Design of Few-Mode Hollow-Core Anti-resonant Fibers with Bridge-Linked Concentric Tube Pairs

This paper proposes a novel bridge-linked dual-nested anti-resonant hollow-core fiber with low-mode transmission performance. The study investigates the influence of the proposed fiber structure parameters on the confinement losses(CL) of each mode in the core. It also provides a detailed analysis of how the effective refractive index and CL of each mode in the fiber change with wavelength under optimal structural parameters. The optimized BLN-ARF can transmit five modes (LP01, LP11, LP21, LP02, and LP31) in the 1-1.6 μm wavelength range. In the 1.6-1.8 μm range, it can transmit four modes (LP01, LP11, LP21, and LP31). The effective refractive index difference Δneff between each mode is greater than 1×10⁻⁴, significantly suppressing coupling between the five LP modes and preventing channel crosstalk between different modes. Furthermore, LP01, LP11, LP02, and LP31 all achieve the lowest CL at 1.12 μm, which are 1.84×10⁻⁷ dB/m, 2×10⁻⁶ dB/m, 2.5×10⁻⁴ dB/m, and 2.86×10^-3 dB/m, respectively. Furthermore, the bending loss and manufacturing tolerances of this BLNARF structure were also investigated.