Planar chiral metasurfaces with maximal and tunable chiroptical response driven by bound states in the continuum

Shi, Tan; Deng, Zi‐Lan; GENG, GUANGZHOU; Zeng, Yixuan; Hu, Guangwei; Overvig, Adam; Li, J.; Qiu, Cheng‐Wei; Alù, Andrea; Kivshar, Yuri S.; Li, Xiangping

doi:10.21203/rs.3.rs-1194502/v1

Cited by 3 publications

(3 citation statements)

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“…The observed nonlinear CD exceeds the best-to-date values achieved for chiral nonlinear dielectric metasurfaces and oligomers. 28,29 Compared to the earlier studies of chiral nonlinear plasmonic metasurfaces showing strong nonlinear CD, 8,13,30−34 the demonstrated harmonic generation efficiency is sufficiently larger. Our results demonstrate how to achieve strong nonlinear chiroptical effects in resonant dielectric metasurfaces with the maximization of frequency conversion efficiency.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…48,60 As a result, for nonlinear applications the benefit of using quasi-BIC resonances over Mie resonances with a lower radiative Q factor remains unclear despite recent predictions. 28,61 In this article, we study dielectric planar resonant metasurfaces for the enhancement of both linear and nonlinear three-dimensional chiroptical effects. We fabricate a set of chiral nonlinear metasurfaces designed to support resonant Mie modes and quasi-BIC modes in the near-IR wavelength range.…”

Section: ■ Introductionmentioning

confidence: 99%

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Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

Koshelev

Tang

et al. 2023

ACS Photonics

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We study the resonant enhancement of linear and nonlinear chiroptical effects in planar silicon metasurfaces with an in-plane asymmetry supporting multipolar Mie resonances and quasi-bound states in the continuum (quasi-BICs). We demonstrate theoretically and observe in experiment the pronounced linear circular dichroism at the quasi-BIC resonances originating from the interaction of modes with the substrate. We further find that both local field enhancement and third-harmonic signal are large for Mie resonances and some quasi-BIC modes due to the critical coupling. We demonstrate experimentally a strong nonlinear chiroptical response associated with high efficiency of the third-harmonic generation and large nonlinear circular dichroism varying from +0.918 ± 0.049 to −0.771 ± 0.004 for the samples with different asymmetries. We reveal the nonreciprocal nature of nonlinear chirality governed by the microscopic symmetry of nonlinearities and macroscopic symmetries of the meta-atom and metasurface lattice. We believe our results suggest a general strategy for engineering nonlinear chiroptical response in dielectric resonant metasurfaces.

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Section: ■ Conclusionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

Koshelev

Tang

et al. 2023

ACS Photonics

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“…[ 1 ] Due to the diverging Q‐factor resonance and zero linewidth radiation, the optical BIC state has been touted as a breakthrough in recent decades. [ 2–4 ] Such properties are deemed to hold great promise for enhancing light–matter interactions and presenting various important applications in solid‐state lasers, [ 5 ] nonlinear phenomena, [ 6,7 ] high‐performance sensing, [ 8,9 ] chiral enhancement, [ 9–11 ] and narrowband filters. [ 12 ] Remarkably, upon slightly perturbing the protected condition, a BIC is transferred into a leaky supercavity mode with a finite lifetime, treated as a quasi‐BIC.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal Lineshape Tailoring in BIC‐Mediated Reconfigurable Metamaterials

Tong

et al. 2022

Adv Funct Materials

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The bound state in the continuum (BIC) is a unique nonradiating eigenstate that possesses rich physics and has attracted intensive attention in the field of optics and photonics. Actively tailoring BICs in a designable fashion is highly desired for diversified photonic devices. However, to date, most BIC‐assisted works have been limited to showing passive control in a fixed structure configuration without tuning the spectral responses. Here, a new scheme to construct a coupled photon cavity for spatiotemporal lineshape tailoring, in which a nonradiating BIC is embedded in the electromagnetic induced transparency (EIT) window, is proposed. This approach uses the phase transition of VO2 inclusions to induce spatial symmetry breaking, leading to the formation of a quasi‐BIC coupled EIT state. As an extra dimension for dynamic tuning, a layer with a transient photoconductivity much shorter than the photon lifetime is introduced to ultrafast switch the leaky modes for both EIT‐ and quasi‐BIC‐coupled EIT cavities. As the symmetry‐protected BIC and coupling effect are quite common in optical metasurfaces, this proposal provides a general paradigm to active steer spatiotemporal spectrum across multiple dimensions, which is thus believed to promote active metadevices for potential applications in modulators, sensors, filters, and dynamic imaging.

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Gap-plasmon-driven spin angular momentum selection of chiral metasurfaces for intensity-tunable metaholography working at visible frequencies

et al. 2022

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Tunable metasurfaces can replace conventional bulky active optical modules to realize practical flat optical devices such as lenses, LiDAR, holography, and augmented reality. However, tunable metasurfaces have generally been limited to switching between two distinct states. Here, we present liquid crystal (LC) integrated chiral metasurfaces, of which the metahologram intensity can be adjusted continuously between fully ‘on’ and ‘off’ states. The chiral metasurface consists of a gap-shifted split ring resonator (SRR), and exhibits spin angular momentum selection that reflects left-circularly-polarized light but perfectly absorbs right-circularly-polarized light (99.9%). The gap-shifted SRR realizes spin angular momentum selection using a metal–dielectric–metal multilayer structure and thereby induces a strong gap-plasmonic response, achieving the maximum calculated circular dichroism in reflection (CDR) of 0.99 at the wavelength of 635 nm. With the chiral metasurface, metaholograms are demonstrated with tunable intensities using LCs that change the polarization state of the output light using an applied voltage. With the LC integrated chiral metasurfaces, 23 steps of polarization are demonstrated for the continuous tuning of the holographic image intensity, achieving measured CDR of 0.91. The proposed LC integrated spin-selective chiral metasurface provides a new resource for development of compact active optical modules with continuously-tunable intensity.

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Planar chiral metasurfaces with maximal and tunable chiroptical response driven by bound states in the continuum

Cited by 3 publications

References 50 publications

Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

Resonant Chiral Effects in Nonlinear Dielectric Metasurfaces

Spatiotemporal Lineshape Tailoring in BIC‐Mediated Reconfigurable Metamaterials

Gap-plasmon-driven spin angular momentum selection of chiral metasurfaces for intensity-tunable metaholography working at visible frequencies

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