We report the generation of h-shaped pulses and rains in a fiber laser with a Fabry–Perót (F–P) subcavity. An h-shaped pulse state composed of a sharp spike as a leading edge and a long flat-top bunch as a tailing one could be switched to an h-shaped pulse rain state by adjusting the polarization controllers (PCs). F–P filtering was found to play a crucial role in the formation of the h-shaped pulses and rains. The leading and tailing edges of the h-shaped pulse were found to be generated in the primary and secondary F–P filtering profiles, respectively. Furthermore, small discrete pulses could be triggered in the subordinate longer-wavelength F–P filtering profiles by adjusting the PCs. Then, for the first time, h-shaped pulse rains were experimentally observed as many small pulses continuously drifting away from the nanosecond-long h-shaped pulses because of their group velocity mismatch. These results will help contribute to a deep understanding of the dynamics of complex pulse patterns in fiber lasers.

我们报告了法布里-珀罗特（FP）子腔光纤激光器中h形脉冲和降雨的产生。通过调整偏振控制器（PC），可以将尖锐的尖峰作为前缘，将长长的平顶束作为拖尾的h型脉冲状态切换为h型脉冲降雨状态。发现FP滤波在h形脉冲和降雨的形成中起着关键作用。发现在主要和次要F-P滤波曲线中分别产生了H形脉冲的前沿和尾沿。此外，通过调整PC，可以在下级较长波长的FP滤波配置文件中触发小的离散脉冲。然后，第一次 实验中观察到h形脉冲雨，因为许多小脉冲由于其群速度失配而不断从纳秒长的h形脉冲中漂移。这些结果将有助于深入了解光纤激光器中复杂脉冲模式的动态。