Enhanced chiral sensing from an all-dielectric metasurface with dual hole defects based on bound states in the continuum

We demonstrate the enhancement of chiral sensing based on bound states in the continuum (BIC) by introducing dual hole defects in an all-dielectric metasurface. The relative position of dual hole defects will influence the scaling law of quality factors with the same asymmetry degree and also enable the inversion of circular dichroism (CD) from -0.87 to a near-unity state of 0.99. Eigenmode analysis and transmission spectrum calculations reveal that the chiral response improves the figure of merit by a factor of 1.5, compared to a transmission response characterized by an ultrahigh quality factor of 2.14 × 10⁵, paving the way for the highly precise chiral sensing applications.