Bound States in the Continuum Underpin Near-Lossless Maximum Chirality in Dielectric Metasurfaces

Maxim V. Gorkunov*, Alexander A. Antonov, Vladimir R. Tuz, Anton S. Kupriianov, Yuri S. Kivshar*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    105 Citations (Scopus)

    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 languageEnglish
    Article number2100797
    JournalAdvanced Optical Materials
    Volume9
    Issue number19
    DOIs
    Publication statusPublished - 4 Oct 2021

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