Surface-Enhanced Spectroscopies of a Molecular Monolayer in an All-Dielectric Nanoantenna

A reduction in the number of loss decay channels present in optical nanoantennas could help enhance an emitter’s radiation efficiency. These losses get amplified for emitters in close proximity to metallic surfaces, such as for self-assembled monolayers, reducing the fluorescence rate. However, such a proximity strongly enhances Raman scattering. A dual-sensing scheme should bypass this shortcoming, and switching from metals to high refractive index dielectrics could aid in that direction. In order to show this, we fabricated silicon nanodimers and coated them with a β-carotenal monolayer for detecting surface-enhanced Raman scattering and fluorescence emission of the same probe. We obtained a surface-enhanced Raman scattering (SERS) factor of 1720 ± 300 for the C–C bond stretching of the polyene chain and a surface fluorescence enhancement (SEF) factor of 470 ± 90. Furthermore, our theoretical studies of different materials and emitters located on the surface of nanostructures demonstrate that low-loss dielectric materials provide a robust architecture for enhancing the response of efficient emitters. These results could have a direct impact on the development of deterministic high-rate single-photon sources