereira de Santana; Peter Haring Bolívar
University of Siegen - High Frequency and Quantum Electronics, Germany

We describe and characterize a Fano-resonance frequency shift measurement setup at 300GHz for ex-situ biomolecule detection applications. By quantifying experimental contributions from each uncertainty source, trade-offs can be adapted to achieve the desired system stability requirements. We obtain a 10 MHz standard deviation in determining resonance position with repeated sample exchange and repositioning, and determine the future to attain a 2 MHz frequency shift precision at 300GHz.

Tu-Po2-102
Dual-band Electromagnetically Induced Transparency Effect In Asymmetrically Coupled Terahertz Metamaterials
Dipa Ghindani¹; Rakesh Sarkar²; Monika Devi Koijam²; Ravikumar Jain³; Arnab Pattanayak³; Shriganesh Prabhu³; Gagan Kumar^2
1Tata Institute of Fundamental Research, India; ²Department of Physics, Indian Institute of Technology Guwahati, India; ³Tata Institute of Fundamental Research, Foton Lab, India

In this article, we propose a metamaterial geometry capable of exhibiting dual-band electromagnetic induced transparency (EIT) effect in terahertz frequency regime. The meta-molecule unit consists of two C resonators of different dimensions, placed alternately on both sides of a cut-wire (CW). Our study can play an important role in the development of multi-band slow light devices and also for sensing applications.

Tu-Po2-103
THz Wave Generation In Nonlinear Crystal ?eta-BBO
Jingguo Huang¹; Zhiming Huang¹; Yury Andreev²; Grigory Lanskii²; Dmitrii Lubenko³; Nazar Nikolaev⁴; Valery Losev^3
1Shanghai Institute of Technical Physics CAS, China; ²Institute of Monitoring Climatic and Ecological Systems SB RAS, Russian Federation; ³Institute of High Current Electronics SB RAS, Russian Federation; ⁴Institute of Automation and Electrometry SB RAS, Russian Federation

Nonlinear crystals of beta-barium borate, beta-BBO (further BBO) are widely used to generate THz radiation in a laser filament in two-color optical systems, in which BBO is used to for the second harmonic generation of the pump radiation. It should be outlined that BBO crystal can be used for frequency conversion of visible - IR laser emissions into the THz range in accordance with the recent study. Possessing high damage threshold, despite of low nonlinear coefficients, BBO crystal can be considered as an effective nonlinear crystal for THz generation by parametric nonlinear processes. In this experiment, the THz pulses are realized from BBO crystal pumped by 10-mJ Ti: Sapphire laser complex operating at 950 nm at room temperature. Generation is achieved in spectral range 0.25-0.8 THz.

Tu-Po2-104
15NH3 Terahertz Gas Laser Pumped By A Mid-infrared Quantum-Cascade Laser
Martin Wienold; Alsu Zubairova; Heinz-Wilhelm Hübers
German Aerospace Center (DLR), Germany

We present an optically pumped terahertz gas laser, which is based on a distributed-feedback mid-infrared quantum-cascade laser as a pump source, a standing wave resonator, and 15NH3 as a gain medium.

Tu-Po2-105
High Performance Terahertz Absorption Of Nanostructured NiCr Film For A Pyroelectric Detector
Ziji Liu; Zhiqing Liang; Xing Zheng; Yadong Jiang
University of Electronic Science and Technology of China, China

Nanostructured metallic films is an effective THz absorption layer for pyroelectric detectors.The THz responsivity for detector tested by lock in amplifier reaches 8.38Ã-104V/W and the lowest noise equivalent power value(NEP) reaches 1.27Ã-10-10W/Hz1/2 at 20Hz operating frequency use 2.52THz radiation, which is suitable for THz imaging application. Meanwhile it provides a feasible approach for fabricating high responsivity THz detector

Tu-Po2-106
A Novel Terahertz Microfluidic Chip
Bo Su; Jiahui Wang; Yiwei Wen; Jingsuo He; Shengbo Zhang; Cunlin Zhang
Capital Normal University, People's Republic of China, China

we fabricate a new terahertz microfluidic chip, which can detect liquid samples using THz-TDS system or asynchronous optical sampling system. The chip has a sandwich structure, and consists of substrate, cover and microchannel layer. The substrate and cover are made of two materials, PMMA and cycloolefin copolymers (COC). The microchannel layer is fabricated by PDMS. Through van der Waals force, the substrate, cover and microchannel layer are sealed together. We use the chip to study the transmission of terahertz to deionized water and the influence of different kinds and concentration of electrolyte solution on hydrogen bond in aqueous solution, and the results prove the feasibility of this method.

Tu-Po2-107
Quasi-Optical Design Of ECRH Mirrors For ITER First Plasma Operations
Francesco Fanale¹; Alessandro Bruschi¹; Olivier Darcourt²; Daniela Farina¹; Lorenzo Figini¹; Franco Gandini³; Mark Andrew Henderson³; Ryan Hunt³; Alessandro Moro¹; Paola Platania¹; Burkhard Plaum^4
1Consiglio Nazionale delle Ricerche - Istituto di Fisica del Plasma, Italy; ²Arial Industries, France; ³ITER Organization, France; ⁴Universität Stuttgart - Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie, Germany

A set of components will be installed during ITER fist plasma operation to protect the vacuum vessel and other in-vessel auxiliary systems from the plasma and from the stray radiation injected at the Electron Cyclotron harmonics to generate breakdown and sustain burn-through. This paper focuses on the quasi-optical design of the system of three mirrors redirecting the microwave beams coming from the Electron Cyclotron Resonance Heating (ECRH) upper launcher to the plasma resonance after proper shaping. In particular, the system consists of two shaped mirrors and one grating mirror. The non-absorbed EC power is then intercepted and absorbed into a beam dump located in one equatorial port.

Tu-Po2-108
Terahertz Filter With Flat-top Transmission Response
Antonio Ferraro¹; Alfonso A. Tanga²; Dimitrios C. Zografopoulos¹; Gabriele C. Messina³; Michele Ortolani²; Romeo Beccherelli^1
1Consiglio Nazionale delle Ricerche - Istituto per la Microelettornica e Microsistemi CNR-IMM, Italy; ²Department of Physics, Sapienza University of Rome, Italy; ³Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi (CNR-ISC), Italy

A new terahertz filter based on the coupling of guided-mode resonances and Fabry-Perot resonance is presented resulting in a flat top response. The spectral response lies in the sub-THz communication windows with central frequency of 300 GHz. The filter performance shows high transmittance, with less than 3dB losses, and high out-of-band rejection. The filter is fabricated via standard photolithography on thin films of the Zeonor polymer. This typology of THz components provides a cost-effective functional solution for narrowband filtering in emerging THz devices and systems for telecommunication.

Tu-Po2-109
Polarization And Sectioning Characteristic Of THz Confocal Microscopy
Min Wan¹; Dovilė Čibiraitė²; Bing Li³; Hui Yuan²; Viktor Krozer²; Hartmut Roskos²; Da Yong Wang³; John Sheridan^1
1School of Electrical & Electronic Engineering, University College Dublin, Ireland; ²Physikalisches Institut, Goethe University Frankfurt, Germany; ³College of Applied Sciences, Beijing University of Technology, China

A 300 GHz confocal microscope has been implemented and tested consistent lateral and axial spatial resolution under difference polarization have been demonstrated.

Tu-Po2-110
Generation And Measurement Of Traceable THz Frequencies
Gregory Gäumann; Jacques Morel
Federal Institute of Metrology METAS, Switzerland

The THz radiation is generated by optical heterodyning of two lasers in a phomixer and the frequency traceability is achieved either by measuring the laser frequencies with a traceable wavemeter or by directly referencing the two lasers to a self-referenced optical frequency comb (OFC) locked to an atomic clock. This method will allow achieving a relative THz frequency uncertainty below 8?10-9.

Tu-Po2-111
Tail-suppressed THz Photocurrent By A Bi-polar Photoconductive Antenna Fabricated On Semi-insulating GaAs
Anup Kumar Sahoo¹; Hsiao-Hua Wu²; Yu-Cheng Hong¹; Yu-Chen Chang¹; Osamu Wada³; Ci-Ling Pan^1
1Department of Physics, National Tsing Hua University, Taiwan; ²Department of applied physics, Tunghai University, Taiwan; ³Office for Academic and Industrial Innovation (Oacis), Kobe University, Japan

We designed and fabricated bi-polar type photoconductive antenna (PCA) for efficient generation of broadband terahertz (THz) radiation. The falling time of overlayingly generated photocurrent from bi-polar PCA can be achieved 200 fs via superimposing two primariy opposite polarity photocurrent pulses having falling time of 100 ps with time delay of 200 fs. The simulation results disclosed a possibility to shift the central frequency from 0.1 to 1.3 THz and enhance the THz power by twice in the range 1.5 - 3.3 THz by using low cost substrate with long carrier life time such as semi-insulating gallium arsenide (SI-GaAs).

Tu-Po2-112

THz To Inspect Graphene And Thin Film Materials
Álvaro Cordón¹; Luis Miranda¹; Cristian Martínez¹; Andrea Inés¹; David Etayo¹; Montserrat Fernández¹; Pablo Rodríguez¹; Elena Taboada¹; Albert Redó-Sánchez¹; Mónica Castrillo¹; Miguel A. G. Laso²; Israel Arnedo^1,2
1Das-Nano, Spain; ²Universidad Publica de Navarra (UPNA), Dept. Electrical, Electronic and Communications Eng., Spain

In this paper, we present a system that provides meso-scale characterization of thin film materials, covering the gap between nano-scale and macro-scale methods. Nano-scale methods are slow and cannot characterize large surfaces. Macroscale methods generate characterization that averages the magnitudes and, thus, cannot provide localized information. Our system works in reflection as opposed to state-of-the-art methods and provides mobility, carrier density, and conductance maps in the THz range. Moreover, it can be integrated with reactors and enables monitoring of the fabrication of materials in real-time, supporting, for instance, the production of graphene at industrial scale.

Tu-Po2-113
Excitonic Terahertz Emission From Silicon At Steady-State Interband Photoexcitation
Alexey Zakhar'in; Alexander Andrianov
Ioffe Institute, Russian Federation

Terahertz range photoluminescence from specially designed structures with tunnel coupled double quantum wells under interband optical excitation has been investigated. A series of narrow emission lines were observed and interpreted as intersubband radiative transitions between electron quantum confinement levels.