Abstract: ZnO thin films were deposited on SiO2 substrate by magnetron sputtering technique. The crystal structure, surface topography, band gap width and photoluminescence properties of the thin films were characterized by X-ray diffraction, atomic force microscope, UV\|Vis spectrophotometer and fluo
rescence spectrometer. The third\|order nonlinear optical properties of the thin films were measured by Z-scan method using femtosecond laser （wavelength of 800 nm, pulse width of 50 fs）. The results show that the third order nonlinear refractive index and nonlinear absorption coefficient of the film are all positive, the values are 3.50×10^-18 m²/W and 2.88×10^-11 m/W.

Key words: order nonlinear optics, zinc oxide thin film, magnetron sputtering, third\, Z-scan