biostudies-literatureUnknown10(46)Lv WC points, circular polarization in momentum space, play crucial roles in chiral wave manipulations. However, conventional approaches of achieving intrinsic C points using photonic crystals with broken symmetries suffer from a low <i>Q</i> factor and high sensitivity to structural geometry, rendering them fragile and susceptible to perturbations and disorders. We report magneto-optical (MO) bound states in the continuum (BICs) with a symmetry-preserved planar photonic crystal. We achieve intrinsic C points at Γ point that are robust against variation in both structural geometry and external magnetic field. MO coupling between two modes induces Zeeman splitting, leading to MO BICs and quasi-BICs with circular eigenstates for high-<i>Q</i> chiral responses. Furthermore, switchable C point hanScience advanceseads0157https://www.ebi.ac.uk/biostudies/studies/S-EPMC11566988biostudies-literatureRobust generation of intrinsic C points with magneto-optical bound states in the continuum.PMC11566988Lv WHuang JGenevet PSong QQin HSu ZLi BZhang CShi YfalseRobust generation of intrinsic C points with magneto-optical bound states in the continuum.C points, circular polarization in momentum space, play crucial roles in chiral wave manipulations. However, conventional approaches of achieving intrinsic C points using photonic crystals with broken symmetries suffer from a low <i>Q</i> factor and high sensitivity to structural geometry, rendering them fragile and susceptible to perturbations and disorders. We report magneto-optical (MO) bound states in the continuum (BICs) with a symmetry-preserved planar photonic crystal. We achieve intrinsic C points at Γ point that are robust against variation in both structural geometry and external magnetic field. MO coupling between two modes induces Zeeman splitting, leading to MO BICs and quasi-BICs with circular eigenstates for high-<i>Q</i> chiral responses. Furthermore, switchable C point han2024-01-01T00:00:00Z2024 Nov2025-04-21T22:16:03.215Z2025-04-05T18:40:46.076ZS-EPMC115669883954660510.1126/sciadv.ads0157