The possibility of using a photodiode in the Geiger mode for timing of
short light pulses is studied. It is found that the transit time betw
een the Light pulse and the electrical response is determined by a rel
iable exponential growth of electron and hole populations in the deple
tion layer from the initial level because of the photoionization to a
level meeting the detection threshold. This transit time depends on th
e photon number in the light pulse and has to be measured by an auxili
ary linear detector. A device that allows precise timing in the 10-ps
range, whatever the photon number beyond 100, is proposed. (C) 1998 Op
tical Society of America.