Castaldi Giuseppe, Moccia Massimo, Engheta Nader, Galdi Vincenzo
Department of Engineering, Fields & Waves Lab, University of Sannio, Benevento, I-82100, Italy.
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Nanophotonics. 2022 Sep 8;11(20):4479-4488. doi: 10.1515/nanoph-2022-0338. eCollection 2022 Sep.
In analogy with spatial multilayers, we put forward the idea of Herpin equivalence in temporal metamaterials characterized by step-like time variations of the constitutive parameters. We show that, at a given frequency, an arbitrary temporal multistep exhibiting mirror symmetry can be replaced by an equivalent temporal slab with suitable refractive index and travel-time. This enables the synthesis of arbitrary values of the refractive index, in a way that differs fundamentally from the effective-medium approach, and adds new useful analytical machinery to the available toolbox for the study and design of temporal metamaterials, with potentially intriguing applications to anti-reflection coatings and filters.
与空间多层结构类似，我们提出了在本构参数具有阶梯状时间变化特征的时间超材料中的赫平等效概念。我们表明，在给定频率下，任意呈现镜像对称的时间多步结构可以被具有合适折射率和传播时间的等效时间平板所取代。这使得能够以一种与有效介质方法根本不同的方式合成任意折射率值，并为时间超材料的研究和设计的现有工具箱增添了新的有用分析工具，在抗反射涂层和滤波器方面可能有引人入胜的应用。
