Numerical investigation of Cherenkov radiations emitted by an electron beam bunch in isotropic double-negative metamaterials

The electron-beam-induced Cherenkov radiations in isotropic double-negative metamaterials (DNMs) are numerically investigated in this paper. The frequency-dependent permittivity and permeability functions are approximated by the Drude-Lorentz model. This model is implemented by the finite-difference time-domain (FDTD) and the auxiliary difference equation (ADE) methods. The interaction between electromagnetic fields and electrons is simulated by the particle-in-cell (PIC) method. The fundamental physics of the direct and the reversed Cherenkov radiations from an electron beam bunch in a typical sandwich structure is well presented. The numerical results show that the use of an electron beam bunch rather than an ultra short laser pulse to excite DNMs raises questions and novel opportunities regarding the selectivity with which Cherenkov radiations with different components and frequencies can be excited.