Terahertz generation from graphene surface plasmon polaritons excited by a cyclotron electron beam
A novel physical mechanism is reported which can generate coherent and tunable terahertz (THz) radiation. Due to the natural periodicity of 2¿ of circular cylindrical graphene structure, the surface plasmon polaritions (SPPs), excited by a cyclotron electron beam (CEB), can be transformed into radiation. The radiation density is strongly enhanced over two orders, up to 105 W/cm2. The radiation frequency can be widely tuned by adjusting the beam energy and chemical potential. This mechanism opens a way for developing room temperature, tunable, coherent and intense pulsed or even CW THz radiation sources to cover the whole THz frequency regime.