Deep-UV Silicon Polaritonic Metasurfaces for Enhancing Biomolecule Autofluorescence and Two-Dimensional Material Double-Resonance Raman Scattering

High-performance deep ultraviolet (DUV) spectroscopy is crucial in driving innovations for biomedical research, clinical diagnosis, and material science. DUV resonant nanostructures have shown capabilities for significantly improving spectroscopy sensitivity. However, they encounter significant challenges in practical applications, including instability due to oxidation and light-induced damage, and the strong photoluminescent noise background from their constituent materials. An efficient and robust DUV spectroscopy platform based on the polaritonic properties in all-dielectric silicon (Si) metasurfaces is proposed. Unlike conventional dielectric metasurfaces that rely on Mie-type modes, this approach leverages the polaritonic resonances in Si nanostructures—a striking yet underexplored property driven by interband transitions in the DUV regime—for nanophotonic sensing. A polaritonic Kerker-type void metasurface providing strong near-field enhancement localized on the surface is designed and fabricated. The metasurface facilitates double-resonance Raman scattering, a process that reveals key information about lattice dynamics and electronic structures, for analyzing 2D semiconductor monolayers. It also demonstrates superior stability in solvents and enhances biomolecule autofluorescence. These capabilities demonstrate the versatile potential of Si metasurfaces as a scalable, robust platform for interdisciplinary DUV spectroscopy applications, including advanced biomedical research and the investigation of emerging nanomaterials.