Flat metallic surfaces coated with a dielectric grating: excitations of surface plasmon–polaritons and guided modes

The electromagnetic response of flat metallic surfaces coated with a dielectric grating is studied theoretically. We found that two kinds of optical modes, namely, surface plasmon–polaritons (SPPs) bound to the metallic/grating interfaces and guided modes (GMs) in the dielectric grating, can be excited by externally incident light. Both SPPs and GMs display well-defined band structures due to the introduced periodicity in the dielectric grating.