金纳米颗粒及其复合体系的制备与光学性质的研究

The surface plasmon resonance of the metal nanomaterials vary according to the morphology of nanostructures, the surrounding environment and other factors. And also, the optical property of the surrounding medium is influenced by the surface plasmon resonances of metal material. Based on gold nanoparticles，this research would investigate the optical properties of gold nanoparticles and its hetero-nanostructures. Mainly, we are going to study the preparation of gold nanoparticles with different morphology, explore the methods of controlling the self-assembly process of the gold nanoparticles. We will try to grow AuAg, Au-semiconductor hetero-nanostructures based on the gold nanoparticles. The influence of structure parameters and surrounding environment, plasmon-exciton interaction on the optical properties of the hetero-nanomaterial will be investigated. The surface plasmon resonance properties of the metal nanostructures will be systematically analyzed using FDTD numerical simulation. Combining the experimental results and theoretic analysis, the design and application of optical performance on gold and its hetero-nanostructures will be achieved. Through this project, a new metal-metal/semiconductor nanostructure which aims at the supply for the research of light-matter interaction and for the potential applications will be provided. We've accumulated some relevant knowledge which has laid down an important foundation for our research.

金属纳米材料的表面等离激元共振特性会随着纳米材料的形貌、自组装方式及周围介质等因素的改变而发生变化，同时其亦会影响周围介质的光学性能。本课题拟在金纳米颗粒的基础上，对金纳米颗粒及其复合异质结构的光学性质进行探究。主要是探究不同形貌的金纳米颗粒的制备工艺，并在此基础上实现对金纳米颗粒自组装过程的精确调控；同时以金纳米颗粒为核制备AuAg，Au-半导体等复合异质纳米结构，探究异质结构中表面等离激元共振光学特性与材料本身及周围环境的依赖关系，以及表面等离激元与激子相互作用影响下的异质结构的光学性质。通过有限时域差分法(FDTD)模拟材料局域电场分布，结合实验探测结果进行分析，实现对金及其复合纳米材料光学性能的设计和应用。本项目旨在为光与物质相互作用的研究与应用提供具备优良光学性能的金属-金属/半导体异质结构，我们对相关的制备工艺及性质分析已有初步的积累，为本课题的展开提供了重要研究基础。

金属纳米材料的表面等离激元共振特性会随着纳米材料的形貌、自组装方式及周围介质等因素的改变而发生变化，同时其亦会影响周围介质的光学性能。本项目针对Au-Ag非对称异质结构的非线性光学性能进行了研究。Au-Ag非对称异质结构具有很强的横向八极共振强度，且随着银壳层的厚度的增加，强度逐渐增加。我们研究了在纵向偶极和横向八极共振模式共振激发下的三阶非线性效应。在八极共振模式下，该结构的非线性品质因子得到了很大的改善，八极共振激发下，单光子非线性品质因数W=4.4，双光子非线性品质因数T=0.14，满足W>1和T<1的条件，适合于做全光开关器件。非对称Au-Ag结构在强的八极共振模式下等离激元共振增强二次谐波效应，首次证明了八极模式在谐波共振下具有很强的二次谐波增强效应。在偶极和八极同时共振时，与纯的金纳米棒相比，非对称金银异质结构的二次谐波强度增强了21倍。且该结构的二次谐波相比双光子发光对激发的极化方向表现的更敏感。