基于双非相干光反馈半导体激光器获取优质超宽带微波频率梳的技术探索

Due to the ability for providing simultaneously multi-frequency microwave signals, the microwave frequency comb has extensive application potential in the frequency-hopping radar, the electro magnetic compatibility (EMC) test and the subcarrier multiplexing (SCM) in Radio-over-Fiber (RoF) system. However, through adopting currently exsiting schemes, it is difficult to obtain high-performance (including tunable comb spacing, pure comb line and balanced comb line power) and ultra broadband (up to the order of 40GHz bandwidth) microwave frequency comb. The aim of this project is to explore a novel low cost scheme for generating the high-performance and ultra broadband microwave frequency comb, which is based on combining the frequency locking state of the semiconductor laser (SL) with double incoherent optical feedback and bandwidth enhancement induced by the optical injection technique. In this project, at first, a seed soure of microwave frequency comb, whose bandwidth is the order of 10GHz and line spacing can be tuned, will be obtained based on the harmonic frequency-locking state in a SL with double incoherent optical feedback. Secondly, the bandwidth of the microwave frequency comb will be enhanced to the order of 40GHz by injecting the obtained seed soure to another SL. Finally, the key factors to affect the comb line purity and comb line power flatness will be investigated, and a practical scheme will be proposed to make come line narrowed and come line power balanced. By carrying on this project, we hope to exploit a new technique for generating the high-performance and ultra broadband microwave frequency comb, which can speed up the development of relative application fields.

微波频率梳因可同时提供多频微波信号，从而在捷变频雷达、电磁兼容性(EMC）测试以及光载无线(RoF)系统的副载波复用(SCM)等领域有着广泛的应用。现有的微波频率梳产生方案还难以获得优质(梳距可调、梳线细锐且功率均衡)超宽带(带宽达40GHz水平)微波频率梳。本项目旨在基于双非相干光反馈半导体激光器(SL)呈现的频率锁定态，结合光注入实现频谱拓展，探索获得优质超宽带微波频率梳的低成本方案。拟开展的主要工作如下：(1)利用双非相干光反馈下SL的频率锁定态获得带宽为10GHz水平、梳距可调的频率梳种子源；(2)将该种子源注入到另一个SL以实现全光频谱拓展，使其带宽提高至40GHz水平；(3)探明影响频率梳梳线的频率纯度、以及梳线功率平坦度的关键因素，提出切实可行的能实现梳线细锐、梳线功率均衡的方案。本项目的实施可望自主研发并掌握优质超宽带微波频率梳的获取新技术，带动相关应用领域的发展。

微波频率梳既可提供单频微波信号，也可同时提供多频微波信号，因而在捷变频雷达、电磁兼容性(EMC）测试以及光载无线(RoF)系统的副载波复用(SCM)等领域有着广泛的应用。现有的微波频率梳产生方案还难以获得优质(梳距可调、梳线细锐且功率均衡)超宽带微波频率梳。本项目基于半导体激光器(SL)在不同外部扰动下呈现的非线性动力学行为，在优质超宽带微波频率梳获取方面开展了相关理论和实验探索,并取得了一系列研究成果。首先, 实验和理论研究了半导体激光器(SL)在不同外部微扰下的非线性动力学行为，得到了不同系统参数下激光器所呈现的非线性动力学状态,绘制了SL在不同参数空间的动态分布图谱, 掌握了半导体激光器呈现各种非线性动力学状态的实验操控技术。其次，探索全光频谱拓展的相关理论和技术方法，探明微波频率梳频谱拓展的关键实验调控技术。然后，通过采用多个外部扰动相结合、以及低频调制等技术提高微波信号的频率稳定性，实验得到了线宽达KHz量级的稳定的毫米波信号。最后，基于SL的非线性动力学行为研究了优质微波频率梳获取的相关理论和技术方法，探究调控微波频率梳信号的最优参数设置和技术方案。本项目建立了优质微波频率梳获取的研究平台，自主探索和掌握了一系列相关关键技术，研究成果对微波频率梳的获取和进一步应用有一定的参考价值。