Effect of SiO2 cladding on properties of annealed proton-exchanged LiNbO3 waveguides

We show that SiO 2 cladding effects on optical properties of annealed proton-exchanged (APE) LiNbO 3 waveguides as well as on kinetic of annealing process. Annealing with previously deposited SiO 2 film reduces the optical losses in APE LiNbO 3 waveguides. The structural phase diagram of H x Li 1-x NbO 3 is also modified if annealing is performed with previously deposited SiO 2 layer. The physical mechanisms, including evaporation of H 2 O and/or Li 2 O during annealing without deposited film and, as a result, formation of defects and lithium deficit phase is discussed.