Calibration of Frequency Discriminator and Application for Doppler Lidar Based on Fiber Mach-Zehnder Interferometer

The wind measuring sensitivity and dynamic range for Fiber Mach-Zehnder Interferometer (FMZI) based Doppler lidar are analyzed. The detection dynamic range is +/- 199.5 m/s and +/- 13.3 m/s for 0.1 m and 1.5 m Optical Path Difference (OPD). The optimal sensitivity is 2.15Yo with the change of wind speed of 1 m/s, corresponding to an optimal OPD of 0.45 m. The OPD error will result in retrieval wind velocity error. When the OPD is equal to 0.145 9 m or 1.088 9 m, the retrieval wind velocity error is 1.028 m/s or 0.138 m/s for 1 nm OPD error. We employed laser wavelength tuning method to determine the OPD of FMZI. The experiment has been implemented to calibrate OPD. This interferometer is used as a frequency discriminator in the lidar to detect the actual wind speed. The inversion of the wind speed is in good agreement with the coherent detection of the wind speed, which proves the correctness of the calibration detection.