Enhanced coherent THz radiation by dual groove grating Smith-Purcell effect

The phenomenon of free electrons crossing the periodic structure surface to stimulate radiation is called Smith-Purcell (SP) effect. Former researchers have discovered that by using the open resonator array, SP radiation can have a specific frequency and angle. What's more, this frequency is consist with its resonance mode. However, grating with too small grooves would have lower radiant efficiency, so we present a new structure that add a larger groove at each period of grating, which can not only maintain its radiant characters, but also enhance its radiation intensity. We also use this structure in the transmission grating, which has some better radiant characters than traditional reflection grating. This discovery will provide a new method for the research of high power coherent THz radiation source.