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2009
Journal Article
Titel
Wideband antireflection coatings by combining interference multilayers with structured top layers
Abstract
The residual reflectance obtained for a broad wavelength range depends mainly on the refractive index of the last layer. Using interference layer stacks composed of naturally available low- and high-index materials, the residual reflection for a broad range cannot be adjusted below a certain limit. However, nanostructured (gradient) and porous layers are effective media with a refractive index lower than that of natural materials. Results demonstrate that an interference layer stack combined with a structured layer as the last layer yields better antireflection properties owing to the low effective index of the structure.