Vectorial near-field coupling
Vectorial near-field coupling
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DOI：
10.1038/s41565-019-0441-y
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发表时间：
2019-07-01
影响因子：
38.3
通讯作者：
Lienau, Christoph
中科院分区：
文献类型：
--
作者：
Esmann, Martin;Becker, Simon Fabian;Lienau, Christoph
两个相邻偶极子之间的光学近场的相干交换在光学性质、量子动力学以及许多自然发生和人工纳米系统的功能中起着至关重要的作用。这些相互作用具有挑战性，以量化实验。它们只在几个纳米范围内延伸，并且敏感地依赖于耦合偶极子的失谐、退相和相对取向（即矢量特性）。在这里，我们引入等离子体纳米聚焦光谱记录相干光散射光谱与5 nm的空间分辨率从一个圆锥形的金纳米锥的顶点。顶点仅由倏逝场激发，并耦合到单个金纳米棒中的等离子体共振。我们解决了共振能量的变化和线加宽的偶极距离和相对取向的函数。我们演示了这些现象是如何从相互作用的光学近场的不同矢量分量之间的模式耦合，特别是从纳米棒的锥形顶点的横向和纵向极化率的耦合。
The coherent exchange of optical near fields between two neighbouring dipoles plays an essential role in the optical properties, quantum dynamics and thus the function of many naturally occurring and artificial nanosystems. These interactions are challenging to quantify experimentally. They extend over only a few nanometres and depend sensitively on the detuning, dephasing and relative orientation (that is, the vectorial properties) of the coupled dipoles. Here, we introduce plasmonic nanofocusing spectroscopy to record coherent light scattering spectra with 5 nm spatial resolution from the apex of a conical gold nanotaper. The apex is excited solely by evanescent fields and coupled to plasmon resonances in a single gold nanorod. We resolve resonance energy shifts and line broadenings as a function of dipole distance and relative orientation. We demonstrate how these phenomena arise from mode couplings between different vectorial components of the interacting optical near fields, specifically from the coupling of the nanorod to both transverse and longitudinal polarizabilities of the taper apex.