Metallodielectric gratings with subwavelength slots:  Optical properties

We report an experimental and theoretical study of the properties of metallodielectric gratings with subwavelength slots in the thin metal limit. These structures were fabricated using a bench top nanopatterning method that produces metallic periodic structures with subwavelength features without the need for lithographic masks by directing the deposition of metal onto prepatterned surfaces. In the size and thickness regime explored in this study two excitations are possible: surface plasmons (SP’s) and Rayleigh anomalies. The transmissive and reflective properties of these structures are reported, and very good agreement between theory and experiment is achieved. The dispersion of both the Rayleigh anomalies and SPs is measured. In addition, the near-field properties of each of these excitations are calculated. Plasmon-plasmon interactions, which produce gaps in the dispersion relation for the surface waves, are observed.