设计了一种三芯光子晶体光纤(PCFs)偏振分束器。利用光纤的谐振现象,实现了偏振状态的分离。当三芯光子晶体光纤中三个超模式的模式折射率满足一定条件时,将产生谐振现象。通过选择合适的光纤结构参数,可使某一偏振方向的光接近谐振条件,而另一偏振方向的光远离谐振条件。在光纤的输出端,由于耦合的程度不同,两个偏振光的功率集中在不同的纤芯区,从而达到分离偏振光的目的。应用有限元法(FEM)计算了三芯光子晶体光纤中的模式折射率,选择了合适的光纤结构参数。应用全矢量光束传播法(BPM)分析了这种光纤偏振分束器的性能。结果表明,在1.55 μm工作波长上,长度为1.039 mm的光纤即能实现偏振状态的隔离,隔离度达到-36.98 dB,隔离度<-11 dB的带宽可达到24 nm。

A polarization splitter based on resonant tunneling phenomenon in three-core photonic crystal fibers (PCFs) is presented. The supermodes in three-core PCFs will be resonant if their effective refractive indices satisfy some conditions. Choosing the appropriate parameters of PCFs, one polarization light will be close to the resonant condition and the other will be far away from the resonant condition. In the end of PCFs, the light power of the two polarizations can be confined in different cores. Full-vector finite element method (FEM) is applied to calculate the effective refractive indices in three-core PCFs. Full-vector beam propagation method (BPM) is employed to analyze the performance of the splitter. Numerical simulations demonstrate that it is possible to obtain a 1.039-mm-long polarization splitter for 1.55-μm light, and the extinction ratio can reach -36.98 dB. In this case, the bandwidth with the extinction ratio better than -11 dB is 24 nm.