Acoustic Imaging with Metamaterial Luneburg Lenses

Xie, Yangbo; Fu, Yangyang; Jia, Zhetao; Li, Junfei; Shen, Chen; Xu, Yadong; Chen, Huanyang; Cummer, Steven A.

doi:10.1038/s41598-018-34581-7

Cited by 67 publications

(49 citation statements)

References 25 publications

(18 reference statements)

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“…[86] Copyright 2017, The Authors, published by Springer Nature Limited), b) labyrinthine structures [1,5,42,43,74,93,95,96,160,161] (Image reproduced with permission. [74] Copyright 2013, AIP Publishing LLC), and c) crystal lattice structures [40,60,62,76,82,83,84,94,97,98,103,104,162] (Image reproduced with permission. [84] Copyright 2020, AIP Publishing LLC).…”

Section: Discussionmentioning

confidence: 99%

“…Reproduced under terms of the CC-BY license. [62] Copyright 2018, The Authors, published by Springer Nature Limited. d) Monolayer of silica spheres assembled using the wedge-shaped cell convective technique.…”

Section: Arrangement and Assembly Methodsmentioning

confidence: 99%

“…Moreover, standard clear resins for SLA require postprocessing for optical transparency, and incomplete or improper curing of the resin may alter print geometry (e.g., bending), affecting the performance of AMM or PC. Polyjet [62,91] printing presents itself as an attractive alternative, with its ability to directly print multimaterial composite structures using photopolymers, exhibiting an extremely smooth surface finish. Surface roughness for a glossy finish can go as low as 0.5 μm (root mean square, RMS).…”

Section: Printing Technologiesmentioning

confidence: 99%

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Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

et al. 2020

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Acoustic metamaterials (AMMs) and phononic crystals (PCs) have garnered significant attention in recent years, as part of the collective driving force toward creating intelligent acoustic devices. Advancements in these fields have greatly enhanced the way we manipulate sound waves through transmission, reflection, refraction, absorption, diffraction, or attenuation. In the past decade, AMMs and PCs have enabled novel applications such as acoustic lensing, [1-3] cloaking, [4] levitation, [5] and holography. [6-8] While these exotic structures have been well explored through theoretical and numerical analysis, [9-13] their physical realization is an important topic that is rarely discussed. Considering the ubiquity of sound and the powerful capabilities of AMMs and PCs, the impact of these acoustic structures could be phenomenal. Across the full acoustic frequency spectrum, practical applications such as noise cancellation, [14] underwater detection, [15] medical imaging, [16] and energy harvesting [17,18] could benefit key sectors in our society like healthcare, well-being, environmental sustainability, and security. Moreover, AMMs and PCs can help to usher in next-generation technologies for personalized, immersive multisensory [19-22] experiences. The manipulation of sound can enrich the way we communicate and interact with our surroundings, not simply through audio, but also through tactile sensations. In the future, AMMs and PCs could be used in virtual reality (VR) setups, [23] compact wearable devices, and dynamic midair volumetric displays [24] that are controllable and capable of providing haptic feedback. [25] Beyond the notion that AMMs and PCs can replace phased arrays, they could readily complement one another for more precise control. In commercial devices, AMM and PC functionalities could even be combined together in different ways, e.g., transmissive and sound absorptive structures, for improved performance. To unlock the full potential of AMMs and PCs, it is therefore vital to ensure that practical, physical realization is pursued alongside theoretical investigation in the development of viable acoustic designs. Building an AMM or PC requires some form of fabrication or assembly or both. Fabrication refers to the technologies and processes used to manufacture an object, whereas assembly refers to the strategic amalgamation of parts for a constructive purpose.

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Section: Discussionmentioning

confidence: 99%

Section: Arrangement and Assembly Methodsmentioning

confidence: 99%

Section: Printing Technologiesmentioning

confidence: 99%

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Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

et al. 2020

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“…The most feasible way of construction and design is therefore as stacked perforated dielectric substrates similarly as in [31]. Another construction options are generally based on an additive manufacturing, where the building unit-cells can be of various shapes as cubes (Polymer Jetting -PJ) [32], cuboid grid (Fused Decomposition Modeling -FDM) [33] or 3D crosses (Stereolithography -SLA) [34]. However, it is hard to realize such structures at mm-waves above 80 GHz because of the xy resolution limit of the conventional 3D printers for reliable printing (FDM ≈ 0.4 mm depending on the print nozzle diameter [35], SLA ≈ 0.15 mm depending on the laser spot size [36]), and the requirement for supporting structures, which are too difficult to remove.…”

Section: ( )mentioning

confidence: 99%

Gradient-Index-Based Frequency-Coded Retroreflective Lenses for mm-Wave Indoor Localization

et al. 2020

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This paper introduces retroreflective lenses for millimeter-wave radio-frequency indoor localization. A three-dimensional (3D) gradient-index Luneburg lens is employed to increase radar cross section (RCS) of photonic-crystal high-Q resonators and its performance is compared to conventional radar retroreflectors. A classic Luneburg lens with and without a reflective layer is realized with 25 mm diameter (6.7 0), showing a realized gain of 24.6 dBi and a maximum RCS of-9.22 dBm 2 at 80 GHz. The proposed Luneburg lens with embedded high-Q resonators as frequency-coded particles in a photonic crystal structure, operating as a reflective layer, achieved a maximum RCS of-15.84 dBm 2 at the resonant frequency of 76.5 GHz and showed a repeatable response each 18° over ±36° in two perpendicular planes. With this high RCS of the Luneburg lens, a maximum readout range of 1.3 m could be achieved compared to 0.15 m without the lens at 76.5 GHz for the same transmit power, receiver sensitivity, and gain of the reader antenna.

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“…[29,30] The main shortcomingo fT iO 2 that hinders its practical application is its wide band gap (E g % 3.2 eV = 388 nm and E g % 3.0 eV = 413 nm for anatasea nd rutile,r espectively).Therefore, the photoexcitation wavelengths essential to the initiatedp hotoreactions are associated with UV light. [32][33][34] To overcome this disadvantage, various strategies to improve the photocatalytic efficiency of TiO 2 have been employed.…”

Section: Titanium Dioxidementioning

confidence: 99%

Graphitic Carbon Nitride and Titanium Dioxide Modified with 1 D and 2 D Carbon Structures for Photocatalysis

et al. 2018

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Enhancing the photocatalytic performance of graphitic carbon nitride (g-C N , GCN) and titanium dioxide (TiO ) has played a key role in the energy and environmental protection research community. Therefore, it is necessary to explore the synergy of both materials with carbon nanostructures for photocatalysis. Among the variety of carbon materials, graphene flakes and nanotubes, as nanoadditives to improve electron charge transfer and the optical absorption behavior in the visible-light region, have been widely explored. Thus, flake-like (2 D) and tubular (1 D) carbon structures in composition with GCN and/or TiO are reviewed, as are their photocatalytic response. Current trends clearly indicate that this type of molecular hybrids can be efficiently exploited in this field. This Minireview covers state-of-the-art research over the period of 2015 to 2018.

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Acoustic Imaging with Metamaterial Luneburg Lenses

Cited by 67 publications

References 25 publications

Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

Gradient-Index-Based Frequency-Coded Retroreflective Lenses for mm-Wave Indoor Localization

Graphitic Carbon Nitride and Titanium Dioxide Modified with 1 D and 2 D Carbon Structures for Photocatalysis

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