Opt Lett. 2018 Jun 15;43(12):2856-2859. doi: 10.1364/OL.43.002856.
We present numerical investigation of the mechanism of surface-enhanced circular dichroism of a chiral medium near nanoantennas. Strong circular dichroism was observed from the chiral medium surrounding nanoantennas with multipolar resonant modes, and the strong circular dichroism was more correlated to the multipolar resonances than to nearfield enhancement or optical helicity enhancement. According to this observation, we suggest multipolar radiative coupling between the nanoantennas and chiral medium as a possible mechanism of the strong chiral response. This work clarifies a mechanism of surface-enhanced chiral responses and would be useful for designing an enantiomeric-sensing platform and realizing devices relying on strong chirality, such as topological metamaterials for scattering-immune propagation of light and negative index metamaterials.
我们提出了近纳米天线手性介质的表面增强圆二色性机制的数值研究。在具有多极共振模式的纳米天线周围的手性介质中观察到了强圆二色性，并且强圆二色性与多极共振比与近场增强或光学螺旋度增强更相关。根据这一观察，我们建议纳米天线和手性介质之间的多极辐射耦合作为强手性响应的一种可能机制。这项工作阐明了表面增强手性响应的机制，对于设计对映体感应平台和实现依赖于强手性的器件，如拓扑超材料用于光的散射免疫传播和负折射率超材料，将是有用的。
