Reflection tuning via destructive interference in metasurface

Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly desired in plenty of applications.In this paper,we propose a new design of metasurface with just one single layer dielectric structure to tune the reflection of an interface by destructive interference in a subwavelength scale.By arranging the orientation of nano-antennas,the reflectivity tuning from 20%to 90%can be achieved at the wavelength of 1550 nm.Moreover,such reflectivity tuning of the designed metasurface works at the tunable wavelength from1500 nm to 1600 nm.This ultra-thin solution can achieve similar performance as the traditional bulky components without diffraction orders,while the design and fabrication are much simple and flexible.The ultra-thin and tunable properties indicate the great potentials of this method to be applied in laser fabrication,optical communication and optical integration.

从紧局域态解密平带

平带系统由于平带自身不存在结构,是研究由电子——电子关联导致的各种新奇物理效应的理想量子平台.因此,从理论上寻找各种新型的平带系统就十分的重要.实现一个平带的核心要素是找到系统中蕴含的紧局域激发.本文开发了一种系统的方法,从一个简单的一维链出发,通过一系列有约束的变形,得到存在一个在边缘处波函数完全相干相消激发的一个有限系统.利用该方法构造的有限系统经过简单平移和组合就可以产生各种新型二维平带系统.此时,这些被构造出来的有限系统中,边缘处波函数完全相干相消的激发就构成了这些新型二维平带系统中的紧局域态.此外,作者还证明了该方法可以扩展到准晶和多轨道平带系统的构造中,并将这种设计方法扩展到了三维平带系统的构造中.