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Global Mie Scattering: Polarization Morphologies and the Underlying Topological Invariant.
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论文类型：期刊论文
发表刊物：ACS omega
所属单位：光电学院，国家光电研究中心
刊物所在地：美国
学科门类：工学
项目来源：自然科学基金
文献类型：J
卷号：5
期号：23
页面范围：14157-14163
关键字：Photonics,Scattering,Magnetic properties,Molecular structure,Polarization
DOI码：10.1021/acsomega.0c01843
发表时间：2020-06-02
教研室：c716
摘要：In various subdisciplines of optics and photonics, Mie theory has been serving as a fundamental language and playing indispensable roles widely. Conventional studies related to Mie scattering largely focus on local properties such as differential cross sections and angular polarization distributions. Though spatially integrated features of total cross sections in terms of both scattering and absorption are routine for investigations, they are intrinsically dependent on the specific morphologies of both the scattering bodies and the incident waves, consequently manifesting no sign of global invariance. Here, we propose a global Mie scattering theory to explore topological invariants for the characterization of scatterings by any obstacles of arbitrarily structured or polarized coherent light. It is revealed that, independent of distributions and interactions among the scattering bodies of arbitrary geometric and optical parameters, in the far field, inevitably, there are directions where the scatterings are either zero or circularly polarized. Furthermore, for each such singular direction, we can assign a half-integer index and the index sum of all those directions are bounded to be a global topological invariant of 2. The global Mie theory we propose, which is mathematically simple but conceptually penetrating, can render new perspectives for light scattering and topological photonics in both linear and nonlinear regimes and would potentially shed new light on the scattering of acoustic and matter waves of various forms.
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