Investigation on three key problems for the optical signal detection in space-borne coherent wind lidar

Space-borne coherent wind lidar, which estimates the radial component of the velocity vector from the mean frequency of the backscattered laser field from atmospheric aerosol particles as the result of interference with the reference local signal, is an attractive and feasible instrument for global measurements of winds. Since the space-borne coherent wind lidar is a complicated and critical optical system, and the accuracy of radial wind velocity is dependent on many factors. For the sake of enhancing the velocity accuracy, it is very important to improve the system sensitivity of the wind lidar, since the backscattered optical signal for the long range propagation is very weak. In this paper, it is proposed that the new enhanced IQ detection, phase nonlinearity for the laser propagating in the optical system, and the enhanced dual-balanced coherent detection method.