A strategy to improve the robustness of bound states in the continuum

Bound states in the continuum (BICs) supported by dielectric metasurfaces have significantly propelled the progress in optical technologies, notably for manipulating potent light-matter interactions. However, achieving a robust quasi-BIC mode with high Q factor by adjusting geometric parameters remains a challenge, primarily the Q factors strongly depend on the asymmetric parameters and the stringent fabrication requirements. Here, we propose a novel strategy to enhance the robustness of the Q factor through the continuous excitation of the magnetic dipole mode with low energy loss. Through a specialized multi-cell structure, the nanoarrays can continuously excite the magnetic dipoles contributed by different structural components over a broad range of geometrical parameters, exhibiting exceptional robustness and high quality resonance. This work provides a theoretical scheme that offers new directions for obtaining robust high Q resonances and developing potential applications for high-performance optical devices.