Au-BaTiO3复合薄膜的脉冲激光沉积制备及其非线性光学效应

利用脉冲激光沉积技术制备了掺杂金纳米颗粒的钛酸钡复合薄膜Au-BaTiO3,用高分辨透射电镜和X射线光电子能谱对薄膜进行了表征。从透射电镜照片可以看出,制备的样品中金颗粒大小约为2~3 nm,呈球形,均匀分布在载体介质中。X射线光电子能谱给出了Ba3d、Ti2p和Au4f电子芯能级结合能,结果表明载体介质是以BaTiO3的形式存在,而Au以金属的状态掺杂其中。330~800 nm范围的线性吸收谱表明样品中Au颗粒的共振吸收峰在500 nm附近。用单光束纵向扫描方法测量了样品的三阶非线性光学效应,使用的光源为调Q的YAG激光器,波长为532 nm,脉宽为10 ns,得到的非线性折射率和非线性吸收系数分别为-2.42×10-6esu和2.22×10-6m/W,表明了Au-BaTiO3复合薄膜有较大的非线性光学响应。

Third-Order Optical Nonlinearity and Preparation of Au-BaTiO3 Composite Films by Pulsed Laser Deposition

Composite films with nanoscale Au particles uniformly embedded in BaTiO3 matrices (Au-BaTiO3) were prepared by using pulsed laser deposition (PLD) technique. High-resolution transmission electron microscope (TEM) and X-ray photoelectron spectroscope (XPS) were used to characterize the films. It could be seen from the TEM micrographs that the film exhibited a very homogeneous distribution of spherical Au particles. The diameter of the Au particles was estimated to be 2～3 nm. The X-ray photoelectron core-level spectra of Ba3d, Ti2p and Au4f lines were presented and suggested the films were composed of metal Au embedded BaTiO3 matrix. The optical absorption of the films was measured in the wavelength range of 330～800 nm, and the absorption peak due to the surface plasmon resonance of Au particles was found around 500 nm. The third-order optical nonlinearity of the composite films was investigated by the Z-scan method using a Q-switched Nd:YAG laser with a wavelength of 532 nm and a pulse width of 10 ns. The nonlinear refractive index n2 and the nonlinear absorption coefficient β were determined to be -2.42×10-6 esu and 2.22×10-6 m/W, which showed that the Au-BaTiO3 thin films had a large nonlinear optical susceptibility.