Abstract
In this paper, we have investigated the enhancement of the plasmonic light beaming efficiency by near-field resonance in different subwavelength metallic slit-groove beaming structures. We show that by selecting the suitable film thickness and separation distance of beaming gratings, the intensity of the near field can be greatly enhanced by resonance, which leads to the increase of the beaming efficiency in the far field. Moreover, we obtain a nanocavity above the nanoslit by integrating a metal nanostrip with a conventional beaming structure. The resonance of this nanocavity can further enhance the near-field intensity and improve the beaming efficiency.