Negative refraction in anisotropic waveguides made from quantum metamaterials

We describe two metamaterial waveguide designs which display negative refraction. Both use quantum well nanostructures to engineer tunable resonances in the dielectric response, which can be designed using the rules of quantum mechanics. One uses coupling to a plasmonic resonance in adjacent metallic layers to enhance the size of the negative refraction effect. The negative refraction appears close to the quantum well intersubband transition energy, and is sensitive to the two-dimensional concentration of electrons within the wells and in adjacent conducting layers, thus offering the potential for switchable devices. These quantum metamaterials are highly distributed multilayered optically anisotropic systems with comparatively low absorption in the negatively refracting spectral region, and they can readily be grown by conventional semiconductor epitaxial growth technologies.