少层超表面高效调控光学特性和新型光场研究

Metasurfaces have powerful tunabilities in the manipulation of the phase, polarization, amplitude, and propagation mode for electromagnetic wavefront, which have been becoming one of the important research directions and hot topics of the metamaterials. However, single-layer metasurfaces are usually limited by low conversion efficiency, and cannot simultaneously control several optical parameters, such as phase, polarization, amplitude, and so on. Few-layer metasurfaces can introduce more degrees of freedom and physical mechanisms to effectively overcome the limits of the single-layer metasurfaces. We will theoretically and experimentally study the high-performance tuning of the new optical characteristics and optical fields by few-layer metasurfaces in this project. We will propose and study some new physical mechanisms by cascaded, coupled, resonant or interfered effects between the layers of the few-layer metasurfaces. We will realize full manipulation of the phase, polarization, amplitude, and associated control of several optical parameters. Then, we can further generate, improve and tune the novel type of optical effects and optical fields by few-layer metasurfaces. Based on the absorption characteristics of materials at different frequencies, we will also design metallic, dielectric, or composite few-layer metasurfaces to achieve the novel optical effects and optical fields with high conversion efficiency. Furthermore, we will further dynamically tune the optical characteristics and optical fields of few-layer metasurfaces by adding graphene layer into the system of the few-layer metasurfaces. We hope to promote the development of few-layer metasurfaces in the nanophotonics devices and applications, and form our own characteristics and advantages in the international research field by carrying on this project.

超表面对电磁波相位、偏振、振幅、传播模式等特性有着强大的调控能力，成为近几年超材料的重要发展方向和研究热点之一。然而，单层超表面存在转换效率低，不能同时操控相位、偏振和振幅等局限性。少层超表面可以引入新的自由度和物理机制，能有效解决单层超表面的诸多局限。本项目拟从理论和实验两方面开展少层超表面高效调控光学特性和新型光场的研究，通过层之间串级、耦合、共振或干涉等新型物理机制，实现对光束相位、偏振、振幅及多参量联合的完全调控，研究其新型光学效应和新型光场的产生、提高和调控；基于不同波段材料的吸收特性，设计金属、电介质硅或金属-电介质硅复合少层超表面，实现高转换效率的新型效应和新型光场；将石墨烯加入到少层超表面的关键位置，进行少层超表面光学特性和新型光场的动态调控研究。我们希望通过本项目的开展，推动少层超表面在纳米光子学器件中的应用发展，争取在该领域的国际研究中形成自己的特色和优势。

超表面对电磁波相位、偏振、振幅、传播模式等特性有着强大的调控能力，成为近几年超材料的重要发展方向和研究热点之一。然而，单层超表面存在转换效率低，不能同时操控相位 、偏振和振幅等局限性。少层超表面可以引入新的自由度和物理机制，能有效解决单层超表面的诸多局限。本项目拟从理论和实验两方面开展少层超表面高效调控光学特性和新型光场的研究，实现对光束相位、偏振、振幅及多参量联合的完全调控，研究其新型光学效应和新型光场；实现高转换效率的新型效应和新型光场；将石墨烯加入到少层超表面的关键位置，进行少层超表面光学特性和新型光场的动态调控研究。.主要研究成果如下：（1）设计了少层超表面，分析了层与层之间的作用机制，对光场特性如偏振、相位、振幅等进行了调控。实现透射效率达到60%的非对称透射以及转换效率54%的偏振转换；实现了异常折射、完美吸收等新效应。（2）实现新型光场的产生和调控，如相位和振幅可调节的艾里光束；实现新应用如大角度（0-60°）的高效率、高数值孔径且工作波段覆盖从1100nm到1700nm的傅里叶微透镜；实现偏振依赖、饱和度可调的结构色以及全色度70%到90%的超高饱和颜色。（3）利用石墨烯超表面实现了效率动态可调的5阶异常折射和15阶拉盖尔高斯光束；设计二硫化钼少层超表面实现偏振不灵敏的超薄近完美吸收器；基于PB相位的非线性编码超表面，在非线性光学效应中来设计多维信息通道，实现光信息的多路复用。