Terahertz polarization-maintaining subwavelength dielectric waveguides

Abstract

A terahertz (THz) birefringent waveguide, steering the polarization state of guided modes, is one of the basic components in polarization-sensitive THz systems. In this paper, we propose subwavelength dielectric waveguides with rectangular- and elliptical-core shapes to achieve high birefringence in the THz regime. We implement numerical models to analyze the impact of structural parameters on polarization-maintaining guidance, followed by the frequency dependent propagation performances. Operating at 0.3 THz, the modal birefringence can be of the order of 10−3 or even higher, while the losses of two orthogonally polarized modes are less than 0.088 dB cm−1. Further simulations indicate the waveguides are insensitive to bends (bending radius of 5 mm), and the waveguide coupling efficiency could be greater than 0.9 if a linearly polarized Gaussian beam input is exploited.