基于声光互作用动量匹配的相干探测光学降噪方法研究

In transmission and receiver, noise accumulation leads to SNR degradation, while noise suppression is a technical problem in practical application. With the development of the acousto-optic technology and its applications in communication system, looking for an effective method to reduce noise is of great significance for improving receiving ability in weak signal environment. In this project, the impact of signal phase and the stability of built grating on acousto-optic diffraction is analyzed based on momentum matching and coupled wave theory , and then optical signal processing is realized based on acousto-optic interaction, meanwhile noise suppression and SNR improvement in transmission is researched. This project aims to explore a new receiving technique that acousto-optic device is applied to coherent optical detection in order to further reduce noise in communication bandwidth on the basis of traditional electronic communication receiving technology. By the experimental platform established, the relationship between grating characteristics and diffraction efficiency of acousto-optic interaction is further analyzed, moreover, in order to improve the photoelectric detection efficiency of receiving system, the effect of optical match on the fluctuation of output noise in coherent detection system is studied, furthermore the optical de-noising methods and measures in coherent detection is discussed based on the momentum matching of acousto-optic interaction, thus a new technique is provided for de-noising processing in communications.

通信信号传输与接收将伴随噪声积累和信噪比恶化，而噪声抑制是系统应用中的技术难题，随着声光技术的发展及在通信系统中的应用，研究弱信号环境下信号接收能力，寻找有效的信号降噪方法具有重要意义。项目运用动量匹配原理和耦合波理论，分析信号相位与稳定光栅建立对声光衍射的影响关系，通过声光互作用机理实现光信号处理，研究通信信号传输中噪声的抑制及信噪比改善，探讨声光器件在相干光探测的重要应用，在传统电通信接收技术基础上，进一步改善通信带宽内降噪问题，探索一种新体制信号接收技术。通过建立系统实验测试平台，进一步分析声光互作用光栅特性与衍射效率关系，研究光学匹配对相干系统输出噪声起伏的影响，探讨声光效应动量匹配的相干探测光学降噪方法和措施，达到提高接收系统光电探测效率的目的，为通信信号降噪处理提供一种新的技术途径。

信息安全、有效、可靠的传输是通信领域所追求的目标，由于通信传输是一个伴随信号衰落和噪声积累的过程，加上外界背景因素的干扰，使得到达接收前端信号被噪声淹没，导致无法进行判决。如何降低外界噪声干扰，在接收端获得一定通信质量，是通信系统急待解决的技术难题。声光信号处理是一种新体制侦察接收信号处理方法，它可以完成宽带内瞬变信号的同时探测，实现空间频谱信号的无缝跟踪测量，在当今信号密集、形式复杂的大带宽现代通信和雷达应用领域中显示出巨大的优势。.本项目完成了利用声光偏转器与激光器构建的光学结构单元设计、激光注入与光纤耦合单元设计、相干光平衡探测仿真及光学降噪系统实现研究，利用声光偏转器完成激光与超声（射频）的互作用，通过设计的光学结构单元，对一定带宽内的射频信号进行处理，获得平稳的衍射光信号；采用激光注入器将空间激光（532nm）耦合到保偏光纤，再通过2*2的光纤耦合器完成光信号的平衡相干处理，最后由平衡探测器实现光电信号转换，得到信噪比改善的射频信号。.本项目最终完成相干型声光侦察接收演示样机的制作，进行了实验室测试和外场试验，与同类电子侦察接收相比，经声光光学可处理中心频率为400MHz、带宽为100MHz的通信射频信号，经与传统电子接收探测系统实验测试对比其接收信噪比提高了5dB，接收瞬时带宽提高一倍，实验结果达到设计要求。本项目研究设计的基于声光效应的相干接收机，利用光学进行信号处理优势显著，为通信信号处理领域提供一种新的技术手段，对我国国防军事信号侦测技术具有一定的参考价值。