Anti-resonant hollow core fiber with excellent bending resistance in the visible spectral range

The development of wideband guided hollow-core anti-resonant fiber (HC-ARF) that covers the sensitive range of the human eye's visible spectrum is progressing rapidly. However, achieving low-loss wideband transmission with a small bending radius remains a challenging issue to be addressed. In light of this, we propose a novel, to our knowledge, HC-ARF with a nested double-semi-elliptical cladding structure in the visible spectral region. By employing finite element method simulations, we investigate the confinement loss, bending loss, and single-mode performance of this fiber design. The result shows that the confinement loss of this new fiber exhibits below 10^-5dB·m^-1 across almost the entire visible band range, with a minimum loss of 1.55 × 10^-7dB·m^-1 achieved for λ = 650 nm. Furthermore, this fiber demonstrates excellent resistance to bending and can maintain an ultra-low bending loss as low as 3 × 10^-7dB·m^-1 even under extreme bending conditions with a radius of only 3 cm. Notably, its 3-dB bending radius reaches just 3.5 cm for λ = 532 nm. Additionally, it exhibits outstanding single-mode conductivity under various bending scenarios and achieves a high extinction ratio of up to 10⁴ for higher-order modes after parameter optimization for specific wavelengths.