Circular dichroism (CD) caused by the response of a chiral object to circularly polarized light has been well established, and the strong CD of plasmonic metamolecules has also become of interest in recent years; however, their response if the light also has orbital angular momentum is unclear. In this paper, the dichroism of a plasmonic cuboid-protuberance chiral structure under the illumination of a light beam with both orbital and spin angular momenta is numerically investigated. Distinguished spectra are observed under the different momenta. The circular dichroism under the combination of vortex beam and light spin is enhanced. This phenomenon is attributed to the partial spatial excitation of the nanoparticle, and the strong dichroism is simultaneously caused because of the interaction of the induced electric and magnetic modes and other higher-order modes caused by the partial excitation of the vortex beam. This research provides further insight into chiral light-matter interactions and the dichroism of light with orbital angular momentum.

中文翻译：

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电和磁偶极矩相互作用与手性金属纳米粒子的几何不对称性引起的轨道角动量二色性

由手性物体对圆偏振光的响应引起的圆二色性（CD）已被广泛确立，近年来等离子体等离子大分子的强CD也引起了人们的兴趣。然而，他们对光是否也具有轨道角动量的反应尚不清楚。本文研究了在具有轨道和自旋角动量的光束照射下等离激元长方体-手性结构的二向色性。在不同的动量下观察到了可分辨的光谱。涡旋光束与光自旋相结合下的圆二色性增强。这种现象归因于纳米粒子的部分空间激发，由于由涡流光束的部分激发引起的感应的电磁模式和其他高阶模式的相互作用，同时导致了强烈的二向色性。这项研究为手性光与物质的相互作用以及轨道角动量的光的二色性提供了进一步的见解。