  Single-photon detectors (SPDs) are the most sensitive instruments for light
detection. In the near-infrared range, SPDs based on III-V compound
semiconductor avalanche photodiodes have been extensively used during the past
two decades for diverse applications due to their advantages in practicality
including small size, low cost and easy operation. In the past decade, the
rapid developments and increasing demands in quantum information science have
served as key drivers to improve the device performance of single-photon
avalanche diodes and to invent new avalanche quenching techniques. This Review
aims to introduce the technology advances of InGaAs/InP single-photon detector
systems in the telecom wavelengths and the relevant quantum communication
applications, and particularly to highlight recent emerging techniques such as
high-frequency gating at GHz rates and free-running operation using
negative-feedback avalanche diodes. Future perspectives of both the devices and
quenching techniques are summarized.
