Error Probabilities for Optical Receivers That Employ Dynamically Biased Avalanche Photodiodes

A novel theory was recently reported for the avalanche multiplication process in avalanche photodiodes (APDs) under dynamic reverse-biasing conditions. It has been shown theoretically that the bit-synchronized, periodic modulation of the electric field in the multiplication region can offer improvements in the gain-bandwidth product by reducing intersymbol interference in optical receivers. This paper reports a rigorous formulation of the sensitivity of optical receivers that employ dynamically biased APDs. To enable the sensitivity analysis, a recurrence theory is developed to calculate the joint probability distribution function (PDF) of the stochastic gain and avalanche buildup time in APDs that are operated under dynamic biasing. It is shown that in an ideal buildup-time limited scenario, a minimum receiver sensitivity of -20 dBm is predicted at an optimal gain of approximately 47 for a 60 Gb/s communication system, compared to a minimum of 0 dBm in the static-bias case. The receiver sensitivity analysis also reveals that, as the peak-to-peak voltage of the dynamic reverse bias increases, the device optimal gain increases while maintaining a short avalanche buildup time and reduced ISI. Of course, a point of diminishing return exists in practice when the tunneling current in the multiplication region becomes dominant.