We investigate the performance of separate absorption multiplication I
nGaAs/InP avalanche photodiodes as single-photon detectors for 1.3- an
d 1.55-mu m wavelengths. First we study afterpulses and choose experim
ental conditions to limit this effect. Then we compare the InGaAs/InP
detector with a germanium avalanche photodiode; the former shows a low
er dark-count rate. The effect of operating temperature is studied for
both wavelengths. At 173 K and with a dark-count probability per gate
of 10(-4), detection efficiencies of 16% for 1.3 mu m and 7% for 1.55
mu m are obtained. Finally, a timing resolution of less than 200 ps i
s demonstrated. (C) 1998 Optical Society of America.