Pub Date : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327887
M. Havenith
Summary form only given. Terahertz (THz) absorption spectroscopy is a powerful tool to study (bio)molecular hydration. The development of THz technology helped to full the experimental gap in this frequency range. These experimental advances had to go hand in hand with the development of theoretical concepts that have been developed in the recent years to describe the underlying solute-induced sub-picosecond dynamics of the hydration shell. This frequency range covers the so-called rattling modes of the ion with its hydration cage and allows to derive major conclusions on the molecular picture of ion hydration, a key issue in chemistry. THz spectroscopy allows the quantification of the hydration shell around ions, and the characterization ion pairs. By a combination of experiment and theory, it is now possible to rigorously dissect the THz spectrum of a solvated biomolecule into the distinct solute, solvent and solute-solvent coupled contributions. Moreover, we highlight recent results that show the significance of hydrogen bond dynamics for molecular recognition. In all of these examples, a gradient of water motion toward functional sites of proteins is observed, the so-called “hydration funnel”.
{"title":"It is water what matters: THz absorption spectroscopy as a new tool to study solvation dynamics","authors":"M. Havenith","doi":"10.1109/IRMMW-THZ.2015.7327887","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327887","url":null,"abstract":"Summary form only given. Terahertz (THz) absorption spectroscopy is a powerful tool to study (bio)molecular hydration. The development of THz technology helped to full the experimental gap in this frequency range. These experimental advances had to go hand in hand with the development of theoretical concepts that have been developed in the recent years to describe the underlying solute-induced sub-picosecond dynamics of the hydration shell. This frequency range covers the so-called rattling modes of the ion with its hydration cage and allows to derive major conclusions on the molecular picture of ion hydration, a key issue in chemistry. THz spectroscopy allows the quantification of the hydration shell around ions, and the characterization ion pairs. By a combination of experiment and theory, it is now possible to rigorously dissect the THz spectrum of a solvated biomolecule into the distinct solute, solvent and solute-solvent coupled contributions. Moreover, we highlight recent results that show the significance of hydrogen bond dynamics for molecular recognition. In all of these examples, a gradient of water motion toward functional sites of proteins is observed, the so-called “hydration funnel”.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"14 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84493825","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327573
S. Cauffman, M. Blank, P. Borchard, K. Felch
A 140 GHz gyrotron capable of producing output powers up to 900 kW for 1000-second pulses has been developed at CPI. Factory testing demonstrated 1000-second operation at the 25 A CW current limit of the test facility, at which the output power was about 500 kW, and demonstrated 900 kW operation for short pulses. The gyrotron was then shipped to Hefei, China, and installed as part of the electron cyclotron heating and current drive system for the EAST tokamak. Commissioning of the gyrotron at the EAST site is currently in progress, with the goal of demonstrating operation at full parameters (900 kW for 1000-second pulses).
{"title":"Design and testing of a 900 kW, 140 GHz gyrotron","authors":"S. Cauffman, M. Blank, P. Borchard, K. Felch","doi":"10.1109/IRMMW-THZ.2015.7327573","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327573","url":null,"abstract":"A 140 GHz gyrotron capable of producing output powers up to 900 kW for 1000-second pulses has been developed at CPI. Factory testing demonstrated 1000-second operation at the 25 A CW current limit of the test facility, at which the output power was about 500 kW, and demonstrated 900 kW operation for short pulses. The gyrotron was then shipped to Hefei, China, and installed as part of the electron cyclotron heating and current drive system for the EAST tokamak. Commissioning of the gyrotron at the EAST site is currently in progress, with the goal of demonstrating operation at full parameters (900 kW for 1000-second pulses).","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"11 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78698965","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}
M. Klos, R. Bartholdt, J. Klier, J. Lampin, R. Beigang
Summary form only given. We present investigations of photoconductive antennas (PCA) based on low temperature grown GaAs (LT GaAs) on silicon substrates for terahertz (THz) detection and generation. The PCAs consist of 2 μm thick layers of LT GaAs bonded on a high resistivity silicon substrate in order to reduce the intrinsic absorption losses around 8 THz due to a strong phonon resonance in GaAs. Using 20 fs long pump pulses around 800 nm and dipole antennas with dipole length between 20 μm and 60 μm a maximum bandwidth above 10 THz and a maximum dynamic range exceeding 90 dB at 0.5 THz were obtained. The average output power was measured with a calibrated detector to be 5 μW at a repetition rate of 80 MHz.
{"title":"Photoconductive antennas based on low temperature grown GaAs on silicon substrates for broadband terahertz generation and detection","authors":"M. Klos, R. Bartholdt, J. Klier, J. Lampin, R. Beigang","doi":"10.1117/12.2217505","DOIUrl":"https://doi.org/10.1117/12.2217505","url":null,"abstract":"Summary form only given. We present investigations of photoconductive antennas (PCA) based on low temperature grown GaAs (LT GaAs) on silicon substrates for terahertz (THz) detection and generation. The PCAs consist of 2 μm thick layers of LT GaAs bonded on a high resistivity silicon substrate in order to reduce the intrinsic absorption losses around 8 THz due to a strong phonon resonance in GaAs. Using 20 fs long pump pulses around 800 nm and dipole antennas with dipole length between 20 μm and 60 μm a maximum bandwidth above 10 THz and a maximum dynamic range exceeding 90 dB at 0.5 THz were obtained. The average output power was measured with a calibrated detector to be 5 μW at a repetition rate of 80 MHz.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"14 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78880248","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327833
M. Mandehgar, D. Grischkowsky
We demonstrate that dispersive compensation can be achieved for the communication channels within the atmospheric THz windows using the long-path THz-TDS system. However, the THz pulse broadening cannot be eliminated due to the bandwidth reduction of the propagating THz pulse due to the frequency dependent absorption of the channels.
{"title":"Dispersion compensation of the THz communication channels in the atmosphere","authors":"M. Mandehgar, D. Grischkowsky","doi":"10.1109/IRMMW-THZ.2015.7327833","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327833","url":null,"abstract":"We demonstrate that dispersive compensation can be achieved for the communication channels within the atmospheric THz windows using the long-path THz-TDS system. However, the THz pulse broadening cannot be eliminated due to the bandwidth reduction of the propagating THz pulse due to the frequency dependent absorption of the channels.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"90 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72808822","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327609
Quan Li, Xueqian Zhang, Z. Tian, Ranjan Singh, L. Du, J. Gu, C. Ouyang, Jiaguang Han, Weili Zhang
With simultaneous optical and electrical excitations, we experimentally demonstrate an active modulation of transmitted terahertz waves through a graphene-silicon hybrid structure. A large transmission modulation of 83% was observed. Meanwhile, a “diode” behavior was found in such a structure, where terahertz waves transmits when biased with a positive voltage while attenuates under a low negative voltage.
{"title":"Active terahertz modulations based on graphene-silicon hybrid structures","authors":"Quan Li, Xueqian Zhang, Z. Tian, Ranjan Singh, L. Du, J. Gu, C. Ouyang, Jiaguang Han, Weili Zhang","doi":"10.1109/IRMMW-THZ.2015.7327609","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327609","url":null,"abstract":"With simultaneous optical and electrical excitations, we experimentally demonstrate an active modulation of transmitted terahertz waves through a graphene-silicon hybrid structure. A large transmission modulation of 83% was observed. Meanwhile, a “diode” behavior was found in such a structure, where terahertz waves transmits when biased with a positive voltage while attenuates under a low negative voltage.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"30 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72864823","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327660
Ming Xu, W. Shi, Xiaoqing He, Zhijin Yan, Hong Liu
In order to explore the efficient THz emitter with GaAs photoconductive semiconductor switch (PCSS), it's necessary to achieve the suppression of high gain mode in high electric field. The infrared activation and inhibition of high field domains is achieved and the good hold-off characteristics is obtained with 32 kV.
{"title":"Suppression of high gain GaAs photoconductive semiconductor switch at high electric field","authors":"Ming Xu, W. Shi, Xiaoqing He, Zhijin Yan, Hong Liu","doi":"10.1109/IRMMW-THZ.2015.7327660","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327660","url":null,"abstract":"In order to explore the efficient THz emitter with GaAs photoconductive semiconductor switch (PCSS), it's necessary to achieve the suppression of high gain mode in high electric field. The infrared activation and inhibition of high field domains is achieved and the good hold-off characteristics is obtained with 32 kV.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"35 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86839116","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327628
Xiao Rao, Jintao Fan, Yanfeng Li
We propose a novel bandgap fiber for the transmission of terahertz (THz) radiation based on a Kagome lattice of air holes. The fiber core comprises a triangular lattice of air holes having the same or a smaller size than the cladding air holes. Numerical simulation of a 19-cell fiber is carried out using finite element method. Proper design of the fiber parameters allows the transmission of broadband THz radiation in the 1.0~2.3 THz range.
{"title":"Broadband porous-core bandgap terahertz fiber based on Kagome lattice of air holes","authors":"Xiao Rao, Jintao Fan, Yanfeng Li","doi":"10.1109/IRMMW-THZ.2015.7327628","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327628","url":null,"abstract":"We propose a novel bandgap fiber for the transmission of terahertz (THz) radiation based on a Kagome lattice of air holes. The fiber core comprises a triangular lattice of air holes having the same or a smaller size than the cladding air holes. Numerical simulation of a 19-cell fiber is carried out using finite element method. Proper design of the fiber parameters allows the transmission of broadband THz radiation in the 1.0~2.3 THz range.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"22 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87364446","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327703
I. Zotova, N. Ginzburg, M. Glyavin, A. Sergeev, R. Rozental, A. Fokin
Based on the description of wave propagation by a parabolic equation the time-domain theory of non-autonomous operation of gyrotrons with low-Q resonators has been developed. The influence of external signal is taking into account by modification of boundary condition at resonator output. Developed model can be effectively used for simulations of frequency-locking of gyrotron by external signal in soft and hard operation modes, frequency pooling with reflection from remote load, synchronization of several coupling gyrotrons.
{"title":"Non-autonomous regimes in gyrotrons with low-Q resonators","authors":"I. Zotova, N. Ginzburg, M. Glyavin, A. Sergeev, R. Rozental, A. Fokin","doi":"10.1109/IRMMW-THZ.2015.7327703","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327703","url":null,"abstract":"Based on the description of wave propagation by a parabolic equation the time-domain theory of non-autonomous operation of gyrotrons with low-Q resonators has been developed. The influence of external signal is taking into account by modification of boundary condition at resonator output. Developed model can be effectively used for simulations of frequency-locking of gyrotron by external signal in soft and hard operation modes, frequency pooling with reflection from remote load, synchronization of several coupling gyrotrons.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"43 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87392534","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327805
A. Garufo, G. Carluccio, N. Llombart, A. Neto
Summary form only given. The generation of THz signals resorting to photosensitive semiconductors has been the object of various analysis in the recent years. Typically, such sources consist in a optically pumped semiconductor which is coupled to an antenna to generate THz power. In this paper a theoretical model, based on a spectral Green's function formulation, for infinite slot fed by a THz photoconductor generator is shown. An equivalent circuit model is then derived, which gives a description of the involved THz power generation and radiation mechanisms. Such model is a useful engineering tool for the analysis and the design of photo-conductive slot antennas.
{"title":"Equivalent circuit model based on spectral Green's function representation for photo-conductive slot antennas","authors":"A. Garufo, G. Carluccio, N. Llombart, A. Neto","doi":"10.1109/IRMMW-THZ.2015.7327805","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327805","url":null,"abstract":"Summary form only given. The generation of THz signals resorting to photosensitive semiconductors has been the object of various analysis in the recent years. Typically, such sources consist in a optically pumped semiconductor which is coupled to an antenna to generate THz power. In this paper a theoretical model, based on a spectral Green's function formulation, for infinite slot fed by a THz photoconductor generator is shown. An equivalent circuit model is then derived, which gives a description of the involved THz power generation and radiation mechanisms. Such model is a useful engineering tool for the analysis and the design of photo-conductive slot antennas.","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"53 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86282947","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 : 2015-11-12DOI: 10.1109/IRMMW-THZ.2015.7327761
Joo-Gwang Lee, Chihyun Cho
This paper describes how to calibrate phase response of oscilloscopes, especially at low frequencies from 10 MHz to 1 GHz. The method uses the phase response of a standard mixer calibrated by three-mixer method as the reference phase. We describe basic principles and show results obtained using a balanced mixer and a real-time oscilloscope (1 GHz BW).
{"title":"Phase calibration of oscilloscopes at low frequencies","authors":"Joo-Gwang Lee, Chihyun Cho","doi":"10.1109/IRMMW-THZ.2015.7327761","DOIUrl":"https://doi.org/10.1109/IRMMW-THZ.2015.7327761","url":null,"abstract":"This paper describes how to calibrate phase response of oscilloscopes, especially at low frequencies from 10 MHz to 1 GHz. The method uses the phase response of a standard mixer calibrated by three-mixer method as the reference phase. We describe basic principles and show results obtained using a balanced mixer and a real-time oscilloscope (1 GHz BW).","PeriodicalId":6577,"journal":{"name":"2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)","volume":"22 1","pages":"1-2"},"PeriodicalIF":0.0,"publicationDate":"2015-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82699545","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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