标量和矢量光束作用下复合超材料非线性光学特性研究

The studies about the nonlinear optical characteristics for metamaterials and their applications have been becoming the forefront of international research and the competitive interest in new technology fields. However, the current researches mainly focus on the design of different structures to realize nonlinear effects.The impacts of different types of incident beam are rarely discussed. In addition, there is seldom an alternative way to obtain the large nonlinear, besides to design the metamaterial structure with the smaller gap or sharper angle. However, both of these nanostructures have reached current fabrication limits or need a very complicated fabrication process. This project aims to design and fabricate composite metamaterials to realize localized field enhancement in two or more times, and analyze the different mechanisms of localized field enhancement. Then, we will theoretically and experimentally study second-order and third-order optical nonlinear characteristics of composite metamaterials, and further analyze the generated mechanisms of second-harmonic generation and all-optical switch. Moreover, we will construct the relationships between the polarization, phase, amplitude and incident angle of the incident scalar and vector beams and the polarization and conversion efficiency of the second-harmonic generation, or the threshold power and switching time of the all-optical switch.The new effects, new phenomena and new optical nonlinear mechanisms generated by scalar and vector beams will also be explored. We hope to promote the development of composite metamaterials in the nanophotonic devices and applications, and form our own characteristics and advantages in the international research field by carrying on this project.

超材料非线性光学特性及其应用的研究已经成为当今国际研究前沿和新技术领域竞争热点。目前关于它的研究主要集中在设计不同结构实现非线性效应，不同类型光束本身性质的影响很少涉及；另外，目前主要通过缩小结构间隙和增加边缘尖锐度来获得大非线性，这在实验制备上遇到了瓶颈。本项目拟设计并制作复合超材料，从新角度实现局域场二次或多次增强，分析其局域场增强的不同机制；进一步从理论和实验上研究复合超材料的二阶和三阶非线性光学特性，探索其二次谐波效应和光开关的机制；并建立标量和矢量光束的偏振、相位、振幅和入射角度等同二次谐波的偏振、转换效率及光开关的阈值功率、响应时间等之间的关系，分析产生的新效应、新现象和新非线性机制。我们希望通过本项目的开展，推动复合超材料在纳米光子学器件中的应用发展，争取在国际上该领域的研究中形成自己的优势和特色。

本项目拟设计并制作复合超材料，从新角度实现局域场二次或多次增强，分析其局域场增强的不同机制；进一步从理论和实验上研究复合超材料的二阶和三阶非线性光学特性，探索其二次谐波效应和光开关的机制；并建立标量和矢量光束的偏振、相位、振幅和入射角度等同二次谐波的偏振、转换效率及光开关的阈值功率、响应时间等之间的关系，分析产生的新效应、新现象和新非线性机制。. 通过项目的实施，我们在以下几方面取得了一系列高水平研究成果：（1）提出了简单的双层金属微结构，通过引入三阶性材料实现了完美吸收特性的动态调控；（2）将氧化钒纳米天线和传统的等离子透镜相结合形成复合超材料，实现对径向矢量光束焦距近场和远场之间灵活的动态调控；（3）提出了一种应用L型金属天线和双棒纳米天线形成的双层超薄杂化超材料，实现了光的类二极管非对称透射；（4）设计双层等离子体超表面材料来实现同时控制样品透射光的相位和偏振方向，生成了具有不同拓扑荷数的涡旋光和标准径向、角向矢量光束；（5）通过设计三层金属纳米棒嵌入在氮化硅中的少层超表面，在近红外波段实现高效率的双带非对称透射以及圆偏光的偏振转化；（6）通过设计正交金纳米棒构成的超表面，可简单的产生相位和振幅可调节的爱里光束。