Infrared Diffraction Radiation from Two in-Line Dielectric Rods Covered with Graphene

We analyze the terahertz and infrared range diffraction radiation (DR) of a modulated beam of electrons flowing near two graphene-covered dielectric nanorods. In our treatment, we assume that the velocity of the charged particles beam is fixed and use the Kubo formalism and resistive-type boundary conditions for the graphene cover description. To satisfy the boundary conditions, we apply the separation of variables in the local coordinates and the addition theorem for the cylindrical functions. This transforms the DR problem to a Fredholm second-kind matrix equation for the field expansion coefficients. As a result, the scattering and absorption characteristics and the near and far field patterns are determined with controlled accuracy. The obtained data show the resonance effects related to the excitation of the plasmon supermodes of four different classes of symmetry. Our work could be used in design of elementary cells of dielectric laser accelerators.