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

We show that SiO2 cladding effects on optical. properties of annealed proton-exchanged (APE) LiNbO3 waveguides as wen as on kinetic of annealing process. Annealing with previously deposited SiO2 film reduces the optical losses in APE LiNbO3 waveguides. The structural phase diagram of HxLi1-xNbO3 is also modified if annealing is performed with previously deposited SiO2 layer. The physical mechanisms, including evaporation of H2O or/and Li2O during annealing without deposited film and, as a result, formation of defects and lithium deficit phase is discussed.