Tunable dual-band electromagnetically induced transparency-like effect in an all-dielectric metasurface based on quasi-bound states in the continuum

A spectrally separated and tunable dual-band electromagnetically induced transparency (EIT)-like effect with high quality factors (Q-factor) is investigated in an all-dielectric metasurface. The effect originates from the destructive interference between magnetic and electric dipole modes and the quasi-bound states in the continuum (QBICs) induced by symmetry breaking. The metasurface unit cell consists of a central Si cuboid bar flanked by two identical Si elliptical bars. By displacing the cuboid bar within the x-y plane, two symmetry-protected electric-quadrupole BICs are converted into quasi-BICs, exciting two distinct high-Q QBIC modes. The resulting dual transparency windows both exhibit a high transmittance of approximately 0.99, with calculated Q-factor as high as ∼ 0.8 × 10 4 and ∼ 1.6 × 10 4 , respectively. This work provides a robust platform for achieving high-performance, tunable multi-band EIT analogs, promising for applications in sensors and slow-light devices.