Superconducting nanowire single-photon detectors at a wavelength of 940 nm

Abstract: We develop single-photon detectors comprising single-mode fiber-coupled superconducting nanowires, with high system detection efficiencies at a wavelength of 940 nm. The detector comprises a 6.5-nm-thick, 110-nm-wide NbN nanowire meander fabricated onto a Si substrate with a distributed Bragg reflector for enhancing the optical absorptance. We demonstrate that, via the design of a low filling factor (1/3) and active area ({\Phi} = 10 {\mu}m), the system reaches a detection efficiency of ~60% with a dark count rate of 10 Hz, a recovery time <12 ns, and a timing jitter of ~50 ps.