Excitation of High-mode Spoof Surface Plasmon Polaritons(SSP) on a Metallic Grating by Electron Beam at Terahertz Spectrum

Spoof surface plasmon polaritons(SSP) on the corrugated metallic surfaces can find many interesting applications from microwave to terahertz band. In this paper, we propose a new excitation method of high-order SSP mode on a lamellar grating by injected electron beam. The dispersion characteristics and field confinement of SSP modes on the structure are presented by theoretical and numerical methods at terahertz frequencies. Besides, the excitation of high-order SSP mode by injected electron beam are modeled and implemented by numerical simulations based on FDTD algorithm. It is shown that the needed beam energy is much higher than the previously shown fundamental SSP mode excitation with metallic grating. Thus, it is very challenging to excite higher-order SSP mode by electron beam in the structure. Also, the output performances of the excited high-order SSP mode are also analyzed. The presented studies on the excitation of high-order SSP mode by electron beam pave the ways for the development of novel terahertz radiation source which can operate at higher frequency band and/or multi-frequency spectrum.