Metal-dielectric optical resonance in metasurfaces and SERS effect

Abstract

Anomalous optical response of the metasurface, fabricated from regular silicon resonators is investigated. The resonators have form of two-dimensional regular bars that are covered by nano-thin silver film. Computer simulations as well as real experiment demonstrate deep minima in the reflectance in the optical spectral range. We believe the resonances are due to the excitation of propagating and localized surface em waves. The multiple metal-dielectric resonances result in much enhanced local electromagnetic fields on the surface of the resonators. To investigate the surface enhanced Raman scattering (SERS) effect the metasurface is covered by molecules of 4-mercapto-phenylboronic acid that form covalent bonds with the silver layer. We obtain over $$10^5$$ enhancement of the Raman scattering, by direct matching Raman signals from the metasurface and the flat silver surface. The designed metasurface is used as an effective SERS substrate.