We show that a metamaterial slab with arbitrary values of $\varepsilon$ and $\mu$ behaves as a cloak at a finite frequency for a small object located sufficiently close to it due to the suppression of the object's optical excitations by enhanced reflections. Reflections due to propagating components can partially suppress the excitation, while evanescent components can cloak the object completely. In particular, a Veselago slab with $\varepsilon =\mu =-1+i\delta$, as well as a class of anisotropic negative refractive index slabs, can completely cloak the small object placed within a finite distance from the slab when $\delta \to 0$.

• Received 23 December 2010

DOI:https://doi.org/10.1103/PhysRevB.83.115124