The simulation results of the coupling of a radiation dipole with a surface plasmon (SP),which is induced on a metal/dielectric interface of a single groove (SG) plus a gratingstructure, are demonstrated. With the SG structure, the dipole can effectively coupleenergy into an SP feature, which has a mixed nature of localized surface plasmon (LSP)and surface plasmon polariton (SPP). The SPP energy is confined by a grating structurewith a well designed grating period and position. With such a cavity configuration,the SPP energy can be well preserved. Both the dipole–SP coupling behaviorsin the frequency and time domains are numerically illustrated. The results areuseful for designing a metal/dielectric interface nanostructure for implementing aSPASER (surface plasmon amplification by stimulated emission of radiation) system.