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Semenov, A. D., Gol’tsman, G. N., Gogidze, I. G., Sergeev, A. V., Gershenzon, E. M., Lang, P. T., et al. (1992). Subnanosecond photoresponse of a YBaCuO thin film to infrared and visible radiation by quasiparticle induced suppression of superconductivity. Appl. Phys. Lett., 60(7), 903–905.
Abstract: We observed subnanosecond photoresponse of a structured superconducting YBa2Cu3O7−δ thin film to infrared and visible radiation. We measured the voltage response of a current biased film (thickness 700 Å) in a resistive state to radiation pulses. From our results we conclude a response time of about 90 ps and a responsivity of about 4×1010 Ω/J. We attribute the response to Cooper pair breaking and suppression of the superconducting energy gap induced by nonequilibrium quasiparticles.
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Gershenzon, E. M., Gol'tsman, G. N., Ptitsina, N. G., & Riger, E. R. (1986). Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium. Sov. Phys. JETP, 64(4), 889–897.
Abstract: Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3).
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Chuprina, I. N., An, P. P., Zubkova, E. G., Kovalyuk, V. V., Kalachev, A. A., & Gol'tsman, G. N. (2017). Optimisation of spontaneous four-wave mixing in a ring microcavity. In J. Phys.: Conf. Ser. (Vol. 47, pp. 887–891).
Abstract: Abstract. A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the disper- sion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numeri- cal calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: com- pletely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable.
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Ozhegov, R. V., Smirnov, A. V., Vakhtomin, Y. B., Smirnov, K. V., Divochiy, A. V., & Goltsman, G. N. (2009). Ultrafast superconducting bolometer receivers for terahertz applications. In Proc. PIERS (867). 777 Concord Avenue, Suite 207 Cambridge, MA 02138: The Electromagnetics Academy.
Abstract: The research by the group of Moscow State Pedagogical University into the hot-electron phenomena in thin superconducting films has led to the development of new types of detectors and their use both in fundamental and applied studies. In this paper, we present the results of testing the terahertz HEB receiver systems based on ultrathin (∼ 4 nm) NbN and MoRe detectors with a response time of 50 ps and 1 ns, respectively. We have developed three types of devices which differ in the way a terahertz signal is coupled to the detector and cover the following ranges: 0.3–3 THz, 0.1–30 THz and 25–70 THz. In the case of the receiving system optimized for 0.3–3 THz, the sensitive element (a strip of asuperconductor with planar dimensions of 0.2μm (length) by 1.7μm (width)) was integrated witha planar broadband log-spiral antenna. For additional focusing ofthe incident radiation a silicon hyperhemispherical lens was used. For the 0.1–30 THz receivingsystem, the sensitive element was patterned as parallel strips(2μm wide each) filling an area of 500×500μm2with a filling factor of 0.5. In the receivingsystem of this type we used direct coupling of the incident radiation to the sensitive element. Inthe 25–70 THz range (detector type 2/2a in Table 1) we used a square-shaped superconductingdetector with planar dimensions of 10×10μm2. Incident radiation was coupled to the detectorwith the use of a germanium hyperhemispherical lens.The response time of the above receiving systems is determined by the cooling rate of the hotelectrons in the film. That depends on the electron-phonon interaction time, which is less forultrathin NbN than in MoRe.
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Smirnov, K. V., Vakhtomin, Y. B., Divochiy, A. V., Ozhegov, R. V., Pentin, I. V., Slivinskaya, E. V., et al. (2009). Single-photon detectors for the visible and infrared parts of the spectrum based on NbN nanostructures. In Proc. Progress In Electromagnetics Research Symp. (pp. 863–864). Moscow, Russia.
Abstract: The research by the group of Moscow State Pedagogical University into the hot-electron phenomena in thin superconducting films has led to the development of new types ofdetectors [1, 2] and their use both in fundamental and applied studies [3–6]. In this paper, wepresent the results of the development and fabrication of receiving systems for the visible andinfrared parts of the spectrum optimised for use in telecommunication systems and quantumcryptography.
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