Surface Acoustic Wave Focusing and Induced Rayleigh Waves

Vines, R. E.; Tamura, Shin–ichiro; Wolfe, J. P.

doi:10.1103/physrevlett.74.2729

Cited by 56 publications

(24 citation statements)

References 7 publications

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“…At a distance exceding a few wavelengths, the formed ripple pattern has the shape of the wave surface, obtained by plotting the group velocity as a function of the emission angle. This effect was observed very neatly for surface waves in the experiments of Vines et al [4] and Sugarawa et al [5]. Here, we investigate the converse problem: can we construct an extended source using an appropriate IDT that will focus elastic energy to a single point on the surface of a piezoelectric solid?…”

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confidence: 99%

Subwavelength focusing of surface acoustic waves generated by an annular interdigital transducer

Laude

Gérard

Khelfaoui

et al. 2008

Applied Physics Letters

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We propose and demonstrate experimentally the concept of the annular interdigital transducer that focuses acoustic waves on the surface of a piezoelectric material to a single, diffraction-limited, spot. The shape of the transducing fingers follows the wave surface. Experiments conducted on lithium niobate substrates evidence that the generated surface waves converge to the center of the transducer, producing a spot that shows a large concentration of acoustic energy. This concept is of practical significance to design new intense microacoustic sources, for instance for enhanced acouto-optical interactions.A variety of anisotropic propagation phenomena are observed in solids, that are mainly determined by the symmetries of the rank-four elastic constant tensor [1]. The piezoelectric effect offers a convenient means of generating elastic waves, by transforming electrical to mechanical energy. The wide majority of elastic wave experiments in piezoelectric solids employ planar or interdigitated transducers (IDT) emitting plane waves with well-defined wave vectors [2]. In such a situation, a displacement field mimicking an ideal plane wave is often looked for and propagation is adequately described by phase quantities, such as the phase velocity. In non piezoelectric materials, surface acoustic waves can be excited using a focused laser beam [3]. In many instances, the surface can be considered to be excited at a single source point. In this case, the surface supports outgoing waves that depart from the source and propagation in the far field depends on the angular dispersion of the spatial group velocity. At a distance exceding a few wavelengths, the formed ripple pattern has the shape of the wave surface, obtained by plotting the group velocity as a function of the emission angle. This effect was observed very neatly for surface waves in the experiments of Vines et al. [4] and Sugarawa et al. [5]. Here, we investigate the converse problem: can we construct an extended source using an appropriate IDT that will focus elastic energy to a single point on the surface of a piezoelectric solid?A circular IDT has already been proposed by Day and Koerber [6] for substrates with in-plane isotropy (orthotropy). Since phase and group velocities are equal in this case, the wave surface reduces to a simple circle. A more recent alternative, the so-called focused interdigital transducer (FIDT), makes use of acoustic emission only within a circular arc [7,8]. In this case, the acoustic field is strongly dependent on the angular extent of the arc and on the focal length of the transducer. Another limit comes from the anisotropy of the substrate which leads * D. Gérard is now with the Institut Fresnel, Domaine Universitaire de Saint Jérôme, F-13397 Marseille cedex 20, France. † C. F. Jerez-Hanckes is also with the Centre de Mathématiques Appliquées, CNRS, Ecole polytechnique, F-91128 Palaiseau, France, and EPCOS Sophia Design Center, 1300 Route des Crêtes, F-06560, Sophia-Antipolis, France. to aberrations at the focal point. In t...

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confidence: 99%

Subwavelength focusing of surface acoustic waves generated by an annular interdigital transducer

Laude

Gérard

Khelfaoui

et al. 2008

Applied Physics Letters

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“…Surface motion or strain-induced refractive index changes, in particular, provide suitable mechanisms for the optical sensing of surface acoustic waves ͑SAWs͒ on solids with visible optical wavelengths. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Developments in this field have been driven by the possibilities for nondestructively monitoring SAW propagation for the characterization of the elastic properties of isotropic and anisotropic materials, the mechanical properties of thin films, and SAW devices such as filters. [15][16][17][18][19][20] Moreover, the imaging of SAW propagation on crystals is of fundamental interest because of the complex focusing patterns that arise from the variation of sound velocity with propagation direction.…”

Section: Introductionmentioning

confidence: 99%

“…[15][16][17][18][19][20] Moreover, the imaging of SAW propagation on crystals is of fundamental interest because of the complex focusing patterns that arise from the variation of sound velocity with propagation direction. [1][2][3][4][5][6] Various optical detection techniques for SAW have been proposed: knife-edge techniques, [13][14][15] interferometric techniques, [4][5][6]17,18,21,22 holographic techniques, 7,8,[10][11][12]15 Schlieren techniques, 16 diffraction techniques, 19 and Brillouin scattering techniques. 15,23 Full information on the SAW field for a general broadband wave disturbance can be most simply obtained by real time detection, and the knife-edge and interferometric techniques have proved most successful for this.…”

Section: Introductionmentioning

confidence: 99%

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Tachizaki

Muroya

Matsuda

et al. 2006

Review of Scientific Instruments

139

110

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We describe an improved two-dimensional optical scanning technique combined with an ultrafast Sagnac interferometer for delayed-probe imaging of surface wave propagation. We demonstrate the operation of this system, which involves the use of a single focusing objective, by monitoring surface acoustic wave propagation on opaque substrates with picosecond temporal and micron lateral resolutions. An improvement in the lateral resolution by a factor of 3 is achieved in comparison with previous setups for similar samples.

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“…We also plot the stop band distribution of both the surface and bulk acoustic waves which would be observable in an ultrasound imaging experiment. 8,12,13 II. FORMULATION We assume the system to be an elastic continuum composed of a periodic array of cylinders of material A embedded in a background material B.…”

Section: Introductionmentioning

confidence: 99%

Surface acoustic waves in two-dimensional periodic elastic structures

1998

Self Cite

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Acoustic waves localized at the surface of two-dimensional ͑2D͒ periodic elastic structures, or 2D phononic crystals, are studied theoretically by taking account of the elastic anisotropy of constituent materials. The surface considered is perpendicular to the axis of a periodic array of cylinders embedded in a background material. The dispersion relations of the surface modes are calculated for circular cylinders of AlAs which form a square lattice in a GaAs matrix. The folding and anisotropy of the surface wave branches, as well as the existence of pseudosurface waves, are found. The stop band distributions of the surface, pseudosurface, and bulk waves are plotted in a form relevant for comparison with ultrasound imaging experiments.

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Surface Acoustic Wave Focusing and Induced Rayleigh Waves

Cited by 56 publications

References 7 publications

Subwavelength focusing of surface acoustic waves generated by an annular interdigital transducer

Subwavelength focusing of surface acoustic waves generated by an annular interdigital transducer

Scanning ultrafast Sagnac interferometry for imaging two-dimensional surface wave propagation

Surface acoustic waves in two-dimensional periodic elastic structures

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