基于电光外调制非线性效应的脉冲微波信号精细生成与快速调谐

Pulsed microwave signals are indispensible for the signal sources in the fields of the electronic warfare, the cognitive radio, and scientific detection. To meet the requirements on precise generation and fast tuning of pulsed microwave signals, the project will focus on the development of novel photonic mechanisms, experimental approaches, and prototype machines by using the external electro-optic modulation, with the intrinsic advantages of photonic technology and devices on wide frequency coverage, large instantaneous bandwidth, and low frequency-dependent loss. Firstly, the nonlinear effect from the external modulation and its characteristics in the time and the frequency domains are investigated. Two generation methods using the single-wavelength source and the dual-wavelength one are then developed with a clear demonstration on the corresponding principle for generating pulsed microwave signals. Using photonic frequency shift, switch, and phase shift, approaches for the precise generation of pulsed microwave signals can be formed with a precise control on the carrier frequency/central frequency, the linear or nonlinear frequency modulation. At the mean time, methods and approaches for fast tuning on multiple parameters can be demonstrated, such as the carrier frequency/central frequency, the type of frequency modulations and their coefficients, and the repetition rate. Next, to confirm the above theory and methods and to evaluate the characteristics of generated signals, several experiments will be performed. A prototype machine including both the precise generation and fast tuning will be fabricated and tested in the training base of electronic warfare. These research works and achievements will be able to enhance the quality of the photonic generation and tuning of microwave signals, to enrich the generation theory and techniques of microwave signals, and to accelerate the field applications of microwave photonics.

脉冲微波信号是电子对抗、认知无线电、科研探测等领域的重要源头。本项目立足于光子技术及器件的宽频段覆盖、大瞬时带宽、低频率相关损耗，瞄准脉冲微波信号的精细生成与快速调谐，基于电光外调制开展新颖光子学机理与方法、实验、原型机研究。首先，系统探究电光外调制非线性效应及其时频特征与规律，以之发展演化出单、双波长型光源下两种生成策略，阐明其脉冲微波信号产生机理。结合光域频移、开关、相位延迟等手段，形成脉冲信号的精细生成方法，包括载频/中心频率、线性/非线性调频的精准控制；同时，形成多维信号参数的灵活、快速调谐方法，包括载频/中心频率、调频类型及参数、重复频率等。进而，开发实验方案，对机理和方法进行验证，并构建一个集精细生成与快速调谐于一体的脉冲信号源原型机，进行基地实测。本项目将极大地提升光子学微波信号生成与调谐性能，丰富微波信号生成理论与途径，推动微波光子学的行业实践应用。

面向高频、宽带、可调谐脉冲微波信号的重要需求，结合对电光外调制技术及其非线性效应机理的深入研究，探索脉冲微波信号生成与调谐的新思路与方法，实现了高频连续波、线性啁啾、非线性啁啾以及其他复杂波形脉冲微波信号的精细生成与快速调谐，并将其拓展应用于微波频率/微波多普勒频移的测量、微波信号的滤波/传感/检测等方面，取得了一系列较创新性成果：共计发表期刊论文15篇、国际会议论文(特邀报告)6篇，申请/授权发明专利5项。具体内容包括：.1.) 针对连续波微波信号，基于电光外调制非线性效应设计了两种不同类型的高频微波信号精细生成与快速调谐方案，依次采用电光偏振调制加交错滤波、级联电光马赫曾德尔调制器加四波混频的方式，分别实现了八倍频和二十四倍频的高频微波信号生成与调谐。.2.) 针对线性/非线性调频微波信号，基于电光外调制非线性效应的时频特征，遵循构建两个光相位调制信号拍频结构的核心思路，分别设计了单光载波型和双光载波型两种不同类型的啁啾微波脉冲信号精细生成方案。同时，从生成脉冲信号关键参数与低频驱动信号参数间的关联性出发，实现了精确且快速的调谐功能。.3.) 针对复杂波形微波信号，采用电光外调制和谐波调控技术，设计了一种三角波、矩形波、锯齿波等生成方案，实现了三角形微波脉冲信号的精细生成与快速调谐。该方案可进一步拓展生成其他类型复杂波形。.4.) 在基于电光外调制非线性效应的微波信号生成研究基础上，进一步探讨了其在不同场景下的重要应用，实现了微波频率/微波多普勒频移的测量、微波信号的滤波/传感/检测等。