New Approaches to Design and Realization of Dielectric GRIN Flat Lenses

This work presents approaches to design andimplement three-dimensional (3D) graded index (GRIN) flat lenses consisting of concentric annular segments (in the radial direction). Generally, design of GRIN flat lenses calls for segments with very specific tailored permittivity which makes the realization of the lens challenging. To facilitate fabrication of the lens, each segment is replaced with a same-thick symmetric three-layered structure consisting of a layer of high permittivity material which is sandwiched between two low permittivity layers. Silica and silicon are utilized as low and high permittivity materials, respectively. Finally, by increasing the number of layers, a multi-layered GRIN flat lens with an enhanced focusing performance presented.