Smith–Purcell radiation improved by multi-grating structure

Abstract

The photonic crystal structure has attracted much attention due to its ability to confine light. In this paper, we present our study on an improved Smith–Purcell radiation from a simple metal photonic crystal excited by moving electrons. Different from the wide-band Smith–Purcell radiation from a single metal grating, the results show that the injected electrons could induce more dipole oscillations inside the multi-grating structure, and it leads to the enhancement of the radiation intensity. In addition, there are strong resonances in metal multi-grating structure, and the resonance characteristics may narrow the radiation band, which leads to a radiation with an obvious peak in the spectrum. Therefore, the multi-grating structure has the ability to enhance the radiation intensity and shape the radiation frequency band. By optimizing the structure parameters, coherent and tunable Smith–Purcell radiation can be realized, and it provides a potential way to develop band-controllable light or THz radiation source.