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

We show SiO2 cladding effects on the optical properties of annealed proton- exchanged LiNbO3 waveguides as well as on the kinetics of annealing process . Annealing with previously deposited SiO2 film reduces the optical losses in annealed proton-exchanged LiNbO3 waveguides. The structural phase diagra m of HxLi1-xNbO3 is also modified if annealing has been performed with a pr eviously deposited SiO2 layer. The physical mechanisms, including evaporati on of H2O and/or Li2O during annealing without deposited film and, as a res ult, formation of defects and a lithium deficit phase, are discussed. (C) 2 000 American Institute of Physics. [S0021-8979(00)04907-0].