Smirnov, K. V., Ptitsina, N. G., Vakhtomin, Y. B., Verevkin, A. A., Gol’tsman, G. N., & Gershenzon, E. M. (2000). Energy relaxation of two-dimensional electrons in the quantum Hall effect regime. JETP Lett., 71(1), 31–34.
Abstract: The mm-wave spectroscopy with high temporal resolution is used to measure the energy relaxation times τe of 2D electrons in GaAs/AlGaAs heterostructures in magnetic fields B=0–4 T under quasi-equilibrium conditions at T=4.2 K. With increasing B, a considerable increase in τe from 0.9 to 25 ns is observed. For high B and low values of the filling factor ν, the energy relaxation rate τ −1e oscillates. The depth of these oscillations and the positions of maxima depend on the filling factor ν. For ν>5, the relaxation rate τ −1e is maximum when the Fermi level lies in the region of the localized states between the Landau levels. For lower values of ν, the relaxation rate is maximum at half-integer values of τ −1e when the Fermi level is coincident with the Landau level. The characteristic features of the dependence τ −1e (B) are explained by different contributions of the intralevel and interlevel electron-phonon transitions to the process of the energy relaxation of 2D electrons.
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Kitaeva, G. K., Kornienko, V. V., Kuznetsov, K. A., Pentin, I. V., Smirnov, K. V., & Vakhtomin, Y. B. (2019). Direct detection of the idler THz radiation generated by spontaneous parametric down-conversion. Opt. Lett., 44(5), 1198–1201.
Abstract: We study parametric down-conversion (PDC) of optical laser radiation in the strongly frequency non-degenerate regime which is promising for the generation of quantum-correlated pairs of extremely different spectral ranges, the optical and the terahertz (THz) ones. The possibility to detect tenuous THz-frequency photon fluxes generated under low-gain spontaneous PDC is demonstrated using a hot electron bolometer. Then experimental dependences of the THz radiation power on the detection angle and on the pump intensity are analyzed.
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Rasulova, G. K., Pentin, I. V., Vakhtomin, Y. B., Smirnov, K. V., Khabibullin, R. A., Klimov, E. A., et al. (2020). Pulsed terahertz radiation from a double-barrier resonant tunneling diode biased into self-oscillation regime. J. Appl. Phys., 128(22), 224303 (1 to 11).
Abstract: The study of the bolometer response to terahertz (THz) radiation from a double-barrier resonant tunneling diode (RTD) biased into the negative differential conductivity region of the I–V characteristic revealed that the RTD emits two pulses in a period of intrinsic self-oscillations of current. The bolometer pulse repetition rate is a multiple of the fundamental frequency of the intrinsic self-oscillations of current. The bolometer pulses are detected at two critical points with a distance between them being half or one-third of a period of the current self-oscillations. An analysis of the current self-oscillations and the bolometer response has shown that the THz photon emission is excited when the tunneling electrons are trapped in (the first pulse) and then released from (the second pulse) miniband states.
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Lobanov, Y. V., Vakhtomin, Y. B., Pentin, I. V., Rosental, V. A., Smirnov, K. V., Goltsman, G. N., et al. (2021). Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser. Optical Engineering, 60(8), 1–8.
Abstract: Quantum cascade lasers (QCL) are widely adopted as prominent and easy-to-use solid-state sources of terahertz radiation. Yet some applications require generation and detection of very sharp and narrow terahertz-range pulses with a specific spectral composition. We have studied time-resolved light-current (L–I) characteristics of multimode THz QCL operated with a fast ramp of the injection current. Detection of THz pulses was carried out using an NbN superconducting hot-electron bolometer with the time constant of the order of 1 ns while the laser bias current was swept during a single driving pulse. A nonmonotonic behavior of the L–I characteristic with several visually separated subpeaks was found. This behavior is associated with the mode competition in THz QCL cavity, which we confirm by L–I measurements with use of an external Fabry–Perot interferometer for a discrete mode selection. We also have demonstrated the possibility to control the L–I shape with suppression of one of the subpeaks by simply adjusting the off-axis parabolic mirror for optimal optical alignment for one of the laser modes. The developed technique paves the way for rapid characterization of pulsed THz QCLs for further studies of the possibilities of using this approach in remote sensing.
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Kuznetsov, K. A., Kornienko, V. V., Vakhtomin, Y. B., Pentin, I. V., Smirnov, K. V., & Kitaeva, G. K. (2018). Generation and detection of optical-terahertz biphotons via spontaneous parametric downconversion. In Proc. ICLO (303).
Abstract: We study spontaneous parametric downconversion (SPDC) in the strongly non-degenerate regime when the idler wave hits the terahertz range. By using the hot-electron bolometer, for the first time the SPDC-generated idler-wave photons were directly detected in the terahertz frequency range. Spectrum of corresponding signal photons was measured using standard technique by the CCD camera. Possible applications of correlated optical-terahertz biphotons are discussed.
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