Broadband high birefringence and low dispersion terahertz photonic crystal fiber

We propose a novel type of triangular lattice terahertz photonic crystal fiber with high birefringence and low dispersion in a wide spectrum range. The proposed structures have circular and elliptical air holes in the cladding. Properties of birefringence, confinement loss, and group velocity dispersion have been studied by using full-vector finite-element methods. Through adjusting the structural parameters of the photonic crystal fiber, birefringence up to 10⁻³ could be achieved in the frequency range of 0.1–5 THz. Moreover, group velocity dispersion curve in this frequency range is flat and the values are nearly zero. Therefore, it can be used to transmit broadband THz pulses with the polarization maintained. (paper)