Au:TiO2和Au:Al2O3纳米颗粒复合膜的线性和非线性光学特性

主要从实验和理论两个方面，探讨了不同Au颗粒尺寸和不同基质对Au：TiO₂和Au：Al₂O₃复合膜线性和非线性光学性质的影响.用吸收光谱研究了Au颗粒尺寸和基质与Au复合膜表面等离子体共振带之间的关系；用皮秒Z扫描技术研究了共振和非共振情况下(激发光波长分别为532nm和1064nm)，Au颗粒尺寸和基质与复合膜三阶非线性极化率的关系.基于表面等离子体共振理论和局域场增强理论对复合膜进行了分析，得到了不同Au颗粒大小和不同基质时Au复合膜的 关键词： 金属纳米颗粒 复合膜 三阶非线性 表面等离子体共振

The optical and nonlinear optical properties of Au: TiO2 and Au: Al2O3 composite films

On the basis of measurement and theoretical analysis，optical and nonlinear optical properties of the Au：TiO₂ and Au：Al₂O₃ composite films with different Au nanoparticle size and different substrates were investigated. The relationship between the Au nanoparticle size and substrates and the surface plasmon resonance (SPR) of Au composite films were characterized by UV-VIS-NIR spectroscopy，and the dependence of third-order nonlinear susceptibility of the composite films on Au nanoparticle size and substrates was investigated by picosecond Z-scan technique with different exciting wavelengths (532nm and 1064nm). The analysis of optical properties of these films was carried out using the theories of surface plasmon resonance and localized field enhancement，respectively. The experimental and theoretical results revealed the dependence of third-order nonlinear susceptibilities χ⁽³⁾ on Au nanoparticle size and substrates. For Au nanoparticle of size around 35nm embedded in TiO₂ substrate with larger permittivity and the exciting wavelength at 532nm close to the surface plasmon resonance (618nm—632nm)，the third-order nonlinear susceptibility χ⁽³⁾ showed a maximum value of 25×10^-9esu.