Characterization of annealed, proton-exchanged optical waveguides in ZnO:LiNbO(3) crystal

We report a systematic study of the annealing process in proton-exchanged ZnO:LiNbO(3) optical waveguides. A z-cut multimode waveguide was subjected to annealing for different durations of time. A two-stage change in index profiles with annealing time was observed, which was consistent with the change in the m-line spectrum. A power-law relationship was established to correlate the optical parameters with annealing time. Annealed Li(+) concentration in the waveguide was solved based on the thermal diffusion equation. An analytical function was used to model the annealed-index profile of single-mode, proton-exchanged waveguides. Good agreement between the theoretical analysis and the experimental result was obtained.