Control of mode profiles in proton-diffused LiNbO/sub 3/ waveguides using self-aligned SiO/sub 2/ cladding

Channel waveguides fabricated in LiNbO/sub 2/ by proton diffusion with a self-aligned SiO/sub 2/-cladding structure are discussed. Proton diffusion in width and depth directions is amenable to process parameters, so that it provides a simple method for control of mode profiles. Using this method, symmetric depth mode profiles and an aspect ratio of 1.15 at lambda =0.6328 mu m have been achieved for efficient fiber-to-waveguide coupling.>