熔锥型保偏耦合器的传输特性决定了其光学原理与功能的实现。为了从理论上分析各参量对保偏耦合器传输特性的影响,基于热结构电磁多物理场耦合理论,建立了熔锥型熊猫光纤耦合器双锥模型,应用有限元法,分析了各参量对熊猫光纤耦合器传输特性的影响。结果表明应力区与包层折射率差影响耦合区纵向电磁场的分布,折射率差越大,纵向电磁场分布的变形也越大；HEx11模和HEy11模的传播常量对偏振主轴角度差不敏感,偏振主轴角度差是通过耦合系数进而影响保偏光纤耦合器的消光比的；HEx11模的传播常量对熔锥的熔锥区横截面椭圆率比较敏感,横截面椭圆率变化6.67%时Δβx11变化0.14%,计算结果表明当熔锥区横截面椭圆率为0.56时可获得较高性能的耦合器。

The optics principle and functions of fused polarization-maintaining fiber coupler is determined by propagation properties. In order to investigate the effects of parameters, based on the theory of thermal-structural-electromagnetic multiphysics field interaction, the biconical models of the fused PANDA fiber coupler were given. Using finite element method the effects of the propagation properties for fused PANDA fiber coupler is analyzed. The results show that longitudinal electromagnetic field distribution is influenced by the refractive index difference between the stress applying part (SAP) and cladding, the distortion of distribution is increase with the D-valve. The propagation constants for HEx11 and HEy11 modes are insensitive to the angle disparity of the birefringent axes, and they affect to the extinction ratio directly by coupling coefficient. The propagation constants for HEx11 mode is sensitive to the ellipticity of fused taper section, the change of Δβx11 is 0.14% when the ellipticity fusion is increased 6.67%, and the numerical results show that it can get high performance when the ellipticity of fused taper section is 0.56.