Penetration Depth Reduction with Plasmonic Metafilms

In many optical systems, such as metal films, dielectric reflectors, and photonic crystals, electromagnetic waves experience evanescent decay. The spatial length scale of such a decay defines the penetration depth, and a number of technologically important applications in free-space and integrated optics benefit significantly from a small penetration depth. In this paper, we introduce an ultrathin metafilm consisting of alternating regions of metal and dielectric, which has a much smaller penetration depth than that of a corresponding metal thin film. We demonstrate that the reduction of the metafilm’s penetration depth is a direct result of the enhanced effective mass in its photonic band structure. Our results can lead to enhanced device performance in lightweight ultrahigh reflectivity reflectors and to an increased packing density of subwavelength plasmonic channel waveguides.