Causality-Based Criteria for a Negative Refractive Index Must Be Used With Care
Causality-Based Criteria for a Negative Refractive Index Must Be Used With Care
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DOI：
10.1103/physrevlett.101.167401
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发表时间：
2008-10-17
影响因子：
8.6
通讯作者：
McCall, M. W.
中科院分区：
文献类型：
--
作者：
Kinsler, P.;McCall, M. W.
利用 Kramers-Kronig 关系中表达的因果关系原理，我们推导出负折射率的通用标准，该标准允许在观察频率 omega 下存在不完美的透明度。它还允许我们将损耗的全局属性（即其频率响应）与其在 omega 处的局部行为联系起来。然而，基于因果关系的标准依赖于群速度，而不是坡印廷矢量。由于两者并不等同，我们提供一些简单的例子来比较这两个标准。
Using the principle of causality as expressed in the Kramers-Kronig relations, we derive a generalized criterion for a negative refractive index that admits imperfect transparency at an observation frequency omega. It also allows us to relate the global properties of the loss (i.e., its frequency response) to its local behavior at omega. However, causality-based criteria rely on the group velocity, not the Poynting vector. Since the two are not equivalent, we provide some simple examples to compare the two criteria.