介绍了光纤激光器的理论模型和结构组成，搭建了976 nm激光二极管(LD)泵浦的准连续输出双包层掺镱光纤激光器系统。制作了激光脉冲电源方波发生电路，该电源在脉冲工作模式下重频≤1 000 Hz，脉宽从10 μs~50 ms可调，占空比≤50%。分析了稀土掺杂双包层光纤的各项性能和能级系统，并实验研究了准连续掺镱双包层光纤激光器的输出特性。在最大泵浦功率为812 W，重频为50 Hz和脉宽为10 ms下，测得其最大脉冲输出功率为267 W。

The theoretical mode and structure composition of a fiber laser are introduced in this paper, and a double-clad Yb3+-doped quasi-continuous wave fiber laser system is set up by using 976 nm LD as pumped source. A square wave generator circuit for the laser pulse power source is developed, which can offer a repetition frequency below 1 000 Hz, pulse adjustable width between 10 μs and 50 ms and duty ratio under 50% in a pulse mode. The characteristics and energy level system of the 11 m Yb3+ doped double-clad fiber laser are researched, and its ouput characteristics are measured. The results show that the highest output power is 267 W at pulse width of 10 ms and repetition frequency of 50 Hz when the maximum pump power is 812 W.