Design of Chiral Metasurfaces with Independent Control of Quality Factor Based on Guided-Mode Resonance

Chiral metasurfaces with high quality factors (Q-factors) have significant application value in fields such as polarization detection and chiral sensing. However, for most current chiral metasurfaces, the Q-factor and circular dichroism (CD) are intrinsically intertwined due to their common structural origin, which fundamentally hinders their independent tuning. To address this challenge, a planar chiral metasurface structure based on guided-mode resonance (GMR) is proposed. Positional offsets along two orthogonal directions are introduced within a dual-dielectric-column unit to generate an intrinsic chiral response, while a scale factor s is used to modify the dimensions of one dielectric column with the relative positional asymmetry fixed. The results show that the Q-factor can be continuously tuned from 4073 to 28,142 over the primary tuning range 0.7 ≤ s ≤ 1.4, while the CD remains above 0.9. Moreover, the structure maintains a tunable Q-factor and high CD under weak material loss and the considered structural deviations. Overall, these results demonstrate a single-scale-factor approach for continuous Q-factor tuning while preserving a strong and stable chiral response.