Single photon detection at 1.3 micron using a gated avalanche photodiode.

We have done experiments on the detection of single photons at a wavelength of 1.3 micron using a gated Ge avalanche photodiode pulse biased above breakdown. The influence of traps on the breakdown voltage was measured and the possibility of using such an ultrasensitive photodiode as a quantum limited detector for optical communications is discussed.