Banzer Peter, Peschel Ulf, Quabis Susanne, Leuchs Gerd
Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1, D-91058 Erlangen, Germany.
Opt Express. 2010 May 10;18(10):10905-23. doi: 10.1364/OE.18.010905.
We demonstrate an experimental method to separately test the optical response of a single sub-wavelength nano-structure to tailored electric and magnetic field distributions in the optical domain. For this purpose a highly focused y-polarized TEM10-mode is used which exhibits spatially separated longitudinal magnetic and transverse electric field patterns. By displacing a single sub-wavelength nano-structure, namely a single split-ring resonator (SRR), in the focal plane, different coupling scenarios can be achieved. It is shown experimentally that the single split-ring resonator tested here responds dominantly as an electric dipole. A much smaller but yet statistically significant magnetic dipole contribution is also measured by investigating the interaction of a single SRR with a magnetic field component perpendicular to the SRR plane (which is equivalent to the curl of the electric field) as well as by analyzing the intensity and polarization distribution of the scattered light with high spatial resolution. The developed experimental setup as well as the measurement techniques presented in this paper are a versatile tool to investigate the optical properties of single sub-wavelength nano-structures.
我们展示了一种实验方法，用于在光学领域分别测试单个亚波长纳米结构对定制电场和磁场分布的光学响应。为此，使用了高度聚焦的y偏振TEM10模式，该模式呈现出空间上分离的纵向磁场和横向电场模式。通过在焦平面中移动单个亚波长纳米结构，即单个开口环谐振器（SRR），可以实现不同的耦合场景。实验表明，此处测试的单个开口环谐振器主要作为电偶极子响应。通过研究单个SRR与垂直于SRR平面的磁场分量（等同于电场的旋度）的相互作用，以及通过高空间分辨率分析散射光的强度和偏振分布，还测量到了一个小得多但在统计上仍显著的磁偶极子贡献。本文所开发的实验装置以及测量技术是研究单个亚波长纳米结构光学特性的通用工具。
