Generalized Maxwell Fish-Eye Lens as a Beam Splitter: A Case Study in Realizing All-Dielectric Devices From Transformation Electromagnetics

A 2-D generalized Maxwell fish-eye lens has been fabricated with all-dielectric polymer/ceramic composite materials and evaluated numerically and experimentally. The graded refractive index profile of the lens was discretized into a concentric-ring structure and functioned as a two-way beam splitter. Epoxy composites, with a broad dielectric constant range that can be precisely controlled, were used to cast the lens using a low-cost manufacturing method that can readily accommodate different geometries. The lens was tested with a near-field microwave imaging system to demonstrate its capability of controlling waves at an operating frequency of 18 GHz. The measured results had some differences from the expected behavior, which are considered in detail and provided some insights into the practical manufacturing and measurement constraints for graded dielectric composites. Possible routes to increase the number of output beams are discussed.