Terahertz Switch Based on Waveguide-Cavity-Waveguide Comprising Cylindrical Spoof Surface Plasmon Polariton

This paper demonstrates a terahertz (THz) switch that comprises a metallic perfect conductor in the form of periodically corrugated cylindrical waveguides surrounding a dielectric medium consisting of GaAs compound semiconductor. The proposed switch deploys a composite waveguide-cavity-waveguide structure. The switch controls its state by dynamically altering the optical properties of an engineered nonlinear material inside the cavity, while the corrugated waveguides on both sides of the cavity are incorporated to limit the propagation of electromagnetic (EM) waves at nearly THz frequencies only. At the resonant frequency, the corrugated waveguide allows strong EM confinement inside the grooves. The cavity has been designed to achieve a high quality factor as well as to trap EM waves for a significant period of time. Small changes in the GaAs refractive index inside the grooves can alter the cavity resonant frequency. Localized doping near the metal conductor inside the cavity is implemented so that by applying a voltage between the metal electrode and the depletion region in the dielectric medium, the switch can be altered from the ON state to the OFF state, and vice versa.