Design of Polarization Beam Splitter Based on Rectangular Core Photonic Crystal Fiber Without Holes in the Cladding

A new polarization beam splitter (PBS) based on rectangular core photonic crystal fibers (RC-PCFs) is proposed. Based on the full-vector finite element method, RC-PCFs without holes in the cladding are introduced to improve the design flexibility of multi-core PCF structure. An anisotropic lattice distribution using staggered arrangement of silicon nitride rods and air holes is employed in the core region to increase the birefringence. Optimization of the rectangular core structure is conducted to achieve single-polarization single-mode (SPSM) property. Afterwards, utilizing two SPSM PCFs, in the proposed PBS, two orthogonal polarization waves are only coupled to corresponding PCFs with a device length of $185~\mu $ m, and the crosstalk-free PBS is achieved.