Analysis of nonideal solid-state photomultiplier (SSPM) for optical receivers

Recently, interest has been shown in superlattice avalanche photodiodes (APDs) in which multiple ionisation per initiating carrier per stage occurs as a basis for a solid-state photomultiplier (SSPM). In the paper we present a new discrete ionisation model for the SSPM which is used to predict the gain and noise characteristics of these devices. The expressions obtained here are quite general and can be applied to photomultiplier tubes, single ionisation or two-ionisation superlattice APDs, and conventional APDs as special cases. The performance of optical receivers employing SSPMs is also examined, showing that residual hole ionisation must be vanishingly small if significant advantage is to be gained from employing multiple ionizations per stage. The analysis and illustrative results presented should provide useful guidelines for the design of advanced APDs embodying these principles.