结构偏差对保偏光子晶体光纤色散特性的影响

Influence of Structure Deformation on Dispersion Character of Polarization-Maintaining Photonic Crystal Fibers

光子晶体光纤(PCF)具有很多特殊性质,这些性质强烈依赖其具体结构。由于光子晶体光纤制作过程复杂,容易造成各种变形,包括包层气孔的位置偏移或变形等,从而明显影响该光子晶体光纤的性能。选用商品保偏单模光子晶体光纤作为研究对象,改变了环绕中心石英芯的两个大空气孔之一的形状和尺寸。固定气孔尺寸和形状,改变其位置;再固定其位置,改变一个大气孔的直径;最后同时改变二者,分析其交叉影响。仿真结果显示当一个气孔变形或偏移后,光子晶体光纤的等效折射率、零色散波长、偏振拍长、导模模场形状等参数均发生变化,说明结构偏差对保偏光子晶体光纤性质有明显影响。

Photonic crystal fiber （PCF） has many special characteristics, which strongly depend on its structure. The location error or deformation of the cladding holes can be introduced readily during the complex fabrication process, which will change the characteristics of the PCF intensely. A commercial single-mode polarization- maintaining PCF was investigated when the size and location of one of the two larger side holes were changed. In order to give relationship between the location error or deformation of the cladding holes and the dispersion characteristics, the simulations of the PCF dispersion characteristic were given for the case that the location of one side larger hole was changed while the size and form kept invariable. Secondly the case, that the size of one side larger hole was changed without shifting, was simulated. The simulation results for the case of changing both location and size of this hole were demonstrated at last. All the simulation results show that the structure deformation affects the properties of the polarization-maintaining PCF strongly because the effective index of refraction, zero group velocity dispersion wavelength, polarization beating length, mode structure etc. are changed.