Plasmonic sensors based on funneling light through nanophotonic structures

Abstract: We present a refractometric sensor realized as a stack of metallic gratings with subwavelength features and embedded within a low-index dielectric medium. Light is strongly confined through funneling mechanisms and excites resonances that sense the analyte medium. Two terminations of the structure are compared. One of them has a dielectric medium in contact with the analyte and exploits the selective spectral transmission of the structure. The other design has a metallic continuous layer that generates surface plasmon resonances at the metal/analyte interface. Both designs respond with narrow spectral features that are sensible to the change in the refractive index of the analyte and can be used for sensing biomedical samples.