Planar waveguide device

Abstract From the Canadian patent

A planar waveguide device including metallic electrodes has a buffer layer of reduced ordinary index of refraction formed in a substrate between its waveguide and electrodes. The device is preferably formed by first fabricating the waveguide in an x-or y-cut substrate of crystalline material, subsequently overcoating the substrate, including the waveguide, with a layer of magnesium, oxidizing the magnesium at temperature to form the buffer layer and then laying the electrodes over the buffer layer. Alternatively, the buffer layer may be formed by a proton exchange process.