Impact of photodetector’s nonlinear response on coherent laser Doppler speedometer

Photodetector is an important part of coherent laser Doppler speedometer, and the optical intensity response of which has a great impact on the system's signal-to-noise ratio (SNR). In order to improve the detection performance, the impact of photodetector's nonlinear response on the laser Doppler speedometer was studied. The response function was deduced by using polynomial analysis. The output voltage waveform under nonlinear response was compared with that under linear response, theoretically demonstrating the impact of photodetector's nonlinear response on the SNR of the system. Comparison experiments indicate that through the suppression of the nonlinear response, the SNR raises from 16 dB to 35 dB, which results in the correction of the analysis.