Reusable high-<i>Q</i> plasmonic metasurface

Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices. However, these applications are often limited by inherent metallic losses. Significant efforts have been made to achieve high quality-factor ( Q -factor) resonances in plasmonic metasurfaces, particularly through surface lattice resonances (SLRs) and bound states in the continuum (BICs). Despite these advances, a direct comparison between these two mechanisms remains unexplored. Here, we report a reusable plasmonic metasurface that supports multiple high- Q resonances by leveraging hybrid plasmonic–photonic modes. By systematically tuning the lattice constant and dielectric cladding thickness, we achieve substantial Q -factor enhancements of both SLRs and BICs in a monolithic device with a small footprint of 200 μm ×200 μm by using an incoherent light source. A direct comparison between these two resonances is also discussed. This high- Q performance holds significant promise for applications in sensing, lasing, and nonlinear and quantum optics, paving the way for the development of next-generation nanophotonic devices.