▎ 摘　　要

The transformation of an electromagnetic wave into a propagating plasmon in a periodical dual-grating-gated graphene structure is theoretically investigated. The electromagnetic wave is incident at normal direction upon the structure. The most effective transformation appears in two cases: (i) a combined excitation of the radiative and "nonradiative" gated plasmon modes and (ii) excitation of the plasmon modes with the wavevectors in multiples of the structure inverse period. We find a 70% transformation of the incident power into a propagating plasmon for a 1-ps carrier momentum relaxation time in graphene when canceling the transmission of the electromagnetic wave through the graphene structure by a metallic ground plate and blocking the reflection with a Fabry-Perot resonator.