Suppression of Li2O out-diffusion from Ti-diffused LiNbO3 optical waveguides

Abstract

Light guides fabricated by Ti diffusion into y‐cut LiNbO₃ are attractive because of the possibility of using the larest electro‐optic coefficient (r₃₃). However, the accompanying Li₂O out‐diffusion gives rise to unwanted guided modes which are a problem in electro‐optic modulators. To overcome this problem it is necessary to reintroduce Li back into the crystal by some means. Here we report on a simplebut effective process (using Li₂O) to suppress Li₂O out‐diffusion and realize single‐mode Ti‐diffused LiNbO₃ light guides in a y‐cut orientation. A natural extension of the above process to Ti‐diffused LiTaO₃ light‐guiding structure should be possible.