Novel design of a diamond-core photonic crystal fiber for terahertz wave transmission

In this paper, we report a novel diamond-core optical crystal fiber with the fiber cladding of square air holes in hexagonal lattice structure and the core of circular air holes in diamond lattice structure for practical low-loss terahertz (THz) wave guiding. The whole PCF is based on cyclic-olefin copolymer (COC), which is commercially known as TOPAS. We demonstrate that the designed PCF shows an ultrahigh birefringence of the order 10~
³
. Other important propagation characteristics such as confinement loss, effective mode area and waveguide dispersion are also investigated.