Excitation of graphene plasmons as an analogy with the two-level system

•The excitation of graphene plasmons (GPs) in graphene-covered grating is equivalent to the resonance of an oscillator.•We establish the equivalent circuit of two-level system to analyze the resonant character.•The excitation of GPs in different two-coupled graphene-covered gratings are numerically studied to validate our theoretical model.

The excitation of graphene plasmons (GPs) is presented as an interaction between the GPs and the incident electromagnetic field. In this Letter, the excitation of GPs in a plasmonic system is interpreted as an analogy with the two-level system by taking the two-coupled graphene-covered gratings as an example. Based on the equivalent circuit theory, the excitation of GPs in the graphene-covered grating is equivalent to the resonance of an oscillator. Thus, according to the governing equation, the electric currents at the resonant frequencies for two-coupled graphene-covered gratings correspond to the energy states in a two-level system. In addition, the excitation of GPs in different two-coupled graphene-covered gratings is numerically studied to validate our theoretical model. Our work provides an intuitive understanding of the excitation of GPs using an analogy with the two-level system.