Generating Coherent Terahertz Radiation via Brillouin Zone Overlapping

A method to generate coherent terahertz (THz) radiation into free space via Brillouin zone overlapping is introduced in this paper. When the free electron bunch passes over the metallic grating, the spoof surface plasmon (SSP) is stimulated and confined in the surface. By loading a rod array above the grating, the Brillouin zones of the rod array and grating overlap. In this way, part of the dispersion curves of the SSP wave lies in the radiative region, achieving the transformation from SSP to radiation wave into the free space. Moreover, the field intensity of the coherent THz radiation shows an enhancement about 20 times compared with that of ordinary Smith-Purcell radiation (SPR) generated from the rod array. This method is promising for developing compact and efficient THz radiation source.