Pu Guoqing, Yi Lilin, Zhang Li, Luo Chao, Li Zhaohui, Hu Weisheng
1State Key Lab of Advanced Communication Systems and Networks, Shanghai Institute for Advanced Communication and Data Science, Shanghai Jiao Tong University, Shanghai, 200240 China.
Sun Yat-sen University/Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China.
Light Sci Appl. 2020 Jan 28;9:13. doi: 10.1038/s41377-020-0251-x. eCollection 2020.
Mode-locked fiber lasers based on nonlinear polarization evolution can generate femtosecond pulses with different pulse widths and rich spectral distributions for versatile applications through polarization tuning. However, a precise and repeatable location of a specific pulsation regime is extremely challenging. Here, by using fast spectral analysis based on a time-stretched dispersion Fourier transform as the spectral discrimination criterion, along with an intelligent polarization search algorithm, for the first time, we achieved real-time control of the spectral width and shape of mode-locked femtosecond pulses; the spectral width can be tuned from 10 to 40 nm with a resolution of ~1.47 nm, and the spectral shape can be programmed to be hyperbolic secant or triangular. Furthermore, we reveal the complex, repeatable transition dynamics of the spectrum broadening of femtosecond pulses, including five middle phases, which provides deep insight into ultrashort pulse formation that cannot be observed with traditional mode-locked lasers.
基于非线性偏振演化的锁模光纤激光器可通过偏振调谐产生具有不同脉冲宽度和丰富光谱分布的飞秒脉冲，以用于多种应用。然而，特定脉冲状态的精确且可重复定位极具挑战性。在此，通过使用基于时间拉伸色散傅里叶变换的快速光谱分析作为光谱判别标准，并结合智能偏振搜索算法，我们首次实现了对锁模飞秒脉冲光谱宽度和形状的实时控制；光谱宽度可在10至40纳米范围内调谐，分辨率约为1.47纳米，且光谱形状可被编程为双曲正割或三角形。此外，我们揭示了飞秒脉冲光谱展宽的复杂、可重复的跃迁动力学，包括五个中间阶段，这为传统锁模激光器无法观测到的超短脉冲形成提供了深入见解。
