Surface plasmons on metamaterials

Abstract

The field of plasmonics has historically been a playground exclusively for the optics community. Primarily this is because the response of metals becomes dominated by their large conductivities at much lower frequencies, making it difficult to exploit the unique properties of surface plasmon (SP) modes. Indeed SPs on flat, perfectly conducting substrates are better described as simple surface currents or grazing photons. However the realization that one can form metal-dielectric composites to support surface waves with plasmon-like properties has opened the field of plasmonics to the terahertz and microwave domains. Pendry et al. [Science, 305, 847 (2004)] were among the first to speculate about an extension of plasmonics into long wavelength regimes. They demonstrated that the perforated surface of a perfect conductor can support a SP-like mode whose behavior is determined purely by the geometry of the substrate. Beginning with our initial experimental verification of these SP-like modes excited via grating-coupling, we present an overview of some of our recent microwave studies. We progress to study the classical method of prism coupling and also consider the enhanced transmission phenomenon (mediated by plasmon-like surface modes) through hole arrays. Finally the first experimental evidence of coupled SP-like modes between two such perforated metal substrates placed in close proximity will be presented.