A single-mode fiber polarization beam splitter based on a dual-hollow-core anti-resonant structure

Abstract This paper proposes a dual-core hollow-core anti-resonant fiber polarization beam splitter (DHC-ARF PBS) that incorporates an incomplete circular cladding tube to enhance the design degrees of freedom of the device. The structure consists of four incomplete circular outer cladding tubes distributed at certain angles, two pairs of complete circular inner cladding tubes located in the vertical and horizontal directions respectively, and eight circular nested tubes are incorporated within them. The fiber forms two cores, A and B, with the gap between one pair of cladding tubes located horizontally serves as a coupling channel for regular power transfer between the dual cores. The influence of the structural parameters on the performance of the splitter was analyzed using the finite element method (FEM), and a parameter optimization design was carried out. Simulation results indicate that at a device length of 2.97 cm, covering the wavelength range from 1.48 μm to 1.6 μm with a polarization extinction ratio (PER) as low as −20 dB, demonstrating excellent beam-splitting capability. Furthermore, the higher-order mode extinction ratio (HOMER) exceeds 100 over a broad wavelength range from 1.32 to 1.71 μm, reaching a notably high value of 552.26 at 1.55 μm, which confirms outstanding single-mode performance. The fundamental mode transmission loss is less than 1.82 dB m −1 . The PBS has significant potential application value in optical communications and all-fiber systems.