Optical Properties of One-, Two-, and Three-Dimensional Arrays of Plasmonic Nanostructures

This Feature Article describes research on the optical properties of arrays of silver and gold nanoparticles, particles that exhibit localized surface plasmon resonances in the visible and near-infrared. These resonances lead to strong absorption and scattering of light that is strongly dependent on nanoparticle size and shape. When arranged into multidimensional arrays, the nanoparticles strongly interact such that the collective properties can be rationally designed by changing the dimensions of the array (one-, two-, or three-dimensional), interparticle spacing, and array shape or morphology. Emerging from this work is a large body of literature focusing on one-, two-, and three-dimensional arrays, which provide unique opportunities for realizing materials with interesting and unusual photonic and metamaterial properties. Electrodynamics theory provides an accurate description of the optical properties, often based on simple models such as coupled dipoles, effective medium theory, and anomalous diffraction. In turn, simple models and simulation methods allow for the prediction and explanation of a variety of observed optical properties. In one and two dimensions, these tunable optical properties range from extinction spectra that are red- or blue-shifted compared to the isolated particles to lattice plasmon modes that involve strong interactions between localized plasmon resonances in the nanoparticles and photonic modes that derive from Bragg diffraction in the crystalline array. Three-dimensional arrays can exhibit unique effective medium properties, such as negative permittivity that leads to metallic optical response even when there is less than 1% metal content in the array. They also can be rationally designed to have photonic scattering modes dictated and controlled by interactions between nanoscale plasmonic nanoparticles and the mesoscale superlattice crystal habit (i.e., the crystalline size, shape, and morphology). This discussion of plasmonic arrays across multiple dimensions provides a comprehensive description of those factors that can be easily tuned for the design of plasmon-based optical materials.