Abstract

A single-photon detector (SPD) at 1550 nm is essential for quantum key distribution (QKD) based on optical fiber links. A cooled InGaAs/InP avalanche photodiode (APD) is a candidate for the SPD, because it has a high detection efficiency with a low dark count probability. However, the maximum detection speed (the repetition frequency of the gate) was very slow (<10MHz), which is due to the afterpulsing phenomenon. Recently we proposed the sinusoidal gating scheme and demonstrated the high-speed (500~800MHz) single-photon detection with a low afterpulsing probability⁽¹. In the scheme, the overall afterpulsing probability is somewhat high when the gating frequency is lower than 100MHz.

© 2007 IEEE