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arXiv 1602.08862physics.optics
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超颖表面的局域光学态密度

The local density of optical states of a metasurface

Per Lunnemann, Femius A. Koenderink

摘要:

虽然超材料通常用于近场功能,如完美的透镜或隐身,但它们通常通过对远场平面波的响应来量化。在这里,我们提出了一个离散磁散射体晶格附近的局域态密度的理论分析,即,对点源近场激励的响应。基于Ewald求和的点偶极理论和阵列扫描方法,我们可以快速半解析地计算任意磁电偶极散射体组成的无限二维晶格中磁电点源的局域态密度(LDOS).该方法考虑到辐射阻尼以及所有推迟电动相互作用在一个自洽的方式。我们表明,磁散射体的晶格证据特征Drexhage振荡。然而,振荡是相移相对于电散射晶格一致的差异预期的反射离开均匀的磁分别电镜。此外,我们确定在源-表面分离制度的超表面可以被视为一个均匀的界面,并在均匀化失败。一个强大的频率和平面内的位置依赖性的LDOS接近晶格揭示耦合到由晶格支持的导模。

英文摘要:

While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a point-dipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous interface, and in which homogenization fails. A strong frequency and in-plane position dependence of the LDOS close to the lattice reveals coupling to guided modes supported by the lattice.

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