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Zolotov, P., Vakhtomin, Y., Divochiy, A., Morozov, P., Seleznev, V., & Smirnov, K. (2017). Development of fast and high-effective single-photon detector for spectrum range up to 2.3 μm. In Proc. SPBOPEN (pp. 439–440).
Abstract: We present the results of development and testing of the single-photon-counting system operating in the wide spectrum rane up to 2.3 mcm. We managed to increase system detection efficiency up to 60% in the range of 1.7-2.3 mcm optimisation of the fabrication methods of superconducting single-photon detectors and application of the single-mode fiber with enlarged core diameter.
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Korneev, A., Divochiy, A., Marsili, F., Bitauld, D., Fiore, A., Seleznev, V., et al. (2008). Superconducting photon number resolving counter for near infrared applications. In P. Tománek, D. Senderáková, & M. Hrabovský (Eds.), Proc. SPIE (Vol. 7138, 713828 (1 to 5)). Spie.
Abstract: We present a novel concept of photon number resolving detector based on 120-nm-wide superconducting stripes made of 4-nm-thick NbN film and connected in parallel (PNR-SSPD). The detector consisting of 5 strips demonstrate a capability to resolve up to 4 photons absorbed simultaneously with the single-photon quantum efficiency of 2.5% and negligibly low dark count rate.
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Korneev, A., Minaeva, O., Divochiy, A., Antipov, A., Kaurova, N., Seleznev, V., et al. (2007). Ultrafast and high quantum efficiency large-area superconducting single-photon detectors. In M. Dusek, M. S. Hillery, W. P. Schleich, I. Prochazka, A. L. Migdall, & A. Pauchard (Eds.), Proc. SPIE (Vol. 6583, 65830I (1 to 9)). Spie.
Abstract: We present our latest generation of superconducting single-photon detectors (SSPDs) patterned from 4-nm-thick NbN films, as meander-shaped 0.5-mm-long and 100-nm-wide stripes. The SSPDs exhibit excellent performance parameters in the visible-to-near-infrared radiation wavelengths: quantum efficiency (QE) of our best devices approaches a saturation level of 30% even at 4.2 K (limited by the NbN film optical absorption) and dark counts as low as 2x10-4 Hz. The presented SSPDs were designed to maintain the QE of large-active-area devices, but, unless our earlier SSPDs, hampered by a significant kinetic inductance and a nanosecond response time, they are characterized by a low inductance and GHz counting rates. We have designed, simulated, and tested the structures consisting of several, connected in parallel, meander sections, each having a resistor connected in series. Such new, multi-element geometry led to a significant decrease of the device kinetic inductance without the decrease of its active area and QE. The presented improvement in the SSPD performance makes our detectors most attractive for high-speed quantum communications and quantum cryptography applications.
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Milostnaya, I., Korneev, A., Minaeva, O., Rubtsova, I., Slepneva, S., Seleznev, V., et al. (2005). Superconducting nanostructured detectors capable of single photon counting of mid-infrared optical radiation. In A. Rogalski, E. L. Dereniak, & F. F. Sizov (Eds.), Proc. SPIE (Vol. 5957, 59570A (1 to 9)). SPIE.
Abstract: We report on our progress in research and development of ultrafast superconducting single-photon detectors (SSPDs) based on ultrathin NbN nanostructures. Our SSPDs were made of the 4-nm-thick NbN films with Tc 11 K, patterned as meander-shaped, 100-nm-wide strips, and covering an area of 10×10 μm2. The detectors exploit a combined detection mechanism, where upon a single-photon absorption, a hotspot of excited electrons and redistribution of the biasing supercurrent, jointly produce a picosecond voltage transient signal across the superconducting nanostripe. The SSPDs are typically operated at 4.2 K, but their sensitivity in the infrared radiation range can be significantly improved by lowering the operating temperature from 4.2 K to 2 K. When operated at 2 K, the SSPD quantum efficiency (QE) for visible light photons reaches 30-40%, which is the saturation value limited by the optical absorption of our 4-nm-thick NbN film. With the wavelength increase of the incident photons,the QE of SSPDs decreases significantly, but even at the wavelength of 6 μm, the detector is able to count single photons and exhibits QE of about 10-2 %. The dark (false) count rate at 2 K is as low as 2x10-4 s,-1 which makes our detector essentially a background-limited sensor. The very low dark-count rate results in a noise equivalent power (NEP) below 10-18 WHz-1/2 for the mid-infrared range (6 μm). Further improvement of the SSPD performance in the mid-infrared range can be obtained by substituting NbN for another, lower-Tc materials with a narrow superconducting gap and low quasiparticles diffusivity. The use of such superconductors should shift the cutoff wavelength below 10 μm.
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Korneev, A., Minaeva, O., Rubtsova, I., Milostnaya, I., Chulkova, G., Voronov, B., et al. (2005). Superconducting single-photon ultrathin NbN film detector. Quantum Electronics, 35(8), 698–700.
Abstract: Superconducting single-photon ultrathin NbN film detectors are studied. The development of manufacturing technology of detectors and the reduction of their operating temperature down to 2 K resulted in a considerable increase in their quantum efficiency, which reached in the visible region (at 0.56 μm) 30%—40%, i.e., achieved the limit determined by the absorption coefficient of the film. The quantum efficiency exponentially decreases with increasing wavelength, being equal to ~20% at 1.55 μm and ~0.02% at 5 μm. For the dark count rate of ~10-4s-1, the experimental equivalent noise power was 1.5×10-20 W Hz-1/2; it can be decreased in the future down to the record low value of 5×10-21 W Hz-1/2. The time resolution of the detector is 30 ps.
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