Squeezed lattice elliptical-hole terahertz fiber with high birefringence

A highly birefringent elliptical-hole terahertz (THz) fiber with a squeezed lattice is proposed. This THz fiber is formed through regular linear deformation of a circular porous fiber by squeezing it in one direction, which may be fabricated with the existing fabrication technology. By numerical analysis we show that, with a moderate amount of deformation, the proposed THz fiber can exhibit high birefringence on a level of 10−2 over a wide THz frequency range. And the THz fiber guiding loss caused by material absorption can be reduced effectively, since a dominant fraction of modal power is distributed in the airholes inside the dielectric material.