Tunable negative refraction and subwavelength imaging in the metal-dielectric composites of nonspherical particles

The metal-dielectric composite, in which the metallic spheroidal nanoparticles are all identically aligned with their principal axes, is proposed to realize the tunable negative refraction by the adjustment of the metallic particles. We focus on the negative fraction case that isin_ex > 0, isin_ez < 0. Tunable slab lenses based on such composites are helpful to realize subwavelength imaging. We aim at the effects of the shape of the nanoparticles on the subwavelength imaging resolution. In addition, the shape of the particles is easy to be changed by applying an external electric field, and thus the tunable lenses from the shape-dependent composites can be realized in practice.