Sonic gradient index lens for aqueous applications

Martin, Theodore P.; Nicholas, Michael; Orris, Gregory J.; Cai, Liang-Wu; Torrent, Daniel; Sánchez‐Dehesa, José

doi:10.1063/1.3489373

Cited by 141 publications

(91 citation statements)

References 14 publications

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“…The phase through the electronic circuit is tunable as well, and it is an additional degree of freedom usable in some applications. For example, it can be used to implement unidirectional acoustic lenses by varying the phase delay through each cell in the same way reciprocal passive metamaterial lenses are designed [1][2][3][4][5][6] .…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the extended range of material parameters provided by metamaterials has lead to the implementation of devices such as acoustic lenses [1][2][3][4][5][6] , or even exotic structures designed using coordinate transformation methods 7,8 . Recently, significant attention has been given to unidirectional devices that pass acoustic energy in only one direction [9][10][11][12][13][14][15] and therefore mimic the general behaviour of diodes in the microwave regime, and Faraday rotator media in the optical domain.…”

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confidence: 99%

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Non-reciprocal and highly nonlinear active acoustic metamaterials

2014

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Unidirectional devices that pass acoustic energy in only one direction have numerous applications and, consequently, have recently received significant attention. However, for most practical applications that require unidirectionality at audio and low frequencies, subwavelength implementations capable of the necessary time-reversal symmetry breaking remain elusive. Here we describe a design approach based on metamaterial techniques that provides highly subwavelength and strongly non-reciprocal devices. We demonstrate this approach by designing and experimentally characterizing a non-reciprocal active acoustic metamaterial unit cell composed of a single piezoelectric membrane augmented by a nonlinear electronic circuit, and sandwiched between Helmholtz cavities tuned to different frequencies. The design is thinner than a tenth of a wavelength, yet it has an isolation factor of 410 dB. The design method generates relatively broadband unidirectional devices and is a good candidate for numerous acoustic applications.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Non-reciprocal and highly nonlinear active acoustic metamaterials

2014

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“…Our metasurface is essentially a metamaterial/ phononic crystal hybrid structure 10 and both the local and non-local responses can be leveraged for the purpose of shaping the wavefront with a much larger degree of control than traditional acoustic wave manipulation methods. Such thin planar acoustic metasurfaces, along with existing bulk metamaterials [11][12][13][14][15][16][17][18][19][20] , provide a new design methodology for acoustic wave modulation, sensing and imaging applications.…”

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confidence: 99%

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface

et al. 2014

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Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications.

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“…GRIN geometries are utilized for a broad range of metamaterial applications including scattering reduction [6,7], wave focusing [8][9][10][11][12][13][14][15][16], and bending [1][2][3]17,18]. In contrast to previous lens designs, we present a lens composed of impedance-matched, hollow-shell elements with sound speeds higher than water.…”

Section: Introductionmentioning

confidence: 94%

Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

et al. 2015

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Spatial gradients in a refractive index are used extensively in acoustic metamaterial applications to control wave propagation through phase delay. This study reports the design and experimental realization of an acoustic gradient-index lens using a sonic crystal lattice that is impedance matched to water over a broad bandwidth. In contrast to previous designs, the underlying lattice features refractive indices that are lower than the water background, which facilitates propagation control based on a phase advance as opposed to a delay. The index gradient is achieved by varying the filling fraction of hollow, air-filled aluminum tubes that individually exhibit a higher sound speed than water and matched impedance. Acoustic focusing is observed over a broad bandwidth of frequencies in the homogenization limit of the lattice, with intensity magnifications in excess of 7 dB. An anisotropic lattice design facilitates a flatfaceted geometry with low backscattering at 18 dB below the incident sound-pressure level. A threedimensional Rayleigh-Sommerfeld integration that accounts for the anisotropic refraction is used to accurately predict the experimentally measured focal patterns.

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Sonic gradient index lens for aqueous applications

Cited by 141 publications

References 14 publications

Non-reciprocal and highly nonlinear active acoustic metamaterials

Non-reciprocal and highly nonlinear active acoustic metamaterials

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface

Transparent Gradient-Index Lens for Underwater Sound Based on Phase Advance

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