|Yu Ying-Ying, Li Xu-You, Sun Bo, He Kun-Peng|
|College of Automation, Harbin Engineering University, Harbin 150001, China|
Abstract We propose a design and optimization for directional coupling in terahertz hybrid-cladding hollow waveguide.. It is composed of two square hollow waveguides which are touched with each other and surrounded by a metallic layer. By employing the finite element method, the coupling performance and loss property are numerically investigated. Numerical results indicate that this directional coupler with hybrid-cladding can realize ultra-narrow-band coupling. And it provides a low confinement loss performance: the confinement loss can reach as low as 6.27×10-5 cm-1. Moreover, the further analyses of configuration and performance show that confinement loss and frequency range shift for the low-confinement-loss frequency regime can be realized and optimized by appropriately tuning the thickness values of metallic and dielectric layer. In addition, through the further analysis of coupling performance, the possibilities of realizing ultra-narrow-band couplings in different frequency ranges are demonstrated. It is a powerful candidate for high precision optical fiber sensing, and communication in terahertz splitting fields.