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Seliverstov, S. V., Rusova, A. A., Kaurova, N. S., Voronov, B. M., & Goltsman, G. N. (2017). AC-biased superconducting NbN hot-electron bolometer for frequency-domain multiplexing. In Proc. 28th Int. Symp. Space Terahertz Technol. (pp. 120–122).
Abstract: We present the results of characterization of fast and sensitive superconducting antenna-coupled THz direct detector based on NbN hot-electron bolometer (HEB) with AC-bias. We discuss the possibility of implementation of the AC-bias for design the readout system from the multi-element arrays of HEBs using standard technique of frequency-domain multiplexing. We demonstrate experimentally that this approach does not lead to significant deterioration of the HEB sensitivity compared with the value obtained for the same detector with DC- bias. Results of a numerical calculations of the HEB responsivity at AC-bias are in a good agreement with the experiment.
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Tarkhov, M., Morozov, D., Mauskopf, P., Seleznev, V., Korneev, A., Kaurova, N., et al. (2006). Single photon counting detector for THz radioastronomy. In Proc. 17th Int. Symp. Space Terahertz Technol. (pp. 119–122).
Abstract: In this paper we present the results of the research on the superconducting NbN-ultrathin-film single- photon detectors (SSPD) which are capable to detect single quanta in middle IR range. The detection mechanism is based on the hotspot formation in quasi-two-dimensional superconducting structures upon photon absorption. Spectral measurements showed that up to 5.7 gm wavelength (52 THz) the SSPD exhibits single-photon sensitivity. Reduction of operation temperature to 1.6 K allowed us to measure quantum efficiency of -4% at 60 THz. Although further decrease of the operation temperature far below 1 K does not lead to any significant increase of quantum efficiency. We expect that the improvement of the SSPD's performance at reduced operation temperature will make SSPD a practical detector with high characteristics for much lower THz frequencies as well.
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Hübers, H. - W., Semenov, A., Schubert, J., Gol'tsman, G., Voronov, B., & Gershenzon, E. (2000). Performance of the phonon-cooled hot-electron bolometric mixer between 0.7 THz and 5.2 THz. In Proc. 8-th Int. Conf. on Terahertz Electronics (pp. 117–119).
Abstract: We report on the phonon cooled NbN hot electron bolometer as mixer in the terahertz frequency range. Its hybrid antenna consists of a hyperhemispheric silicon lens and a logarithmic-spiral feed antenna. Noise temperatures have been measured between 0.7 THz and 5.2 THz. A quarter wavelength layer of Parylene works as antireflection coating for the silicon lens and reduces the noise temperature by about 30. It was found that the antenna pattern at 2.5 THz is determined by the feed antenna and not by the diameter of the lens.
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Zolotov, P. I., Vakhtomin, Y. B., Divochiy, A. V., Seleznev, V. A., & Smirnov, K. V. (2016). Technology development of resonator-based structures for efficiency increasing of NBN detectors of IR single photons. Proc. 5th Int. Conf. Photonics and Information Optics, , 115–116.
Abstract: This paper presents a technology of fabrication of NbN superconductive single- photon detectors, using resonator structures. The main results are related to optimization of the process of NbN sputtering over substrate with metallic mirrors and SiO 2 /Si 3 N 4 layers /4 thick. Investigation of the quantum efficiency of fabricated devices at 1.6 K on 1.55 μm showed triple-magnified value compared to standard Si/NbN structures.
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Tretyakov, I., Kaurova, N., Voronov, B. M., & Goltsman, G. N. (2018). About effect of the temperature operating conditions on the noise temperature and noise bandwidth of the terahertz range NbN hot-electron bolometers. In Proc. 29th Int. Symp. Space Terahertz Technol. (113).
Abstract: Results of an experimental study of the noise temperature (Tn) and noise bandwidth (NBW) of the superconductor NbN hot-electron bolometer (HEB) mixer as a function of its temperature (Tb) and NbN bridge length are presented. It was determined that the NBW of the mixer is significantly wider at temperatures close to the critical ones (Tc) than are values measured at 4.2 K. The NBW of the mixer measured at the heterodyne frequency of 2.5 THz at temperature Tb close to Tc was ~13 GHz, as compared with 6 GHz at Tb = 4.2 K. This experiment clearly demonstrates the limitation of the thermal flow from the NbN bridge at Tb ≪ Tc for mixers manufactured by the in situ technique. This limitation is close in its nature to the Andreev reflection on the superconductor/metal boundary. In this case, the noise temperature of the studied mixer increased from 1100 to 3800 K.
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