Anti-resonant fiber with nested U-shape tubes for low-loss terahertz waveguides

A novel terahertz anti-resonant fiber is designed and described. The high-resistivity silicon in the fiber mitigating the effective material loss and the nested double-layer U-shape tubes work together to reduce the transmission loss. The confinement loss and effective material loss are analyzed and optimized by the finite element method. The optimized fiber shows a total loss of 3.1 × 10⁻³ dB/m at 1 THz and the low-loss transmission bandwidth is 0.44 THz in the range of 0.5–1.5 THz. The influence of bending on the transmission loss is analyzed and the bending loss is less than 2.1 × 10⁻² dB/m at 1 THz for bending radii bigger than 60 cm. The anti-resonant fiber delivers excellent performance and has high commercial potential in terahertz waveguides. © 2023 Elsevier Ltd