A novel dispersion flattened and single-mode terahertz photonic crystal fiber with material-filled structure

A novel kind of terahertz (THz) photonic crystal fibers (PCFs) based on the material-filled structure is proposed in this paper. Different materials can be selectively filled into parts of air-holes in the designed THz PCFs, and then perfect features such as single-mode transmission and ultra-flattened dispersion are obtained easily in large frequency ranges near 1THz. Employing full-vectorial finite element method (FEM) and plane wave expansion method (PWE), confinement losses and modal dispersion with different structural parameters and diverse refractive indices of the filled materials are investigated respectively. Numerical results show that the proposed PCFs have acceptable confinement losses, low and flattened dispersions whose absolute values are lower than 1ps/nm*km. Moreover, its structure is simple and its feature is insensitive to variations of parameters. It is helpful for PCFs design and real fabrication in the potential THz applications.