Electron beam induced terahertz Čerenkov radiation from multilayer graphene sandwiches

Terahertz lasing by electron beam propagating over a graphene/dielectric sandwich structure is considered. A dispersion equation for the surface electromagnetic modes propagating along graphene sheets is derived and Čerenkov synchronism between surface wave and electron beam is predicted at achievable parameters of the system. The generation frequency tuning is proposed by varying the graphene doping, the number of graphene sheets, the distance between sheets, etc.