Polarization-maintaining terahertz bandgap fiber with a quasi-elliptical hollow-core

We present a polarization-maintaining photonic bandgap fiber (PBGF) in terahertz (THz) regime, consisting of a quasi-elliptical hollow-core (QEHC) and triangularly arranged hexagonal holes in cladding. Thanks to the specially designed core shape, the QEHC-PBGF can support two stable polarization-maintaining fundamental modes. From numerical simulations, birefringence, confinement loss and group velocity dispersion of the fundamental mode group are 9.4 × 10−4, 3 × 10−3 cm−1 and 0.39 psTHz−1 cm−1 at 0.9 THz, respectively. Moreover, we investigate the fiber fabrication tolerance in the context of polarization-maintaining and confinement performances. The proposed QEHC-PBGF is anticipated to be useful in polarization sensitive THz applications.