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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.
Li et al. (2025) studied this question.