Design of a negative curvature hollow-core fiber for transmitting a single-mode dark hollow beam

Abstract

We propose a nested negative curvature hollow-core fiber that can stably transmit a single-mode (LP11 mode) dark hollow beam with low loss. A pair of resonant tubes is nested inside the cladding tubes in the horizontal direction to enhance the confinement loss of the fundamental mode LP01. Two pairs of glass sheets at different positions within the four cladding tubes in the non-horizontal direction are introduced to suppress the comparatively low loss higher-order modes LP21 and LP02. The numerical simulation results indicate that the loss ratio between the fundamental mode and LP11 mode can reach 28703 when the transmission wavelength is 1.54 µm, and the LP11 mode has the lowest confinement loss of 0.0049 dB/m. Meanwhile, the loss ratios of higher-order modes such as LP21, LP02, and LP31 with the target LP11 mode are above 100. The effective bandwidth of single-mode dark hollow beam transmission can reach 5 nm. This provides an optical fiber solution for single-mode dark hollow beam transmission, which has potential applications in atomic optics, quantum information, and nonlinear optics.