Silicon nitride based photonic crystal fiber with highly improved birefringence for low loss terahertz propagation

We propose a structure of porous core photonic crystal fiber with a suspended and porous elliptical core that provides considerable properties for terahertz wave guidance. The propagation features of the structure are simulated and compared over the terahertz frequency region when TOPAS and silicon nitride are used as based materials. Our results reveal that the TOPAS based structure could enhance the birefringence up to 0.123 at the frequency of 1.4 THz, with a relatively comparable total loss of 0.2 cm −1 . Moreover, it is confirmed that introducing silicon nitride as the base material to the proposed structure leads to a significant birefringence of 0.89 at the frequency of 0.6 THz, with a confinement loss of 10 −4 cm −1 and effective material losses of 10 −3 cm −1 .