连续谱中束缚态的拓扑结构：来自主导辐射的角结构
Topology of bound states in the continuum from the angular structure of leading radiation
- Virginia Tech（弗吉尼亚理工大学）
- City University of Hong Kong（香港城市大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文揭示连续谱中束缚态的主导辐射角结构编码拓扑性质，可识别拓扑电荷跃迁条件及新BIC族分叉，并在C6v结构中直接发现q=-5的超BIC，具有超高品质因子，应用于拓扑光子学。
AI中文摘要：
我们证明，与连续谱中束缚态（BIC）相关的主导辐射的角结构直接编码了拓扑性质，识别了拓扑电荷跃迁的临界条件，并揭示了结构变化下新BIC族的分叉。对于Γ点的BIC，旋转和时间反演对称性决定了主导辐射的允许角谐波，从而决定了可能的拓扑电荷。作为示例，我们直接在具有三角晶格圆形空气孔的C6v介电板中识别出一个q=-5的BIC，而无需计算邻近共振或跟踪BIC的合并。该BIC也是一个超BIC，在动量空间的所有方向上展现出超高品质因子Q~1/δ^10，其中δ为波矢失谐参数。我们还使用C4v结构分析了拓扑跃迁及相关的离Γ点BIC的分叉。我们的结果可能在谐振、结构化和拓扑光子学中找到应用。
英文摘要：
We show that the angular structure of the leading radiation associated with a bound state in the continuum (BIC) directly encodes topology, identifies the critical conditions for topological-charge transitions, and reveals the bifurcation of new BIC families under structural variations. For at-$Γ$ BICs, rotational and time-reversal symmetries determine the allowed angular harmonics of the leading radiation and hence the possible topological charges. As an example, we directly identify a BIC with $q=-5$ in a $C_{6v}$ dielectric slab with a triangular lattice of circular air holes, without computing nearby resonances or tracking the merging of BICs. This BIC is also a super-BIC, exhibiting an ultrahigh quality factor $Q\sim 1/δ^{10}$ along all directions in momentum space, where $δ$ is the wavevector detuning parameter. We also use a $C_{4v}$ structure to analyze a topological transition and the associated bifurcation of off-$Γ$ BICs. Our results may find applications in resonant, structured, and topological photonics.
