Terahertz generation from graphene surface plasmon polaritons excited by an electron beam
A physical mechanism is presented which can generate coherent and tunable terahertz (THz) radiation. Due to the dramatical lifting of SPPs energy, the dispersion can cross the light line, thus, the SPPs excited by an moving electron beam can be transformed into THz radiation. The radiation power density is enhanced nearly three orders, up to 105 W/cm2. The radiation frequency can be widely tuned by adjusting the beam energy and chemical potential. This mechanism could provide a promising way for developing room temperature, tunable, coherent and intense THz radiation sources to cover the whole THz band.