以新型光学聚合物Topas环烯烃共聚物(折射率为1.53)为基质,设计了四种微结构聚合物光纤.应用有限元方法对各种光纤在波长0.5—2.0μm范围内的基模有效折射率、模场面积和数值孔径进行了计算.研究了结构参数对模场分布、单模特性和色散特性的影响.得出了具有极大/小模场面积、无限单模传输和平坦近零色散的光纤结构参数.与石英、聚甲基丙烯酸甲酯基质的微结构光纤相比,该光纤具有更大的数值孔径和较宽的平坦近零色散范围.为光纤的制备提供了理论指导.
Four kinds of microstructured polymer optical fibers based on Topas cyclic olefin copolymer(COC) are designed. The effective index of the fundamental mode,the mode area and the numerical aperture are calculated by using the finite element method. Effects of structure parameters upon the mode field distribution,single mode property and dispersion property are discussed. Structure parameters corresponding to very large or very small effective mode area,endless single mode operation and flattened-near-zero dispersion are obtained. These fibers have larger numerical apertures compared with silica or PMMA based ones,and display flattened-near-zero dispersion.