Characterization of hybrid waveguide for Terahertz guidance

Abstract

It has been reported that the conventional two-wire waveguide is a good candidate for guiding the Terahertz (THz) wave. However, the waveguide may not be suitable for some practical purposes because of its environmental sensitivity and bulky setup. In this study, we proposed the hybrid waveguide as an alternative THz waveguide. The waveguide structure is mainly composed of transparent dielectric material to a THz wave with a central square of air gap flanked by a pair of copper wires along the waveguide axis. The waveguide is robust due to the mechanical support of the metal wires. At the same time, the dielectric cover can prevent any environmental disturbance that could affect the wave propagation properties. The numerical studies of the proposed waveguide were carried out by commercial software COMSOL Multiphysics, which is based on finite element analysis. The simulation results show that the proposed hybrid waveguide can provide low loss and low dispersion due to the guidance mechanism of the surface plasmon wave propagation similar to the conventional two-wire structure. Using two identical copper wires with the radii, the air hole width, and the center-to-center distance given as 150, 300, and 600 µm, respectively, results in the linearly polarized THz wave confined within the central square of the air gap. The effective refractive index of the proposed waveguide fundamental mode is 1.34 at the operating frequency of 0.2 THz. In addition, high modal energy is confined, and a low absorption loss is achieved.