Dynamic Plasmonic Optics in Dense Nanorod Phases

Metal plasmonic nanorods both interact strongly with light and can be aligned by an external electric field, presenting a new paradigm for displays and high-speed optical devices. While the utility of these materials has been clearly forecasted, the limits of their performance have formerly remained untested. We now demonstrate highly dense nanorod phases and map nanorod alignment at concentrations across several orders of magnitude. First, we refine organic ligand and solvent chemistry to achieve stable Au nanorod suspensions. We fabricate custom plasmonic pixel cells with precise optical path lengths and directly measure the pixels’ exceptional optical densities in a lab-designed apparatus incorporating laser illumination and high-sensitivity detectors. We apply alternating current electric fields to the pixels, rapidly inducing orientational order among the nanorods, resulting in a large contrast in transmitted optical power. Finally, we reveal nanorod behavior through in situ optical microscopy during alignment. By formulating, understanding, and controlling highly concentrated and optically dense plasmonic nanorod phases, we begin to exploit their properties for dynamic optoelectronic applications.