种子注入单纵模主动调Q光纤激光器关键技术研究

The single-longitudinal-mode actively Q-switched pulses with large energy, narrow linewidth and high frequency stability have wide applications in high-resolution spectroscopy, coherent detection, nonlinear frequency conversion and other fields. In recent years, single-longitudinal-mode active Q-switched fiber lasers based on injection seeding technique have become a research hotspot in the field of single-longitudinal-mode Q-switched lasers owing to the advantages such as high conversion efficiency, good beam quality, simple structure, and small size. At present, the narrow-linewidth single-longitudinal-mode pulses have been achieved in the injection-seeded single-longitudinal-mode active Q-switched fiber lasers, but the pulse energy is low and the frequency is unstable. To solve these problems, this project intends to construct an injection-seeded single-longitudinal-mode active Q-switched fiber lasers with double-clad doped fiber, and then obtain the large-energy narrow-linewidth pulses by optimizing the cavity structure, seeding parameters, switching characteristics, and suppressing nonlinear effects such as SBS. Meanwhile, the frequency stabilization scheme for injection-seeded single-longitudinal-mode active Q-switched fiber lasers is studied and proposed, and the frequency stabilization system is built to achieve high-precision frequency stability. This project will not only solve the key problems faced by the injection-seeded single-longitudinal-mode active Q-switched fiber lasers, but also lay a theoretical and technical foundation for the further development of small-sized single-longitudinal-mode Q-switched laser sources, which is of great significance.

大能量、窄线宽、高频率稳定性的单纵模主动调Q脉冲在高分辨光谱、相干探测、非线性变频等领域具有极其重要的应用。基于注入种子技术的单纵模主动调Q光纤激光器因具有转换效率高、光束质量好、结构简单、体积小等一系列优势，近些年来成为单纵模调Q激光领域研究热点。目前，种子注入单纵模调Q光纤激光器已经实现窄线宽的单纵模脉冲输出，但是存在脉冲能量较低和频率不稳的问题。针对这些问题，本项目拟采用双包层掺杂光纤构建注入种子单纵模调Q光纤激光器，并通过优化腔结构、种子光参数和开关特性以及抑制SBS等非线性效应，实现大能量、窄线宽脉冲输出；同时研究提出注入种子单纵模调Q光纤激光器稳频方案并在实验上构建稳频系统，实现对频率的高精度稳定。通过本项目研究不仅将解决注入种子单纵模调Q光纤激光技术所面临的关键问题，而且还可为进一步发展小型化单纵模调Q激光源奠定理论与技术基础，具有极其重要的意义。

本项目针对种子注入单纵模主动调Q光纤激光器中的关键技术展开研究工作。建立了注入种子单纵模调Q双包层光纤激光器理论模型，探明了种子光特性对输出调Q脉冲的影响；基于自主设计研制的低噪声窄线宽1064nm单频光纤激光器作为注入种子，以及ASE增益自饱和效应得到有效抑制的掺镱双包层调Q光纤激光器，构建了注入种子单纵模调Q光纤激光器，实现了大能量的单纵模纳秒激光脉冲输出；在此基础上，提出设计了注入种子单纵模调Q光纤激光器的PDH稳频方案，实现了激光频率的稳定。通过本项目研究，解决了种子注入单纵模主动调Q光纤激光器中存在的脉冲能量较低和频率不稳等问题，为发展高品质的窄线宽调Q激光源奠定理论与技术基础。