Simulation and testing of a graded negative index of refraction lens

TLDR

The GRIN lens was fabricated from a NIM slab with a variable index perpendicular to propagation, with the gradient calculated by ray tracing using the isotropic Eikonal equation and the unit cells designed by an electromagnetic code. The lens was tested and its index of refraction, approximated with ten discrete steps in an effective medium simulation, agreed with experimental measurements.

Abstract

A gradient index (GRIN) lens using a negative index of refraction material (NIM) has been designed and tested. The GRIN lens was fabricated using a NIM slab with a variable index of refraction perpendicular to the propagation direction. Ray tracing calculations based on the isotropic Eikonal equation determined the index of refraction gradient required for a given focal length. An electromagnetic code was then used to design the required ring and wire unit cells. Finally, the index of refraction was approximated using ten discrete steps in an effective medium simulation for the GRIN lens that agreed with the experimental measurements.