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Author Chulkova, G.; Milostnaya, I.; Korneev, A.; Minaeva, O.; Rubtsova, I.; Voronov, B.; Okunev, O.; Smirnov, K.; Gol’tsman, G.; Kitaygorsky, J.; Cross, A.; Pearlman, A.; Sobolewski, R.; Slysz, W.
Title Superconducting nanostructures for counting of single photons in the infrared range Type Conference Article
Year 2005 Publication Proc. 2-nd CAOL Abbreviated Journal Proc. 2-nd CAOL
Volume 2 Issue Pages 100-103
Keywords SSPD, SNSPD
Abstract (up) We present our studies on ultrafast superconducting single-photon detectors (SSPDs) based on ultrathin NbN nanostructures. Our SSPDs are patterned by electron beam lithography from 4-nm thick NbN film into meander-shaped strips covering square area of 10/spl times/10 /spl mu/m/sup 2/. The advances in the fabrication technology allowed us to produce highly uniform 100-120-nm-wide strips with meander filling factor close to 0.6. The detectors exploit a combined detection mechanism, where upon a single-photon absorption, an avalanche of excited hot electrons and the biasing supercurrent, jointly produce a picosecond voltage transient response across the superconducting nanostrip. The SSPDs are typically operated at 4.2 K, but they have shown that 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 optical absorption of our 4-nm-thick NbN film. For 1.55 /spl mu/m photons, QE was /spl sim/20% and decreases exponentially with the increase of the optical wavelength, but even at the wavelength of 6 /spl mu/m the detector remains sensitive to single photons and exhibits QE of about 10/sup -2/%. The dark (false) count rate at 2 K is as low as 2 /spl times/ 10/sup -4/ s/sup -1/, what makes our detector essentially a background-limited sensor. The very low dark-count rate results in the noise equivalent power (NEP) as low as 10/sup -18/ WHz/sup -1/2/ for the mid-infrared range (6 /spl mu/m). Further improvement of the SSPD performance in the mid-infrared range can be obtained by substituting NbN for the other, lower-T/sub c/ superconductors with the narrow superconducting gap and low quasiparticle diffusivity. The use of such materials will shift the cutoff wavelength towards the values even longer than 6 /spl mu/m.
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Area Expedition Conference Second International Conference on Advanced Optoelectronics and Lasers
Notes Approved no
Call Number Serial 1461
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Author Chulkova, G.; Milostnaya, I.; Tarkhov, M.; Korneev, A.; Minaeva, O.; Voronov, B.; Divochiy, A.; Gol'tsman, G.; Kitaygorsky, J.; Pan, D.; Sobolewski, R.
Title Superconducting single-photon nanostructured detectors for advanced optical applications Type Conference Article
Year 2006 Publication Proc. Symposium on Photonics Technologies for 7th Framework Program Abbreviated Journal
Volume 400 Issue Pages
Keywords SSPD, SNSPD
Abstract (up) We present superconducting single-photon detectors (SSPDs) based on NbN thin-film nanostructures and operated at liquid helium temperatures. The SSPDs are made of ultrathin NbN films (2.5-4 nm thick, Tc= 9-11K) as meander-shaped nanowires covering the area of 10× 10 µm2. Our detectors are operated at the temperature well below the critical temperature Tc and are DC biased by a current Ib close to the meander critical current Ic. The operation principle of the detector is based on the use of the resistive region in a narrow ultra-thin superconducting stripe upon the absorption of an incident photon. The developed devices demonstrate high sensitivity and response speed in a broadband range from UV to mid-IR (up to 6 µm), making them very attractive for advanced optical technologies, which require efficient detectors of single quanta and low-density optical radiation.
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Area Expedition Conference
Notes Approved no
Call Number RPLAB @ sasha @ chulkova2006superconducting Serial 1021
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Author Gol'tsman, G.; Korneev, A.; Minaeva, O.; Rubtsova, I.; Milostnaya, I.; Chulkova, G.; Voronov, B.; Smirnov, K.; Seleznev, V.; Słysz, W.; Kitaygorsky, J.; Cross, A.; Pearlman, A.; Sobolewski, Roman
Title Superconducting nanostructured detectors capable of single-photon counting in the THz range Type Conference Article
Year 2005 Publication Proc. 16th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 16th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 555-557
Keywords NbN SSPD, SNSPD
Abstract (up) We present the results of the NbN superconducting single-photon detector sensitivity measurement in the visible to mid-IR range. For visible and near IR light (0.56 — 1.3μm wavelengths) the detector exhibits 30% quantum efficiency saturation value limited by the NbN film absorption and extremely low level of dark counts (2x10 -4 s -1). The detector manifested single-photon counting up to 6 μm wavelength with the quantum efficiency reaching 10 -2 % at 5.6 μm and 3 K temperature.
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Series Editor Series Title Abbreviated Series Title
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Area Expedition Conference
Notes Approved no
Call Number Serial 1476
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Author Gol’tsman, G.; Korneev, A.; Tarkhov, M.; Seleznev, V.; Divochiy, A.; Minaeva, O.; Kaurova, N.; Voronov, B.; Okunev, O.; Chulkova, G.; Milostnaya, I.; Smirnov, K.
Title Middle-infrared ultrafast superconducting single photon detector Type Conference Article
Year 2007 Publication 32nd IRMW / 15th ICTE Abbreviated Journal 32nd IRMW / 15th ICTE
Volume Issue Pages 115-116
Keywords SSPD, SNSPD
Abstract (up) We present the results of the research on quantum efficiency of the ultrathin-film superconducting single-photon detectors (SSPD) in the wavelength rage from 1 mum to 5.7 mum. Reduction of operation temperature to 1.6 K allowed us to measure quantum efficiency of ~1 % at 5.7 mum wavelength with the SSPD made from 4-nm-thick NbN film. In a pursuit of further performance improvement we endeavored SSPD fabricating from 4-nm-thick MoRe film as an alternative material. The MoRe film exhibited transition temperature of 7.7K, critical current density at 4.2 K temperature was 1.1times10 6 A/cm 2 , and diffusivity 1.73 cmVs. The single-photon response was observed with MoRe SSPD at 1.3 mum wavelength with quantum efficiency estimated to be 0.04%.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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Area Expedition Conference
Notes Approved no
Call Number Serial 1246
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Author Milostnaya, I.; Korneev, A.; Rubtsova, I.; Seleznev, V.; Minaeva, O.; Chulkova, G.; Okunev, O.; Voronov, B.; Smirnov, K.; Gol'tsman, G.; Slysz, W.; Wegrzecki, M.; Guziewicz, M.; Bar, J.; Gorska, M.; Pearlman, A.; Kitaygorsky, J.; Cross, A.; Sobolewski, R.
Title Superconducting single-photon detectors designed for operation at 1.55-µm telecommunication wavelength Type Conference Article
Year 2006 Publication J. Phys.: Conf. Ser. Abbreviated Journal J. Phys.: Conf. Ser.
Volume 43 Issue Pages 1334-1337
Keywords NbN SSPD, SNSPD
Abstract (up) We report on our progress in development of superconducting single-photon detectors (SSPDs), specifically designed for secure high-speed quantum communications. The SSPDs consist of NbN-based meander nanostructures and operate at liquid helium temperatures. In general, our devices are capable of GHz-rate photon counting in a spectral range from visible light to mid-infrared. The device jitter is 18 ps and dark counts can reach negligibly small levels. The quantum efficiency (QE) of our best SSPDs for visible-light photons approaches a saturation level of ~30-40%, which is limited by the NbN film absorption. For the infrared range (1.55µm), QE is ~6% at 4.2 K, but it can be significantly improved by reduction of the operation temperature to the 2-K level, when QE reaches ~20% for 1.55-µm photons. In order to further enhance the SSPD efficiency at the wavelength of 1.55 µm, we have integrated our detectors with optical cavities, aiming to increase the effective interaction of the photon with the superconducting meander and, therefore, increase the QE. A successful effort was made to fabricate an advanced SSPD structure with an optical microcavity optimized for absorption of 1.55 µm photons. The design consisted of a quarter-wave dielectric layer, combined with a metallic mirror. Early tests performed on relatively low-QE devices integrated with microcavities, showed that the QE value at the resonator maximum (1.55-µm wavelength) was of the factor 3-to-4 higher than that for a nonresonant SSPD. Independently, we have successfully coupled our SSPDs to single-mode optical fibers. The completed receivers, inserted into a liquid-helium transport dewar, reached ~1% system QE for 1.55 µm photons. The SSPD receivers that are fiber-coupled and, simultaneously, integrated with resonators are expected to be the ultimate photon counters for optical quantum communications.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 1742-6588 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1450
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