Non-paraxial analysis of curved analogue lens with multiple-phase jump

Abstract

The non-paraxial analysis of the analogue waveguide Fresnel lens with curved entrance diopter and multiple-phase jump is presented. The finite length of the element's pads is included into the design. The alteration of both the curvature and the multiplication factor allows us to reduce off-axis aberration and to overcome the photolithographic resolution limits which seriously affect the fabrication of conventional analogue lenses. In the modelling, a hybrid numerical procedure has been used, which is a combination of ray tracing inside the lens and Fresnel-Huygens integral behind the lens; this procedure has been shown to work reliably in the non-paraxial region. The curved analogue lens based on the assumption of infinitesimal pad's length and the plane analogue lens with multiple-phase jump are also discussed as special cases of the generalized structure. Finally, the possibility of chromatic aberration's reduction is examined.