Abstract: Anatase TiO₂ films were fabricated on fused quartz by pulsed laser deposition （PLD） technique and the single-phase anatase films were obtained under the optimal conditions. The X-ray diffraction and atomic force microscope were used to investigate the structure and surface characters of the film. The third-order optical nonlinearities of the films were measured by Z-scan technique using a femtosecond laser (50fs) of 800nm. From the transmission spectra, the optical bandgap and linear refractive index of the TiO₂ film are determined to be 3.18eV and 2.1, respectively. The nonlinear absorption coefficient and nonlinear refractive index are determined to be -6.2×10^-11m/W and -6.32×10^-17m²/W, respectively.The real and imaginary parts of third-order nonlinear susceptibility χ(³) are determined to be -7.1×10^-11esu and -4.42×10^-12esu, respectively. And the following figure of merit T=βλ/n₂ is calculated to be 0.8 for the film, indicating that the anatase TiO₂ films have great potential applications to nonlinear optical devices.

Key words: TiO₂, films, Z-scan, third-order optical nonlinearities