Thomas Philip A, Tan Wai Jue, Fernandez Henry A, Barnes William L
Department of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom.
Nano Lett. 2020 Sep 9;20(9):6412-6419. doi: 10.1021/acs.nanolett.0c01963. Epub 2020 Aug 7.
Light-matter interactions can occur when an ensemble of molecular resonators is placed in a confined electromagnetic field. In the strong coupling regime the rapid exchange of energy between the molecules and the electromagnetic field results in the emergence of hybrid light-matter states called polaritons. Multiple criteria exist to define the strong coupling regime, usually by comparing the splitting of the polariton bands with the line widths of the uncoupled modes. Here, we highlight the limitations of these criteria and study strong coupling using spectroscopic ellipsometry, a commonly used optical characterization technique. We identify a new signature of strong coupling in ellipsometric phase spectra. The combination of ellipsometric amplitude and phase spectra yields a distinct topological feature that we suggest could serve as a new criterion for strong coupling. Our results introduce the idea of ellipsometric topology and could provide further insight into the transition from the weak to strong coupling regime.
当分子谐振器的集合置于受限的电磁场中时，光与物质之间就会发生相互作用。在强耦合 regime 中，分子与电磁场之间快速的能量交换导致了称为极化激元的混合光 - 物质态的出现。存在多种标准来定义强耦合 regime，通常是通过将极化激元带的分裂与未耦合模式的线宽进行比较。在这里，我们强调了这些标准的局限性，并使用光谱椭偏仪（一种常用的光学表征技术）来研究强耦合。我们在椭偏相位谱中识别出强耦合的一种新特征。椭偏振幅谱和相位谱的结合产生了一种独特的拓扑特征，我们认为这可以作为强耦合的一个新标准。我们的结果引入了椭偏拓扑的概念，并可能为从弱耦合 regime 到强耦合 regime 的转变提供进一步的见解。
