Fabrication of SiO2-TiO2 strip waveguides by laser direct writing

SiO2-TiO2 strip optical waveguides have been fabricated by laser densification of SiO2-TiO2 sol-gel films using a Ytterbium fiber lasers and following chemical etching process. Effects of laser processing parameters and dried temperature of SiO2-TiO2 sol-gel films on the dimensions of strip optical waveguides were systematically studied. And the mechanism on laser densification of SiO2-TiO2 films was discussed. The experimental results demonstrate that the width and thickness of strip waveguides increase with laser power density until SiO2-TiO2 films are damaged by laser irradiation. The available range of laser power density for laser densification increase through enhancing dried temperature of SiO2-TiO2 films, which mainly thanks to the increasing stress capacity in the films. The width of strip optical waveguides can be markedly decreased from 110 to 25 mu m in the case of the same thickness by enlarging available range of laser power density. The mechanism on laser densification of SiO2-TiO2 films is mainly based on shrinkage of nanoscale pore within SiO2-TiO2 films duo to the energy transferred from silicon substrate.