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 × 10 6 and an HOM extinction ratio (HOMER) of 3.92 × 10 5 . 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.