Terahertz generation from Dirac semimetals surface plasmon polaritons excited by an electron beam
A physical mechanism of coherent terahertz (THz) generation from surface plasmon polaritons (SPPs) is presented. In a structure of bulk Dirac semimetals (BDSs) film with dielectric medium loading, the excited SPPs by an electron beam can be directly transformed into THz radiation when meeting the Cherenkov radiation condition. The radiation frequency can be widely tuned by adjusting the beam energy and chemical potential. The radiation power density is enhanced over two orders, up to 10 5 W/cm 2 . This mechanism could provide a promising way to develop room temperature, tunable, coherent and intense THz radiation sources to cover the whole THz band.