Quasi-BICs triggered by Brillouin zone folding toward tunable terahertz circular dichroism.

Authors

Xinyi Niu, Jiusheng Li, Guo-Hua Qiu

Published in

Physical chemistry chemical physics : PCCP. Sep 21, 2026. Epub Sep 21, 2026.

Abstract

Chiral quasi-bound states in the continuum (QBICs) have demonstrated significant potential in light-matter interaction research. However, chiral responses are primarily constrained by the rapid decay of the quality factor (Q) under symmetry breaking, making the stability of high Q-values particularly crucial. In this paper, we propose a novel high-Q QBIC dual-ring structure, which employs Brillouin zone folding (BZF) to fold the bound states at the edges of the first Brillouin zone into the radiative continuum. While maintaining circular dichroism (CD) unchanged, it achieves independent control over the Q-factor. This structure can achieve a high Q-factor of 10⁶, along with nearly perfect CD response and 100% depth modulation. This stable high-Q chiral metasurface technology shows promising applications in fields such as terahertz switches and chiral polarization detection.

PMID:
42765199
Bibliographic data and abstract were imported from PubMed on 21 Sep 2026.

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