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Gayduchenko, I. A., Moskotin, M. V., Matyushkin, Y. E., Rybin, M. G., Obraztsova, E. D., Ryzhii, V. I., et al. (2018). The detection of sub-terahertz radiation using graphene-layer and graphene-nanoribbon FETs with asymmetric contacts. In Materials Today: Proc. (Vol. 5, pp. 27301–27306).
Abstract: We report on the detection of sub-terahertz radiation using single layer graphene and graphene-nanoribbon FETs with asymmetric contacts (one is the Schottky contact and one – the Ohmic contact). We found that cutting graphene into ribbons a hundred nanometers wide leads to a decrease of the response to sub-THz radiation. We show that suppression of the response in the graphene nanoribbons devices can be explained by unusual properties of the Schottky barrier on graphene-vanadium interface.
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Zolotov, P., Divochiy, A., Vakhtomin, Y., Moshkova, M., Morozov, P., Seleznev, V., et al. (2018). Photon-number-resolving SSPDs with system detection efficiency over 50% at telecom range. In Proc. AIP Conf. (Vol. 1936, 020019).
Abstract: We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanced previously reported system detection efficiency at telecom range for such detectors. Our results show that implementation of optical cavity helps to develop four-section device with quantum efficiency over 50% at 1.55 µm. Performed experimental studies of detecting multi-photon optical pulses showed irregularities over defining multi-photon through single-photon quantum efficiency.
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Baeva, E., Sidorova, M., Korneev, A., & Goltsman, G. (2018). Precise measurement of the thermal conductivity of superconductor. In Proc. AIP Conf. (Vol. 1936, 020003 (1 to 4)).
Abstract: Measuring the thermal properties such as the heat capacity provide information about intrinsic mechanisms operated inside. In general, the ratio between electron and phonon specific heat Ce/Cp shows how the absorbed energy shared between electron and phonon subsystems. In this work we make estimations for amplitude-modulated absorption of THz radiation technique for investigation of the ratio Ce/Cp in superconducting Niobium Nitride (NbN) at T = Tc. Our results indicates that experimentally the frequency of modulation has to be extra large to extract the quantity. We perform a new technique allowed to work at low frequency with accurately measurement of absorbed power.
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Gayduchenko, I., Fedorov, G., Titova, N., Moskotin, M., Obraztsova, E., Rybin, M., et al. (2018). Towards to the development of THz detectors based on carbon nanostructures. In J. Phys.: Conf. Ser. (Vol. 1092, 012039 (1 to 4)).
Abstract: Demand for efficient terahertz radiation detectors resulted in intensive study of the carbon nanostructures as possible solution for that problem. In this work we investigate the response to sub-terahertz radiation of detectors with sensor elements based on CVD graphene as well as its derivatives – carbon nanotubes (CNTs). The devices are made in configuration of field effect transistors (FET) with asymmetric source and drain (vanadium and gold) contacts and operate as lateral Schottky diodes. We show that at 300K semiconducting CNTs show better performance up to 300GHz with responsivity up to 100V/W, while quasi-metallic CNTs are shown to operate up to 2.5THz. At 300 K graphene detector exhibit the room-temperature responsivity from R = 15 V/W at f = 129 GHz to R = 3 V/W at f = 450 GHz. We find that at low temperatures (77K) the graphene lateral Schottky diodes responsivity rises with the increasing frequency of the incident sub-THz radiation. We interpret this result as a manifestation of a plasmonic effect in the devices with the relatively long plasmonic wavelengths. The obtained data allows for determination of the most promising directions of development of the technology of nanocarbon structures for the detection of THz radiation.
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Divochiy, A., Misiaszek, M., Vakhtomin, Y., Morozov, P., Smirnov, K., Zolotov, P., et al. (2018). Single photon detection system for visible and infrared spectrum range. Opt. Lett., 43(24), 6085–6088.
Abstract: We demonstrate niobium nitride based superconducting single-photon detectors sensitive in the spectral range 452-2300 nm. The system performance was tested in a real-life experiment with correlated photons generated by means of spontaneous parametric downconversion, where one photon was in the visible range and the other was in the infrared range. We measured a signal to noise ratio as high as 4x10(4) in our detection setting. A photon detection efficiency as high as 64% at 1550 nm and 15% at 2300 nm was observed.
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