研究了基于主振荡-功率放大(MOPA)结构的高重频窄脉宽光纤激光器的输出特性及影响因素。分析了高功率输出条件下, 受激拉曼散射(SRS)对激光增益特性和光谱特性的影响, 指出SRS是限制光纤激光器功率提高的主要原因。通过扩大增益光纤的有效模场面积、缩短光纤长度, 有效抑制了SRS的产生, 获得了平均功率64 W, 重复频率50 kHz, 脉冲宽度14 ns的脉冲激光输出。分析了光纤弯曲对激光输出特性的影响, 结果表明, 适当减小光纤的盘绕直径可以在一定程度上改善输出激光的光束质量。

The output characteristics and their influence factors of a fiber laser with high repetition rate and narrow pulse width based on master-oscillator power amplifier (MOPA) architecture are experimentally investigated. Under the condition of high output power, the impacts of the stimulated Raman scattering (SRS) on the gain characteristics and laser spectrum characteristics are analyzed through experiments. It is pointed out that SRS effect is the main restriction of power increases of fiber laser. By increasing the effective mode-field area and shortening the length of fiber, stimulated Raman scattering is suppressed successfully. The average output power of 64 W is achieved at repetition rate of 50 kHz with a pulse width of 14 ns. Meanwhile, the impacts of the fiber bending diameter on the output characteristics of laser are also experimentally investigated. The results show that reducing the diameter of bending properly can improve beam quality of output laser in a certain extent.