Impact of bending angle on antiresonant fibers with optimized symmetric geometries

Abstract

Hollow core fibers are unique in reducing signal latency, as well as providing low dispersion and low nonlinearity. Their adoption is hindered by cost, particularly for complex structures that provide the lowest loss. Designs of antiresonant nodeless fiber (ANF) with uniformly sized capillaries, symmetric structures, and without nesting have simple structures that could more readily achieve commercial exploitation. We investigate simple ANF structures for short-reach applications where reduced latency is critical and transmission lengths are short enough to allow a trade-off on loss.

A common design rule in ANF targets a ratio of 0.68 for capillary diameter to core diameter. We find that when such a design is combined with a large core diameter, the fiber is highly sensitive to bending orientation. We identify ANF designs that offer single-mode operation with acceptable loss, as well as robustness to bending radius and orientation. When there is no bending, our best design has a simulated loss of $\le$ 7 dB/km at the worst-case C-band wavelength. At bending radii of 21 and 18 cm, the worst-case loss over all bending orientations and throughout the C-band is 14.5 and 17.52 dB/km, respectively. Higher-order mode suppression exceeds 20 dB under all conditions (bending and wavelength).