Creation of acoustic vortex knots

Zhang, Hongkuan; Zhang, Weixuan; Liao, Yunhong; Zhou, Xiaoming; Li, Junfei; Hu, Gengkai; Zhang, Xiangdong

doi:10.1038/s41467-020-17744-x

Cited by 60 publications

(38 citation statements)

References 51 publications

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“…However, such high-energy ILX states are expected to have small oscillator strengths relative to the lowenergy ILXs. Thus, the increased oscillator strength and the reduced dipole moment can be attributed to a mixing of such high-energy states with the MoSe 2 A exciton A Mo , in the fashion of hybridized inter/intralayer exci-tons recently reported in some bilayer systems (17,18). As a result of this inter/intralayer exciton mixing, R F detects several features in the intralayer exciton range (11).…”

mentioning

confidence: 77%

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

Barré

Karni

Liu

et al. 2022

Science

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Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. Because such excitons display weak electron-hole overlap, most studies have examined only the lowest-energy excitons through photoluminescence. We directly measured the dielectric response of interlayer excitons, which we accessed using their static electric dipole moment. We thereby determined an intrinsic radiative lifetime of 0.40 nanoseconds for the lowest direct-gap interlayer exciton in a tungsten diselenide/molybdenum diselenide heterostructure. We found that differences in electric field and twist angle induced trends in exciton transition strengths and energies, which could be related to wave function overlap, moiré confinement, and atomic reconstruction. Through comparison with photoluminescence spectra, this study identifies a momentum-indirect emission mechanism. Characterization of the absorption is key for applications relying on light-matter interactions.

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confidence: 77%

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

Barré

Karni

Liu

et al. 2022

Science

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“…At present, various metallic and dielectric metasurfaces have been designed to implement multifunctional planar optical devices, such as metalens [ 14 , 15 ], vortex beam converter [ 16 ] and polarization conversion devices [ 17 , 18 ]. Some subtle metasurfaces have been proposed to construct nanoscale topological light fields [ 19 , 20 ], and a metasurface that consists of rectangular gold nanorods was proposed to realize holographic reconstruction of vortex knots and links [ 21 , 22 ]. Guo et al proposed and experimentally demonstrated a full-dielectric metasurface that can construct vortex knots and links at the nanoscale.…”

Section: Introductionmentioning

confidence: 99%

Spatially Multiplexing of Metasurface for Manipulating the Focused Trefoil and Cinquefoil Vector Light Field

et al. 2021

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The trefoil and cinquefoil vector field are of essential significance for fundamental topology properties as the Hopf link and trefoil knots in the light field. The spatially multiplexing metasurfaces were designed with two sets of periodical nanoslits arranged alternately, each had independent geometric spiral phases and metalens phases to produce and focus vortex of the corresponding circular polarized (CP) light. By arranging the orientations of the two slit sets, the two CP vortices of the desired topological charges were obtained, the superposition of the vortices were realized to generate the vector field. With the topological charges of the vortices set to one and two, and three and two, respectively, the focused trefoil and cinquefoil vector light fields were acquired. The work would be important in broadening the applications of metasurface in areas as vector beam generations and topology of light field.

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“…Recent years have witnessed the great development of acoustic vortex beams owing to their extensive applications in a wide range of fields, such as sound communication [1,2] and particle trapping [3][4][5]. The acoustic vortex beam can transfer different-order vortex wavefronts with orbital angular momentum, opening up a new degree of freedom for sound modulations [6][7][8][9][10]. Traditionally, by designing active sound arrays composed of phased sources [2,[11][12][13], researchers have experimentally realized acoustic vortex beams to manipulate micro-particles underwater.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Bessel Vortex Beam by Quasi-Three-Dimensional Reflected Metasurfaces

et al. 2021

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Vortex beams have a typical characteristic of orbital angular momentum, which provides a new degree of freedom for information processing in remote communication and a form of non-contact manipulation for trapping particles. In acoustics, vortex beams are generally observed on the surface of a metamaterial structure or in a waveguide with a hard boundary owing to the characteristic of easy diffusion in free space. The realization of an acoustic vortex beam with a long-distance propagation in free space still remains a challenge. To overcome this, we report a type of acoustic Bessel vortex (ABV) beam created by a quasi-three-dimensional reflected metasurface in free space based on phase modulation. By using the Bessel and vortex phase profiles, we can realize an ABV beam with the high performances of both Bessel and vortex beams, and its effective propagation distance is larger than 9.2λ in free space. Beyond that, we discuss the bandwidth and topological charge of the ABV beam in detail, and the fractional bandwidth can reach about 0.28. The proposed ABV beam has the advantages of a high-performance vortex, long-distance propagation, and broad bandwidth, which provide a new pathway for designing multifunctional vortex devices with promising applications.

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Creation of acoustic vortex knots

Cited by 60 publications

References 51 publications

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

Optical absorption of interlayer excitons in transition-metal dichalcogenide heterostructures

Spatially Multiplexing of Metasurface for Manipulating the Focused Trefoil and Cinquefoil Vector Light Field

Acoustic Bessel Vortex Beam by Quasi-Three-Dimensional Reflected Metasurfaces

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