Highly confined photon transport in subwavelength metallic slot waveguides

We report experimental realization of subwavelength slot waveguides that exhibit both micrometer-range propagation and high spatial confinement of light. Attention is given to rectangular waveguides with a Si3N4 core and Ag cladding; core thicknesses of 50-100 nm and widths of 250 nm - 10 mu m are explored. Propagation lengths of similar to 5 lambda are achieved with light confined to lateral and transverse dimensions of similar to lambda/5 and similar to lambda/2, respectively. This unique combination of light localization and propagation is achieved via interacting surface plasmons, which produce short modal wavelengths and strong field confinement at each metal/dielectric interface.