全光纤Mach-Zehnder干涉仪的多普勒测风激光雷达鉴频技术研究

Atmospheric wind field is an important parameter to study the atmospheric dynamics, and the incoherent Doppler wind lidar with directly frequency discriminator detection has become an important means for obtaining the atmospheric wind field information. The aim of the project is to study the Doppler wind lidar technology using all-fiber Mach-Zehnder (M-Z) interference frequency discriminator, which has feature of a high transmittance, wide field of view, a large luminous flux, high stability and small size. The research is mainly focused on the detection theories and methods of atmospheric wind lidar with fiber M-Z frequency discriminator, and the key technologies of the parameter optimization design of the frequency discriminator, fiber-coupled technology， stray light isolation and so on. Using the laser wavelength of 532nm, the coupling efficiency of telescope with single-mode fiber is studied to obtain the optimal coupling method by considered the different coupling mode ; the wind field detection theory is used to optimize the frequency discriminator parameters of the fiber M-Z interferometer for obtaining the best detection efficiency of the wind field. The advanced optical design means are used to optimize the system design of frequency discriminator for obtaining the optimal parameters and design methods. By using existing laboratory conditions, a Doppler lidar experiment system with all-fiber M-Z interference frequency discriminator is to be built and the experimental research is carried out in order to obtain the best design of the system. The frequency discrimination range of fiber M-Z interferometer proposed in the project includes from ultraviolet to infrared waveband.The research results of this project will provide usefully new technology and methods to research and development of future small wind lidar based on space or satellite platform.

大气风场是研究大气动力学的重要参数，非相干多普勒激光雷达已成为大气风场探测的重要手段。项目提出并构建高透过率、宽视场、大光通量、高稳定性的全光纤Mach-Zehnder(M-Z)干涉鉴频的多普勒测风激光雷达技术，重点研究光纤M-Z 鉴频器的激光雷达大气风场探测理论与方法、鉴频器参数优化设计、光纤耦合与光纤杂散光的隔离等关键技术。针对532nm波长激光，研究不同耦合方式下望远镜与单模光纤的耦合效率，获得最佳耦合方式；基于风场探测理论及先进光学设计方法，优化光纤M-Z干涉仪的鉴频参数及设计方法，获取最佳风场探测效率。利用现有实验室条件搭建一套全光纤M-Z干涉鉴频的多普勒测风激光雷达实验系统，并开展实验研究，获取最佳系统设计方案。本项目提出的光纤M-Z干涉仪可对紫外到近红外波段的激光鉴频，研究成果将为未来小型多普勒测风雷达的发展、空基或星基平台测风激光雷达技术的研究及发展提供新的技术及方法。

项目针对多普勒测风激光雷达鉴频系统展开研究，提出了采用高透过率、宽视场、大光通量、高稳定性的全光纤Mach-Zehnder干涉仪（All Fiber Mach-Zehnder Interferometer,简称FMZI）作为鉴频器，重点研究了基于FMZI鉴频器的激光雷达大气风场探测理论与反演算法、鉴频器参数优化设计及不光纤耦合效率等关键技术，设计并搭建了多普勒激光雷达风场探测模拟系统，完成了在模拟风场条件下的系统的探测，验证了系统设计原理、方法及技术的可行性。.项目在分析激光雷达大气风场探测理论及方法的基础上，针对不同鉴频器件在激光雷达风场探测中应用及特点，以Fabry-perot干涉仪与M-Z干涉仪为对象，重点研究分析了其作为能量探测与条纹图像检测时的探测灵敏度、信噪比、误差等性能参数。最终提出了FMZI作为激光雷达风场探测鉴频器的方法，理论分析验证了FMZI作为鉴频器实现多普勒鉴频的可行性及优越性。设计了基于FMZI鉴频器的多普勒激光雷达系统，研究并完成了FMZI鉴频器参数的优化设计及大气风场的反演算法，重点分析了两臂光程差的设置对系统测风灵敏度及系统信噪比影响。针对不同风场范围探测需求，设计了基于米散射理论的对流层底层大气风场探测的单FMZI-1鉴频系统，优化臂长差为74.8cm，可实现最高灵敏度2.62%/(m/s), ±18.2m/s的风场探测。针对大风场探测（±100m/s）需求，提出了采用双FMZI作为鉴频器件，采用小臂长差（13.7cm）、大动态范围（±100m/s）的鉴频器（FMZI-2）对风速区间进行定位， FMZI-1进行风速精细探测，通过数据融合校正而实现大动态范围高灵敏度的风场探测。理论仿真及分析证明该方法可以实现±100m/s大动态范围内风速误差小于1m/s的大气风场探测，解决了同时实现高灵敏度与大动态范围探测的技术难点。.设计并研制了一套基于机械转轮机构的大气风场模拟系统，并搭建了基于新型FMZI鉴频器的多普勒测风激光雷达实验校正系统，完成了实验室条件下多普勒激光雷达风场模拟测试，获得了模拟风场的测量误差为0.25m/s，验证了FMZI作为多普勒激光雷达鉴频器的可行性。鉴于FMZI鉴频器的优异性能，本项目的研究成果可为新型小型化多普勒激光雷达发展以及未来建立星载平台全球风场探测激光雷达提供新的技术支持及解决方法。