A Simple Birefringent Terahertz Waveguide Based on Polymer Elliptical Tube

We propose a simple birefringent terahertz (THz) waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one direction. Simulations based on the full-vector finite element method (FEM) show that this kind of waveguides exhibits high birefringence on a level of 10−2 over a wide THz frequency range. Moreover, as a majority of modal power is trapped in the air core inside the polymer elliptical tube, the THz waveguide guiding loss caused by material absorption can be reduced effectively. (fundamental areas of phenomenology (including applications))