Milostnaya, I and Korneev, A and Rubtsova, I and Seleznev, V and Minaeva, O and Chulkova, G and Okunev, O and Voronov, B and Smirnov, K and Gol'tsman, G and Slysz, W and Wegrzecki, M and Guziewicz, M and Bar, J and Gorska, M and Pearlman, A and Kitaygorsky, J and Cross, A and Sobolewski, Roman (2006) Superconducting single-photon detectors designed for operation at 1.55-┬Ám telecommunication wavelength. Journal of Physics: Conference Series, 43 . pp. 1334-1337.
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Official URL: http://stacks.iop.org/1742-6596/43/1334
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 (1.55┬Ám), 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-┬Ám photons. In order to further enhance the SSPD efficiency at the wavelength of 1.55 ┬Ám, 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 ┬Ám 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-┬Ám 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 ┬Ám 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.
|Deposited By:||Prof. Alexey Ivanov|
|Deposited On:||06 Feb 2010 11:10|
|Last Modified:||06 Feb 2010 11:53|
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