Observation of intrinsic chiral bound states in the continuum

Chen, Yang; Deng, Huachun; Sha, Xinbo; Chen, Weijin; Wang, Ruize; Chen, Yuhang; Wu, Dong; Chu, Jiaru; Kivshar, Yuri S.; Xiao, Shumin; Qiu, Cheng‐Wei

doi:10.1038/s41586-022-05467-6

Cited by 235 publications

(79 citation statements)

References 38 publications

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“…This research represents an effective approach for wavefront control and shall significantly accelerate the practical applications of meta-devices or meta-systems. [47][48][49]…”

Section: Discussionmentioning

confidence: 99%

Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Liu

Jiang

et al. 2023

Laser & Photonics Reviews

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Diffractive gratings are crucial elements for optical systems but suffer from rapid power drop at large angles. Recently, metagratings have shown their capability of deflecting light in an arbitrary direction. However, the experimental efficiency at large-angle is still low and the zeroth-order crosstalk is difficult to suppress. Here a new approach for large-angle and high-efficiency anomalous refraction in the visible spectrum is demonstrated. By introducing out-of-plane asymmetry, it is shown that meta-atoms with simple configurations have similar degrees of freedom as their topologically optimized counterparts. Consequently, the slanted titanium dioxide (TiO 2 ) metagratings can steer light to 80°with high relative efficiency (98.5%) and absolute efficiency (89.5%), which represents the ratio of the energy in target diffraction order to the total transmittance energy and to the total incident energy, respectively. Most importantly, the simple configurations make the TiO 2 metagratings easy to fabricate, and the experimental efficiency for large (80°) angle of refraction is preserved at a considerably high value of 94.0% (relative) and 83.6% (absolute). This approach represents an effective route in meta-devices and shall trigger new classes of high-performance nanophotonic systems.

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“…This research represents an effective approach for wavefront control and shall significantly accelerate the practical applications of meta-devices or meta-systems. [47][48][49]…”

Section: Discussionmentioning

confidence: 99%

Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Liu

Jiang

et al. 2023

Laser & Photonics Reviews

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“…Artificial chiral material, i.e., chiral metamaterial that is capable of enormously amplifying such chiral effects, becomes one of the vital subfields of the nanophotonic community. , To date, chiral metamaterials have been used to realize the chiral optical source, , negative refraction, , circular polarizer, biosensing, , beam splitter, watermarking, , and circular polarized light detection, − resembling powerful artificial tools to engineer the chiral light–matter interaction. In general, the conventional ways to introduce chirality of metamaterials are based on planer chiral structures, , twisted structures, − helix structures, − and the helical arrangement of metal nanoparticles. − Since most of the artificial metamaterials are not immune to fabrication disorder and imperfection, elaborate nanotechnology and precise fabrication are deemed a necessity to maximize chiroptical response. − …”

Section: Introductionmentioning

confidence: 99%

Localized Spontaneous Chiroptical Response in Disordered Plasmonic Nanoaggregates

Ouyang

et al. 2023

ACS Photonics

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Metamaterials exhibiting orders-of-magnitude enhanced artificial chiroptical response than natural counterparts have been intensely investigated. The underlying principle of these chiral responses heavily hinges on an elaborate nanostructure fabrication to generate either intrinsic geometry chirality or handedness-dependent mode interference. Here, we unveil that localized spontaneous chiroptical response can be leveraged by plasmonic nanoaggregates with a disordered coupling effect. The near-field coupling among disordered individual gold nanoparticles leads to localized hot spots that are sensitive to the handedness of light. As a consequence, the nearby nanoparticles showcase nearunity circular dichroism in linear absorption to left-and rightcircularly polarized light. It directly leads to a subsequent selective photothermal deformation of plasmonic nanoparticles, which produces prominent nonlinear circular dichroism in two-photon fluorescence by circular polarization beams. Such localized spontaneous chirality is then experimentally evidenced by nanoscale multiplexing watermarks in polychromatic beams with left-and right-circular polarizations. Our results might open a new strategy to tailor the chiroptical response in disordered photonic systems and facilitate the study of chiral light−matter interactions at the deepsubwavelength regime.

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“…Recent research has extensively explored the utilization of quasi-BICs for manipulating spontaneous emission and lasing. − These quasi-BICs, arising from coherent oscillations of electric and magnetic multipoles within periodic photonic systems, have enabled low-threshold lasing with multiple topological vortex options and a wide range of wavelengths. − Strong coupling with excitons has even facilitated polariton Bose–Einstein condensation . Structural symmetry breaking has been employed to split the topological charge carried by BIC into two halves, resulting in high-purity and directionally chiral light emission. , These advancements have significantly enhanced our understanding of manipulating topological and chiral emission as well as reducing lasing thresholds, driven by the infinite Q -factors of BICs. However, the practical implementation of light-emitting devices, like light-emitting diodes and lasers, requires careful consideration of the out-coupling efficiency, which determines how efficiently generated light is extracted and emitted into free space in the desired direction.…”

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confidence: 99%

“…6 Structural symmetry breaking has been employed to split the topological charge carried by BIC into two halves, resulting in high-purity and directionally chiral light emission. 7,9 These advancements have significantly enhanced our understanding of manipulating topological and chiral emission as well as reducing lasing thresholds, driven by the infinite Q-factors of BICs. However, the practical implementation of light-emitting devices, like light-emitting diodes and lasers, requires careful consideration of the out-coupling efficiency, which determines how efficiently generated light is extracted and emitted into free space in the desired direction.…”

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confidence: 99%

Dual Control of Enhanced Quasi-Bound States in the Continuum Emission from Resonant c-Si Metasurfaces

Zhang

Liu

et al. 2023

Nano Lett.

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Optical bound states in the continuum (BICs) offer strong interactions with quantum emitters and have been extensively studied for manipulating spontaneous emission, lasing, and polariton Bose−Einstein condensation. However, the out-coupling efficiency of quasi-BIC emission, crucial for practical light-emitting devices, has received less attention. Here, we report an adaptable approach for enhancing quasi-BIC emission from a resonant monocrystalline silicon (c-Si) metasurface through lattice and multipolar engineering. We identify dual-BICs originating from electric quadrupoles (EQ) and out-of-plane magnetic dipoles, with EQ quasi-BICs exhibiting concentrated near-fields near the c-Si nanodisks. The enhanced fractional radiative local density of states of EQ quasi-BICs overlaps spatially with the emitters, promoting efficient out-coupling. Furthermore, coupling the EQ quasi-BICs with Rayleigh anomalies enhances directional emission intensity, and we observe inherent opposite topological charges in the multipolarly controlled dual-BICs. These findings provide valuable insights for developing efficient nanophotonic devices based on quasi-BICs.

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Observation of intrinsic chiral bound states in the continuum

Cited by 235 publications

References 38 publications

Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Localized Spontaneous Chiroptical Response in Disordered Plasmonic Nanoaggregates

Dual Control of Enhanced Quasi-Bound States in the Continuum Emission from Resonant c-Si Metasurfaces

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Observation of intrinsic chiral bound states in the continuum

Cited by 235 publications

References 38 publications

Slanted TiO2 Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Slanted TiO2 Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Localized Spontaneous Chiroptical Response in Disordered Plasmonic Nanoaggregates

Dual Control of Enhanced Quasi-Bound States in the Continuum Emission from Resonant c-Si Metasurfaces

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Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible

Slanted TiO₂ Metagratings for Large‐Angle, High‐Efficiency Anomalous Refraction in the Visible