基于自差相干探测的星地激光通信接收关键技术研究

For the self-homodying coherent detection with the particular advantage of simple construction and easy to resist the influence of turbulence compared to the homodyne detection, the satellite-to-ground laser communication is regard as the only way to solve the bottleneck of data transmission between satellite to a ground station, and is one of the current research hotspots in the field of laser communication, a better solution is expected in the aspects of key receiving techniques such as eliminating the wavefront aberration and improving spatial light coupling efficiency and so on. This project attempts to investigate the key receiving technology of satellite-to-ground laser communication system with self-homodying coherent detection scheme by using the signal light's receiving-coupling- analyzing process as the research main line. Firstly, the diversity of signal light's wavefront distortion is researched in detail, a quick and efficient wavefront aberration compensation algorithm is explored, and the receiving scheme with the function of wavefront distortion adaptive compensation will be constructed. Secondly, the instantaneous probability density function of coupling efficiency for space light to a single-mode fiber is deeply analyzed, and a corresponding new method with high and stable coupling efficiency is given. At last, a new mode of the free space channel is established and different factors on affecting the performance of satellite-to-ground laser communication system is researched completely. This project will gives a new receiving method with the function of wavefront aberration compensation and with the simple structure, and explore the distributive characteristics of instantaneous coupling efficiency for space light to a single-mode fiber and the new coupling method, and reveal the mechanism of multi-factor which affects the properties of satellite-to-ground laser communication system with self-homodying cohetent scheme. The implementation of the project has important theoretical significance and application value for developing a new generation of satellite-to-ground laser communication system.

基于自差相干探测的星地激光通信因具有结构简单、抗湍流等零差相干探测不具备的独特优势，被认为是解决星地数据传输"瓶颈"的不二选择，是当前激光通信领域的研究热点之一，但在应对波前畸变及空间光耦合等接收关键技术方面尚需更有效的解决方案。鉴于此，本项目以信号光的接收-耦合-性能分析为主线开展研究：首先分析波前畸变的作用机制，探索快速高效的畸变补偿新算法，构建自适应补偿接收方案；其次,分析空间光至单模光纤耦合的瞬时起伏特性，探索高效稳定的耦合新方法；最后，综合考虑畸变补偿及耦合模块对信道的影响，构建完善的信道模型，分析不同因素对接收性能的作用机理。本项目将构建结构简单功能健全的波前畸变自适应补偿新接收方案，探索空间光至单模光纤的瞬时耦合效率概率分布特征和新颖耦合方法，完善信道模型，揭示影响自差相干探测星地激光通信接收性能的多因素作用机理。项目的实施对发展新一代星地激光通信具有重要的理论意义和应用价值

空间光通信具有传输速率高、抗干扰能力强、灵活便捷等优点，在民用和军事方面具有很高的应用价值。在星地激光通信系统中，由于大气信道的随机性和特殊性，特别是大气湍流效应会使信号光强闪烁而引起波前畸变，导致通信系统误码率上升，甚至会使得通信链接中断。本项目主要研究星地激光相干光通信接收关键技术，包括波前畸变补偿技术、空间光至单模光纤耦合技术以及星地空间光信道性能提升等，具体的研究工作总结如下：. 采用光楔扫描系统实现对光束扫描，光束波前畸变叛别，并利用G-S算法改善波前质量。.提出了双层微透镜阵列聚合至光子灯笼的空间光到单模光纤耦合方法，为光信号的接收提供了保障。.研究了星地激光通信信道特征，提出了反向脉冲位置宽度调制方式、反向差分脉冲位置宽度调制方式；提出了新型组合副载波调制方式，分别在对数正态分布湍流信道模型以及负指数分布湍流信道模型中，详细分析了其系统的误码率，并与副载波BPSK调制系统的误码率进行了比较。.基于指数韦伯信道模型，研究了DPSK采用选择空间分集接收时的平均误码率和中断概率，推导出了系统采用选择空间分集接收时，信道的概率密度函数和累积分布函数、等增益空间分集时的平均误码率；在Gamma-Gamma衰落信道和指向误差的共同作用下，推导出了BPSK在采用并行多跳网络技术时平均误码率和中断概率的解析解表达式，并在此基础上详细研究了多跳网络中继数量、信道数量对通信系统的影响。.利用Gauss-Hermite正交积分近似、Meijer G函数替换以及拉盖尔正交分解求积法等方法详细推导出了PPM、BPSK和BPSK-SIM-PPM三种调制方式在各种湍流信道下的平均误码率的解析表达式，并通过蒙特卡洛对以上调制方式在各种湍流信道的性能进行仿真。.提出了一个基于PPM硬判决检错的ARQ-FSO光通信系统，推导出在不同强度湍流信道下误码率和通过率公式，并通过蒙特卡洛仿真对ARQ-FSO系统模拟验证。.深入研究了基于等增益合并和选择合并分集接收的多元正交幅度调制自由空间光通信系统的性能；利用高斯埃尔米特正交积分公式，推导得出了在对数正态分布和负指数分布衰落信道和大气衰减效应影响下的基于EGC方案的MQAM调制的平均误比特率和中断概率表达式。.基于表面等离子体激源，提出了多种光束滤波器方案，为提升接收信号光质量提供了保障。