光载超宽带冲激雷达脉冲与回波信号波分复用非线性传输机理研究

Ultrawideband (UWB) impulse radar is attracting more and more attention in the civilian and military applications due to its advantages of high resolution, better ability to penetrate, low probability of interception and small close-blind. However, its action distance is short, and it is difficult to electronically generate ultra-short pulses for UWB impulse radar. UWB radar pulses with a sub-nanosecond or picosecond order of magnitude can be generated with microwave photonic technologies, and the optically generated radar pulses can be transmitted after a long distance distribution over fiber. In this way, the disadvantage of UWB impulse radar with short action distance can be overcome in a certain degree. For this distributed UWB radar system over fiber, the transmission characteristics of optical fiber become the main factor affecting the system performance and limiting the system application. By theoretical analysis and numerical modeling, the action mechanisms of noise in optical devices and transmission characteristics of optical fiber on UWB impulse radar pulses and echoes will be studied in the project. And the impact rules of laser noise, fiber dispersion and nonlinearities on the waveform and spectrum of the signal and on the signal-to- noise ratio of the echoes will be revealed. Also an optimal scheme of dispersion management suitable for the distributed UWB radar system over fiber will be put forward. The anticipated achievements can provide theoretical fundaments for the application of remote distributed UWB radar system. Meanwhile it is of important science value for updating the domestic level of research on UWB radar.

超宽带（UWB）冲激雷达具有距离分辨率高、穿透力强、截获概率低及近距离盲区小等优点，在民用及军用领域受到越来越多的关注。但其作用距离短，且电域内较难产生UWB冲激雷达所需的超短脉冲。应用微波光子技术可产生亚纳秒甚至皮秒量级的UWB雷达脉冲，并可采用分布式结构，基于光纤将光学方法产生的雷达脉冲传输至远端发射，在一定程度上克服UWB冲激雷达作用距离受限的不足。对于这种分布式光载UWB雷达系统，光纤传输特性成为影响系统性能和限制系统应用的主要因素。本项目通过理论分析及数值建模与仿真，研究光器件噪声及光纤传输特性对UWB冲激雷达脉冲与回波的作用机理，揭示光源噪声、光纤色散和非线性对传输信号波形和频谱及接收回波信噪比的影响规律，提出适用于分布式光载UWB冲激雷达系统的最优色散管理方案。预期成果可为分布式远程光载UWB冲激雷达的应用奠定理论基础，对提升我国UWB雷达领域的研究水平也具有重要的科学价值。

本项目按照研究计划，建立了光载超宽带（UWB）冲激雷达脉冲与回波信号双向传输系统仿真模型；研究了激光器线宽、光纤色散和非线性效应对UWB脉冲波形与频谱，以及对回波信号信噪比的影响；研究了高斯一到五阶微分型UWB雷达脉冲及回波信号对光纤色散的容忍度及相应的色散管理方案。通过这些研究，提出一种基于高斯脉冲驱动单个双并行马赫曾得调制器的高斯一到五阶微分型UWB雷达脉冲的产生方法，并设计了一种基于射频信号驱动单个双并行马赫曾得调制器的多波形发生器；提出一种应用单驱动的光强度调制器和单模光纤产生高斯四阶微分型UWB脉冲的方法，并进行了实验验证；数值仿真比较了不同UWB脉冲在光纤中的色散传输特性，说明了高斯高阶微分型UWB脉冲具有更高的色散容限，基于色散补偿光纤（DCF）的后色散欠补偿方案适用于光载各阶UWB冲激雷达脉冲系统。项目除完成了原定的理论及仿真研究内容，还进行了一些实验研究，所得研究结果可应用于分布式光载UWB冲激雷达系统的设计中，并为微波光子技术在雷达领域的应用奠定了一定的理论及实验基础。