利用半导体光放大器(SOA)实现了一种脉宽可调谐的暗脉冲光纤激光器。将基于SOA的光纤激光器的一部分输出反馈注入SOA,由于SOA的非线性偏振旋转效应,输出脉冲经历不同的偏振演化,从而得到暗脉冲输出。通过改变反馈腔长度可以实现暗脉冲的脉宽调谐。分析了半导体光放大器的非线性偏振效应及暗脉冲的产生机理。并在实验中观察到了脉宽可调谐的暗脉冲输出。通过改变反馈腔长,在重复频率不变(11.31 MHz)的条件下,得到了脉宽为5.91~22.34 ns可调的暗脉冲。 A pulse width tunable dark pulsed fiber laser is realized using a semiconductor optical amplifier (SOA). Part of the output of an SOA-based fiber laser is injected into the SOA. Due to the non-linear polarization rotation effect of the SOA, the output pulses undergo different polarization evolutions, resulting in a dark pulse output. Dark pulse pulse width tuning can be achieved by changing the feedback cavity length. The nonlinear polarization effect and dark pulse generation mechanism of the semiconductor optical amplifier are analyzed. And in the experiment observed pulse width tunable dark pulse output. By changing the length of the feedback cavity, a dark pulse with adjustable pulse width of 5.91 ~ 22.34 ns was obtained under the same repetition frequency (11.31 MHz).