A Terahertz Electronic Source Based on the Spoof Surface Plasmon With Subwavelength Metallic Grating

A terahertz electronic source based on the spoof surface plasmon (SSP) with 2-D subwavelength metallic grating is presented. The SSP dispersion relation of plasmonic grating is derived by a simplified modal expansion method, and the coupling and interaction between the SSP and the electron beam is studied by particle-in-cell simulation. The results reveal that the output performance highly depends on the location of electron beam from grating surface. For an injected electron beam with 19.15 kV and 0.5 A, the SSP output power can reach 22.7 W for the optimized distance of the beam from the grating surface at a frequency near 1 THz for the given structure. Besides, the influence of different electron beam parameters on output power is also investigated and we find that pulse electron beam is preferable than continuous electron beam for good performance. There is an optimized operation frequency for the given beam voltage. Furthermore, output performance can be improved by changing grating structure parameters. By decreasing the grating groove filling factor from 0.8 to 0.2, the SSP output power can be increased from 17.2 to 23.6 W. The SSP power can also be significantly enhanced from 14 to 28.6 W using shallow grating with a groove depth changing from 76 to 56 μm for the optimized operation frequency with the same electron beam. The present work may provide a new avenue to obtain powerful THz electronic sources.