基于硫化钨饱和吸收体的低抖动光纤锁模激光器

Low-timing-jitter all-fiber femtosecond mode-locked lasers have wide applications in ultrafast physical phenomenon research, ultra-high-speed signal processing, aeronautics, astronautics and national security. One of the key factors of mode-locked lasers is saturable absorber. Tungsten disulfide (WS2) as a kind of transition metal dichalcogenides, has sub-bandgap saturable absorption and ultrafast relaxation time and thus can be integrated into all-fiber systems and realize low-timing-jitter mode locking operation. However, the physical principle of sub-bandgap absorption of WS2 is unclear yet and the influence of its relaxation property on the laser noise also requires further investigation. This project will investigate these two aspects and realize a WS2-based low-timing-jitter all-fiber mode-locked laser. The main research contents include: the preparation of WS2 nanosheets, research on the sub-bandgap absorption of the edge states, fabrication of WS2-polymer saturable absorber, influence of WS2 relaxation property on laser noise and its optimization. The research of the project will reveal the physical principle of WS2 sub-bandgap absorption and provide technological support on the high-precision applications of WS2-based low-timing-jitter mode-locked lasers on national security, aeronautics, astronautics and frequency metrology.

低抖动全光纤飞秒锁模激光器在超快物理现象探究、超高速信息处理、航空航天、国防等诸多领域都有广泛应用。锁模激光器的关键因素之一是饱和吸收体。硫化钨作为过渡金属硫化物材料，具有亚带隙饱和吸收特性和超快的弛豫时间，可集成于全光纤系统，实现激光器的低抖动锁模运行。但硫化钨材料表现出的亚带隙饱和吸收特性的物理机理尚不是很清楚，饱和吸收体材料弛豫特性对激光器噪声的影响也有待深入探索。本项目将对此开展深入研究，并实现基于硫化钨的低抖动全光纤锁模激光器。主要研究内容包括：硫化钨纳米片制备；硫化钨纳米片边缘态具有的亚带隙饱和吸收特性研究；硫化钨-聚合物饱和吸收体薄膜制备；硫化钨材料弛豫特性对锁模激光器噪声影响与优化。通过项目研究，阐明硫化钨亚带隙饱和吸收特性的物理机理，为基于硫化钨饱和吸收体的低抖动锁模激光器研制及其在国防、航空航天和频率计量等高精度领域的应用提供技术支撑。

在项目执行期中，对设立的研究内容进行了研究和探索。成功制备出了性能较好的硫化钨薄膜饱和吸收体，并将其应用于锁模激光器。锁模激光器的重复频率达到561 MHz，时间抖动小于30 fs，均达到了项目所设立的指标。探索了硫化钨材料的热光特性，并利用这种特性实现了全光的开关和调制。相关工作收到国际同行关注，共发表SCI论文11篇，受邀在Photonics Research（影响因子5.2）和Optics Communications（影响因子1.8）上撰写邀请论文，有一篇论文ESI热高被引论文。另外还申请了12项发明专利，培养了4名研究生。..在以上成果的支持下，进一步得到了2019年自然科学基金面上项目（61875122，高重频、低噪声集成锁模激光芯片研制）的资助，将继续研究利用二维纳米材料实现片上锁模激光器的方案。以上工作将为我国集成光电子芯片真正走向实用化，并服务于我国芯片、大数据和国防等重大需求提供技术支撑。