Metal disc-type splitter with radially placed gratings for terahertz surface waves

A novel way to split terahertz (THz) surface waves is presented on the basis of propagation characteristics of spoof surface plasmon polaritons. Metal disc-type splitters with a centre hole and radially placed gratings are proposed and analysed using the finite-difference time-domain (FDTD) method in cylindrical co-ordinates. Numerical results demonstrate that the discs act as bi- and multi-directional THz surface wave splitters with large coupling regions, the frequency of which is selected by grating structures.