biostudies-literatureZhou CNational Natural Science Foundation of China (National Science Foundation of China)84https://www.ebi.ac.uk/biostudies/studies/S-EPMC12830976biostudies-literatureUnknown15(1)Ultrahigh-Q optical resonances are the cornerstone of next-generation nanophotonic technologies, but their simultaneous realization of robustness and on-chip practicality remains a significant challenge. In this work, we present tetramer composite metasurfaces capable of supporting two distinct classes of ultrahigh-Q resonances: centroid symmetry-protected bound states in the continuum (SP-BICs) and area-conserved guided-mode resonances (GMRs). By employing a four-hole supercell design, we demonstrate that centering each hole within its subcell preserves C_4v symmetry, thereby enabling SP-BICs. Controlled lateral displacement transforms them into quasi-BICs with Q > 10⁶. Independently, enforcing diagonal-hole area conservation within the super unit cell generates degenerate GMRs Light, science & applicationsRobust ultrahigh-Q resonances in tetramer metasurfaces through centroid symmetry protection and area conservation.PMC1283097662222514623500731216400812474377Li GJin RHuang JZhou CHe HHuang LfalseRobust ultrahigh-Q resonances in tetramer metasurfaces through centroid symmetry protection and area conservation.Ultrahigh-Q optical resonances are the cornerstone of next-generation nanophotonic technologies, but their simultaneous realization of robustness and on-chip practicality remains a significant challenge. In this work, we present tetramer composite metasurfaces capable of supporting two distinct classes of ultrahigh-Q resonances: centroid symmetry-protected bound states in the continuum (SP-BICs) and area-conserved guided-mode resonances (GMRs). By employing a four-hole supercell design, we demonstrate that centering each hole within its subcell preserves C_4v symmetry, thereby enabling SP-BICs. Controlled lateral displacement transforms them into quasi-BICs with Q > 10⁶. Independently, enforcing diagonal-hole area conservation within the super unit cell generates degenerate GMRs 2026-01-01T00:00:00Z2026 Jan2026-06-06T22:30:26.78Z2026-06-06T03:10:45.533ZS-EPMC128309764157766110.1038/s41377-025-02164-7