Quasi-Gated Superconducting Nanowire Single-Photon Detector

Superconducting nanowire single-photon detectors (SNSPDs) are attractive because of their wide response band, low noise, and high repetition rate in practical applications. Owing to these advantage, SNSPDs are particularly useful for high efficiency (>80%) in laser-ranging systems operating at 1064 nm. However, the superconducting nanowire may latch in a permanent resistive state because of the backscattering problem, which may prevent it from detecting targeted reflection photons. This paper proposes an SNSPD that operates in a quasi-gated mode with the help of a programmed source and improved feeding circuit. The programmed source switches the SNSPD off at a low level, and switches it on at a high level. Such an on-off switching process enables the SNSPD to recover automatically from latching through compulsory initialization in each period, therefore, resolving the problem caused by strong backscatterings in laser ranging systems. The quasi-gated SNSPD can also be used in other applications operating in a nonstop mode, even with occasional latchings.