Abstract

Avalanche photodetectors (APDs) for 1.0 to 1.6μm wavelengths are known to be more sensitive than p-i-n photodiodes because of the internal multiplication provided by impact ionisation. However the multiplication process also produces avalanche noise which impairs the signal to noise ratio and limits sensitivity at high values of multiplication. The widely used theory of McIntyre[1] shows that the excess noise factor, F, falls for a small (≪1) ratio of ionisation coefficients k=β/α, where α is the ionisation coefficient of the initiating carrier.

© 1998 IEEE