Wang Jiajun, Wang Xinhao, Wu Zhaochen, Zhao Xingqi, Wu Shunben, Shi Lei, Kivshar Yuri, Zi Jian
Fudan University, State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Shanghai 200433, China.
Fudan University, Institute for Nanoelectronic Devices and Quantum Computing, Shanghai 200438, China.
Phys Rev Lett. 2025 Apr 4;134(13):133802. doi: 10.1103/PhysRevLett.134.133802.
Bound states in the continuum (BICs) are exotic optical topological singularities that defy the typical radiation within the continuum of radiative modes and carry topological polarization vortices in momentum space. Enabling ultrahigh quality factors, BICs have been applied in realizing lasing and Bose-Einstein condensation, and their momentum-space vortex topologies have been exploited in passive systems, revealing novel spin-orbit photonic effects. Here, we demonstrate the inherent spin-orbit locking in topological BIC lasing. Utilizing C_{4v} and C_{6v} photonic crystal slabs, we achieve distinct spin-orbit locking combinations in BIC lasing of +1 and -2 topological charges. Spin-orbit locking phenomena are directly observed by momentum-space spin-dependent self-interference patterns. Real-space spin separations, as a counterpart of the momentum-space spin-orbit locking, are also revealed. Our results reveal new spin-orbit locking phenomena in BIC lasing, presenting significant potential for advancements in topological photonic source applications.
连续域束缚态（BICs）是一类奇特的光学拓扑奇点，它们在辐射模式连续谱中违背了典型的辐射规律，并在动量空间中携带拓扑极化涡旋。由于具有超高的品质因数，BICs已被应用于实现激光发射和玻色 - 爱因斯坦凝聚，并且它们在动量空间中的涡旋拓扑结构已在无源系统中得到利用，揭示了新颖的自旋 - 轨道光子效应。在此，我们展示了拓扑BIC激光中固有的自旋 - 轨道锁定。利用具有C₄ᵥ和C₆ᵥ对称性的光子晶体平板，我们在拓扑电荷为 +1和 -2的BIC激光中实现了不同的自旋 - 轨道锁定组合。通过动量空间中自旋相关的自干涉图案直接观察到自旋 - 轨道锁定现象。作为动量空间中自旋 - 轨道锁定的对应物，实空间中的自旋分离也被揭示出来。我们的结果揭示了BIC激光中新型的自旋 - 轨道锁定现象，为拓扑光子源应用的发展展现出巨大潜力。
