等离激元超表面的耦合现象研究

Optical interferences between two interfaces are a type of important phenomena which can be found everywhere, from the rainbow colors on soap bubbles, anti-reflection coating on lenses, to the F-P cavity in lasers. Conventionally, only smooth optical interfaces on lossless dielectric materials were interested, and the interference is solely determined by the distance between the interfaces since the phase changes of the reflected light are either 0 or π at those interfaces. Recently, it is found that light will not follow the Snell or Fresnel laws at a nanostructured interface (i.e., meta-surface) and this will lead to many new possibilities for the interference-based devices. Inspired by this idea, here, we propose the study on the interference effects between meta-surfaces. We will use the scanning probe microscope technique to control the relative position of two meta-surfaces, and measure the far-/near-field couplings and associated effects. In addition, with the help of scanning probe microscope, we will investigate the coupling induced optical forces between meta-surfaces, a fundamentally important effect in the field of optomechanics. This project not only will broaden our knowledge of interference phenomena, deepen our understanding of meta-surfaces, but also will lead to many important applications in the fields of thin-film-based devices, optomechanics, and spectroscopy.

界面间的光干涉是一类应用广泛的重要光学现象，从等厚条纹、增透膜，到法布里-珀罗谐振腔均可归于此类现象。传统上，人们关注于无损材料平滑界面间的干涉，干涉结果只依赖于界面间的距离。最新研究发现，当引入二维人工微纳结构（即超表面）时，光在界面上的行为将不再遵循传统的反射/折射定律，反射与折射光的方向、振幅、相位和偏振可被任意调控，这为光学界面间的干涉效应带来了众多新的可能。受此启发，本项目将研究等离激元超表面间的干涉耦合效应及其伴随的光力作用。计划使用扫描探针技术以纳米精度操控两个等离激元超表面在三维空间中的相对位置，研究对应的光耦合效应与空间位置的关系；并利用扫描探针显微镜，在实验上探索等离激元超表面间的光力作用及其与耦合模式间的联系。通过此项目的研究，我们将拓展并深化对界面间干涉耦合现象的理解，为开发新型的微纳光学器件打下基础。

项目主要研究二维等离激元纳米结构间的各类光学耦合现象，旨在揭示耦合对结构光学性质及光力作用的影响，为未来高性能等离激元器件的开发提供基础。项目执行期间，基本按申请书中所列研究内容开展,并且根据目前国内外的研究发展状况以及项目中的新发现进行了多个拓展性研究。（1）在理论上研究了复杂层状（台阶状）等离激元结构中的层间耦合现象，设计了具有多个空间模式匹配且可独立调控的共振模式的等离激元纳米结构。（2）结合扫描探针技术、微纳加工技术与力学传感技术建立起了一套适合于纳米结构耦合测量的系统，演示了二维等离激元纳米结构间的等厚干涉现象，将等厚干涉方法的测量精度提升至3皮米。（3）研究了二维等离激元纳米结构间的光力作用，观测到了距离依赖的光力作用，为研究复杂二维等离激元结构之间的可控耦合现象提供了实验基础。项目执行期间，在Adv. Mater.，Light Sci. & Appl.，Chem.Rev.等期刊上发表论文11篇，专利授权1项，申请4项（含一项国际专利）。