Fig. 5. Comparisons between conventional TiO₂ media and metamaterial TiO₂ media to convert evanescent waves into propagating waves.

(A) Conventional media composed of homogeneous anatase TiO₂. (B) Metamaterial media derived from closely stacked 15-nm anatase TiO₂ nanoparticles. (C) Mean electric field amplitude as a function of distance from point sources (transverse electric–polarized, incoherent). The amplitude decays exponentially in conventional media, and most of the evanescent wave energy is lost within a distance of 50 nm. (D) In metamaterial media, evanescent waves interact with TiO₂ nanoparticles and turn into propagating waves that travel outward to the far field. A periodicity of 160 nm is observed. (E and F) Two point sources (45-nm separation) imaged with conventional (E) and metamaterial media (F), at positions z = 2 nm (near-source), z = 23 nm (near field, inside slab), and z = 650 nm (far field, outside slab). In the far field, the conventional media fails to resolve the two points, whereas the metamaterial media can successfully resolve them.