Performance comparisons between PIN and APD photodetectors for use in optical communication systems

In this report, a performance comparison of the conventional PIN photodiode with the Avalanche Photodiode (APD) in an optical communication system is presented. The effects of bandwidth, gain, extinction ratio, shot noise and thermal noise are compared and studied in detail. It was shown that the Q factor produced by each detector is heavily affected by the thermal noise in the PIN device, and by both the thermal and shot noise in the APD. It was also found that the APD's gain plays a significant role, and the shot noise has to be carefully dealt with. Additionally, the relationship of receiver sensitivity with thermal and shot noise was investigated and compared.