Superconducting Nanowire Single-Photon Detector
A superconducting nanowire single-photon detector (SNSPD) is a device which is made of a thin film of superconducting material that’s shaped like a meandering nanowire that detects single photons in the infrared and optical ranges. SNSPDs are operated with current bias just below the critical current of the superconducting nanowire, which is typically operated at temperatures below 3 K. The active area of the detector is designed such that photons at the output of optical fibre are collected effectively. The photon which is absorbed by the nanowire has enough energy to disturb Cooper pairs and generate hot spots, forcing the supercurrent to flow through resistive regions of nanowire, resulting in generation of a measurable output voltage pulse.The voltage pulse from this event can be detected in an external circuit.
Advantage of SNSPDs over other single photon detectors are high detection efficiency very low time jitter, ultra-fast detection rates, negligible intrinsic dark counts. SNSPDs are used in applications ranging from fundamental research, communications, remote sensing, Quantum optics, and astronomy.
