Plasmonic Metasurfaces for Nonlinear Optics and Quantitative SERS

Abstract

Plasmonic metasurfaces consist of two-dimensional arrays of metallic nanoresonators (plasmonic "metaatoms"), which exhibit collective and tunable resonance properties controlled by electromagnetic near-field coupling. These man-made surfaces can produce a range of unique optical properties unattainable with natural materials. In this review, we focus on the emerging applications of metasurfaces with precisely engineered plasmonic properties for nonlinear optics and surface-enhanced Raman spectroscopy (SERS). In practice, these applications are quite susceptible to material losses and structural imperfections, such as variations in size, shape, periodicity of meta-atoms, and their material states (crystallinity, impurity, and oxidation, etc.). In these aspects, conventional top-down lithographic techniques are facing major challenges due to inherent limitations in intrinsic material properties and material quality introduced during growth, synthesis, and fabrication processes, as well as achievable lithographic resolution. Moreover, they are prohibitively expensive and timeconsuming for fabrication over large areas. Here, we show that colloidal silver crystals (millimeter-sized single-crystalline plates and thiolate-capped nanoparticles) synthesized by solution-based chemical methods are excellent material platforms for the fabrication of high-quality plasmonic metasurfaces. In particular, both top-down (focused ion-beam milling) and bottom-up (centimeter-scale self-assembly) techniques can be exploited to generate uniform and precisely engineered colloidal metasurfaces for broadband tunable (across the full visible range) second-harmonic generation and quantitative SERS at the single-molecule level.

Gold Nanoparticles Thin Films with Thermo‐ and Photoresponsive Plasmonic Properties Realized with Liquid‐Crystalline Ligands

“…SPR parameters depend on particle shape, composition, size, and organization of building blocks which can be tuned via synthetic tools . Control over nanoparticle plasmonic properties enabled their use in a diverse set of applications, including surface enhanced Raman spectroscopy, nonlinear optics, and sensing . An additional possibility is the application of such nanoparticles as metamaterials .…”

Plasmonic Enhancement and Manipulation of Optical Nonlinearity in Monolayer Tungsten Disulfide

“…Plasmonic nanostructures and metasurfaces are particularly attractive to enhance light–matter coupling in monolayer TMDCs because the electromagnetic field can be strongly localized and enhanced within the near‐field region of plasmonic nanostructures . Such advantages have been recognized immediately after the inception of monolayer TMDCs as an emerging 2D photonic materials .…”

Enhanced Self-Organized Dewetting of Ultrathin Polymer Blend Film for Large-Area Fabrication of SERS Substrate

“…The wide accepted and dominant mechanism behind the SERS is the electromagnetic enhancement mechanism. In the electromagnetic enhancement mechanism, the larger enhancement factor of SERS is due to the enhanced electromagnetic field, where the optical excitations of localized surface plasmons (LSPs) resonances in metallic nanostructure enhance the Raman signal intensity56. Under conditions of surface plasmon excitation, both the incident laser field and the scatter Raman field are amplified.…”