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Vorobyov VV, Kazakov AY, Soshenko VV, Korneev AA, Shalaginov MY, Bolshedvorskii SV, et al. Superconducting detector for visible and near-infrared quantum emitters [Invited]. Opt Mater Express. 2017;7(2):513–26.
Abstract: Further development of quantum emitter based communication and sensing applications intrinsically depends on the availability of robust single-photon detectors. Here, we demonstrate a new generation of superconducting single-photon detectors specifically optimized for the 500–1100 nm wavelength range, which overlaps with the emission spectrum of many interesting solid-state atom-like systems, such as nitrogen-vacancy and silicon-vacancy centers in diamond. The fabricated detectors have a wide dynamic range (up to 350 million counts per second), low dark count rate (down to 0.1 counts per second), excellent jitter (62 ps), and the possibility of on-chip integration with a quantum emitter. In addition to performance characterization, we tested the detectors in real experimental conditions involving nanodiamond nitrogen-vacancy emitters enhanced by a hyperbolic metamaterial.
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Seleznev VA, Divochiy AV, Vakhtomin YB, Morozov PV, Zolotov PI, Vasil'ev DD, et al. Superconducting detector of IR single-photons based on thin WSi films. In: J. Phys.: Conf. Ser. Vol 737.; 2016. 012032.
Abstract: We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7 K) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors' SDE (system detection efficiency) with increasing bias current (I b) reaches a constant value of ~30% (for X=1.55 micron) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>0.6-Ic. The minimal dark counts level (DC) made 1 s-1 limited with background noise. Hence WSi is the most promising material for creating single-photon detectors with record SDE/DC ratio and noise equivalent power (NEP).
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Korneeva YP, Mikhailov MY, Pershin YP, Manova NN, Divochiy AV, Vakhtomin YB, et al. Superconducting single-photon detector made of MoSi film. Supercond Sci Technol. 2014;27(9):095012.
Abstract: We fabricated and characterized nanowire superconducting single-photon detectors made of 4 nm thick amorphous Mox Si1−x films. At 1.7 K the best devices exhibit a detection efficiency (DE) up to 18% at 1.2 $\mu {\rm m}$ wavelength of unpolarized light, a characteristic response time of about 6 ns and timing jitter of 120 ps. The DE was studied in wavelength range from 650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their maximum DE limited by photon absorption in the thin MoSi film.
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Smirnov AV, Karmantsov MS, Smirnov KV, Vakhtomin YB, Masterov DV, Tarkhov MA, et al. Terahertz response of thin-film YBCO bolometers. Tech Phys. 2012;57(12):1716–9.
Abstract: The bolometric response of high-temperature thin-film YBCO superconducting detectors to an electromagnetic radiation with a frequency of 2.5 THz is measured for the first time. The minimum value of the noise-equivalent power of the detectors is 3.5 × 10−9 W/Hz−−−√. The feasibility of further increasing the sensitivity of the detectors is discussed.
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Vakhtomin YB, Finkel MI, Antipov SV, Smirnov KV, Kaurova NS, Drakinskii VN, et al. The gain bandwidth of mixers based on the electron heating effect in an ultrathin NbN film on a Si substrate with a buffer MgO layer. J of communications technol & electronics. 2003;48(6):671–5.
Abstract: Measurements of the intermediate frequency band 900 GHz of mixers based on the electron heating effect (EHE) in 2-nm- and 3.5-nm-thick superconducting NbN films sputtered on MgO and Si substrates with buffer MgO layers are presented. A 2-nm-thick superconducting NbN film with a critical temperature of 9.2 K has been obtained for the first time using a buffer MgO layer.
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Baeva EM, Sidorova MV, Korneev AA, Smirnov KV, Divochy AV, Morozov PV, et al. Thermal properties of NbN single-photon detectors. Phys Rev Applied. 2018;10(6):064063 (1 to 8).
Abstract: We investigate thermal properties of a NbN single-photon detector capable of unit internal detection efficiency. Using an independent calibration of the coupling losses, we determine the absolute optical power absorbed by the NbN film and, via resistive superconductor thermometry, the temperature dependence of the thermal resistance Z(T) of the NbN film. In principle, this approach permits simultaneous measurement of the electron-phonon and phonon-escape contributions to the energy relaxation, which in our case is ambiguous because of the similar temperature dependencies. We analyze Z(T) with a two-temperature model and impose an upper bound on the ratio of electron and phonon heat capacities in NbN, which is surprisingly close to a recent theoretical lower bound for the same quantity in similar devices.
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Lobanov YV, Vakhtomin YB, Pentin IV, Rosental VA, Smirnov KV, Goltsman GN, et al. Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser. Optical Engineering. 2021;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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