Metal-dielectric optical resonance in metasurfaces and SERS effect

• Published in: Optical and quantum electronics 2020, Vol.52 (1), Article 26
• Main Authors: Sarychev, A. K., Bykov, I. V., Boginskaya, I. A., Ivanov, A. V., Kurochkin, I. N., Lagarkov, A. N., Nechaeva, N. L., Ryzhikov, I. A.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Computer Communication Networks; Computer simulation; Covalent bonds; Electrical Engineering; Electromagnetic fields; Fundamentals of Laser Assisted Micro- & Nanotechnologies 2019; Lasers; Metasurfaces; Optical Devices; Optical resonance; Optics; Photonics; Physics; Physics and Astronomy; Raman spectra; Reflectance; Resonators; Silver; Substrates; Wave propagation
• ISSN: 0306-8919; 1572-817X
• DOI: 10.1007/s11082-019-2141-0

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.