Abstract: TiO2 films were prepared by electron beam evaporation deposition technique with different deposition rates. Based on transmittance spectrums of the samples, the optical band gaps of films were obtained. The refractive index, extinction coefficient and thickness of the films were investigated by using an ellipsometer. The electric field intensity of the film was analyzed and the laser damage characteristics were studied. It was found that the optical band gap of TiO₂ film was relatively stable in the range of process factors, and the change corresponding to the deposition rate was not significant, among 3.95eV -3.97eV. The ellipsometry test results showed that the refractive index increased from 1.9782, 1.9928, to 2.0021 (at the wavelength of 1064 nm) with the increasing of deposition rate from 0.088nm/s，0.128nm/s to 0.18 nm/s, whereas decreased to 1.9663 at the deposition rate of 0.327nm/s. The extinction coefficient of the film increased with the enhancement of deposition rate. Broken by the same high energy laser, the sizes of the laser damage spots of the films which deposited at the low deposition rate were almost the same. However, the spot size was significantly enlarged when the film was prepared at the deposition rate of 0.327nm/s. The films with low absorption and high laser-induced damage threshold can be obtained at low deposition rates.

Key words: thin film, TiO₂, optical band gap, refractive index, LIDT, electric field intensity