基于扫描式光纤F-P干涉仪的大气Rayleigh-Brillouin散射谱型精细探测方法与实验研究

Atmospheric temperature is one of important parameters for the description of the atmospheric state. At present, the measurement methods based on Rayleigh-Brillouin scattering are employed to relatively detect atmospheric temperature profiles. That is to say, the definition of response functions and calibration procedures is required for temperature retrieval. In this project, the fine detection method of the spectrum shape of Rayleigh-Brillouin scattering based on scanning fiber F-P interferometer is investigated. The researches are focused on the following key contents, including the method of the hyperspectral scanning filter for Rayleigh-Brillouin scattering spectroscopy, the design and optimization of scanning fiber F-P interferometer, the acquisition method of frequency spectrum data and the high-precision model of spectrum shape of Rayleigh–Brillouin scattering. The impacts on spectrum envelope of the return signal, caused by the Doppler-broadened spectrum of the Rayleigh-scattering spectrum width and Brillouin-scattering spectrum shape, are decoupled by experimental method. Mie-Scattering correction method and fitting model of spectrum shape are amended according to the experimental results. The research provides a new solution of filter system for the achievement of all-time, high-precision and absolute detection of atmospheric temperature in the future. There is reference significance for the investigation of filter system of similar lidar. Simultaneously, the scanning filter method provides a feasible solution for the filter system with the characteristics of miniaturization, high anti-interference and high stability in the space-based platform.

大气温度是描述大气状态的重要基本特征参量之一。目前，基于瑞利-布里渊散射的大气温度探测方法多应用于大气温度的相对探测，即温度反演时需要响应函数和校准程序。本项目提出基于扫描式光纤法布里-珀罗干涉仪的大气瑞利-布里渊散射谱型精细探测方法研究，重点研究：瑞利-布里渊散射谱的高光谱扫描分光方法；扫描式光纤法布里-珀罗干涉仪参数设计与动态滤波性能优化；瑞利-布里渊散射谱数据的获取与谱型拟合模型的数学建模；利用实验方法解耦瑞利散射多普勒展宽与布里渊散射线型对回波信号包络谱的影响以及对残余米散射信号抑制方法和谱型拟合模型修正等技术与方法。项目研究成果将为大气温度的全天时和高精度绝对探测提供了全新的分光系统解决方案，对同类激光雷达的分光系统研究也具有借鉴意义，可为我国未来星载测温高光谱激光雷达的发展提供全新的小型化、高抗干扰性和高稳定性的瑞利-布里渊散射分光系统设计技术及解决方案。

针对目前高光谱激光雷达进行大气温度探测中的瓶颈问题，即温度反演需要响应函数和校准程序，本项目紧密围绕气体瑞利-布里渊散射谱形探测、扫描分光与鉴频开展研究，获得了不同环境参数条件下气体瑞利-布里渊散射谱形特征参数，实现了气体温度的绝对探测。项目以气体分子散射理论、多光束干涉选频理论与晶体电光效应为基础，开展了KD*P电光晶体固体腔扫描法布里-珀罗干涉仪参数设计、动态滤波性能优化，干涉仪实现了20mm大通光口径、200MHz量级频谱分辨率与MHz的光谱扫描频率。结合自研温压控制精度分别为0.02℃和0.1KPa大气环境试验箱和锁频精度0.3MHz的脉冲激光锁频技术，及高光谱分辨率分光系统，获得了不同温压条件下气体瑞利-布里渊散射谱的高光谱扫描分光方法及构建了探测离散点散射谱数据的拟合模型，通过采用扫描通道残余米散射信号抑制方法对拟合模型进行了优化，优化后气体温度反演误差小于0.6K。该瑞利-布里渊散射谱形精细探测方法在大气温度绝对探测领域具有良好的应用前景，也为高光谱分辨率激光雷达全天时和高精度绝对探测大气温度廓线奠定了技术基础。对于同类激光雷达的高光谱分辨率分光系统研究具有借鉴意义，也是国内首次提出扫描分光方法。此外，该方法也进一步为人类活动关系密切、气象要素日夜变化明显的城市大气边界层内温度的精细观测；研究各类天气过程的时空特征，变化规律及其物理机制，特别为城市热岛、高温热浪监测及预报等城市气象观测提供有效的探测和研究手段。该研究对提高区域温度预报的准确性，建立数值模式、研究大气污染扩散等区域性气候变化，有着重要的研究价值和显著的社会效益。