Fiber-coupled single-photon detectors based on NbN superconducting nanostructures for practical quantum cryptography and photon-correlation studies
Wojciech Słysz, M. Węgrzecki, Jan Bar, P. Grabiec, Małgorzata Górska, Val Zwiller, Christian Latta, Pascal Böhi, I. Milostnaya, Olga V. Minaeva, A.V. Antipov, O. Okunev, Alexander A. Korneev, К. В. Смирнов, B. Voronov, N. Kaurova, Gregory N Gol'tsman, Aaron J. Pearlman, Allen S. Cross, I. Komissarov · Applied Physics Letters · 2006
We have fabricated and tested a two-channel single-photon detector system based on two fiber-coupled superconducting single-photon detectors (SSPDs). Our best device reached the system quantum efficiency of 0.3% in the 1540-nm telecommunication wavelength with a fiber-to-detector coupling factor of about 30%. The photoresponse consisted of 2.5-ns-wide voltage pulses with a rise time of 250ps and timing jitter below 40ps. The overall system response time, measured as a second-order, photon cross-correlation function, was below 400ps. Our SSPDs operate at 4.2K inside a liquid-helium Dewar, but their optical fiber inputs and electrical outputs are at room temperature. Our two-channel detector system should find applications in practical quantum cryptography and in antibunching-type quantum correlation measurements.