Application of dual-balanced detection in laser velocimeter

To increase the measurement distance and sensitivity of laser Doppler velocimeter, the dual-balanced detection receiving system was designed based on Mach-Zehnder ring structure. The SNR expression of balanced detection system based on the balanced light current is derived and simulated. The simulation shows that the SNR of balanced detection is higher than that of the heterodyne detection when quantum conversion efficiency ratio of two detectors ranges from 0.236 to 1, and the signal-to-noise ratio is the highest when the ratio is 1. The simulation results were demonstrated by experiments.