Toroidal Quasi-BIC Circular dichroism (CD) is vital for chiral light-matter interactions but weak in natural materials. In the Research Article (DOI: 10.1002/adom.202501368), Haitao Li, Xiaoxiao Wu, and co-workers demonstrate a truly planar metasurface enabling giant CD via a toroidal-dipole-dominated chiral Q-BIC. It achieves near-unity CD and fast, angle-sensitive switching, promising for polarization- and angle-selective photonic devices.
Kang et al. (Sun,) studied this question.