Institute of Optics, Information and Photonics, University of Erlangen-Nürnberg, Staudtstraße 7/B2, 91058 Erlangen, Germany.
Nature. 2012 Aug 9;488(7410):167-71. doi: 10.1038/nature11298.
The development of new artificial structures and materials is today one of the major research challenges in optics. In most studies so far, the design of such structures has been based on the judicious manipulation of their refractive index properties. Recently, the prospect of simultaneously using gain and loss was suggested as a new way of achieving optical behaviour that is at present unattainable with standard arrangements. What facilitated these quests is the recently developed notion of 'parity-time symmetry' in optical systems, which allows a controlled interplay between gain and loss. Here we report the experimental observation of light transport in large-scale temporal lattices that are parity-time symmetric. In addition, we demonstrate that periodic structures respecting this symmetry can act as unidirectional invisible media when operated near their exceptional points. Our experimental results represent a step in the application of concepts from parity-time symmetry to a new generation of multifunctional optical devices and networks.
新型人工结构和材料的发展是当今光学领域的主要研究挑战之一。迄今为止，此类结构的设计主要基于对其折射率特性的巧妙控制。最近，有人提出同时利用增益和损耗作为实现目前无法用标准器件实现的光学行为的新方法。促进这些探索的是光学系统中最近提出的“奇偶时间对称”概念，它允许增益和损耗之间的受控相互作用。在这里，我们报告了在大规模时间晶格中光传输的实验观察，这些晶格是奇偶时间对称的。此外，我们还证明了在其异常点附近工作时，符合这种对称性的周期性结构可以作为单向隐形介质。我们的实验结果代表了将奇偶时间对称的概念应用于新一代多功能光学器件和网络的一个步骤。
