Directional excitation of surface plasmons with subwavelength slits

Abstract

We propose a method to manipulate the excitation direction of surface plasmons using subwavelength slits fabricated in a metallic film. By designing the specific effective index for each slit, the relative phase of plasmonics generated at the slit exit aperture can be tailored. Therefore, the electromagnetic field intensity along one direction on the metal surface can be enhanced or suppressed by surface plasmon interference. Numerical calculations performed by the finite-difference time-domain method illustrate our theoretical design.