金属纳米线垂直阵列复合介孔薄膜可控制备及其三阶非线性增强

With the characteristics of low cost, easy preparation and outstanding designability, amorphous nonlinear thin film materials has been the first choice material to achieve photonic devices with high performance and low cost in all-optical network, but its third-order nonlinear coefficient is too small and needs to be improved. Materials containing metal nanoparticals or nanowires with characteristics such as the field enhancement effect and the surface plasma resonance effect has attracted many researchers' interests, which can solve the above problem effectively and induce the enhancement of third-order optical nonlinearity. Based on our early studying on the chalcohalide glasses with metal nano-particals to induce effectively enhancement of third-order nonlinearity. In this project, objectives are to prepare the mesoporous films of this project is to produce thin films with mesopore channels orienting perpendicularly to the solid surface using ITO conductive glasses as substrate and CTAB as template under an applied electric field. On this basis, we will utilize the method of electrochemical deposition to grow metal nanowires by using the conductivity of ITO glasses and the limited space of mesopore channels which is used as a template. And the metal nanowire arrays orienting perpendicularly to the ITO template will be obtained through the perpendicularly oriented mesopore channels. We will also describe the mechanism of the enhancement of the third-order nonlinearity by the process of energy transfer, controlled growth conditions, its morphology and the interaction between hosts and objects during the growth process of the metal nanowires. The mesoporous composite film that we have achieved with metal nanowires perpendicular arrays with high third-order nonlinearity will become the ideal materials for preparing the photonic integrated devices with low cost such as optical switching.

非晶态非线性光学薄膜材料由于低成本、易制备及可设计性强等优良特性成为全光网络高性能光子器件集成化低成本制备的首选材料，但其三阶非线性系数亟待提高。利用金属纳米粒子或纳米线等局域场增强和表面等离子体共振效应等使材料产生三阶非线性增强，可以有效地解决此问题而成为目前研究热点。在我们前期硫卤玻璃中离子注入金属纳米晶形成有效实现三阶非线性增强的研究基础上，本项目以ITO导电玻璃为基板，通过外加电场作用，以 CTAB为模板剂制备出孔道排列垂直于基板的介孔薄膜。在此基础上再利用基板导电性和介孔空间限域性在介孔中电沉积制备出金属纳米线，通过介孔的垂直有序性获得垂直于基板的金属纳米线阵列。结合金属纳米线生长中能量传递过程、生长条件及其形貌、介孔环境中主客体相互作用等阐明薄膜三阶非线性增强机理，可控制备出高三阶非线性金属纳米线垂直阵列复合介孔薄膜，并有望成为光开关等光子器件集成化低成本制备的重要使用材料。

寻找高非线性系数的非晶态非线性光学材料制备光电子器件可以有效降低成本。利用金属纳米粒子或纳米线等局域场增强等产生三阶非线性增强，可以有效地解决此问题。本项目借助电场辅助作用，在酸性条件下以TEOS为无机硅源，表面活性剂CTAB为模板剂采用三电极法在ITO导电玻璃基底上制备出具有有序排列且孔道垂直取向的介孔薄膜，并进行了孔径调节以满足需求。利用介孔孔道的限域作用，采用恒电压还原的方法，成功将银纳米粒子负载在介孔二氧化硅薄膜的孔道中，得到金属银纳米线阵列。对含有金属银的介孔复合薄膜利用X射线衍射、高分辨透射电镜以及X射线光电子能谱等观察分析了复合薄膜的物相组成、形貌和三阶非线性光学性能。结果表明，复合薄膜中含有0价的银纳米颗粒，其大小与介孔孔道相当，主要分布在10~72 nm的深度范围内，质量百分比为7.44% 。从高分辨透射电镜图中看出负载银纳米粒子之后，薄膜的孔道仍然保持有序性，孔道直径为2~3 nm。Z-Scan结果表明复合薄膜中存在非线性饱和吸收，其非线性折射系数为负值。计算结果表明复合薄膜中最大的极化率的值为1.53*10-10 esu，是空白介孔二氧化硅极化率的值的5倍，比纳米晶硫卤玻璃提高了1000倍（Ag注入56GeS2–24Ga2S3–20KBr硫卤玻璃为5.34*10-13 esu）。银纳米粒子的等离子体共振所引发的近场效应大大的提高了复合薄膜的三阶非线性光学性质。从对比中还发现，银纳米粒子的电沉积时间对复合薄膜的非线性光学性质起着极大的作用，合适的电压和反应时间能够得到相对较高的三阶非线性光学性能。通过电化学方法简单可控制备出高三阶非线性金属纳米线垂直阵列复合介孔薄膜，并有望成为光开关等光子器件集成化低成本制备的重要使用材料，满足全光网络中低成本制备对非线性光学薄膜材料的使用需求。