抄録
I review the recent progress on single-photon detectors developed for detecting 1550-nm photons. Thermoelectrically cooled single-photon detectors based on indium-gallium-arsenide avalanche photodiodes are simple to operate and are desirable for practical applications. Methods for reducing the dark count rate and after-pulsing probability are discussed. I also briefly explain the concepts of upconversion-based singlephoton detectors and ultra-low-noise superconducting single-photon detectors.