Approximate Model for Universal Broadband Antireflection Nano-Structure

In this work we investigate the effect of broadband antireflection of a medium by a layer of embedded nano-cavities arranged near the surface. It is shown that this structure is versatile and allows near 100% transmittance in a wide spectral range practically for any dielectric material. The approximate model of nano-structured layer is suggested that allows to determine the parameters of the system necessary for achieving antireflection of any a priori given media without complicated numerical calculations. The transmission spectrum of a medium modified by such a structure is entirely defined by a radius and a depth of bedding of the nano-porous layer.