Highly birefringent and low loss anti-resonant hollow-core fiber with stadium-shaped nested structure

Abstract We propose a stadium-shaped nested anti-resonant hollow-core fiber (SSAF), designed to enable high birefringence and low loss in the near-infrared bands. A numerical investigation and simulation for variations in the parameters of the stadium-shaped nested structure were conducted, and the confinement loss (CL) was reduced by parameter optimization, while a birefringence of 10-4 was maintained. With optimized SSAF structure, the birefringence and CL are improved to 1.39 ×10−4 and 26.5 dB/km at 1.38 µm, 1.28 ×10−4 and 2.64 dB/km at
1.55 µm, respectively. Meanwhile, it exhibits favorable single-mode characteristics and achieves a high-order mode extinction ratio (HOMER) of up to 103, and the superior bending resistance characteristics were validated. Our work offers valuable guidance for designing and optimizing highly birefringent anti-resonant hollow-core fiber (ARF), and the proposed
SSAF has great application potential in polarization-dependent transmission and interferometric fiber gyroscopes.