We report an experimental study of switchable rectangular pulses generation in a passively mode-locked double-clad thulium-doped fiber laser operating in the anomalous dispersion regime. A fiber loop mirror and a polarization imbalanced nonlinear optical loop mirror (NOLM) forms the linear cavity. The loop in the NOLM includes a quarter-wave retarder, which allows switching between two regimes of rectangular pulse generation. The laser generates rectangular noise-like pulses (NLPs) or dissipative soliton resonance (DSR) pulses with 1.18 MHz repetition rate at ∼1990 nm. At the maximum pump power of 10 W, rectangular pulses with energy of up to 540 nJ in DSR operation and 482 nJ in NLP operation were obtained with output average power of 640 mW and 571 mW, respectively.

我们报告了在异常色散状态下工作的被动锁模双包层掺th光纤激光器中可切换矩形脉冲产生的实验研究。光纤环形镜和偏振不平衡非线性光学环形镜（NOLM）形成线性腔。NOLM中的环路包括一个四分之一波长延迟器，该延迟器允许在两个矩形脉冲生成方式之间进行切换。激光产生矩形噪声状脉冲（NLP）或耗散孤子共振（DSR）脉冲，其重复频率在〜1990 nm处为1.18 MHz。在10 W的最大泵浦功率下，在输出平均功率分别为640 mW和571 mW的情况下，获得在DSR操作中能量高达540 nJ和在NLP操作中能量高达482 nJ的矩形脉冲。