作为高功率光纤激光器谐振腔的输出端, 低反光纤光栅(Output Coupler, OC)的反射率值较小, 采用基于透射谱的方法测量OC反射率时, 光源功率不稳定或光谱仪测量的误差, 会使得OC反射率的测量结果产生较大误差。因此提出一种基于菲涅耳反射原理, 获得反射谱测量OC反射率的方法。通过实验对该方法进行了验证,结果表明该方法的测量精度和稳定性有了显著提高。同时分析了该方法带来的带宽测量不准确的问题, 提出了使用折射率匹配液的方法解决了该问题。

As the output end of the high power fiber laser resonator, the reflectivity value of the output coupler(OC) was small. When the OC reflectivity was measured by the transmission spectrum method, the instability of the light source power or the error form measured spectrometer can cause a large error in the result of OC′s reflectivity. Based on Fresnel reflection principle, a method of measuring OC reflectivity by reflectance spectrum was proposed. Validating the method by experiments, the results show that the measurement accuracy and stability of the method have been improved remarkably. At the same time, the inaccuracy of bandwidth measurement caused by this method was analyzed, and a method of using index matching liquid was proposed to solve the problem.