采用双包层掺镱光纤作为增益介质，多模连续泵浦激光二极管作为泵浦源，构造了两级光放大系统；采用电路直接调制的半导体激光器作为种子源，研制了主振荡功率放大结构全光纤化脉冲光纤激光器。对不同脉冲宽度、重复频率下的激光器输出功率特性和二级放大器的增益特性进行了实验研究。在一级泵浦光功率为2 W、二级泵浦光功率为31 W的条件下，通过对种子源直接调制，得到了中心波长为1.06 μm、峰值功率为10.4 kW、最大平均功率为21.3 W的脉冲激光输出。在900 kHz重复频率下具有最高增益16.7 dB。实验结果表明，脉冲宽度和重复频率与激光输出功率呈正相关；在高重复频率下，光放大器增益特性与脉冲宽度呈负相关。

A two-stage optical amplification system is constructed by using double-clad Yb-doped fiber as the gain medium and multi-mode continuous pumped laser diode as the pump source. The circuit-direct modulated semiconductor laser is used as seed source to develop Master-Oscillator Power-Amplified (MOPA) fiberized pulsed fiber lasers. The output power characteristics of the fiber laser and gain characteristics of the secondary amplifier under different pulse width and repetition frequency are studied experimentally. A pulsed laser output with central wavelength of 1.06 μm, peak power of 10.4 kW and maximum average power of 21.3 W is obtained by adjusting the seed source under the condition that the primary pumped power is 2 W and secondary pumped power is 31 W. The maximum gain can reach 16.7 dB at 900 kHz repetition frequency. The experimental results show that the pulse width and repetition frequency are positively correlated with the laser output power. At high repetition frequency, the gain characteristics of optical amplifier are positively correlated with the pulse width.