A triple Fano resonance Si-graphene metasurface for multi-channel tunable ultra-narrow band sensing.

In this work, a dielectric metasurface composed of a silicon nanodisk etched with a square hole is proposed. By introducing symmetry breaking, the symmetry-protected bound states in the continuum (SP-BIC) is transformed into a quasi-BIC (Q-BIC), simultaneously inducing triple Fano resonances in the near-infrared light band corresponding to one dipole and two Q-BIC resonances. The characteristics of Q-BIC resonances are elucidated through multipole decomposition and near-field distribution analysis.