The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Karl Friedrich Renk - One of the best experts on this subject based on the ideXlab platform.
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analysis of the nonequilibrium photoresponse of superconducting films to Pulsed Radiation by use of a two temperature model
Physical Review B, 1995Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Yu P Gousev, Karl Friedrich RenkAbstract:Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the Radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, Radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the Radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, and ${\mathrm{TlBa}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{9}$ superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments.
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Two-temperature model of nonequilibrium photoresponse of superconducting films to Pulsed Radiation
Physica C-superconductivity and Its Applications, 1994Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Karl Friedrich RenkAbstract:Abstract Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been simulated making use of different effective temperatures to describe electron and phonon nonequilibrium distributions. Fitting of calculated voltage transients to experimental response signals gives electron-phonon interaction times at the transition temperature 3.5 ps, and 1.8 ps for YBa 2 Cu 3 O 7 , and TlBa 2 Ca 2 Cu 3 O 9 films respectively.
Masanori Hangyo - One of the best experts on this subject based on the ideXlab platform.
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Photoconductive emission and detection of terahertz Pulsed Radiation using semiconductors and semiconductor devices
Journal of Infrared Millimeter and Terahertz Waves, 2012Co-Authors: Masahiko Tani, Elmer S. Estacio, Christopher T. Que, Hidekazu Nakajima, Masakazu Hibi, Kohji Yamamoto, Seizi Nishizawa, Fumiaki Miyamaru, Masanori HangyoAbstract:Recent studies on the techniques and development of photoconductive (PC) semiconductor devices for efficient generation and detection of terahertz (THz) Pulsed Radiation are reported. Firstly, the optimization of PC antenna design is discussed. The PC detection of THz Pulsed Radiation using low-temperature grown GaAs with 1.55-μm wavelength probe is then described. Finally, the enhancement of THz Radiation from InSb by using a coupling lens and magnetic field is investigated. These results reveal valuable insights on the design of an efficient, compact, and cost-effective THz time-domain spectroscopy system based on 1.55-μm fs laser sources.
A.d. Semenov - One of the best experts on this subject based on the ideXlab platform.
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analysis of the nonequilibrium photoresponse of superconducting films to Pulsed Radiation by use of a two temperature model
Physical Review B, 1995Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Yu P Gousev, Karl Friedrich RenkAbstract:Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the Radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, Radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the Radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, and ${\mathrm{TlBa}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{9}$ superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments.
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Two-temperature model of nonequilibrium photoresponse of superconducting films to Pulsed Radiation
Physica C-superconductivity and Its Applications, 1994Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Karl Friedrich RenkAbstract:Abstract Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been simulated making use of different effective temperatures to describe electron and phonon nonequilibrium distributions. Fitting of calculated voltage transients to experimental response signals gives electron-phonon interaction times at the transition temperature 3.5 ps, and 1.8 ps for YBa 2 Cu 3 O 7 , and TlBa 2 Ca 2 Cu 3 O 9 films respectively.
R.w. Falcone - One of the best experts on this subject based on the ideXlab platform.
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subpicosecond electromagnetic pulses from intense laser plasma interaction
Physical Review Letters, 1993Co-Authors: H. Hamster, W White, A. Sullivan, S P Gordon, R.w. FalconeAbstract:Laser pulses with a power of ${10}^{12}$ W and a duration of ${10}^{\mathrm{\ensuremath{-}}13}$ s were focused onto both gas and solid targets. Strong emission of Pulsed Radiation at terahertz frequencies was observed from the resulting plasmas. The most intense Radiation was detected from solid density targets and was correlated with the emission of MeV x rays and electrons. Results indicate that radiative processes in such plasmas are driven by ponderomotively induced space charge fields in excess of ${10}^{8}$ V/cm. This work constitutes the first direct observation of a laser-induced wake field.
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Subpicosecond, electromagnetic pulses from intense laser-plasma interaction
Physical Review Letters, 1993Co-Authors: H. Hamster, S. Gordon, W White, A. Sullivan, R.w. FalconeAbstract:Laser pulses with a power of 10121012 W and a duration of 10-1310-13 s were focused onto both gas and solid targets. Strong emission of Pulsed Radiation at terahertz frequencies was observed from the resulting plasmas. The most intense Radiation was detected from solid density targets and was correlated with the emission of MeV x rays and electrons. Results indicate that radiative processes in such plasmas are driven by ponderomotively induced space charge fields in excess of 108108 V/cm. This work constitutes the first direct observation of a laser-induced wake field.
R. S. Nebosis - One of the best experts on this subject based on the ideXlab platform.
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analysis of the nonequilibrium photoresponse of superconducting films to Pulsed Radiation by use of a two temperature model
Physical Review B, 1995Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Yu P Gousev, Karl Friedrich RenkAbstract:Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the Radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, Radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the Radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$, and ${\mathrm{TlBa}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{9}$ superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments.
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Two-temperature model of nonequilibrium photoresponse of superconducting films to Pulsed Radiation
Physica C-superconductivity and Its Applications, 1994Co-Authors: A.d. Semenov, R. S. Nebosis, M. A. Heusinger, Karl Friedrich RenkAbstract:Abstract Photoresponse of a superconducting film in the resistive state to Pulsed Radiation has been simulated making use of different effective temperatures to describe electron and phonon nonequilibrium distributions. Fitting of calculated voltage transients to experimental response signals gives electron-phonon interaction times at the transition temperature 3.5 ps, and 1.8 ps for YBa 2 Cu 3 O 7 , and TlBa 2 Ca 2 Cu 3 O 9 films respectively.
