Metal-dielectric metamaterials for transformation-optics and gradient-index devices in the visible regime

We investigate the application of metamaterials made of dielectrics with embedded metal nanoparticles for transformation-optics and gradient-index devices. We demonstrate that the permittivity and permeability distribution required for cylindrical cloaking at optical frequencies can be obtained by a composite material made of silver spheres embedded in a PMMA host. We show that this approach can be applied also to devices with an isotropic permittivity distribution and illustrate this for the optical black hole. The key ingredient of our system is the tunability of the plasmonic interactions between the metallic nanoparticles, depending on distance and size. In addition, we discuss possible realizations of the proposed structures.