Thermal induced polarization coupling in double-cladding linearly polarized fiber lasers

In this article, a model is built to analyze the degradation of PER in linearly polarized fiber laser caused by incoherent polarization coupling during the amplification process. The model, for the first time could study the effect of heat on birefringence and the incoherent coupling process during the double-cladding linearly polarized fiber lasers’ amplification process. The model could well explain the PER degradation in our 340 W tandem pumped fiber laser and direct pumped fiber lasers in other groups’ reports. Also, the PER maintenance capability of tandem pumping and direct pumping is first analyzed.