Actively quenched single‐photon avalanche diode for high repetition rate time‐gated photon counting

This paper reports an experimental characterization of the EG&G SPCM‐AQ single‐photon avalanche diode module with an active quenching bias circuit that gives a dead time of ∼35 ns for use in high count rate, fast timing applications. A quantum efficiency of ≳70% and an optimal timing jitter with a full width at one‐thousandth maximum of 1.5 ns is obtained if the light is tightly focused to a spot of <25 μm in the center of the active region, if the signal from the diode before the active quenching circuitry is used as input to the timing electronics, and if an external dead time of ∼55 ns is imposed. Under these conditions, the total probability of obtaining an afterpulse is found to be ∼2×10−3. Limitations of existing time‐correlated single‐photon counting instrumentation for count rates exceeding 106 s−1 are discussed.