Effective coupling between THz electromagnetic radiation and 2D plasmons

Theory of the plasmonic structure “grating - 2DEG” that consists of subwavelength metallic grating and a layer of the 2D-electron gas under the grating is presented. It is shown that frequency dependencies of the transmission, reflection and losses coefficients in THz frequency range have resonance behavior which relates to the 2D-plasmon excitation. The influence of geometrical and electrical parameters of the system on plasmonic resonance is studied in detail. The structure of the electromagnetic field in the near-field zone is analyzed. The spatial dependencies of the electric field components, density of the energy and the polarization of electromagnetic wave are found. It is shown the essential increasing of the local magnitude of the electric field in near-field zone at the plasmonic resonance.