%0 Conference Proceedings %T Advanced nanostructured optical NbN single-photon detector operated at 2.0 K %A Goltsman, G. %A Korneev, A. %A Minaeva, O. %A Rubtsova, I. %A Chulkova, G. %A Milostnaya, I. %A Smirnov, K. %A Voronov, B. %A Lipatov, A. P. %A Pearlman, A. J. %A Cross, A. %A Slysz, W. %A Verevkin, A. A. %A Sobolewski, R. %Y Razeghi, M. %Y Brown, G. J. %S Proc. SPIE %D 2005 %V 5732 %I Spie %F Goltsman_etal2005 %O exported from refbase (https://db.rplab.ru/refbase/show.php?record=1478), last updated on Mon, 17 May 2021 22:09:55 -0500 %X We present our studies on quantum efficiency (QE), dark counts, and noise equivalent power (NEP) of the latest generation of nanostructured NbN superconducting single-photon detectors (SSPDs) operated at 2.0 K. Our SSPDs are based on 4 nm-thick NbN films, patterned by electron beam lithography as highly-uniform 100÷120-nm-wide meander-shaped stripes, covering the total area of 10x10 μm[super:2] with the meander filling factor of 0.7. Advances in the fabrication process and low-temperature operation lead to QE as high as  30-40% for visible-light photons (0.56 μm wavelength)-the saturation value, limited by optical absorption of the NbN film. For 1.55 μm photons, QE was  20% and decreased exponentially with the wavelength reaching  0.02% at the 5-μm wavelength. Being operated at 2.0-K temperature the SSPDs revealed an exponential decrease of the dark count rate, what along with the high QE, resulted in the NEP as low as 5x10[super:-21] W/Hz[super:-1/2], the lowest value ever reported for near-infrared optical detectors. The SSPD counting rate was measured to be above 1 GHz with the pulse-to-pulse jitter below 20 ps. Our nanostructured NbN SSPDs operated at 2.0 K significantly outperform their semiconducting counterparts and find practical applications ranging from noninvasive testing of CMOS VLSI integrated circuits to ultrafast quantum communications and quantum cryptography. %K NbN SSPD %K SNSPD %R 10.1117/12.590455 %U https://doi.org/10.1117/12.590455 %P 520-529