excitation of surface plasmon polaritons in an inhomogeneous graphene-covered grating

Highly confined waves of surface plasmon polaritons (spps) in monolayer graphene are efficiently excited using an etched diffractive grating on silicon. in this paper, an inhomogeneous graphene-covered grating is proposed and the excitation of which is analyzed as an analogy with the two-level system in quantum mechanics. based on the equivalent circuit theory, the excitation of plasmonic waves in an etched diffractive grating is equivalent to the resonance of an oscillator. thus, according to the governing equation, the electric currents for the inhomogeneous graphene-covered grating is correspond to the ket of energy states in the two-level system. in addition, the excitation of spps in an inhomogeneous graphene-covered grating is numerically analyzed to validate the theoretical model. our work offers a new inroad of the excitation of spps in an inhomogeneous graphene-covered grating in an analogy with the two-level system.