Quasi-omnidirectional total light absorption in nanostructured gold surfaces

Theoretical calculations have predicted the possibility of omnidirectional absorption on a metallic surface with a closed packed layer of voids/spheres buried just beneath the surface. We have carried out a series of experiments to verify the existence of this theoretically predicted phenomenon. We report the observation of quasi omnidirectional total absorption of light on our fabricated surfaces and the tunability of the absorption wavelength by varying the size of the spheres/pores. The strongly enhanced absorption is observed for angles of incidence up to 65°.