Analysis of localized plasmonic resonances in nano-disk arrays

Metallic nano-particles support localized surface plasmon resonances (LSPRs) associated with the interaction of free electrons on the metal surface and incoming light. LSPRs can enhance the electric field by several orders of magnitude while confining it to sub-wavelength regions. Recently, we showed that arrays of closely spaced nano-rings can also enhance and localize the magnetic field. Our results showed that the inner radius had very little effect on their performance. Therefore, simpler nano-particles may be used, i.e. nano-disks. Recently, nano-disk arrays have been proposed as building blocks for broadband absorbers. These structures rely on the presence of multiple resonances when nano-disks of different dimensions are combined or, at normal incidence, when odd order multipolar LSPRs are excited.