Tunable wide-angle plasmonic perfect absorber at visible frequencies

We report a perfect absorber metallic hole array with wide-angle near unity absorbance in the visible regime. The periodicity of the structure enables excitation of surface-plasmon polaritons and results in a splitting of the absorbing peaks. An analytical formalism based on perturbation theory provides results in good agreement with experimental data and shows how the absorption peak can be tuned with hole geometry, periodicity, and material parameters. Being extendable to more complex hybrid structures, our result is important for the development of photon harvesting devices and thermal emitters.