Phase function and far-field focusing by flat metal-dielectric lens

Spectral, angular and spatial characteristics at ultraviolet frequencies are calculated of the flat lenses based on layered Ag/TiO₂ structures. It is shown that phase function of MD-structure allows one to predict the ability of lens to focus the light and also to calculate its focal distance. The equation of the lens is obtained for the common case when the lens is sandwiched between different media.