Spin-Orbit-Locking Chiral Bound States in the Continuum

Abstract

Bound states in the continuum (BICs), which are confined optical modes exhibiting infinite quality factors and carrying topological polarization configurations in momentum space, have recently sparked significant interest across both fundamental and applied physics.} Here we show that breaking time-reversal symmetry by external magnetic field enables a new form of chiral BICs with spin-orbit locking. Applying a magnetic field to a magneto-optical photonic crystal slab lifts doubly degenerate BICs into a pair of chiral BICs carrying opposite pseudo-spins and orbital angular momenta. Multipole analysis verifies the non-zero angular momenta and reveals the spin-orbital-locking behaviors. In momentum space, we observe ultrahigh quality factors and near-circular polarization surrounding chiral BICs, enabling potential applications in spin-selective nanophotonics. Compared to conventional BICs, the magnetically-induced chiral BICs revealed here exhibit distinct properties and origins, significantly advancing the topological photonics of BICs by incorporating broken time-reversal symmetry.

References in corpus (29)

• Topological Photonics
• Spin-orbit interactions of light
• Asymmetric metasurfaces with high-$Q$ resonances governed by bound states in the continuum
• Resonantly Trapped Bound State in the Continuum Laser
• Topological nature of bound states in the radiation continuum
• Topologically Enabled Ultra-high-Q Guided Resonances Robust to Out-of-plane Scattering
• Observation of intrinsic chiral bound states in the continuum
• Exciton-polariton topological insulator
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• Chiral Quasi-Bound States in the Continuum
• Observation of optical vortices in momentum space
• Multipolar origin of bound states in the continuum
• Selection Rules for Quasi-Bound States in the Continuum
• Generation and Annihilation of Topologically-Protected Bound States in the Continuum and Circularly-Polarized States by Symmetry Breaking
• Anisotropy-induced photonic bound states in the continuum
• Polariton Bose-Einstein condensate from a Bound State in the Continuum
• Optically controlling the emission chirality of microlasers
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• Singular points of polarizations in the momentum space of photonic crystal slabs
• Singularities and Poincaré Indexes of Electromagnetic Multipoles
• Effective theory of quadratic degeneracies
• Topological unidirectional guided resonances emerged from interband coupling
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Cited by in corpus (4)

• Observation of robust intrinsic C points generation with magneto-optical bound states in the continuum
• Inherent spin-orbit locking in topological bound state in the continuum lasing
• Light-cone-proximal quasi-BICs for chiral lasing at grazing angles
• Magnetically Tunable Chiral Phonon Polaritons with Magneto-optical Bound States in the Continuum