Nested anti-resonant hollow core fiber for terahertz propagation

A novel nested anti-resonant hollow core fiber (NAHF), based on Topas, with low loss and flattened dispersion is proposed for efficient transmission of terahertz wave. Finite element method with an ideally matched layer (PML) boundary condition is used to investigate its guiding properties. A cladding structure of nested anti-resonant elliptical rings is introduced to reduce mode power leakage. The NAHF shows a low confinement loss (< 0.29 cm^-1 ) and a small effective material loss (< 0.019 cm^-1 ) in the frequency range of 0.9-1.5 THz. An ultra-flatted near zero dispersion profile of ±0.029 ps/THz/cm is obtained within a broad frequency range of 0.6-1.5 THz. Furthermore, optimizing the structure parameters in NAHF, higher core power fraction over 80 %, higher effective mode area of ~10^-6 μm² and the bending loss of 3.05×10^-5 cm^-1 at the bending radius of 10 cm are also achieved.