Low-loss and flat dispersion umbrella-shaped and porous-core photonic crystal fiber for terahertz applications

A novel design of a single-mode photonic crystal fiber for applications in the terahertz region is proposed and numerically analyzed. The geometrical and optical parameters of the structure are estimated by using algebraic expressions while the guidance properties are calculated by using the full-vector finite element method. The porous-core of the fiber is suspended by eight equally spaced bridges connected to an outer cladding. The obtained results show that by adjusting the structural parameters appropriately, low-loss and flat dispersion properties could be easily achieved. The numerical results show that our best configuration, with a 60% filling fraction, exhibits a low effective material loss, below 0.2 dB/cm, and a flattened dispersion behavior in the frequency range from 0.79 THz to 1.5 THz.