【摘要】 光子晶体平板等开放边界周期性光子结构是拓扑光子学的重要研究平台，其在动量空间中形成具有丰富拓扑特征的偏振场。在动量空间偏振场中，起核心拓扑作用的奇点——涡旋奇点，与一类特殊的光学模式——连续谱中束缚态（BIC）密切相关。本文基于能带理论，系统阐述了动量空间偏振场的形成机制及其涡旋奇点的拓扑性质，并通过Friedrich-Wintgen耦合机制揭示了偏振奇点与BIC的内在联系。基于这一理论框架，详细分析了BIC及其偏振场在光学涡旋生成、自旋-轨道耦合和偏振转换中的独特优势，并系统讨论了通过结构参数调控实现BIC演化与合并的机制。针对当前该领域最受关注的手性光学响应问题，重点分析了对称性破缺和磁光效应两种调控途径的物理机制与最新进展，阐述了从对称保护BIC到手性准BIC、自旋-轨道锁定BIC以及Janus BIC等模式的演化过程，为基于BIC的新一代手性光子器件设计提供了理论指导和发展路径。更多还原

【Abstract】 Periodic photonic structures with open boundaries, such as photonic crystal slabs, serve as important platforms for studying topological photonics, as they generate polarization fields in momentum space that exhibit rich topological features. Within these momentum-space polarization fields, vortex singularities—the topological singularities that play a pivotal role in the topological characteristics—are intimately connected to a special class of optical modes known as bound states in the continuum(BICs). Grounded in band theory, this review systematically elucidates the formation mechanisms of momentum-space polarization fields and the topological properties of their vortex singularities. Through the FriedrichWintgen coupling mechanism, we reveal an intrinsic connection between polarization singularities and BICs. Based on this theoretical framework, we provide a detailed analysis of the unique advantages of BICs and their associated polarization fields in optical vortex generation, spin-orbit coupling, and polarization conversion. The mechanisms for achieving BIC evolution and merging through structural parameter control are systematically discussed. To address the current focus on chiral optical responses, this review emphasizes the physical mechanisms and latest advances in two modulation approaches: symmetry breaking and magneto-optical effects. We elucidate the evolutionary processes from symmetryprotected BIC to chiral quasi-BIC, spin-orbit locked BIC, and Janus BIC, providing theoretical guidance and developmental pathways for designing next-generation chiral photonic devices based on BICs.更多还原