基于微谐振器的高重频脉冲掺镱光纤激光器特性研究

High-repetition rate pulse has attracted much attention due to the wide application in fields such as astronomy, optical frequency measurement, optical communications and so on. Dissipative four-wave mixing (DFWM) mode-locked technique was regarded as an effective way to generate high-repetition rate pulse. However, due to the limitation of optical components, there is no demonstration of DFWM mode-locked high-repetition rate pulse at 1.0 um. Very recently, the microresonator with sufficiently low dispersion at 1.0 um was successfully designed and fabricated, which provides a new tool for the generation of DFWM mode-locked high-repetition rate pulse in Yb-doped fiber lasers. In this project, by combining the newly proposed microresonator and DFWM mode-locked technique, we will investigate the DFWM mode-locked high-repetition rate pulsed Yb-doped fiber laser and its tuning characteristics. The following issues will be addressed: 1. The pulse stability generated by the DFWM mode-locked Yb-doped fiber laser. 2. The influences of cavity dispersion and pump power level on the pulse characteristics. 3. The tunable operation of high-repetition rate pulse. The project will develop a pulsed Yb-doped fiber laser with a repetition rate of hundreds of GHz as well as tuning operation. Carrying out this project will not only discover the characteristics and dynamics of high-repetition rate pulse at 1.0 um based on DFWM mode-locked technique and microresonator, but also has very important sense to the development of fiber laser technologies.

高重频脉冲由于在天文学、光频测量、高速光通信等众多领域有重要的应用价值，是激光技术领域争相研究的对象。耗散四波混频锁模是获得高重复率脉冲的有效方法。由于器件限制，目前尚未在1.0微米波段实现耗散四波混频锁模高重频脉冲输出。最近，1.0微米波段低反常色散值的微谐振器研制成功，为我们提供了一种崭新的思路。本项目拟将新提出的微谐振器和耗散四波混频锁模技术相结合，研究1.0微米波段的高重复频率脉冲掺镱光纤激光器及其可调谐特性。主要内容有：1.研究耗散四波混频锁模高重频掺镱光纤激光器的脉冲稳定性；2.研究腔内色散值及泵浦功率对高重频脉冲特性的影响；3.探索高重频率脉冲的可调谐特性。本项目旨在突破当前掺镱光纤激光器脉冲重复率几个GHz的水平，实现百GHz量级的高重频脉冲输出，并研究其可调谐特性。本项目的开展，不仅能加深对基于微谐振器光纤激光器系统物理特性的理解，而且对光纤激光技术的发展具有重要意义。

本项目主要研究基于微谐振器的百GHz高重频脉冲光纤激光器及其相关特性，并揭示其内在的物理机制。在本项目的资助下，我们围绕着耗散四波混频锁模超高重频光纤激光器的锁模技术、输出脉冲特性及其性能的提高开展了研究工作，所取得的主要成果可以概括为以下几方面：1. 在超高重频脉冲产生方面：我们研究了微环谐振器的特性，搭建了基于耗散四波混频锁模光纤激光器，获得了百GHz量级高重频脉冲输出，并实现了波长可调谐输出；研制了一种新型的基于石墨烯包覆的宽带微环谐振器，并同时用于掺铒和和掺镱光纤激光器实现百GHz量级脉冲输出。2. 在谐波锁模产生高重频脉冲方面：通过在激光腔内引入合适的高非线性光子器件，获得了高达2.5GHz的高重频超短脉冲输出；观察到了一种新型的双波长谐波锁模脉冲。3. 在光纤激光孤子动力学特性研究方面：我们系列研究了超快光纤激光器中的耗散孤子共振现象，为无波分裂高能量脉冲的产生提供了实验依据；此外，我们创新性地提出利用非线性光放大环镜锁模技术用于光纤激光器中研究孤子矢量特性，并观察到了多种特殊孤子态的矢量孤子，如孤子雨、孤子簇等；同时，利用脉冲拉伸技术，除了发现超快光纤激光器中局域混沌多孤子波包内可以通过长程或短程相互作用产生瞬态光怪波现象，还观察到了具有不经过稳定孤子过渡态的不间断爆炸特点的“连续孤子爆炸”现象。4. 在新型光纤激光超短脉冲锁模技术研究方面：利用新型可饱和吸收材料，如二维材料和金纳米棒，在光纤激光器中获得了高质量的超短脉冲输出。