  A periodic plasmonic meta-material was studied using finite-difference time
domain (FDTD) method to investigate the influence of neighboring particles on
the near unity optical absorptivity. The meta-material was constructed as a
silver nanoparticle (20-90nm) situated above an alumina (Al$_2$O$_3$)
dielectric environment. A full parametric sweep of the particle width and the
dielectric thickness was conducted. Computational results identified several
resonances between the metal-dielectric and metal-air that have potential to
broadening the response through stacked geometry. A significant coupled
resonance between the metal-dielectric resonance and a cavity resonance between
particles was capture as a function of dielectric thickness. This coupled
resonance was not evident below dielectric thicknesses of 40nm and above cavity
widths of 20nm. Additionally, a noticeable propagating surface plasmon
polariton resonance was predicted when the particle width was half the unit
cell length.
