Impact of surface plasmon polaritons and other waves on the radiation of a dipole emitter close to a metallic nanowire antenna.

The radiation of a dipole emitter close to a metallic nanowire optical antenna is investigated theoretically. By considering the excitation and multiple scattering of surface plasmon polaritons (SPPs) on the antenna and neglecting all other surface waves, we build up an intuitive pure-SPP model to comprehensively describe the radiation of the antenna. The model shows that for antennas with short lengths that support lower orders of resonance, waves other than SPPs contribute considerably to the antenna radiation, while SPPs play a dominant role for other cases. The enhancement of the antenna radiation is shown arising from two contributions, the field directly radiated by the emitter and the field resonantly excited by the surface waves on the antenna.