混合导光双芯光子晶体光纤及分束器

设计了一种基于全内反射和光子带隙效应两种导光机制的混合导光双芯光子晶体光纤,以耦合模式理论为基础,利用全矢量有限元法和平面波展开法分析了其有效折射率和耦合长度特性。数值分析结果表明:通过改变光纤中大空气孔直径及孔间距,可以调节耦合长度的大小,通过改变高折射率柱直径以及高折射率柱的有效折射率,可以调节耦合长度大小及耦合长度极大值的位置。利用所设计的混合导光双芯光子晶体光纤制作的偏振分束器,其长度为5.2 mm,在31 nm带宽范围内,分光比小于-30 dB;在60 nm带宽范围内,分光比小于-20 dB。

Splitter and hybrid dual-core photonic crystal fiber

A new type of hybrid dual-core photonic crystal fiber was proposed based on two guiding mechanisms of total internal reflection and photonic band-gap effects.According to coupled-mode theory,the effective index and coupling length were analyzed by using the full-vector finite element method and the plane wave expansion method.Numerical investigations demonstrate that the coupling length of the fiber can be changed significantly by tuning the diameter of four large-air holes and the space between two air holes.The location of the maximum coupling length can be shifted by adjusting the diameter and the refractive index of the high-index inclusion.A polarization splitter was designed by using the hybrid photonic crystal fiber.It is found that the coupling length is 5.2 mm.The extinction ratio is less than-30 dB with band-gap of 31 nm,and the extinction ratio is less than-20 dB with band-gap of 60 nm.