采用脉冲激光沉积技术在熔石英基片上制备了c轴取向的锐钛矿相TiO2薄膜.通过X射线衍射和原子力显微镜对薄膜的结构、结晶性和表面特性进行了表征.通过透射光谱计算得到TiO2薄膜折射率约为2.1，光学带隙约为3.18eV.结合飞秒激光和Z扫描方法测量了薄膜的超快非线性光学特性，结果表明：锐钛矿TiO2薄膜具有负的非线性吸收系数和负的非线性折射率，其大小分别为-6.2×10-11m/W和-6.32×10-17m2/W，对应的三阶非线性极化率的实部和虚部分别为-7.1×10-11esu和-4.42×10-12esu.并计算薄膜的优值比T=βλ/n2≈0.8，表明锐钛矿相的TiO2在非线性光学器件方面具有潜在的应用前景.
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 bandgap 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.
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