Zhang J, Verevkin A, Slysz W, Chulkova G, Korneev A, Lipatov A, et al. Time-resolved characterization of NbN superconducting single-photon optical detectors. In: Armitage JC, editor. Proc. SPIE. Vol 10313. SPIE; 2017. 103130F (1 to 3).
Abstract: NbN superconducting single-photon detectors (SSPDs) are very promising devices for their picosecond response time, high intrinsic quantum efficiency, and high signal-to-noise ratio within the radiation wavelength from ultraviolet to near infrared (0.4 gm to 3 gm) [1-3]. The single photon counting property of NbN SSPDs have been investigated thoroughly and a model of hotspot formation has been introduced to explain the physics of the photon- counting mechanism [4-6]. At high incident flux density (many-photon pulses), there are, of course, a large number of hotspots simultaneously formed in the superconducting stripe. If these hotspots overlap with each other across the width w of the stripe, a resistive barrier is formed instantly and a voltage signal can be generated. We assume here that the stripe thickness d is less than the electron diffusion length, so the hotspot region can be considered uniform. On the other hand, when the photon flux is so low that on average only one hotspot is formed across w at a given time, the formation of the resistive barrier will be realized only when the supercurrent at sidewalks surpasses the critical current (jr) of the superconducting stripe [1]. In the latter situation, the formation of the resistive barrier is associated with the phase-slip center (PSC) development. The effect of PSCs on the suppression of superconductivity in nanowires has been discussed very recently [8, 9] and is the subject of great interest.
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Gol’tsman GN, Gershenzon EM. High speed hot-electron superconducting bolometer. In: Birch JR, Parker TJ, editors. Proc. SPIE. Vol 2104. SPIE; 1993. p. 181–2.
Abstract: Physical limitation of response time of a superconducting bolometer as well as the nature of non-equilibrium detection of radiation have been investigated for Al, Nb and NbN thin films in spectral range from submillimeter to near-infraredwavelengths [1,2]. In the case of ideal heat removal from the film with the f_‘. 100A thickness the detection mechanism is an electron heating effect that is not selective to radiation wavelength in a very broad range. The response time ofan electron heating bolometer is determined by an electron-phonon interaction time. This time is of about 10 ns, 0.5 ns and 20 ps for Al, Nb, and NbN correspondingly near the critical temperature of the superconducting film. Thesensitive area of the bolometer consists of a number of narrow strips (with awidth of 1µm) connected in parallel to contact pads; these pads together witha sapphire substrate and a ground plate represent the microstrip transmissionline with an impedance of 50 Q.
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Danerud M, Winkler D, Zorin M, Trifonov V, Karasik B, Gershenzon EM, et al. Picosecond detection of infrared radiation with YBa2Cu3O7-δ thin films. In: Birch JR, Parker TJ, editors. Proc. SPIE. Vol 2104. Spie; 1993. p. 183–4.
Abstract: Picosecond nonequilibrium and slow bolometric responses from a patterned high-Tc superconducting (HTS) film due toinfrared radiation were investigated using both modulation and pulse techniques. Measurements at A, = 0.85 [tm andA, = 10.6 lim have shown a similar behaviour of the response vs modulation frequency f. The responsivity of the HTS filmbased detector at f ..- 0.6-1 GHz is estimated to be 10-2 – 10-1 V/W.
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Gershenzon EM, Gol'tsman GN. Hot-electron superconducting mixers. In: Birch JR, Parker TJ, editors. Proc. SPIE. Vol 2104. SPIE; 1993. p. 329–30.
Abstract: The creation of low noise heterodyne receivers for frequencies above 1 THz is in the urgentneed for radio astronomy, laser spectroscopy, plasma diagnostic, etc. In this paper we discussthe nonlinear effect related to hot electrons in superconductors, and their potential use in lownoise submilimeter wave mixer. We also discuss results achieved so far as well as possible futuredevelopments.
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Karasik BS, Zorin MA, Milostnaya II, Elantev AI, Gol’tsman GN, Gershenzon EM. Evidence of subnanosecond transition stage in S-N current switching of YBaCuO films. In: Buhrman RA, Clarke JT, Daly K, Koch RH, Luine JA, Simon RW, editors. Proc. SPIE. Vol 2160. SPIE; 1994. p. 74–82.
Abstract: We report on a study of S-N and N-S current switching in high quality YBaCuO films deposited onto ZrO2 and NdGaO3 substrates. The films 60-120 nm thick prepared by laser ablation were structured into single strips and were provided with gold contacts. We monitored the time dependence of the resistance upon application of the voltage step on the film. Experiment performed within certain ranges of voltage amplitudes and temperatures showed the occurrence of the fast stage both in S-N (shorter than 300 ps) and N-S transition. We discuss the mechanism of switching taking into account the hot electron phenomena in YBaCuO. The contributions of various thermal processes in the subsequent stage of the resistance dynamic are also discussed. The basic limiting characteristics (average dissipated power, minimum work done for switching, maximum repetition rate) of a picosecond switch which is proposed to be developed are estimated.
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