Design of short polarization splitter based on dual-core photonic crystal fiber with ultra-high extinction ratio

• A novel type of polarization splitter based on dual-core photonic crystal fiber with outstanding properties is proposed.
• The extinction ratio (ER) of the 0.401 mm long splitter can reach 110.1 dB at the wavelength of 1.55 µm, and the bandwidth of ER over 20 dB and 10 dB can be as wide as 140 nm and 200 nm, respectively.
• An elliptical hole with low-index material-doped is introduced between the two cores to improve the properties and the polarization splitter has a simpler structure.
• An improved method is applied to verify the exact length of the polarization splitter quickly and accurately, and it provides a new idea and method for future study.

A novel (to our knowledge) type of dual-core photonic crystal fiber (PCF) based polarization splitter is proposed. The effects of the geometrical parameters on the performances of the polarization splitter are studied numerically based on full vector finite element method (FEM). Finally, an optimal design based on the proposed dual-core PCF with a length of 0.401 mm is achieved, the extinction ratio (ER) of the splitter can reach 110.1 dB at the wavelength of 1.55 µm, and the bandwidth of ER over 20 dB and 10 dB can be as wide as 140 nm and 200 nm, respectively. This polarization splitter proposed in this paper provides a new structure for designing a splitter with short length, high ER and wide bandwidth simultaneously.