Third-order Nonlinear Optical Properties of TiO2 Films

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 (if 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 x 10(-11) m/W and -6.32 x 10(-17) m(2)/W, respectively. The real and imaginary parts of third-order nonlinear susceptibility chi((3)) are determined to be -7.1 x 10(-11) esu and -4.42 x 10(-12) esu, respectively. And the following figure of merit T = beta lambda/n(2) is calculated to be 0.8 for the Film, indicating that the anatase TiO2 films have great potential applications to nonlinear optical devices.