涡旋光束相干偏振调控增强轨道角动量湍流传输性能研究

Due to the orthogonality and confidentiality of optical orbital angular momentum (OAM), it can provide the potential solutions for enriching the modulation, multiplexing methods and increasing the transmission capacity of optical communication technology. In view of the application range of OAM system in turbulent environment was limited, how to effectively enhance the anti-turbulence ability of OAM modes have become a key problem to be solved urgently. This project denoted to exploit the coherence and polarization manipulation methods of vortex beams to suppress the atmospheric turbulent effects on OAM modes propagation in the turbulence. An accurate simulation model of vortex beams with complex coherence and polarization structure propagation in the turbulent atmosphere is established via the combination of theoretical analysis and numerical simulation methods. Two-scale filtering method and parallel acceleration algorithm are adopted for the purpose of breaking through the key technology in fast and accurate solving propagation problems of vortex beams in the turbulent atmosphere. The propagation behavior of vortex beams in atmospheric turbulence is analyzed, and then the interaction mechanism between vortex beams and turbulent environment is revealed. Spiral spectrum expansion method is used for extracting the characteristics of OAM modes propagation in the turbulence, the correlation between the propagation turbulent effect of a vortex beam and the transmission characteristics of its OAM modes is studied. A new theory and method for enhancing the anti-turbulent ability of OAM modes by the coherence and polarization manipulation of vortex beams is explored. This project will provide a theoretical basis and a technical support for the link performance evaluation of OAM systems, disturbance suppression of OAM modes propagation in the turbulence.

光学轨道角动量具有正交性、保密性等特点，为丰富光通信技术的调制、分复用方式和提升传输容量提供了潜在的解决方案。鉴于湍流环境中轨道角动量系统应用范围受限，如何有效增强轨道角动量抗湍流扰动能力是亟待解决的关键问题，本项目拟开展涡旋光束的相干偏振调控方法来抑制轨道角动量传播受大气湍流扰动影响的研究。结合理论解析和数值仿真方法，实现对复杂相干偏振结构涡旋光束大气湍流传输的精确仿真建模；引入双频滤波方法和并行加速算法突破涡旋光束大气湍流传输的快速精确建模关键技术，分析涡旋光束大气湍流传输行为，揭示涡旋光束与湍流环境之间相互作用机理；利用螺旋谱展开方法提取轨道角动量湍流传播特征，研究涡旋光束湍流传输效应与其轨道角动量传播特性之间的相互关联，探索涡旋光束的相干偏振调控对轨道角动量抗湍流扰动能力进行增强的新理论和新方法，为轨道角动量系统的链路性能评估、轨道角动量传播的湍流扰动抑制等提供理论依据和技术支撑。

电磁波（光波）传播过程中同时载有能量和动量，其动量包括线动量和角动量。自旋角动量与激光的偏振极化状态有关，而轨道角动量与激光的空间相位有关。目前对激光的开发与利用主要集中在线性动量上，而对角动量的信息承载能力尚未得到清晰地认知和有效地利用，轨道角动量是激光的一个重要且尚未加以充分利用的物理属性。轨道角动量维度为激光技术引入了全新的基础问题与前沿概念。涡旋激光其相位波前呈现出典型的螺旋形结构，携带轨道角动量的涡旋激光具有独特的相位及强度空间分布，轨道角动量具有正交性、保密性等特点，为丰富光通信技术的调制、分复用方式和提升传输容量提供了潜在的解决方案，涡旋激光在以激光-物质（目标）相互作用为基础的应用中同样倍受关注。.本项目以携带轨道角动量的涡旋光束为研究对象，采用理论解析和数值仿真方法相结合的方式，系统性地解决开放环境中涡旋激光的传输以及与目标散射建模的问题，研究了涡旋激光在复杂开放环境中的传输行为。利用螺旋谱展开方法提取轨道角动量湍流传播特征，研究了涡旋光束湍流传输效应与其轨道角动量传播特性之间的相互关联，揭示了涡旋光束与湍流环境、物质（目标）之间的相互作用理论。项目基于随机介质波传播与散射理论和信息理论，从涡旋光束的相干/偏振调控与湍流场景建模、特殊相干偏振空间分布的涡旋光束湍流传输建模、相干偏振调控对轨道角动量传播的湍流扰动抑制研究三个方面展开研究。项目研究结果表明通过调控涡旋激光的相干偏振分布可以抑制大气湍流对涡旋激光的轨道角动量模式传播的影响，实现了对复杂相干偏振结构的涡旋光束在大气湍流中传输的精确仿真建模，探索了涡旋光束的相干偏振调控增强轨道角动量传播抗湍流扰动能力的新理论和新方法，实现了具有国内学术前沿领先优势的复杂开放环境下的矢量涡旋光束传输仿真技术的突破，为轨道角动量系统的链路性能评估、轨道角动量传播的湍流扰动抑制等提供了理论依据和技术支撑。