Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370438
M. Fukunari, Taisei Ozura, Masato Watanabe, Y. Yamaguchi, Y. Tatematsu, T. Saito, M. M. Melnikova, A. Rozhnev, N. Ryskin
A complex cavity was fabricated to improve the mode selection property of a gyrotron for the 400 GHz second-harmonic oscillation. A combination of the TE8,3and the TE8,5modes was selected to provide resonant coupling. In the experiment, many fundamental and several second-harmonic modes oscillated independently in either the first or the second cavity. However, no fundamental oscillation was observed in the operation magnetic field region of the TE8,3/TE8,5 mode. The fabrication error of the cavity radii was successfully controlled to be smaller than 1 $mumathrm{m}$. The oscillation of the design mode was observed by the frequency measurements. However, a mode competition with the TE3,5 mode occurred.
{"title":"Frequency Measurements of a Complex-Cavity Gyrotron for 400 GHz Second-Harmonic Oscillation","authors":"M. Fukunari, Taisei Ozura, Masato Watanabe, Y. Yamaguchi, Y. Tatematsu, T. Saito, M. M. Melnikova, A. Rozhnev, N. Ryskin","doi":"10.1109/IRMMW-THz46771.2020.9370438","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370438","url":null,"abstract":"A complex cavity was fabricated to improve the mode selection property of a gyrotron for the 400 GHz second-harmonic oscillation. A combination of the TE8,3and the TE8,5modes was selected to provide resonant coupling. In the experiment, many fundamental and several second-harmonic modes oscillated independently in either the first or the second cavity. However, no fundamental oscillation was observed in the operation magnetic field region of the TE8,3/TE8,5 mode. The fabrication error of the cavity radii was successfully controlled to be smaller than 1 $mumathrm{m}$. The oscillation of the design mode was observed by the frequency measurements. However, a mode competition with the TE3,5 mode occurred.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"26 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72676109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370676
Juin W. Zhou, Zachery B. Harris, Omar B. Osman, Andrew Chen, Mahmoud E. Khani, M. Arbab
To solve the phase ambiguity problem in the THz reflection spectroscopy, current material parameter extraction methods require the sample to make an ideal contact with an optically transparent window. We treat these samples as a multilayer system and present a new algorithm that estimates the thickness of the potential air gap and calculates the complex refractive index of the samples.
{"title":"Material Parameter Extraction Using Terahertz Time-Domain Reflection Spectroscopy in the Presence of Air Gaps","authors":"Juin W. Zhou, Zachery B. Harris, Omar B. Osman, Andrew Chen, Mahmoud E. Khani, M. Arbab","doi":"10.1109/IRMMW-THz46771.2020.9370676","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370676","url":null,"abstract":"To solve the phase ambiguity problem in the THz reflection spectroscopy, current material parameter extraction methods require the sample to make an ideal contact with an optically transparent window. We treat these samples as a multilayer system and present a new algorithm that estimates the thickness of the potential air gap and calculates the complex refractive index of the samples.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"24 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75126288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370529
Aidan W. Schiff-Kearn, Lauren Gingras, Simon Bernier, N. Chamanara, Kartiek Agarwal, J. Ménard, D. Cooke
We demonstrate experimentally a strategy for using relativistic moving dielectric fronts to trigger and affect the generation of coherent terahertz (THz) pulses. Our emission mechanism draws energy from the photoexcitation of built-in static Schottky fields present at metal-semiconductor boundaries in a silicon-filled parallel plate waveguide (PPWG). Fronts tuned to sub-luminal velocity produce THz pulses whose electric field temporal profile displays a stretched plateau of quasi-dc character. Super-luminal fronts, on the other hand, provide access to front-induced interactions giving a clear signature of pulse time-reversal.
{"title":"Tailoring Terahertz Pulses with Moving Fronts: Temporal Stretching and Time-Reversal","authors":"Aidan W. Schiff-Kearn, Lauren Gingras, Simon Bernier, N. Chamanara, Kartiek Agarwal, J. Ménard, D. Cooke","doi":"10.1109/IRMMW-THz46771.2020.9370529","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370529","url":null,"abstract":"We demonstrate experimentally a strategy for using relativistic moving dielectric fronts to trigger and affect the generation of coherent terahertz (THz) pulses. Our emission mechanism draws energy from the photoexcitation of built-in static Schottky fields present at metal-semiconductor boundaries in a silicon-filled parallel plate waveguide (PPWG). Fronts tuned to sub-luminal velocity produce THz pulses whose electric field temporal profile displays a stretched plateau of quasi-dc character. Super-luminal fronts, on the other hand, provide access to front-induced interactions giving a clear signature of pulse time-reversal.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"41 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77743529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370754
H. Zen, H. Ohgaki, R. Hajima
A mid-infrared Free Electron Laser (MIR-FEL) is a candidate to realize a high-repetition-rate atto-second hard X-ray source based on the high harmonic generation (HHG). A new project to conduct a proof of principle experiment of HHG driven by a MIR-FEL has been started since 2018. For this purpose, upgrade project of MIR-FEL at Kyoto University (KU-FEL) has been started to achieve high peak power and ultrashort pulse operation. As the first step of the upgrade, a photocathode drive laser was improved to enable long macro-pulse photocathode operation. The results of the long macro-pulse photocathode operation of KU-FEL will be presented.
{"title":"Upgrade of Mid-Infrared Free Electron Laser at Kyoto University by Long Macro-pulse Photocathode Operation of the Existing RF Gun","authors":"H. Zen, H. Ohgaki, R. Hajima","doi":"10.1109/IRMMW-THz46771.2020.9370754","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370754","url":null,"abstract":"A mid-infrared Free Electron Laser (MIR-FEL) is a candidate to realize a high-repetition-rate atto-second hard X-ray source based on the high harmonic generation (HHG). A new project to conduct a proof of principle experiment of HHG driven by a MIR-FEL has been started since 2018. For this purpose, upgrade project of MIR-FEL at Kyoto University (KU-FEL) has been started to achieve high peak power and ultrashort pulse operation. As the first step of the upgrade, a photocathode drive laser was improved to enable long macro-pulse photocathode operation. The results of the long macro-pulse photocathode operation of KU-FEL will be presented.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"57 1 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77746126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370931
Pascal Strathkötter, A. Stroh, H. Hafez, Wentao Zhang, S. Jerng, S. Chun, D. Turchinovich
We investigate the THz conductivity of the topological insulator Bi2Se3, in a systematic study involving samples of different thicknesses. In our analysis we compare the fits of experimental data to two suggested models, describing the electron and phonon contributions: Drude with Fano-modified Lorentzian resonance, and Drude with a two-Lorentzian resonance. Analysis of the fit accuracy suggests that the asymmetric shape of the lattice resonance in Bi2Se3 might arise from the presence of a surface vibrational state, rather than from the electron-phonon Fano interference, as was previously suggested.
{"title":"Determination of the Terahertz Dielectric Function of the Topological Insulator Bi2Se3","authors":"Pascal Strathkötter, A. Stroh, H. Hafez, Wentao Zhang, S. Jerng, S. Chun, D. Turchinovich","doi":"10.1109/IRMMW-THz46771.2020.9370931","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370931","url":null,"abstract":"We investigate the THz conductivity of the topological insulator Bi2Se3, in a systematic study involving samples of different thicknesses. In our analysis we compare the fits of experimental data to two suggested models, describing the electron and phonon contributions: Drude with Fano-modified Lorentzian resonance, and Drude with a two-Lorentzian resonance. Analysis of the fit accuracy suggests that the asymmetric shape of the lattice resonance in Bi2Se3 might arise from the presence of a surface vibrational state, rather than from the electron-phonon Fano interference, as was previously suggested.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"153 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77882092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370595
A. Leontyev, P. Prudkovskii, G. Kitaeva
We study the statistical properties of optical-terahertz biphotons generated by means of spontaneous parametric down conversion. Numerical dependence of the second-order correlation function is obtained depending on polar angular aperture.
研究了由自发参量下转换产生的光太赫兹双光子的统计性质。得到了二阶相关函数与极角孔径的数值依赖关系。
{"title":"Theoretical study of quantum-correlated optical-terahertz biphotons","authors":"A. Leontyev, P. Prudkovskii, G. Kitaeva","doi":"10.1109/IRMMW-THz46771.2020.9370595","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370595","url":null,"abstract":"We study the statistical properties of optical-terahertz biphotons generated by means of spontaneous parametric down conversion. Numerical dependence of the second-order correlation function is obtained depending on polar angular aperture.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"2 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80131838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370783
Feng Zhang, Izuru Karimata, Hong-Wei Wang, T. Tachikawa, K. Tominaga, M. Hayashi, Tetsuo Sasaki
It has been believed that the short-range correlations of the methylammonium (MA) cations impact the high photovoltaic efficiency of the hybrid organic/inorganic halide perovskite. Employing high-resolution THz spectroscopy technique and solid-state density functional theory method, we have revealed new evidence on 16 correlation patterns of MAs in the MAPbBr3 crystalline system. By integrating the current structural information provided by other analysis methods, we have suggested a fine-structure model for the halide perovskites.
{"title":"Determination of the Fine Structure of a Halide Perovskite using High-resolution THz Spectroscopy and Solid-state Density Functional Theory","authors":"Feng Zhang, Izuru Karimata, Hong-Wei Wang, T. Tachikawa, K. Tominaga, M. Hayashi, Tetsuo Sasaki","doi":"10.1109/IRMMW-THz46771.2020.9370783","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370783","url":null,"abstract":"It has been believed that the short-range correlations of the methylammonium (MA) cations impact the high photovoltaic efficiency of the hybrid organic/inorganic halide perovskite. Employing high-resolution THz spectroscopy technique and solid-state density functional theory method, we have revealed new evidence on 16 correlation patterns of MAs in the MAPbBr3 crystalline system. By integrating the current structural information provided by other analysis methods, we have suggested a fine-structure model for the halide perovskites.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"39 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79365557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370467
M. Bauer, A. Keil, C. Matheis, K. Fukunaga, F. Aramini, M. Palazzo, L. Dall'Aglio, F. Friederich
We present terahertz frequency-modulated continuous-wave (FMCW) measurements of Leonardo da Vinci's “The Last Supper” to investigate the sub-surface structure of the mural painting. We performed non-destructive and contact-free measurements to visualize the preparation layers below the visible painting and possible damages in these layers. In addition, other materials and objects of cultural heritage were investigated in terahertz FMCW reflection and transmission measurements. We demonstrate the potential of terahertz technologies for the investigation of highly sensitive artwork and other objects of cultural heritage.
{"title":"Terahertz FMCW measurements of Leonardo da Vinci's “The Last Supper” and other investigations in the field of cultural heritage","authors":"M. Bauer, A. Keil, C. Matheis, K. Fukunaga, F. Aramini, M. Palazzo, L. Dall'Aglio, F. Friederich","doi":"10.1109/IRMMW-THz46771.2020.9370467","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370467","url":null,"abstract":"We present terahertz frequency-modulated continuous-wave (FMCW) measurements of Leonardo da Vinci's “The Last Supper” to investigate the sub-surface structure of the mural painting. We performed non-destructive and contact-free measurements to visualize the preparation layers below the visible painting and possible damages in these layers. In addition, other materials and objects of cultural heritage were investigated in terahertz FMCW reflection and transmission measurements. We demonstrate the potential of terahertz technologies for the investigation of highly sensitive artwork and other objects of cultural heritage.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"14 1","pages":"01-02"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81595250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370455
M. A. Campo, G. Carluccio, D. Blanco, O. Litschke, S. Bruni, N. Llombart
The use of mm- and sub-mm- waves is becoming increasing interest to be applied in Beyond 5G communication scenarios. The large bandwidth availability in the higher frequencies will enable the expected growth in the capacity of communication networks and devices, which is reaching the saturation with current solutions relaying on lower frequencies, narrow bandwidths and high computational effort. In this work, the use of wideband, low-cost plastic lens antennas is proposed for Beyond 5G scenarios with multiple fixed beams (point-to-multipoint, small cells). Three wideband antenna designs at G-band (140-220GHz) are presented, addressing important requirements in the future antenna systems: high efficiency and gain, circular polarization, and enhanced Field of View.
{"title":"Fly's Eye Lenses for Wideband Beyond 5G Communications","authors":"M. A. Campo, G. Carluccio, D. Blanco, O. Litschke, S. Bruni, N. Llombart","doi":"10.1109/IRMMW-THz46771.2020.9370455","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370455","url":null,"abstract":"The use of mm- and sub-mm- waves is becoming increasing interest to be applied in Beyond 5G communication scenarios. The large bandwidth availability in the higher frequencies will enable the expected growth in the capacity of communication networks and devices, which is reaching the saturation with current solutions relaying on lower frequencies, narrow bandwidths and high computational effort. In this work, the use of wideband, low-cost plastic lens antennas is proposed for Beyond 5G scenarios with multiple fixed beams (point-to-multipoint, small cells). Three wideband antenna designs at G-band (140-220GHz) are presented, addressing important requirements in the future antenna systems: high efficiency and gain, circular polarization, and enhanced Field of View.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"36 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84305215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-08DOI: 10.1109/IRMMW-THz46771.2020.9370555
Rhiannon Lees, H. Sanders, Michael D. Cooke, C. Balocco, A. Gallant
Optical components fabricated using traditional methods are well known as being costly. A potentially cheaper alternative method is 3D printing, however the post-printing processes to reach a desirable finish can also be expensive. This is due to the requirement for several stages of polishing and the use of high-quality metals for strong reflectance percentages. We propose a chemical smoothing post-printing method to produce high quality optical components, for use in the THz region, which are able to achieve comparable performance to commercial components at a significantly reduced cost.
{"title":"Chemical Smoothing as a Method to Manufacture High Quality 3D Printed Optical Components","authors":"Rhiannon Lees, H. Sanders, Michael D. Cooke, C. Balocco, A. Gallant","doi":"10.1109/IRMMW-THz46771.2020.9370555","DOIUrl":"https://doi.org/10.1109/IRMMW-THz46771.2020.9370555","url":null,"abstract":"Optical components fabricated using traditional methods are well known as being costly. A potentially cheaper alternative method is 3D printing, however the post-printing processes to reach a desirable finish can also be expensive. This is due to the requirement for several stages of polishing and the use of high-quality metals for strong reflectance percentages. We propose a chemical smoothing post-printing method to produce high quality optical components, for use in the THz region, which are able to achieve comparable performance to commercial components at a significantly reduced cost.","PeriodicalId":6746,"journal":{"name":"2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)","volume":"17 1","pages":"01-02"},"PeriodicalIF":0.0,"publicationDate":"2020-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84421897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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