Impact of surface waves on the electromagnetic enhancement by a metallic nano-cavity

Abstract

To investigate the impact of surface waves on the electromagnetic enhancement, here we consider a simple geometry of a T-shaped metallic nano-groove that is composed of a narrow central groove and of a wide top trench under illumination by a plane wave. The T-shaped groove is found to have a much higher enhancement factor than a single bare groove without the top trench. By building up an intuitive surface-wave model, the improved field enhancement is attributed to the surface waves that are collected by the top trench and are coupled into the central groove.