Ni Jincheng, Liu Shunli, Hu Guangwei, Hu Yanlei, Lao Zhaoxin, Li Jiawen, Zhang Qing, Wu Dong, Dong Shaohua, Chu Jiaru, Qiu Cheng-Wei
CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui 230027, China.
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.
ACS Nano. 2021 Feb 23;15(2):2893-2900. doi: 10.1021/acsnano.0c08941. Epub 2021 Jan 26.
Optical activity, demonstrating the chiral light-matter interaction, has attracted tremendous attention in both fundamental theoretical research and advanced applications of high-efficiency enantioselective sensing and next-generation chiroptical spectroscopic techniques. However, conventional chiroptical responses are normally limited in large assemblies of chiral materials by circularly polarized light, exhibiting extremely weak chiroptical signals in a single chiral nanostructure. Here, we demonstrate that an alternative chiral freedom of light-orbital angular momentum-can be utilized for generating strong helical dichroism in single chiral nanostructures. The helical dichroism by monochromatic vortex beams can unambiguously distinguish the intrinsic chirality of nanostructures, in an excellent agreement with theoretical predictions. The single planar-chiral nanostructure can exhibit giant helical dichroism of ∼20% at the visible wavelength. The vortex-dependent helical dichroism, expanding to single nanostructures and two-dimensional space, has implications for high-efficiency chiroptical detection of planar-chiral nanostructures in chiral optics and nanophotonic systems.
旋光性展示了手性光与物质的相互作用，在基础理论研究以及高效对映选择性传感和下一代手性光学光谱技术的先进应用中都引起了极大关注。然而，传统的手性光学响应通常在大量手性材料集合体中受圆偏振光限制，在单个手性纳米结构中表现出极其微弱的手性光学信号。在此，我们证明光的轨道角动量这种替代的手性自由度可用于在单个手性纳米结构中产生强烈的螺旋二向色性。单色涡旋光束产生的螺旋二向色性能够明确区分纳米结构的固有手性，与理论预测高度吻合。单个平面手性纳米结构在可见光波长下可表现出约20%的巨大螺旋二向色性。这种与涡旋相关的螺旋二向色性扩展到单个纳米结构和二维空间，对手性光学和纳米光子系统中平面手性纳米结构的高效手性光学检测具有重要意义。
