An electromagnetic multipole expansion beyond the long-wavelength approximation

OPTICS COMMUNICATIONS

卷:407

Article

Alaee, Rasoul^1,2  Rockstuhl, Carsten^1,3  Fernandez-Corbaton, I.³ 

[1] Karlsruhe Inst Technol, Inst Theoret Solid State Phys, D-76131 Karlsruhe, Germany

[2] Max Planck Inst Sci Light, D-91058 Erlangen, Germany

[3] Karlsruhe Inst Technol, Inst Nanotechnol, D-76021 Karlsruhe, Germany

关键词: Multipole moments;    Scattering;    Plasmonics;    Metamaterials;   

DOI  :  10.1016/j.optcom.2017.08.064

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

Free