Studies on the laser-induced damage resistance of sol-gel derived ZrO2-TiO2 composite high refractive index films

ZrO2-TiO2 composite films with mol fraction of Ti in the total amount of Zr and Ti ranging from 0 to 100, have been prepared by the sol-gel spin-coating method. The microstructure, optical properties, and laser-induced damage resistance (LIDR) of these films were investigated, and emphasis was given to the compositional dependence of the laser-induced damage threshold ( LIDT). The experimental results indicate that at a small expense of refractive index, the sol-gel process can considerably improve the LIDR of the films. Moreover, with increasing mol fraction of Ti from 0 to 100, a general decrease of the LIDT in a wide range of 57.1-20.9 J/cm(2) (at 1053 nm, 10 ns pulse duration and in "R/1" testing mode) was observed. Combining the structural and optical analysis results, a possible correlation between the LIDR and optical band gap of the prepared films is presented on the basis of the multiphoton absorption model.