Composite Luneburg lens based on dielectric or plasmonic scatterers.

We present a three-dimensional (3D) Luneburg lens design scheme that employs non-resonant spherical scatterers as inclusions in a host medium for the manipulation of electromagnetic waves. The underlying principle is that the volume fraction of the inclusion scatterers can be varied spatially so as to control the effective permittivity for the desired permittivity profile. Specifically, to achieve desired volume fraction values, simple cubic packing, hexagonal close packing and random packing methods were used for scatterer distribution. The proposed analysis features the plasmonic inclusions as a rational alternative for dielectric inclusions to produce a desired effective value of the permittivity in optics. We demonstrate the applicability of the proposed scheme by employing it to design and simulate Luneburg lens (both in microwave and optics) for beam steering applications. The design leads to polarisation independent functionality in the plane tangent to the lens and yields high antenna gain. The scheme provides a useful means to realize many disruptive applications ranging from the microwaves to optics.