Chiral quasi-bound states in the continuum based on hybrid metasurfaces for enantiomer analysis

Optical sensing offers an effective and promising method for molecular detection, yet quantifying enantiomer concentrations remains a critical challenge. Here, we present a SiC-Au hybrid metasurface supporting the chiral quasi-bound state in the continuum (BIC) mode, manipulated by the rotation angle <i>φ</i>_L. An enantiomer analysis method is proposed to obtain d- and l-enantiomer concentrations from peak wavelength and intensity of circular dichroism (CD). At <i>φ</i>_L = 20°, the hybrid design yields a strong CD value (0.62) and a high quality (<i>Q</i>) factor (295). Moreover, the electric field (EF) and the optical chirality (<i>C</i>) are both strongly localized near the structural surface, enhancing the sensitivity of refractive index (RI) and CD sensing (<i>S</i>_RI = 436 nm/RIU, <i>S</i>_CD = -247). Compared to the all-dielectric metasurface, the hybrid design achieves 11- and 80-fold improvements in <i>S</i>_RI and <i>S</i>_CD, enabling label-free, sensitive, and rapid detection for environmental, biomedical, and industrial applications.