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arXiv · 2510.13507

Unveiling spin-orbital angular momentum locking in photonic Dirac vortex cavities

Haitao Li·Jiusi Yu·Jiayu Fan·Shijie Kang·Bo Hou·Zhi-Kang Lin·Hanchuan Chen·Jian-Hua Jiang·Xiaoxiao Wu
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Abstract

Dirac vortices, originally studied in quantum field theories to predict localized zero-energy modes, were recently realized in photonics, leading to Dirac vortex cavities. With topological protection, Dirac vortex cavities offer robust single-mode large-area localized modes appealing for high-performance micro-lasers and other applications. As a spectrally-isolated single mode, the radiation of a Dirac vortex cavity mode was believed as having vanishing orbital angular momentum due to time-reversal symmetry. Here, we report the direct observation of orbital angular momentum radiation of a Dirac vortex cavity through spin-resolved measurements. Remarkably, we confirm the spin-orbital angular momentum locking in such radiation due to the spin-valley locking and inter-valley couplings. We demonstrate that the spin-orbital angular momentum locking is controlled by the chirality of the Kekul\'e modulation and propose design schemes for arbitrary-order single-mode OAM radiation.

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Haitao Li, Jiusi Yu, Jiayu Fan, Shijie Kang, Bo Hou, Zhi-Kang Lin, Hanchuan Chen, Jian-Hua Jiang, Xiaoxiao Wu. 2025-10-15. Unveiling spin-orbital angular momentum locking in photonic Dirac vortex cavities. https://doi.org/10.1002/lpor.202502844

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