Enhanced optical activity using the orbital angular momentum of structured light
Enhanced optical activity using the orbital angular momentum of structured light
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DOI：
10.1103/physrevresearch.1.033080
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发表时间：
2019-11-06
影响因子：
4.2
通讯作者：
Andrews, David L.
中科院分区：
文献类型：
--
作者：
Forbes, Kayn A.;Andrews, David L.
最近的分子光子学研究突出了具有轨道角动量（OAM）的相位结构光在与物质相互作用时的重要作用。这些研究发现手旋光效应对分子和纳米颗粒对扭曲光子的吸收和散射中的光学OAM的幅度和符号都很敏感。具体地说，它已被示出如何与材料中的电四极跃迁接合的结构化光束允许对扭曲光的螺旋相位结构的独特灵敏度。在本文中，我们强调实验方法和系统，适合观察和量化的手光学过程的瑞利和拉曼的光学活性，和新发现的圆涡旋差分散射效应与结构光，包括离轴光束对准的重要性，输入光束强度结构，多极矩，和散射角的依赖性。它示出，与一个明智的选择的实验装置，手握光学效应，与输入光束的拓扑电荷l或OAM的规模，使光学活性信号被增强，并显着超过那些仅仅基于圆偏振，非结构化光。因此，新技术提供了一个非常有用和重要的光谱应用结构光。现在突出显示具有高OAM的完美光学涡旋在这种旋光性效应中将发挥的更详细的作用，以显示实验应用的巨大范围，特别是在振动旋光性和手性光谱中。
Recent molecular photonics studies have highlighted the significant role that phase-structured light possessing orbital angular momentum (OAM) can have when interacting with matter. These studies discovered chiroptical effects sensitive to both the magnitude and sign of the optical OAM in both the absorption and scattering of twisted photons by molecules and nanoparticles. Specifically, it has been shown how a structured beam engaging with electric-quadrupole transitions in the material allows a unique sensitivity to the helical-phase structure of twisted light. In this paper we highlight experimental methodologies and systems suitable to observe and quantify the chiroptical processes of Rayleigh and Raman optical activity, and the newly discovered circular-vortex differential scattering effect with structured light-including the importance of off-axis beam alignment, input beam intensity structure, multipolar moments, and scattering-angle dependencies. It is shown that with a judicious choice of experimental setup, chiroptical effects that scale with the topological charge l or OAM of the input beam enable optical activity signals to be enhanced and significantly exceed those based solely on circularly polarized, unstructured light. The new technique thus offers a highly useful and important spectroscopic application of structured light. The more detailed role that perfect optical vortices with high OAM will play in such optical activity effects is now highlighted, to show where there is substantial scope for experimental application, specifically in vibrational optical activity and chiral spectroscopy.