拓扑绝缘体锁模超快掺镱光纤激光器的特性研究

Ultrafast Yb-doped fiber lasers have attracted much attention in recent years due to their wide applications in fields such as biomedicine, atom physics and astronomy.a key step to achieve ultrafast Yb-doped fiberlaser is the fabrication of the saturable absorber (SA). As we know, recently Topological Insulator (TI) has been newly proposed as a rising material with the broadband saturable absorption effect for ultrafast fiber lasers. However, the applications of Topological Insulator saturable absorber (TISA) for Yb-doped fiber laser operating at 1 um have not yet been investigated. In this project, we will investigate the characteristics of the ultrafast Yb-doped fiber laser based on the newly proposed TISA. The following issues will be addressed: 1. By employing high-performance TISA, the femtosecond pulse generation will be obtained in a Yb-doped fiber laser. Then the TI mode-locked high-energy dissipative soliton will be investigated. 2. By virtue of high nonlinear effect of TI, we will fabricate functional TISA for investigating soliton dynamics in all-normal-dispersion Yb-doped fiber lasers, such as passive harmonic mode-locking and soliton molecules. 3. The generation of Rogue Waves with ultrahigh peak power will be carefully studied in TI mode-locked Yb-doped fiber lasers. Carrying out this project will not only further develop the performance of TISA and discover the soliton characteristics and dynamics of ultrafast Yb-doped fiber lasers at 1.0 um, but also has very important sense to the development of fiber laser technologies.

超快掺镱光纤激光器在生物医学、原子物理、天文学等众多领域有重要应用价值，是光纤激光技术领域的研究热点。可饱和吸收体的研制是实现超快掺镱光纤激光器的关键技术。拓扑绝缘体是新兴的宽带可饱和吸收材料，然而它在超快掺镱光纤激光器中的应用却尚待研究。针对此问题，本项目拟开展拓扑绝缘体锁模超快掺镱光纤激光器的特性研究。主要内容包括：①采用高性能拓扑绝缘体可饱和吸收体，实现1.0微米波段飞秒脉冲稳定输出，并探索拓扑绝缘体锁模高能量耗散孤子脉冲的产生；②利用拓扑绝缘体高非线性特点，研制功能性的拓扑绝缘体锁模器，在超快掺镱光纤激光器中获得高重频谐波锁模脉冲，并探究全正色散孤子分子现象；③探索拓扑绝缘体锁模超高峰值功率"巨浪波"脉冲的产生及其机理。本项目的开展，不仅能够进一步挖掘拓扑绝缘体可饱和吸收体的优越性能，加深对超快掺镱光纤激光器的孤子动力学特性的理解，而且对光纤激光技术的发展具有重要的现实意义。

本项目主要研究拓扑绝缘体超快光纤激光器的特性，并揭示其内在物理机制。在本项目的资助下，我们围绕着拓扑绝缘体等二维纳米材料超快光纤激光器性能提升及光纤激光器中新型孤子非线性动力学过程开展了研究工作，所取得的主要成果可以概括为以下几方面：（1）. 在超短脉冲产生方面：我们首次提出采用二氧化硅包覆金纳米棒来克服金纳米棒的热损伤性，研制出了高性能的二氧化硅包覆金纳米棒可饱和吸收体，并用于超快光纤激光器中获得了379 fs的锁模脉冲输出；此外，我们还首次使用类拓扑绝缘体材料——黑磷，首次研制出了高性能的黑磷锁模器，并用于激光器中获得了940 fs超短脉冲输出。（2）. 在高能量脉冲产生方面：我们首次在1.1 μm工作波段的掺铋光纤激光器中观察到了耗散孤子共振现象，输出最大脉冲能量为24.82 nJ，将传统孤子光纤激光器的输出脉冲能量提高了2个数量级。（3）. 在高重频脉冲产生方面：我们利用了层状二硫化钼的非线性光学特性，将其制成非线性光纤光子器件并接入光纤激光器中。实验中，随着泵浦功率的升高，我们获得了高达2.5 GHz的稳定高重频脉冲输出；此外，我们创造性地提出将石墨烯沉积在微纳光纤结上制备成具有宽带高非线性效应的全光纤谐振器，分别应用于1.0和1.5 μm波段光纤激光器中并有效地产生了数百GHz重复率的脉冲，将常规超快光纤激光器的重复率提高了3个数量级。（4）. 孤子非线性动力学过程研究方面：通过自主研制基于拓扑绝缘体、石墨烯等材料的高非线性光子器件，并应用光纤激光器中，观察到了耗散怪波、孤子分子、孤子爆炸等一系列新型孤子非线性效应，我们对其进行了细致系统地分析研究，进一步揭示了其中的物理机制。