Terahertz multi-frequency splitter and spoof SPPs switch

In this paper, a spoof surface plasmon polaritons (SPPs)-based multi-frequency splitter in the terahertz (THz) band is realized by designing different grating heights. The structure is composed of an incident aperture waveguide and a composite gratings structure placed on both sides of the incident aperture waveguide. The composite grating structure has different grating heights, which is used to transmit and guide THz waves of different frequencies in different directions. Simulation results show that a mixed incident light consisting of three frequencies, of 0.5 THz, 0.7 THz and 1 THz, can be effectively separated by this splitter. Furthermore, the function of the spoof SPPs switch can be realized by increasing the number of incident aperture waveguides. The simple structure and small size, means that this multi-frequency splitter and switch can be conveniently integrated into THz sensing or THz communication systems.