A Single-Photon Detector Module

A module for recording single-photon pulses is described. It is able to reliably operate in the mode of single-photon counting at a wavelength of 1550 nm (the minimum attenuation in quartz fibers). For this purpose, unique avalanche photodetectors (APDs) based on InGaAs/InP heterostructures with the three-stage cooling to temperatures of -50 degrees C via Peltier elements are used during reception. Test measurements of the level of noise counts, including both dark pulses and afterpulses, have been performed using the developed testing system. The dependences of the recorded noise counts on the duration of gate pulses have been obtained. The nonlinear character of these dependences is evidence of the difference in the contributions of the afterpulsing effect and the dark pulses of the APDs to the noise counts. At short durations of the gate pulses, the major contribution to the noise counts is made by dark pulses of the APDs.