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Shitov, S. V., Levitchev, M., Veretennikov, A. V., Koshelets, V. P., Prokopenko, G. V., Filippenko, L. V., et al. (2001). Superconducting integrated receiver as 400-600 GHz tester for coolable devices. IEEE Trans. Appl. Supercond., 11(1), 832–835.
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Yang, J. K. W., Kerman, A. J., Dauler, E. A., Anant, V., Rosfjord, K. M., & Berggren, K. K. (2007). Modeling the electrical and thermal response of superconducting nanowire single-photon detectors. IEEE Trans. Appl. Supercond., 17(2), 581–585.
Abstract: We modeled the response of superconducting nanowire single-photon detectors during a photodetection event, taking into consideration only the thermal and electrical properties of a superconducting NbN nanowire on a sapphire substrate. Our calculations suggest that heating which occurs after the formation of a photo-induced resistive barrier is responsible for the generation of a measurable voltage pulse. We compared this numerical result with experimental data of a voltage pulse from a slow device, i.e. large kinetic inductance, and obtained a good fit. Using this electro-thermal model, we estimated the temperature rise and the resistance buildup in the nanowire, and the return current at which the nanowire becomes superconducting again. We also show that the reset time of these photodetectors can be decreased by the addition of a series resistance and provide supporting experimental data. Finally we present preliminary results on a detector latching behavior that can also be explained using the electro-thermal model.
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Xiaolong Hu, Holzwarth, C. W., Masciarelli, D., Dauler, E. A., & Berggren, K. K. (2009). Efficiently coupling light to superconducting nanowire single-photon detectors. IEEE Trans. Appl. Supercond., 19(3), 336–340.
Abstract: We designed superconducting nanowire single-photon detectors (SNSPDs) integrated with silver optical antennae for free-space coupling and a dielectric waveguide for fiber coupling. According to our finite-element simulation, (1) for the free-space coupling, the absorptance of the NbN nanowire for TM-polarized photons at the wavelength of 1550 nm can be as high as 96% by adding silver optical antennae; (2) for the fiber coupling, the absorptance of the NbN nanowire for TE-like-polarized photons can reach 76% including coupling efficiency at the wavelength of 1550 nm by adding a silicon nitride waveguide and an inverse-taper coupler.
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Yamashita, T., Miki, S., Qiu, W., Fujiwara, M., Sasaki, M., & Wang, Z. (2010). Temperature dependent performances of superconducting nanowire single-photon detectors in an ultralow-temperature region. IEEE Trans. Appl. Supercond., 21(3), 336–339.
Abstract: We report on the performance of a fiber-coupled superconducting nanowire single-photon detector (SNSPD) from 4 K down to the ultralow temperature of 16 mK for a 1550 nm wave length. The system detection efficiency (DE) increased with de creasing the temperature and reached the considerably high value of 15% with a dark count rate less than 100 cps below 1.5 K, even without an optical cavity structure. We also observed saturation of the system DE in its bias current dependency at 16 mK, which indicates that the device DE of our SNSPD nearly reached intrinsic DE despite the device having a large active area of 20 μm × 20 μm. The dark count was finite even at 16 mK and the black body radiation becomes its dominant origin in the low temperatures for fiber-coupled devices.
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Yang, J. K. W., Kerman, A. J., Dauler, E. A., Cord, B., Anant, V., Molnar, R. J., et al. (2009). Suppressed critical current in superconducting nanowire single-photon detectors with high fill-factors. IEEE Trans. Appl. Supercond., 19(3), 318–322.
Abstract: In this work we present a new fabrication process that enabled the fabrication of superconducting nanowire single photon detectors SNSPD with fill-factors as high as 88% with gaps between nanowires as small as 12 nm. This fabrication process combined high-resolution electron-beam lithography with photolithography. Although this work was motivated by the potential of increased detection efficiency with higher fill-factor devices, test results showed an unexpected systematic suppression in device critical currents with increasing fill-factor.
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