The Experts below are selected from a list of 153102 Experts worldwide ranked by ideXlab platform
Nobuhiko Sarukura - One of the best experts on this subject based on the ideXlab platform.
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excitation fluence dependence of terahertz Radiation mechanism from femtosecond laser irradiated inas under magnetic field
Applied Physics Letters, 2003Co-Authors: Hiroshi Takahashi, Shingo Ono, Alex Quema, R Yoshioka, Nobuhiko SarukuraAbstract:The excitation fluence and magnetic field dependence of terahertz (THz) Radiation Power from InAs is investigated. At low excitation fluence, an enhancement of the THz-Radiation Power is observed independent of the magnetic-field direction. As the excitation fluence is increased, a crossover of the terahertz Radiation mechanism is observed. At excitation fluence above this crossover, the Radiation Power is either enhanced or reduced depending on the magnetic-field direction. These results are explained by considering the different THz-Radiation mechanisms from the InAs surface with or without photoexcited carrier screening.
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saturation of thz Radiation Power from femtosecond laser irradiated inas in a high magnetic field
Applied Physics Letters, 2000Co-Authors: Hideyuki Ohtake, Shingo Ono, Masahiro Sakai, Zhenlin Liu, Takeyo Tsukamoto, Nobuhiko SarukuraAbstract:THz-Radiation Power from femtosecond-pulse-irradiated InAs is found to be saturated at the magnetic field around 3 T. Additionally, we find that this saturation magnetic field strongly depends on geometrical layout. Interesting magnetic-field dependence of the center frequency for THz Radiation is also observed.
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high average Power thz Radiation from femtosecond laser irradiated inas in a magnetic field and its elliptical polarization characteristics
Journal of Applied Physics, 1998Co-Authors: Nobuhiko Sarukura, Hideyuki Ohtake, S IzumidaAbstract:The THz-Radiation Power from bulk InAs irradiated with femtosecond optical pulses is significantly enhanced and reaches 650 μW in a 1.7-T magnetic field with 1.5-W excitation Power. The THz-Radiation Power is related almost quadratically both to the magnetic field and excitation laser Power. We have also found that the Power of the THz-Radiation from an InAs sample in a magnetic field is over one order of magnitude higher than that from GaAs. Additionally, a dramatic change of ellipticity is observed, and the spectra of the horizontal and vertical polarization components are found to differ.
Wojciech Knap - One of the best experts on this subject based on the ideXlab platform.
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Time Resolution and Dynamic Range of Field-Effect Transistor–Based Terahertz Detectors
Journal of Infrared Millimeter and Terahertz Waves, 2019Co-Authors: Przemyslaw Zagrajek, Sergey N. Danilov, Michal Zaborowski, Cezary Kolacinski, Dariusz Obrebski, Dmytro But, Jacek Marczewski, Bartlomiej Salski, Pawel Kopyt, Wojciech KnapAbstract:We studied time resolution and response Power dependence of three terahertz detectors based on significantly different types of field-effect transistors. We analyzed the photoresponse of custom-made Si junctionless FETs, Si-MOSFETs, and GaAs-based high-electron-mobility transistor detectors. Applying monochromatic Radiation of a high-Power, pulsed, line-tunable molecular THz laser, which operated at frequencies in the range from 0.6 to 3.3 THz, we demonstrated that all these detectors have at least nanosecond response time. We showed that detectors yield a linear response in a wide range of Radiation Power. At high Powers, the response saturates varying with Radiation Power P as U = R _0 P /(1 + P / P _ s ), where R _0 is the low-Power responsivity and P _ s is the saturation Power. We demonstrated that the linear part response decreases with Radiation frequency increase as R _0 ∝ f ^− 3, whereas the Power at which signal saturates increases as P _ s ∝ f ^3. We discussed the observed dependencies in the framework of the Dyakonov-Shur mechanism and detector-antenna impedance matching. Our study showed that FET transistors can be used as ultrafast room temperature detectors of THz Radiation and that their dynamic range extends over many orders of magnitude of Power of incoming THz Radiation. Therefore, when embedded with current driven read-out electronics, they are very well adopted for operation with high Power pulsed sources.
Przemyslaw Zagrajek - One of the best experts on this subject based on the ideXlab platform.
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Time Resolution and Dynamic Range of Field-Effect Transistor–Based Terahertz Detectors
Journal of Infrared Millimeter and Terahertz Waves, 2019Co-Authors: Przemyslaw Zagrajek, Sergey N. Danilov, Michal Zaborowski, Cezary Kolacinski, Dariusz Obrebski, Dmytro But, Jacek Marczewski, Bartlomiej Salski, Pawel Kopyt, Wojciech KnapAbstract:We studied time resolution and response Power dependence of three terahertz detectors based on significantly different types of field-effect transistors. We analyzed the photoresponse of custom-made Si junctionless FETs, Si-MOSFETs, and GaAs-based high-electron-mobility transistor detectors. Applying monochromatic Radiation of a high-Power, pulsed, line-tunable molecular THz laser, which operated at frequencies in the range from 0.6 to 3.3 THz, we demonstrated that all these detectors have at least nanosecond response time. We showed that detectors yield a linear response in a wide range of Radiation Power. At high Powers, the response saturates varying with Radiation Power P as U = R _0 P /(1 + P / P _ s ), where R _0 is the low-Power responsivity and P _ s is the saturation Power. We demonstrated that the linear part response decreases with Radiation frequency increase as R _0 ∝ f ^− 3, whereas the Power at which signal saturates increases as P _ s ∝ f ^3. We discussed the observed dependencies in the framework of the Dyakonov-Shur mechanism and detector-antenna impedance matching. Our study showed that FET transistors can be used as ultrafast room temperature detectors of THz Radiation and that their dynamic range extends over many orders of magnitude of Power of incoming THz Radiation. Therefore, when embedded with current driven read-out electronics, they are very well adopted for operation with high Power pulsed sources.
O Petruk - One of the best experts on this subject based on the ideXlab platform.
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approximation of the Radiation Power of electrons due to the inverse compton process in the black body photon field
Astronomy and Astrophysics, 2009Co-Authors: O PetrukAbstract:Aims. An approximation is presented for the inverse-Compton Radiation Power of electrons in the isotropic black-body photon field. Methods. This approximation allows calculation of the inverse-Compton emissivity as an integral over the energies of incident electrons rather than over the field photon energies. Such an approach allows for accurate modeling of IC emission of electrons with energy spectra different from Power law, in tasks where essential CPU resources are needed. Results. The high accuracy of this approximation allows it to be used in a wide range of conditions, from Thomson to extreme Klein-Nishina limits, in different astrophysical objects. This approach also results in some new analytic expressions representing the known results in the Thomson limit.
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approximation for Radiation Power of electrons due to inverse compton process in the black body photon field
arXiv: Astrophysics, 2008Co-Authors: O PetrukAbstract:An approximation for the inverse-Compton Radiation Power of electrons in the isotropic black-body photon field is presented. The approximation allows one to calculate inverse-Compton emissivity as integral over the energies of incident electrons rather than over the field photon energies. Such an approach allows for accurate modeling of IC emission of electrons with energy spectra being different from Power-law, in situation where the CPU resources are limited. High accuracy of this approximation allows one to use it in a wide range of conditions, from Thomson to extreme Klein-Nishina limits. The approach adopted results also in some new analytic expressions representing known results in the Thomson limit.
I A Konstantinovich - One of the best experts on this subject based on the ideXlab platform.
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Radiation Power spectral distribution for two electrons moving in magnetic fields
Semiconductor physics quantum electronics and optoelectronics, 2008Co-Authors: A V Konstantinovich, S V Melnychuk, I A KonstantinovichAbstract:Integral expressions for spectral distributions of the Radiation Power for systems of non-interacting point charged particles moving on arbitrary trajectory in electromagnetic fields in isotropic transparent media and in vacuum are investigated using the Lorentz self-interaction method. Special attention is given to the research of the fine structure of the synchrotron Radiation spectral distribution of two electrons spiraling in vacuum in a relativistic case. The spectra of synchrotron, Cherenkov and synchrotron- Cherenkov Radiations for a single electron are analyzed.
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Radiation Power spectral distribution of the system of electrons moving in a spiral in vacuum
Journal of Optoelectronics and Advanced Materials, 2006Co-Authors: A V Konstantinovich, I A KonstantinovichAbstract:Using the expressions for the average Radiation Power of three and four electrons moving one by one in a spiral in vacuum the synchrotron Radiation spectrum for the first time is obtained and studied. The synchrotron Radiation spectrum of a single electron is compared to these of two, three and four electrons moving in a spiral in vacuum. The influence of the coherence factor on the spectrum of synchrotron Radiation is studied.
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Radiation Power spectral distribution of charged particles moving in a spiral in magnetic fields
2003Co-Authors: A V Konstantinovich, S V Melnychuk, I A KonstantinovichAbstract:The expressions for the momentary and average Radiation Powers of the charged particles moving on an arbitrary determined trajectory in transparent isotropic medi and in vacuum are studied by using the Lorentz's self-interaction method. Special attention is given to the research of the fine structure of the synchrotron Radiation spectral distribution of two electrons moving in a spiral in vacuum. The spectra of synchrotron, Cherenkov and synchrotronCherenkov Radiations for a separate electron are analyzed. (Received May 16, 2003; accepted August 28, 2003)
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Radiation spectra of charged particles moving in a spiral in magnetic fields
2003Co-Authors: A V Konstantinovich, Stepan Melnychuk, I A KonstantinovichAbstract:The expression for the averaged Radiation Power of the charged particles moving in a spiral in transparent isotropic media and in vacuum are studied by using the Lorentz's self-interaction method. Special attention is given to the research of the structure of the synchrotron Radiation spectral distribution of two electrons moving in a spiral in vacuum. The spectra of synchrotron, Cherenkov, and synchrotron-Cherenkov Radiations for a separate electron are analyzed.
