Higher harmonic of Super-radiant Smith-Purcell radiation

Smith-Purcell radiation (SPR) is emitted when free electrons passing along the surface of the periodic grating. When electron bunch matches the surface wave in certain condition, a kind of enhanced coherent radiation can be produced from the interaction between electron bunch and the surface wave, referred to as the superradiant Smith-Purcell radiation (SSPR). Here, the high harmonics SSPR at Terahertz frequency and with stronger intensity is studied through theoretical calculation and electromagnetic simulation. The results show that the 2nd harmonic of Smith Purcell superradiation at 190GHz with 112mW energy and the 3rd Smith Purcell superradiation at 505GHz can be achieved by optimizing the structural parameters. The study of the high harmonics SSPR is of great significance to the development of THz radiation sources.