Unity-Order Index Change in Transparent Conducting Oxides at Visible Frequencies

We report a method for obtaining unity-order refractive index changes in the accumulation layer of a metal-oxide-semiconductor heterostructure with conducting oxide as the active material. Under applied field, carrier concentrations at the dielectric/conducting oxide interface increase from 1 x 10(21)/cm(3) to 2.8 x 10(22)/cm(3), resulting in a local refractive index change of 1.39 at 800 nm. When this structure is modeled as a plasmonic waveguide, the change corresponds to a modal index change of 0.08 for the plasmonic mode.