A photon detector and a photon detection method

摘要

A light signal frequency is provided to a photon source 24 and detection module 20, possibly by a master clock 120. A photon detector 17 is provided comprising a gated single photon avalanche photodiode (SPAD) photon detector. This may be sinusoidally gated independently and/or at a faster rate than the SPAD so that photons would not be expected during certain gated periods. This may also be controlled by the master clock 120. The module 20 distinguishes between pulses occurring during gating when photons are expected and during gating periods when photons are not expected, for example using a NAND gate or switching mechanism. The detector may be used to help distinguish dark counts or afterpulses for quantum key distribution.