论文标题
元表面反射器的效率有多薄？在任何方向和极化的反射方面的通用界限
How Thin and Efficient Can a Metasurface Reflector Be? Universal Bounds on Reflection for Any Direction and Polarization
论文作者
论文摘要
光反射在许多现代技术中起着至关重要的作用。在本文中，对任何方向的最大反射能力和任何极化的分析表达式均针对由复杂标量易感性代表的单个材料制成的通用平面结构给出。最佳的光 - 互动以最大化反射的问题被提出为在诱导电流方面的优化问题的解决方案，但要遵守能量守恒和被动性，该解决方案通过使用拉格朗日二元性承认了全局上限。派生的上限适用于广泛的平面结构，包括跨度，光栅，同质膜，光子晶体板以及更普遍的，无论其几何细节如何，任何不均匀的平面结构。这些边界还为给定的有损材料设定了最小厚度的限制，以实现所需的反射率。此外，我们的结果允许发现参数区域，与现有设计相比，反射结构的效率大大提高。例如，给出了这些发现对设计由真实，不完美（即有损）材料制成的优质和紧凑的反射组件的影响的示例，例如超薄且高效的光栅，极化转换器以及对太阳能/激光帆的轻质镜子。
Light reflection plays a crucial role in a number of modern technologies. In this paper, analytical expressions for maximal reflected power in any direction and for any polarization are given for generic planar structures made of a single material represented by a complex scalar susceptibility. The problem of optimal light-matter interactions to maximize reflections is formulated as the solution of an optimization problem in terms of the induced currents, subject to energy conservation and passivity, which admits a global upper bound by using Lagrangian duality. The derived upper bounds apply to a broad range of planar structures, including metasurfaces, gratings, homogenized films, photonic crystal slabs, and more generally, any inhomogeneous planar structure irrespective of its geometrical details. These bounds also set the limit on the minimum possible thickness, for a given lossy material, to achieve a desired reflectance. Moreover, our results allow discovering parameter regions where large improvements in the efficiency of a reflective structure are possible compared to existing designs. Examples are given of the implications of these findings for the design of superior and compact reflective components made of real, imperfect (i.e., lossy) materials, such as ultra-thin and efficient gratings, polarization converters, and light-weight mirrors for solar/laser sails.
