Abstract
Metasurfaces without a mirror symmetry may exhibit chiral electromagnetic response that differs substantially from any type of polarization transformation. A typical design of chiral metasurfaces is based on a complex arrangement of meta-atoms with chiral shapes assembled into rotationally symmetric arrays. Here it is demonstrated that, in a sharp contrast to our intuition, metasurfaces that break all point symmetries can outperform their rotationally symmetric counterparts and exhibit near-lossless maximum chirality. The authors employ the special type of high-quality-factor resonances—bound states in the continuum (BICs)—that are manifested in physical systems as quasi-BICs, and allow engineering the coupling of light with resonant metasurfaces to achieve maximum chirality. A dielectric metasurface composed of pairs of rectangular bars is designed that fully transmits one circular polarization of light and resonantly reflects the other circular polarization without any polarization conversion. Proof-of-concept experimental results that confirm directly the prediction of maximum chiral response of the BIC-empowered asymmetric resonant dielectric metasurfaces are presented.
Original language | English |
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Article number | 2100797 |
Journal | Advanced Optical Materials |
Volume | 9 |
Issue number | 19 |
DOIs | |
Publication status | Published - 4 Oct 2021 |