Observation of reflectionless absorption due to spatial Kramers-Kronig profile.
Observation of reflectionless absorption due to spatial Kramers-Kronig profile.
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通过空间 KramersâKronig 剖面观察无反射吸收
DOI：
10.1038/s41467-017-00123-4
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发表时间：
2017-07-03
影响因子：
16.6
通讯作者：
Ran L
中科院分区：
文献类型：
--
作者：
Ye D;Cao C;Zhou T;Huangfu J;Zheng G;Ran L
作为电磁学和光学中的一种基本现象，材料吸收已经被广泛研究了几个世纪。然而，在非均匀介质中的全向无反射吸收还有待观察。先前关于变换光学的研究表明，在不涉及增益介质的情况下，不能容易地实现这种吸收。然而，最近关于波传播的理论暗示了实现这种不需要增益的吸收的可行性，只要这种介质的介电常数分布可以满足空间Kramers-Kronig关系。在这项工作中，我们实现了这样的配置文件在一个宽的频带的基础上的一个新的想法的空间频率洛伦兹色散。然后在千兆赫范围内实验观察到宽带、全方向无反射吸收，并且与理论分析和全波模拟非常一致。基于空间频率色散的方法为构造无增益全向无反射吸收体提供了可行性。
As a fundamental phenomenon in electromagnetics and optics, material absorption has been extensively investigated for centuries. However, omnidirectional, reflectionless absorption in inhomogeneous media has yet to be observed. Previous research on transformation optics indicated that such absorption cannot easily be implemented without involving gain media. A recent theory on wave propagation, however, implies the feasibility to implement such absorption requiring no gain, provided that the permittivity profile of this medium can satisfy the spatial Kramers–Kronig relations. In this work, we implement such a profile over a broad frequency band based on a novel idea of space–frequency Lorentz dispersion. A wideband, omnidirectionally reflectionless absorption is then experimentally observed in the gigahertz range, and is in good agreement with theoretical analysis and full-wave simulations. The proposed method based on the space–frequency dispersion implies the practicability to construct gain-free omnidirectionally non-reflecting absorbers.