An electromagnetic multipole expansion beyond the long-wavelength approximation
An electromagnetic multipole expansion beyond the long-wavelength approximation
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DOI：
10.1016/j.optcom.2017.08.064
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发表时间：
2018-01-15
影响因子：
2.4
通讯作者：
Fernandez-Corbaton, I.
中科院分区：
文献类型：
--
作者：
Alaee, Rasoul;Rockstuhl, Carsten;Fernandez-Corbaton, I.
多极展开是研究光与物质相互作用的重要工具。所有关于给定电荷密度分布的电磁场的辐射和耦合的信息都被浓缩成几个数字：源的多极矩。这些数字通常是用长波长近似后得到的表达式计算的。在这里，我们推导出精确的表达式的多极矩的动态源，类似于他们的简单性，他们的近似同行。我们验证我们的新表达式对球形源的分析结果，然后用它们来计算一些选定的源与非平凡的形状的诱导力矩。与近似表达式得到的结果的比较显示出相当大的分歧，即使是亚波长大小的源。我们的表达式是相关的任何科学领域处理电磁场和物质系统之间的相互作用。(C)2017爱思唯尔B.V.保留所有权利。
The multipole expansion is a key tool in the study of light-matter interactions. All the information about the radiation of and coupling to electromagnetic fields of a given charge-density distribution is condensed into few numbers: The multipole moments of the source. These numbers are frequently computed with expressions obtained after the long-wavelength approximation. Here, we derive exact expressions for the multipole moments of dynamic sources that resemble in their simplicity their approximate counterparts. We validate our new expressions against analytical results for a spherical source, and then use them to calculate the induced moments for some selected sources with a non-trivial shape. The comparison of the results to those obtained with approximate expressions shows a considerable disagreement even for sources of subwavelength size. Our expressions are relevant for any scientific area dealing with the interaction between the electromagnetic field and material systems. (C) 2017 Elsevier B.V. All rights reserved.