Plasmonic band gaps and trapped plasmons on nanostructured metal surfaces

Nanostructured metal surfaces comprised of periodically arranged spherical voids are grown by electrochemical deposition through a self-assembled template. Detailed measurements of the angle- and orientation-dependent reflectivity reveal the spectral dispersion, from which we identify the presence of both delocalized Bragg and localized Mie plasmons. These couple strongly producing bonding and antibonding mixed plasmons with anomalous dispersion properties. Appropriate plasmon engineering of the void morphology selects the plasmon spatial and spectral positions, allowing these plasmonic crystal films to be optimized for a wide range of sensing applications.