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-A Q single-photon avalanche diode module with an active quenching bias c ircuit that gives a dead time of similar to 35 ns for use in high coun t 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 mu m in the center of the active region, if the signal from the diode bef ore the active quenching circuitry is used as input to the timing elec tronics, and if an external dead time of similar to 55 ns is imposed. Under these conditions, the total probability of obtaining an afterpul se is found to be similar to 2x10(-3). Limitations of existing time-co rrelated single-photon counting instrumentation for count rates exceed ing 10(6) s(-1) are discussed. (C) 1996 American Institute of Physics.