Smith-Purcell radiation improved by multi-grating structure

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.