Localization and Waveguiding of Surface Plasmon Polaritons in Random Nanostructures

We propose to use channels in strongly scattering nonabsorbing random media for guiding electromagnetic waves, and demonstrate this concept using near-field microscopy of surface plasmon polaritons (SPP's) propagating along the gold film surface covered with randomly located scatterers. In the wavelength range of 725--765 nm, we observe complete inhibition of the SPP propagation inside the random structures composed of ~50-nm-wide gold bumps and their clusters with the density of 50 μm^-2, as well as well-defined SPP guiding along corrugation-free 2- and 4-μm-wide channels.