拓扑绝缘体宽带超快被动锁模机理及实验研究

In recent years, topological insulators (TIs) have aroused the attention of a great number of scientists due to their unique electronic structures and peculiar physical properties. In 2012, our group found experimentally that the TIs have similar nonlinear saturable absorption properties as graphene. Using the TI-based saturable absorber, the ultrafast picosecond soliton pulse can be generated in a passively mode-locked fiber laser for the first time. Based on the previous work, the broadband nonlinear optical properties of TIs and their composites will be studied in depth, and the nonlinear optical characteristics of TIs will be uncovered theoretically and experimentally in the project. The intrinsic relationship between the characteristics of the TIs and the time-frequency properties of ultrafast pulses will be studied. Based on the qualified saturable absorber, the potential and advantages of TI-based passively mode-locked fiber laser to obtain stable, broadband, ultrafast and tunable laser will be explored experimentally.

拓扑绝缘体因其独特的电子结构和奇异特性引起了科学界的强烈兴趣，成为当前的研究热点。2012年，申请人团队测量到拓扑绝缘体具有与石墨烯类似的非线性可饱和吸收特性，并首次应用于光纤激光锁模，实现了皮秒孤子脉冲输出。本申请项目拟在前期工作基础上，深入研究拓扑绝缘体及其复合材料的宽带非线性光学特性，实验测量并系统揭示其非线性光学特性和规律，建立拓扑绝缘体各宏观参量与锁模脉冲时域频域性质的内在关系，制备可饱和吸收锁模器件，实验研究并阐明其在实现稳定、宽波段、超快、可调谐被动锁模光纤激光输出上的潜力和优势。

拓扑绝缘体因其独特的电子结构和奇异特性引起了研究人员的广泛关注。本项目在前期工作基础上，深入研究了拓扑绝缘体及其复合材料的宽带非线性光学特性，实验测量并系统揭示了其非线性光学特性和规律，建立了拓扑绝缘体各宏观参量与锁模脉冲时域频域性质的内在关系，制备了可饱和吸收器件，实验研究并阐明了其在实现稳定、宽波段、可调谐锁模和调Q光纤激光输出上的潜力和优势。主要取得一下一些成果：（1）实验研究了二维拓扑绝缘体材料碲化铋的宽波段三阶非线性光学特性，获得了其宽带非线性光学特性和规律。在超短脉冲激光激发下，二维拓扑绝缘体材料具有强的饱和吸收特性和正的非线性折射率。（2）研究了拓扑绝缘体碲化铋分散液的宽带空间自相位调制效应，并基于非线性传输理论获得了拓扑绝缘体纳米材料的非线性光学参数，研究结果进一步证实了拓扑绝缘体的宽带非线性光学响应。相关结果被APL遴选为封面论文，并被Nature Photonics在其News & Views专栏中以"Topological insulators: Nonlinear opportunities"进行报导。（3）基于拓扑绝缘体可饱和吸收体，实验获得了不同波段稳定工作的脉冲光纤激光光源。在光通信波段，实验获得重复频率17.76 MHz、脉宽448 fs的锁模光纤激光输出；在中红外波段，实验获得了脉宽880 ns、重频 81 kHz的调Q光纤激光输出。. 课题组在IEEE J. Sel. Top. Quantum Electron.、Appl. Phys. Lett.等国际学术刊物上发表SCI论文28篇。此外，在国内外学术会议作邀请报告5人次，申请国家发明专利3项；培养和协助培养博士研究生4名，硕士研究生5名。