Octagonal photonic crystal fiber dual core polarization splitter

An octagonal dual core polarization splitter based on highly birefringent photonic crystal fiber (PCF) is proposed and the full vector finite element method (FEM) is employed to analyze the impacts of structural parameters on birefringence and the coupling length, and simulation results show that high birefringence on the order of 10−3 can be achieved at 1.55 μm, moreover, the hole size and hole pitch both affect birefringence and the coupling length. Based on these results, the PCF's structure is optimized to realize a polarization splitter of 314 μm whose largest extinction ratio is around −50.5 dB at 1.55 μm. Meanwhile, the bandwidth at the extinction ratio of −10 dB is about 170 nm, and around 60 nm at −20 dB.