高三阶光学非线性Cd/CdS-SiO2复合薄膜的电化学–溶胶凝胶制备及表征

以硝酸镉、硫脲和正硅酸乙酯为前驱体, 采用电化学-溶胶凝胶法, 以ITO玻璃为基底制备了透明薄膜。扫描电子显微镜(SEM)表征表明薄膜为纳米束结构。X射线能谱(EDX)表征表明薄膜由Si、O、Cd、S元素组成, Cd/S(原子比)＞1。EDX表征结合循环伏安(CV)实验确定薄膜为Cd/CdS-SiO₂复合薄膜。Z扫描表征表明, 薄膜在1064 nm处表现出自散焦特性的非线性折射效应和饱和吸收特性的非线性吸收特性。薄膜的三阶非线性极化率(χ(3))较高, 达到了1.18×10^-14~1.39×10^-13 (m/V)², 表明薄膜具有优良的三阶光学非线性。分析认为薄膜中CdS的含量对薄膜的光学性非线性起主要作用。

Preparation and Characterization of Cd/CdS-SiO2 Composite Film with High Third-order Optical Nonlinearity by Electrochemically Induced Sol-Gel Method

The sol was prepared with cadmium nitrate, thiourea and tetraethoxysilane as precursors by Sol-Gel method. The transparent film was prepared on ITO substrate by electrochemically induced Sol-Gel method using the as-prepared sol as electrolyte. SEM results showed that the film was made up of nano beams. While EDX results showed that the component elements of the film were Si, O, Cd, S and the atom ratio of Cd to S was more than 1. It could be inferred from both the EDX and cyclic voltammetry’s results that the film composite was Cd/CdS-SiO₂. Z-scan test results showed that the film had third-order optical nonlinearity with self defocusing nonlinear refraction and saturated absorption properties at the wavelength of 1064 nm. The third-order nonlinear optical susceptibility of films could reach 1.18×10^-14 (m/V)² to 1.39×10^-13 (m/V)² which demonstrated that the third-order nonlinear optical properties of these films were excellent. Further analysis showed that the content of CdS in the film remarkably influenced the optical nonlinearity.