Electron-beam-driven anomalous Doppler effects in Smith–Purcell radiation

Abstract

The interaction between electrons and matter is an effective means of light emission, through mechanisms including Cherenkov radiation and Smith–Purcell radiation (SPR). In this study, we show that the superlight inverse Doppler effects can be realized in reverse Smith–Purcell radiation excited by a free electron beam with a homogeneous substrate. In particular, we find that two types of anomalous SPR exist in the homogenous substrate: special SPR and reverse SPR. Our results reveal that the electron velocity can be tuned to simultaneously excite different combinations of normal SPR, special SPR, and reverse SPR. The proposed manifold light radiation mechanism can offer greater versatility in controlling and shaping SPR.