Abstract
An electron-velocity-thresholdless terahertz (THz) Cherenkov radiation (CR) based on equivalent graphene plasmonic metamaterial (EGPMs) is proposed in this paper. A hyperbolic metamaterial (HMM) with hyperbolic equal frequency contours (EFC) is designed and demonstrated by periodically stacking the EGPSs, which mimics the EM characteristics of optical graphene in the THz band and can be used to imitate diverse optical graphene metamaterials. When a sheet electron beam flies over the surface, the electron-velocity-thresholdless CR will be generated since the HMM theoretically supports the infinite wavevector. The field distributions of the generated CR are analyzed for different electron energy values, and the results demonstrate the thresholdless CR phenomenon. The proposed thresholdless scheme may foster the application of the free-electron-driven integrated on-chip THz radiation source.