Anisotropic nanostructured metamaterials for broadband all-angle negative refractionand flat lens imaging

We show that a metamaterial consisting of aligned metallic nanowires in a dielectric matrix has strongly anisotropic optical properties. For filling ratio $f<$1/2, the composite medium shows two surface plasmon resonances (SPRs): the transverse and longitudinal SPR with wavelengths $\lambda _{t}<\lambda _{l}$. For $\lambda _{t}>\lambda _{l}$, the longitudinal SPR, the material exhibits Re $\varepsilon _{//}<$ 0, Re $\varepsilon _{\bot }>$ 0, relative to the nanowires axis, enabling the achievement of broadband all-angle negative refraction and flat lens (superlens) imaging systems. High performance systems made with Au, Ag or Al nanowires in nanoporous templates are designed and predicted to work from the infrared up to ultraviolet frequencies.