基于增益开关技术在高掺杂浓度掺铥光纤中获得了稳定的2 μm种子脉冲激光,输出激光中心波长为1 979.4 nm,脉冲重复频率在1~100 kHz之间可调,输出脉冲宽度变化范围为60~200 ns。采用两级掺铥光纤放大器对该种子脉冲激光进行放大实验,当种子脉冲激光重复频率为20 kHz时获得最大输出平均功率为17.2 W,输出光谱没有观察到明显的放大自发辐射噪声。最大功率输出时,脉冲宽度为82 ns,对应单脉冲能量为0.86 mJ,脉冲峰值功率高于10 kW。

A stable pulsed thulium-doped fiber laser at 2 μm is obtained based on gain-switched techniques, with the central wavelength of 1 979.4 nm. The pulse width and repetition rate of the seed laser can be tuned in the range of 60~200 ns and 1~100 kHz, respectively. After two-stage thulium-doped fiber amplifiers, the average output power of 2 μm seed pulses is scaled up to 17.2 W at 20 kHz, and no obvious amplified spontaneous emission noise is observed. The measured output pulse width is 82 ns and the calculated maximum output pulse energy reaches as high as 0.86 mJ, which corresponds to a peak power exceeding 10 kW.