Strong Coupling and Electromagnetically Induced Transparency in Multiple-BIC-Driven Metasurfaces

Photonic quasi-bound states in the continuum (quasi-BICs) provide an excellent platform for strong light-matter interactions in nanophotonics. In this work, we numerically and experimentally demonstrate that the Si nanorod dimer metasurface offers a new paradigm for realizing multiple wavelength-stabilized and quality-factor-tunable quasi-BICs, through a unique symmetry breaking method that does not alter the metasurface volume. A pronounced electromagnetically induced transparency (EIT) effect, exhibiting a group time delay of 6.7 ps, and strong coupling accompanied by characteristic anticrossing Rabi splitting are realized based on the hybridization between a bright mode and the neighboring quasi-BIC within this multiresonant metasurface. Intriguingly, a sharp transparency window, with tunable bandwidth but a stable wavelength, is achieved. All numerical results are validated by experimental demonstration. Our findings provide a recipe for realizing wavelength-stabilized, quality-factor-tunable quasi-BICs and an EIT-like effect. Our results would find utility in slow light, quantum storage, and nonlinear optics.