Actively manipulating coherent Smith-Purcell radiation with graphene metasurface

A novel physical mechanism is proposed which can actively manipulate coherent Smith-Purcell radiation
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with graphene metasurface. The coherent radiation is generated from the resonantly coupling between waveguide modes excited by a moving electron beam and the diffraction waves by the graphene metafurface. Owing to the controllability of the electron beam and some properties of graphene, the fundamental properties of the coherent Smith-Purcell radiation can be actively manipulated by adjusting the chemical potential of graphene metasurface and electron beam velocity. This mechanism opens a way for dynamically tuning the radiation states of Smith-Purcell radiation.