Design of a Nanovoid Ring-Core Fiber for Ultra-Low-Bending-Loss Few-Mode Transmission

We present a nanovoid-assisted ring-core fiber designed for low-bending-loss few-mode transmission. We develop a 3D model that accounts for stress-induced perturbation in bending-loss evaluation. Our model yields closer agreement with published experimental data compared to conventional conformal mapping. The nanovoid ring-core fiber reduces the bending loss of higher-order modes by up to three orders of magnitude, and improves the degeneracy of the higher-order pair nearly ten-fold at tight bending radii. The proposed fiber maintains the same intermodal separation compared to the reference ring-core fiber across all investigated radii.