Rizza Carlo, Castaldi Giuseppe, Galdi Vincenzo
Department of Physical and Chemical Sciences, University of L'Aquila, L'Aquila I-67100, Italy.
Department of Engineering, Fields and Waves Lab, University of Sannio, Benevento I-82100, Italy.
Phys Rev Lett. 2022 Jun 24;128(25):257402. doi: 10.1103/PhysRevLett.128.257402.
We study a class of temporal metamaterials characterized by time-varying dielectric permittivity waveforms of duration much smaller than the characteristic wave-dynamical timescale. In the analogy between spatial and temporal metamaterials, such a short-pulsed regime can be viewed as the temporal counterpart of metasurfaces. We introduce a general and compact analytical formalism for modeling the interaction of a short-pulsed metamaterial with an electromagnetic wave packet. Specifically, we elucidate the role of local and nonlocal effects, as well as the time-reversal symmetry breaking, and we show how they can be harnessed to perform elementary analog computing, such as first and second derivatives. Our theory validated against full-wave numerical simulations suggests a novel route for manipulating electromagnetic waves without relying on long, periodic temporal modulations. Just as metasurfaces have played a pivotal role in the technological viability and practical applicability of conventional (spatial) metamaterials, short-pulsed metamaterials may catalyze the development of temporal and space-time metamaterials.
我们研究一类时间超材料，其特征在于持续时间远小于特征波动时间尺度的随时间变化的介电常数波形。在空间和时间超材料的类比中，这种短脉冲 regime 可被视为超表面的时间对应物。我们引入一种通用且紧凑的解析形式，用于对短脉冲超材料与电磁波包的相互作用进行建模。具体而言，我们阐明了局部和非局部效应以及时间反演对称性破缺的作用，并展示了如何利用它们来执行基本的模拟计算，如一阶和二阶导数。我们针对全波数值模拟验证的理论提出了一种在不依赖长周期时间调制的情况下操纵电磁波的新途径。正如超表面在传统（空间）超材料的技术可行性和实际适用性中发挥了关键作用一样，短脉冲超材料可能会催化时间和时空超材料的发展。
