On the research of optoelectronic mixing under nonlinear effect of avalanche photodiodes

Optoelectronic mixing (OEM) is the key technology used in optical communications and ranging. Based on the nonlinear model of avalanche photodiodes (APDs), the nonlinear effect caused by space charges and series resistance is considered. The conversion efficiency (CE) and the signal to noise ratio (SNR) of the APDs-based OEM are studied under different illuminations. The theoretical analysis along with the experimental results indicate that when the multiplications of APDs are high (>100), CE remains unchanged but SNR is inversely proportional to the illuminations; When the multiplications are low (<;20), CE is proportional to the multiplications and SNR is proportional to the square of the multiplications.