Hybrid antireflective coating with plasma-etched nanostructure

Antireflective structures with features of sub-wavelength size are appropriate as an alternative to interference coatings for obtaining antireflective properties on optical surfaces. For broadband antireflection or a wide range of incidence angles, a distinct structure depth together with a very low lateral structure size is required, which is difficult to realize. Design considerations show that also thinner nanostructured layers are useful if they are combined with compact interference layers. A nanostructured low-index melamine layer has been prepared by plasma-etching of a vacuum deposited organic thin film. In combination with homogeneous silica layers antireflection properties for a broad range of light incidence angles were achieved.