Development of superconducting nanowire single photon detector (SNSPD) for communication wavelength of 1550 nm

Abstract

We report our progress in the development of superconducting nanowire single photon detectors (SNSPDs). Single photon detector is the key component in quantum communication and quantum optics. Among various single photon detectors, SNSPDs show superior performance in detection efficiency, timing jitter, dark count, and count rate. We fabricate our devices with ultrathin niobium nitride (NbN) or amorphous molybdenum silicide (α-MoxSi1-x) films. 100 nm wide nanowire meander patterns are made on top of a distributed Bragg reflector (DBR). The detector is fiber-coupled and is operated below 2.5 K down to 0.8 K in a closed-cycle GM refrigerator. We use self-alignment scheme for the fiber-coupling in order to avoid possible drift due to the thermal contraction at low temperature. We present our measurement result of detection efficiency, dark count rate and reset time. We then discuss our further direction to increase the detector performance.