Efficient frequency doubling in reverse proton exchanged lithium niobate waveguides

We propose a novel approach for efficient frequency doubling of near infrared light, using the coupled system of buried and surface waveguides obtainable by reverse proton exchange in z-cut lithium niobate. In such guides, supporting TM and TE polarizations, respectively, in spite of the use of the d/sub 31/ nonlinear element, we predict conversion efficiencies as high as 90 or 14% μm/W cm in planar structures excited at 1.32 μm.