Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum

The intrinsic chirality of natural materials is usually weak or absent. To enlarge circular dichroism, chiral metasurfaces supporting bound states in the continuum have been widely investigated. These chiral metasurfaces have demonstrated considerable potential to achieve high quality (Q) factors bu...

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Main Authors: Yang Li, Yu Mao, Shenwei Yin, Yi Zhou, Zefa Sun, Zhixiang Tang
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-04-01
Series:Frontiers in Physics
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Online Access:https://www.frontiersin.org/articles/10.3389/fphy.2025.1572555/full
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author Yang Li
Yu Mao
Shenwei Yin
Yi Zhou
Zefa Sun
Zhixiang Tang
author_facet Yang Li
Yu Mao
Shenwei Yin
Yi Zhou
Zefa Sun
Zhixiang Tang
author_sort Yang Li
collection DOAJ
description The intrinsic chirality of natural materials is usually weak or absent. To enlarge circular dichroism, chiral metasurfaces supporting bound states in the continuum have been widely investigated. These chiral metasurfaces have demonstrated considerable potential to achieve high quality (Q) factors but require ultra-small structure asymmetry and complicated fabrication processes. Here we propose a novel approach to break the in-plane symmetry of the structure by introducing refractive index perturbations. Furthermore, we demonstrate the efficient intrinsic chiral emission from resonant metasurfaces which are composed of two slant titanium dioxide (TiO2) bars arranged on a square lattice. Numerical calculations indicate that the intrinsic chirality of our metasurfaces at normal incidence achieves near-unity circular dichroism of 0.99 and an ultra-high Q factor exceeding 106. The relationship between the two perturbations and CD and Q factor has also been studied, offering the flexibility to enhance and tailor chirality and Q factor simultaneously. Our chiral metasurfaces may lead to applications in chiral lasers, chiral light detectors, chiral biosensing, and chiral nonlinear filters.
format Article
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institution DOAJ
issn 2296-424X
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publishDate 2025-04-01
publisher Frontiers Media S.A.
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series Frontiers in Physics
spelling doaj-art-3ce4fcb1e4ae4ce4965312852e24c7e82025-08-20T03:09:55ZengFrontiers Media S.A.Frontiers in Physics2296-424X2025-04-011310.3389/fphy.2025.15725551572555Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuumYang LiYu MaoShenwei YinYi ZhouZefa SunZhixiang TangThe intrinsic chirality of natural materials is usually weak or absent. To enlarge circular dichroism, chiral metasurfaces supporting bound states in the continuum have been widely investigated. These chiral metasurfaces have demonstrated considerable potential to achieve high quality (Q) factors but require ultra-small structure asymmetry and complicated fabrication processes. Here we propose a novel approach to break the in-plane symmetry of the structure by introducing refractive index perturbations. Furthermore, we demonstrate the efficient intrinsic chiral emission from resonant metasurfaces which are composed of two slant titanium dioxide (TiO2) bars arranged on a square lattice. Numerical calculations indicate that the intrinsic chirality of our metasurfaces at normal incidence achieves near-unity circular dichroism of 0.99 and an ultra-high Q factor exceeding 106. The relationship between the two perturbations and CD and Q factor has also been studied, offering the flexibility to enhance and tailor chirality and Q factor simultaneously. Our chiral metasurfaces may lead to applications in chiral lasers, chiral light detectors, chiral biosensing, and chiral nonlinear filters.https://www.frontiersin.org/articles/10.3389/fphy.2025.1572555/fullmetasurfacechiralitycircular dichroismBICshigh-efficiency
spellingShingle Yang Li
Yu Mao
Shenwei Yin
Yi Zhou
Zefa Sun
Zhixiang Tang
Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
Frontiers in Physics
metasurface
chirality
circular dichroism
BICs
high-efficiency
title Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
title_full Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
title_fullStr Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
title_full_unstemmed Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
title_short Permittivity-asymmetric chiral metasurfaces empowered by bound states in the continuum
title_sort permittivity asymmetric chiral metasurfaces empowered by bound states in the continuum
topic metasurface
chirality
circular dichroism
BICs
high-efficiency
url https://www.frontiersin.org/articles/10.3389/fphy.2025.1572555/full
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AT yizhou permittivityasymmetricchiralmetasurfacesempoweredbyboundstatesinthecontinuum
AT zefasun permittivityasymmetricchiralmetasurfacesempoweredbyboundstatesinthecontinuum
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