Single-Polarization Single-Mode Hollow-Core Anti-Resonant Fiber With Double Tangent Circular Arc Tubes

Abstract

We propose a novel hollow-core anti-resonant fiber (HC-ARF) with double tangent circular arc tubes (CATs) for robust single-polarization single-mode (SPSM) operation. Departing from conventional cladding-asymmetric designs, the SPSM mechanism is achieved by engineering core asymmetry via integrating dual CATs into an 8-tube single-ring HC-ARF. Finite element simulations demonstrate exceptional polarization selectivity: X-polarized fundamental mode (XPFM) and higher-order modes (HOMs) exhibit confinement losses of 4836.19 dB/m and ~300 dB/m at 1550 nm, respectively, while Y-polarized fundamental mode (YPFM) maintains ultralow loss (6.86 × 10⁻⁴ dB/m). This yields a polarization extinction ratio (PER) of 7.05 × 10⁶ and an HOM extinction ratio (HOMER) of 3.92 × 10⁵. The fiber sustains SPSM operation over a 181 nm bandwidth (1481–1662 nm) with outstanding structural tolerance to CAT ellipticity (major/minor axis variations up to 21/16 μm). This core-asymmetric HC-ARF architecture opens new avenues for polarization-sensitive applications requiring ultralow loss and broadband operation.