Generation of pronounced Fano Resonances and tuning of subwavelength spatial light distribution in plasmonic pentamers

Abstract

Arrays of plasmonic pentamers consisting of five metallic nanodisks were designed and fabricated to achieve a pronounced Fano Resonance with polarization-independent far-field spectral response at normal incidence due to the structure symmetry of pentamers. A massspring coupled oscillator model was applied to study plasmon interactions among the nano-disks. It was found that the direction of the excitation light polarization can flexibly tune the spatial localization of near-field energy at sub-wavelength scales while the collective optical properties are kept constant. It can lead to a selective storage of excited energy down to sub-20 nm gap at a normal incident with a single light source. © 2011 Optical Society of America.