为了获得高功率单频单偏振窄线宽激光,对一个带单级放大结构的环形腔结构掺铒光纤激光器系统进行了研究。采用作为可饱和吸收体的未抽运掺铒光纤结合作为波长选择器的高反射率光纤布喇格光栅形成超窄带滤波器,在环形腔内加入光纤偏振控制器和具有高消光比的保偏环行器获得单偏振光。环形腔输出后进行单级光放大以提高输出激光光功率。获得了206mW激光输出,输出功率长时间稳定度达到1.4%。通过光纤延迟自外差线宽测试系统得到输出激光线宽小于500Hz,光纤激光器输出光偏振度长时间稳定在99.7%。结果表明,非保偏可饱和吸收体加光纤布喇格光栅结合部分保偏结构可产生单频单偏振窄线宽激光,激光放大对线宽有明显的展宽效果。

In order to acquire high power,single-frequency,single-polarization narrow-linewidth laser beam,a single-frequency erbium doped loop fiber laser and its amplification configuration were studied.With an un-pumped erbium-doped fiber as saturable absorber,with a high-reflectivity fiber Bragg grating as wavelength selector,a super narrow band filter was constructed.Fiber polarization controller and polarization-maintaining optical circulator with high extinction ratio were incorporated in the loop cavity to obtain single polarization output.A single stage amplifier was used outside the loop cavity to increase the output power.206mW output laser was obtained,and the power stability reached 1.4%.The linewidth of output laser was less than 500Hz measured through fiber delayed self-heterodyne method.The degree of polarization was stable at 99.7%.The result shows that un-polarization-maintaining saturable absorber with fiber Bragg grating together with partially polarization-maintaining structure can lead to single-polarization narrow-linewidth laser,and laser amplification will broaden the linewidth.