Design and research of ultra-low loss terahertz photonic crystal fiber

A photonic crystal fiber (PCF) consisting entirely of circular air holes based on hexagonal cladding and cross-shaped core structure is proposed. The transmission properties of the proposed PCF are simulated calculation by using TOPAS as the background material, the finite element method as the calculation method, and the circular perfectly matched layer (PML) as the boundary condition. The results show that very low transmission loss, including effective material loss (EML) with 1.04 × 10-3 cm-1 , the confinement loss with 2.3 × 10-6 dB/cm, and the bending loss (when the bending radius is 1 cm) with 1.23 × 10-17 cm-1 can be got. When the proposed PCF under the optimal condition, extremely large effective area about 9.69 × 1016 μm2 and flat dispersion about 0.46 ± 0.04 ps/THz/cm can be obtained, and the proposed PCF is in the single mode. Large effective area and ultra-low loss make the proposed PCF hold great future in low loss terahertz systems. Additionally, the proposed PCF with simple structure can be drawn by many methods such as the extrusion method.