Shape-Controlled Second-Harmonic Scattering from Gold Nanotetrapods

In the search for efficient building blocks nonlinear metamaterials, plasmonic nanoparticles have received considerable attention. Their quadratic optical properties result from a complex interplay between nature of bulk material, object shape, surface defects, and retardation effects. This versatility can be used to tailor resulting material. However, despite extensive investigation, separating controlling these contributions still pose challenge. this report, we control morphology colloidal gold with tetrahedral symmetry explore their second harmonic scattering response. The material itself is centrosymmetric but not conferring first hyperpolarizability an almost purely octupolar symmetry. Gradually reshaping into spheres (and thus decreasing asymmetry) reduces response, showing that it controlled by morphology. These results open way toward new kinds plasmonics platforms imaging probes.