In-plane 2D focusing of surface waves by ultrathin refractive structures.

In an attempt to provide a fully dielectric platform for two-dimensional optical circuitry, we report on the focusing features of an ultrathin polymeric lens fabricated on a planar multilayer. The radiation coupled to surface modes sustained by the multilayer can be focused or waveguide-injected into linear ridges by exploiting a dielectric-loading mechanism successfully exploited for plasmons. The low losses of this photonic system also allow long propagation lengths in the visible spectral range. Experimental observations made by fluorescence imaging of the multilayer surface are well supported by computational data obtained through an effective index approach.