类蜂巢 PCF 的结构参数对带隙特性的影响

摘要

PCF(光子晶体光纤)在实际拉制过程中包层会形成间隙孔。文章提出一种类蜂巢晶格结构的光纤，利用全矢量 PWEM (平面波展开法)分析了该结构的圆形和正六边形纤芯的带隙特性，发现纤芯形状对带隙影响作用比较小，验证了 PBG(光子带隙)主要是由包层有序排列的空气孔而形成的。计算分析了包层间隙孔直径 d in t 、包层孔节距Λ和包层空气填充率f 对带隙特性的影响。通过模拟计算发现，在一定 d in t 范围内，增大 f 以及减小Λ，带隙宽度均会增大，并且带隙向高频方向移动。采用实际拉制的光纤进行模场面积计算和 PBG 分布的理论研究，发现该结构光纤的光主要集中在基模传输，同时在可见光波范围内存在 PBG。%Interstitial holes are usually formed in the cladding of Photonic Crystal Fibers (PCF)in the actual drawing process. This paper presents an optical fiber in honeycomb-like lattice structure.Using the full-vector Plane Wave Expansion (PWE) method,it analyzes the bandgap properties of its circular and hexagonal cores,finds that the impacts of the core shape on the bandgap is relatively small and verifies that the Photonic Band Gap (PBG)is formed mainly due to the orderly arranged air holes in the cladding.Furthermore,it calculates and analyzes the effects of the interstitial hole diameter d in t ,hole pitchΛ and air filling ratio f on the bandgap properties.The analog computation results indicate that in certain scope of d in t ,the bandgap width increases with both increasing f and reducingΛ ,and the bandgap shifts towards the high frequency side.Finally,from the mode field area computation of the actually drawn fibers and the theoretical study of PBG distribution,it finds that the light in fibers in this structure mainly focuses on basemode transmission and there exist PBGs in the range of visible light waves.