一种覆盖全通信波段的新型宽带偏振无关双芯光纤定向耦合器的研究

提出了一种新型的双芯光子晶体光纤, 应用全矢量有限元方法分析了光纤各种结构参数对光纤宽带特性和偏振无关特性的影响. 在此基础上优化设计了一种50:50的双芯光子晶体光纤耦合器, 在1.225—1.675 μm波长范围内实现分光比小于1%、两偏振态之间的分光比差小于0.5%的优良特性. 由于引入了仅对偏振特性影响明显的相对独立的中心调制区, 不仅降低了光纤的优化设计难度, 而且实现了与普通单模光纤相匹配的模场特性, 能有效地降低耦合器的接续损耗与制作难度. 研究成果为研制接续损耗低、超宽工作带宽、偏振不敏感等特性的新型光定向耦合器提供了理论基础.

Design and optimization of a novel broadband and polarization-insensitive dual-core photonic crystal fiber coupler over the whole optical communication band

In this paper,a novel broadband polarization-insensitive dual-core photonic crystal fiber with elliptical central hole is proposed and the influence of its structural parameters on coupling characteristic is investigated in detail by the full-vector finite element method. Through optimizing the fiber structural parameters,broadband and polarization-insensitive characteristics are achieved over the whole optical communication band from 1.225μm to 1.675μm.The variation of coupling ratio is stabilized at 50%±1%,and the coupling ratio difference between x polarization and y polarization is less than 0.5%overall the wavelength range.Due to its relatively independent of cores and elliptical central hole and suitable structural parameters,this fiber meets the application requirements,that is,easy to fabricate,easy to splice and low splice loss.This research is freed from the current coupler limit:narrow bandwidth,wavelength dependence,polarization-sensitive,difficulty of fabricating,thereby provides the theoretical basis for the study of the large capacity high speed all-optical networks and multi-wavelength tunable fiber laser.