Mie Resonance Driven Dual‐QBICs All‐Dielectric Metasurface for High Performance Multi‐Channel On–Off Modulation and Sensing

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ABSTRACT All‐dielectric metasurfaces supporting bound states in the continuum (BICs) provide promising avenues for achieving high‐Q resonances and multifunctional photonic devices. Here, we design a Si‐based metasurface composed of two tilted nanobars on a SiO 2 substrate. Full‐wave simulations reveal two quasi‐BICs (QBICs) and a Fano resonance, and these resonances are further validated by theoretical fitting using the Fano–Anderson model. The resonance mechanisms are elucidated through electromagnetic field distributions and Mie theory. By tuning structural and excitation parameters, high‐Q resonances (Q> 10 3 ) are achieved, and both the Q factor and resonant frequency exhibit strong robustness. Exploiting these properties, the metasurface provides six‐channel optical On–Off modulation with a maximum modulation depth (MD) of ∼100%, a minimum insertion loss (IL) of 0.016 dB, and an extinction ratio (ER) of 46.24 dB. Three‐channel refractive index sensing is also achieved, providing an absolute sensitivity of 326.63 nm/RIU, a relative sensitivity of 22.34/RIU, and a maximum figure of merit (FOM) of 2.1 × 10⁵. This work provides a practical approach to realize multi‐channel On–Off modulation and sensing in all‐dielectric metasurfaces, offering a valuable reference for the research of future multifunctional photonic devices.

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