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论文类型：期刊论文

发表刊物：Phys. Rev. Lett

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：122

期号：15

页面范围：153907

关键字：无

DOI码：10.1103/PhysRevLett.122.153907

发表时间：2019-01-22

教研室：c716

摘要：Electromagnetic multipoles have been broadly adopted as a fundamental language throughout photonics, of which general features such as radiation patterns and polarization distributions are generically known, while their singularities and topological properties have mostly been left unattended. Here we map all the singularities of multipolar radiations of different orders, identify their indices, and show explicitly that the index sum over the entire momentum sphere is always 2, consistent with the Poincaré-Hopf theorem. Upon those revealed properties, we attribute the formation of bound states in the continuum to the overlapping of multipolar singularities with open radiation channels. This insight unveils a subtle equivalence between indices of multipolar singularities and topological charges of those bound states. Our work has fused two fundamental and sweeping concepts of multipoles and topologies, which can potentially bring unforeseen opportunities for many multipole-related fields within and beyond photonics.

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发布期刊链接：https://doi.org/10.1103/PhysRevLett.122.153907