提出并演示了一种基于非线性偏振旋转以及半导体可饱和吸收镜的混合锁模掺镱光纤激光器。其中半导体可饱和吸收镜提供可饱和吸收效应实现锁模，而非线性偏振旋转提供光谱滤波实现对脉冲的操控。通过调整偏振控制器可以改变光谱滤波，在同一激光腔中实现两种不同的脉冲演化路径。在正弦型光谱滤波较强时输出单波长至七波长可切换同步锁模脉冲，当正弦型光谱滤波较弱时产生单、双波长耗散孤子锁模脉冲。同时，数值模拟验证了两种脉冲的动态演化过程。该研究加深了光谱滤波对脉冲演化的影响，并为多脉冲动力学的研究提供了新思路。

We explore for the first time the real-time spectra of dissipative soliton (DS) and noise-like pulse (NLP) inter-switching by adjusting the pump power, as well as the dual-pulse collision dynamics for three modes: dual-NLP, NLP-DS, and dual-DS in a single-/dual-wavelength mode-locked fiber laser. Different types of dual-pulses differ in collision duration. During spectral reconstruction, dual-pulses exchange energy twice due to their respective accumulation dynamics. Additionally, collision-induced soliton explosions have chaotic properties, leading to each collision being random. The experimental results advance the study of the dynamics of different pulse types and also contribute to the conduction of in-depth investigations on dual-comb sources.

采用液相剥离法获得厚度约为3.2 nm、层数约为3至4层的碳化钛纳米片（Ti₃C₂T_x），结合旋涂法制备出Ti₃C₂T_x-聚乙烯醇（Ti₃C₂T_x-PVA）薄膜，并借助拉曼光谱、原子力显微镜和平衡双探测系统对Ti₃C₂T_x纳米片的物相组成、厚度及可饱和吸收性能进行了表征。将Ti₃C₂T_x-PVA薄膜作为可饱和吸收体应用于一种808 nm半导体激光二极管端面泵浦Nd∶YAG陶瓷/LBO腔内倍频的556 nm黄绿激光器中实现被动调Q。在分析布儒斯特偏振器和双折射晶体协同选频滤波机理的基础上，通过两者的协同使用，抑制了1 116 nm和1 123 nm处光谱腔内振荡并进一步压缩了1 112 nm处p-偏振光的纵模个数。在5.1 W最高激光二极管泵浦功率下，获得了平均输出功率为86.2 mW、重复频率为745.8 kHz、脉冲宽度为46 ns的556 nm被动调Q脉冲黄绿激光输出。4 h内测得功率不稳定度和激光噪声仅为±0.39％和0.37％，光束质量评价因子为M²_x=1.837和M²_y=1.975。Ti₃C₂T_x-PVA薄膜被动调Q结合“布儒斯特偏振器+双折射晶体”协同选频滤波技术方案为开发高稳定性、低噪声脉冲黄绿激光提供有价值的参考。

We demonstrate a stable narrow linewidth single-frequency erbium-doped fiber laser (EDFL) operating at 1.6 µm. A Fabry–Perot fiber Bragg grating and two cascaded subrings are incorporated in the main ring cavity to achieve single-frequency operation. The experimentally measured optical signal-to-noise ratio is greater than 73 dB. Furthermore, the linewidth of the EDFL is measured to be about 480 Hz by the self-built short-delayed self-heterodyne interferometry device. The laser shows superior stability, with no mode-hopping during the 60-min observation period. The proposed EDFL provides a new experimental idea for realizing a single-frequency fiber laser in the L-band.

We report a Yb-doped mode-locked fiber laser based on a nonlinear amplifying loop mirror (NALM), which is all-normal-dispersion (ANDi), and allows the output wavelength to be tunable. The laser can generate a stable femtosecond dissipative soliton with a maximum output power of 196 mW. Its repetition rate is 112.4 MHz, and the final pulse duration is 236 fs. By adjusting the angle of the reflective diffraction grating, the mode-locked fiber laser was realized to tune the output with a tuning range of 54 nm from 1011.8 nm to 1065.6 nm. To the best of our knowledge, this is the widest tuning range of an ANDi Yb-doped mode-locked fiber laser based on NALM.

Frequency detuning of mode-locked fiber lasers displays many remarkable nonlinear dynamical behaviors. Here we report for the first time the evolution of pulses from mode-locking through period pulsation to Q-switched mode-locking for three fundamental cases. Our experiments are performed in a hybrid actively and passively amplitude-modulated all-fiber polarization-maintaining mode-locked fiber laser, where the amplitude modulation frequency artificially deviates from the fundamental frequency of the cavity. We design and numerically simulate the laser with coupled Ginzburg–Landau equations. The experimentally observed dynamics of the mode detuning process is discussed with the assistance of the fitted model and numerical simulations, showing the generalizability of the optical mode detuning variation process. Our work provides fundamental insights for understanding perturbations in nonlinear optical resonant cavities and expands the ideas for studying chaotic path theory in hybrid mode-locked fiber lasers.

基于光纤环形激光器，设计出由三端口环形器、偏振控制器、未泵浦保偏掺镱光纤和光纤布拉格光栅组成的滤波器件作为高精度滤波器对谐振腔内的模式个数进行抑制，通过调谐偏振控制器，在保偏掺镱光纤内形成的梳状光谱和动态光栅，实现了窄线宽、单、双波长可切换单频掺镱光纤激光器。单波长运行时，在1064.37 nm处测得激光器输出线宽346 Hz，光信噪比大于50 dB，30 min内该激光器波长及功率的不稳定性均在0.01 nm和0.2 dB范围内。通过调节偏振控制器，单波长和双波长可以实现互相切换，双波长分别位于1064.156 nm和1065.236 nm。该技术为超窄线宽激光器的双波长输出提供了新的途径。