Negative refraction and focusing of ultrasound in two-dimensional phononic crystals

Sukhovich, Alexey; Li, Jing; Page, John H.

doi:10.1103/physrevb.77.014301

Cited by 303 publications

(178 citation statements)

References 16 publications

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“…There are other scenarios, however, which allow for the existence of anti-parallel waves such as guided waves [3] and negative group-velocity bands in photonic and phononic crystals (see also [4][5][6]). There exists the possibility of achieving negative refraction in such media [7,8]. In fact, it has been shown recently that negative energy refraction can be accompanied by positive phase-velocity refraction, and conversely that positive energy refraction can be accompanied by negative phase-velocity refraction [9].…”

Section: Introductionmentioning

confidence: 99%

Elastic metamaterials and dynamic homogenization: a review

Srivastava

2015

International Journal of Smart and Nano Materials

122

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In this paper, we review the recent advances which have taken place in the understanding and applications of acoustic/elastic metamaterials. Metamaterials are artificially created composite materials which exhibit unusual properties that are not found in nature. We begin with presenting arguments from discrete systems which support the case for the existence of unusual material properties such as tensorial and/or negative density. The arguments are then extended to elastic continuums through coherent averaging principles. The resulting coupled and nonlocal homogenized relations, called the Willis relations, are presented as the natural description of inhomogeneous elastodynamics. They are specialized to Bloch waves propagating in periodic composites and we show that the Willis properties display the unusual behavior which is often required in metamaterial applications such as the Veselago lens. We finally present the recent advances in the area of transformation elastodynamics, charting its inspirations from transformation optics, clarifying its particular challenges, and identifying its connection with the constitutive relations of the Willis and the Cosserat types.

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Section: Introductionmentioning

confidence: 99%

Elastic metamaterials and dynamic homogenization: a review

Srivastava

2015

International Journal of Smart and Nano Materials

122

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“…[15][16][17][18] In the first section, to illustrate the Bragg effect, a classical 3D crystal of tungsten carbide beads in water is considered. 3,4 Experimental and theoretical transmission spectra in terms of amplitude and phase are shown for two different crystal thicknesses, in order to highlight the characteristic properties of Bragg gaps.…”

Section: Introductionmentioning

confidence: 99%

Band gaps in phononic crystals: Generation mechanisms and interaction effects

Croënne

Lee

et al. 2011

AIP Advances

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A wide range of mesoscopic phononic materials can exhibit frequency bands where transmission is forbidden, i.e. band gaps. Three different mechanisms for their origin can be distinguished, namely Bragg, hybridization and weak elastic coupling effects. Characteristic properties of gaps of different origins are investigated and compared, for a 3D crystal of tungsten carbide beads in water, a 2D crystal of nylon rods in water, and a 3D opal-like structure of weakly sintered aluminum beads. For the second type of crystal, it is shown that Bragg and hybridization gaps can be overlapped, allowing the study of the interaction between these two mechanisms. Atypical dispersion characteristics are demonstrated near the resonance frequency

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“…Yang et al 7 experimentally achieved NR and focusing of ultrasound beams by using the anisotropy of the equifrequency curves (EFCs) in a PC consisting of tungsten carbide beads surrounded by water. NR imaging for all angles of incidence was demonstrated later through the EFCs in the second band of a two-dimensional (2D) PC, where the direction of the wave vector and group velocity are antiparallel to each other [8][9][10] . Intense Bragg scattering at the Brillouin zone can also result in the extreme deformation of the second band EFCs in PCs, which leads to backward-wave NR 11 .…”

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confidence: 99%

Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial

et al. 2014

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Negative refraction of elastic waves has been studied and experimentally demonstrated in three-and two-dimensional phononic crystals, but Bragg scattering is impractical for low-frequency wave control because of the need to scale the structures to manageable sizes. Here we present an elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves. Both negative effective mass density and modulus are observed owing to simultaneous translational and rotational resonances. We experimentally demonstrate negative refraction of the longitudinal elastic wave at the deep-subwavelength scale in the metamaterial fabricated in a stainless steel plate. The experimental measurements are in good agreement with numerical simulations. Moreover, wave mode conversion related with negative refraction is revealed and discussed. The proposed elastic metamaterial may thus be used as a flat lens for elastic wave focusing.

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Negative refraction and focusing of ultrasound in two-dimensional phononic crystals

Cited by 303 publications

References 16 publications

Elastic metamaterials and dynamic homogenization: a review

Elastic metamaterials and dynamic homogenization: a review

Band gaps in phononic crystals: Generation mechanisms and interaction effects

Negative refraction of elastic waves at the deep-subwavelength scale in a single-phase metamaterial

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