Chiral Guided Mode Resonance with Independently Controllable Quality Factor and Circular Dichroism

Chiroptical resonances with high quality factors (Q factors) have recently garnered extensive attention due to their broad applications in lasing and optical sensing. However, the independent manipulation of the Q factor and circular dichroism (CD) of chiroptical resonances has rarely been proposed. Here, we demonstrate that the Q factor and CD of guided mode resonance (GMR) can be independently manipulated by simply varying two structural parameters in a diatomic dielectric metasurface grating, offering a new paradigm for chiroptical resonance manipulation. We reveal that the independent manipulation of the Q factor and CD of the GMR is attributed to the modulation of the collective interference of guided mode fields excited by the two orthogonal linearly polarized normal incidence. GMRs with a Q factor of 183 and CD of ±0.62 have been experimentally validated, which is comparable to state-of-the-art chiral quasi-BICs. These findings provide a powerful platform for the realization of high-Q chiroptical resonances.