Design of a water vapor spectroscopy system for Raman lidar based on sampled fiber Bragg grating

Aiming to minimize the interference of Mie-Rayleigh scattering and solar background light on the water vapor Raman lidar, this study proposes a multi-cascade water vapor spectroscopy system based on sampling fiber Bragg grating (SFBG) and fiber Bragg grating (FBG). The proposed system uses the principle of Raman lidar to detect water vapor. The parameters affecting the SFBG's performance are optimized by the matrix transmission method, and the SFBG performance parameters with high reflectivity and narrow bandwidth at specific wavelengths are obtained. According to the simulation results of the signal strength of each channel, the water vapor backscattering signal is 50 dB and 30 dB stronger than the Mie-Rayleigh scattering and solar background light, respectively. At a signal-to-noise ratio of 10, the detection altitude during the day is 6 km. The results also indicate that the proposed spectroscopy system has stable spectroscopy performance and miniaturized volume, providing a new solution for the development of vehicle-mounted and airborne lidar.