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arXiv · 1511.05786

Free space-coupled superconducting nanowire single photon detectors for infrared optical communications

Francesco Bellei·Alyssa P. Cartwright·Adam N. McCaughan·Andrew E. Dane·Faraz Najafi·Quinyuan Zhao·Karl K. Berggren
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Abstract

This paper describes the construction of a cryostat and an optical system with a free-space coupling efficiency of 56.5% +/- 3.4% to a superconducting nanowire single-photon detector (SNSPD) for infrared quantum communication and spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The minimum spot size coupled to the detector chip was 6.6 +/- 0.11 {\mu}m starting from a fiber source at wavelength, {\lambda} = 1.55 {\mu}m. We demonstrated efficient photon counting on a detector with an 8 x 7.3 {\mu}m^2 area. We measured a dark count rate of 95 +/- 3.35 kcps and a system detection efficiency of 1.64% +/- 0.13%. We explain the key steps that are required to further improve the coupling efficiency.

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Francesco Bellei, Alyssa P. Cartwright, Adam N. McCaughan, Andrew E. Dane, Faraz Najafi, Quinyuan Zhao, Karl K. Berggren. 2015-11-18. Free space-coupled superconducting nanowire single photon detectors for infrared optical communications. https://doi.org/10.1364/oe.24.003248

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