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Antimatched Electromagnetic Metasurfaces for Broadband Arbitrary Phase Manipulation in Reflection.
ACS Photonics ( IF 6.5 ) Pub Date : 2018-01-03 , DOI: 10.1021/acsphotonics.7b01415
Odysseas Tsilipakos 1 , Thomas Koschny 2 , Costas M Soukoulis 1, 2
Affiliation  

Metasurfaces impart phase discontinuities on impinging electromagnetic waves that are typically limited to 0-2π. Here, we demonstrate that multiresonant metasurfaces can break free from this limitation and supply arbitrarily large, tunable time delays over ultrawide bandwidths. As such, ultrathin metasurfaces can act as the equivalent of thick bulk structures by emulating the multiple geometric resonances of three-dimensional systems that originate from phase accumulation with effective material resonances implemented on the surface itself via suitable subwavelength meta-atoms. We describe a constructive procedure for defining the required sheet admittivities of such metasurfaces. Importantly, the proposed approach provides an exactly linear phase response so that broadband pulses can experience the desired group delay without any distortion of the pulse shape. We focus on operation in reflection by exploiting an antimatching condition, satisfied by interleaved electric and magnetic Lorentzian resonances in the surface admittivities, which completely zeroes out transmission through the metasurface. As a result, the proposed metasurfaces can perfectly reflect a broadband pulse imparting a prescribed group delay. The group delay can be tuned by modifying the implemented resonances, thus opening up diverse possibilities in the temporal applications of metasurfaces.

中文翻译:

宽带任意相位反射中的反匹配电磁超表面。

超表面在撞击电磁波上赋予相位不连续性,通常不超过0-2π。在这里,我们证明了多共振超表面可以摆脱这种限制,并在超宽带宽上提供任意大的可调时间延迟。这样,超薄超颖表面可以通过模拟三维系统的多重几何共振而等效于厚的整体结构,该三维系统源自相累积,并通过合适的亚波长超原子在表面本身上实现了有效的材料共振。我们描述了一种构造性的程序,用于定义此类超表面所需的片材导纳率。重要的,所提出的方法提供了精确的线性相位响应,因此宽带脉冲可以在没有任何脉冲形状失真的情况下经历所需的群时延。我们通过利用反匹配条件专注于反射操作,该条件由表面电导率的交错的电和磁洛伦兹共振满足,这完全消除了通过超表面的传输。结果,提出的超颖表面可以完美地反映赋予规定的群时延的宽带脉冲。可以通过修改已实现的共振来调整群延迟,从而在超颖表面的时间应用中打开各种可能性。通过表面电导率的交错的电和磁洛伦兹共振满足,这完全消除了通过超表面的传输。结果,提出的超颖表面可以完美地反映赋予规定的群时延的宽带脉冲。可以通过修改已实现的共振来调整群延迟,从而在超颖表面的时间应用中打开各种可能性。通过表面电导率的交错的电和磁洛伦兹共振满足,这完全消除了通过超表面的传输。结果,提出的超颖表面可以完美地反映赋予规定的群时延的宽带脉冲。可以通过修改已实现的共振来调整群延迟,从而在超颖表面的时间应用中打开各种可能性。
更新日期:2018-01-03
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