Chirality has substantial applications in the fields of medicine, biology, and physics. Previous studies of strong chiral responses mostly involved complex 3D plasmonic nanostructures. In this study, we demonstrate a planar plasmonic composite nanostructure to achieve large circular dichroism (CD) effect by tuning the coupling effect. By introducing a rectangular block to an L-shaped nanostructure, the resonance wavelength at different handed circular polarization incidences is separated. At the same time, the resonance of the composite nanostructure is observable for one circularly polarized light excitation but subdued for another circularly polarized light excitation, leading to a large CD effect. In addition, the CD effects of composite nanostructures are strongly dependent on the structural parameters. These results could provide a novel approach to tune resonance wavelengths and achieve larger CD effects.

中文翻译：

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电场耦合对复合纳米结构圆二色性的影响

手性在医学，生物学和物理学领域具有重要的应用。先前对强手性反应的研究主要涉及复杂的3D等离子体纳米结构。在这项研究中，我们演示了通过调整耦合效应来实现大圆二色性（CD）效应的平面等离子体复合纳米结构。通过将矩形块引入L形纳米结构中，可以分离不同圆偏振入射角处的共振波长。同时，对于一种圆偏振光激发，可观察到复合纳米结构的共振，但对于另一种圆偏振光激发却受到抑制，从而导致大的CD效应。此外，复合纳米结构的CD效应在很大程度上取决于结构参数。