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[EN] In solids, the constitutive relations between strain and stress lead in most cases to a dominant quadratic nonlinear response. However, there exist some solid materials that exhibit negative quadratic nonlinearity, as occurs in common glasses as borosilicate glass or fused silica. In this work, we present the dynamical response of a phononic crystal with modulated nonlinearity. In particular, we analyze a 1D phononic crystal composed of layers of alternating properties with quadratic nonlinearity, each layer presenting an alternating (positive and negative) nonlinear parameter value. First, we observe that the common distortion produced by the nonlinear steepening can be almost compensated. Thus, the propagation through the phononic crystal can be extended far beyond the shock formation distance, avoiding common saturation effects. Second, we show that in the absence of dispersion the artificial material exhibits weakly-cubic nonlinear effective properties. The structure presented here can be employed to avoid nonlinear distortion in waveguides, or to design metamaterials with effective cubic nonlinear properties using quadratic nonlinear building blocks. ; The work was supported by Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through project FIS2015-65998-C2-2. NJ acknowledge financial support from Generalitat Valenciana through grant APOSTD-2017-042 ; Jimenez, N.; Tournat, V.; Romero García, V.; Sánchez Morcillo, VJ. (2018). Modulated-nonlinearity in phononic crystals: From extremely linear to effective cubic nonlinear media. Proceedings of Meetings on Acoustics. 34(1):1-5. https://doi.org/10.1121/2.0000908 ; S ; 1 ; 5 ; 34 ; 1

The properties of sonic crystals (SC) are theoretically investigated in this work by solving the inverse problem k(¿) using the extended plane wave expansion (EPWE). The solution of the resulting eigenvalue problem gives the complex band structure which takes into account both the propagating and the evanescent modes. In this work we show the complete mathematical formulation of the EPWE for SC and the supercell approximation for its use in both a complete SC and a SC with defects. As an example we show a novel interpretation of the deaf bands in a complete SC in good agreement with multiple scattering simulations. © 2011 Copyright 2011 Author(s). ; This work was supported by MCI-Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under grant MAT2009-09438. LMGR would like to thank the UPV for the grant PAID-00-11. VRG is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)." ; Romero García, V.; García Raffi, LM.; Sánchez Pérez, JV. (2011). Evanescent waves and deaf bands in sonic crystals. AIP Advances. 1(4):416011-416019. https://doi.org/10.1063/1.3675801 ; S ; 416011 ; 416019 ; 1 ; 4

[EN] The effect of the presence of a finite impedance surface on the wave propagation properties of a two-dimensional periodic array of rigid cylinders with their axes perpendicular to the surface is both numerically and experimentally analyzed in this work. In this realistic situation the incident wave interacts with two elements: the surface and the array of scatterers. The excess attenuation and the bandgap effects, due to the existence of the surface and the periodicity of the array, respectively, are fundamental to control both the transmission and attenuation of waves on devices based on periodicity. © 2011 Europhysics Letters Association. ; This work was supported by MCI Secretaria de Estado de Investigacion (Spanish Government) and FEDER funds, under grant MAT2009-09438. VR-G is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)". ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2011). Analysis of the wave propagation properties of a periodic array of rigid cylinders perpendicular to a finite impedance surface. EPL. 96:440031-440036. https://doi.org/10.1209/0295-5075/96/44003 ; S ; 440031 ; 440036 ; 96

Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in Journal of Applied Physics , Volume 110, Issue 1 and may be found at http://scitation.aip.org/content/aip/journal/jap/110/1/10.1063/1.3599886. Authors own version of final article on e-print servers ; The physical properties of a periodic distribution of absorbent resonators is used in this work to design a tunable wideband bandstop acoustic filter. Analytical and numerical simulations as well as experimental validations show that the control of the resonances and the absorption of the scatterers along with their periodic arrangement in air introduce high technological possibilities to control noise. Sound manipulation is perhaps the most obvious application of the structures presented in this work. We apply this methodology to develop a device as an alternative to the conventional acoustic barriers with several properties from the acoustical point of view but also with additional esthetic and constructive characteristics. © 2011 American Institute of Physics. ; This work was supported by MEC (Spanish Government) and FEDER funds, under Grant No. MAT2009-09438. ; Romero García, V.; Sánchez Pérez, JV.; García-Raffi, LM. (2011). Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems. Journal of Applied Physics. 110(1):149041-149049. https://doi.org/10.1063/1.3599886 ; S ; 149041 ; 149049 ; 110 ; 1 ; Yablonovitch, E. (1987). Inhibited Spontaneous Emission in Solid-State Physics and Electronics. Physical Review Letters, 58(20), 2059-2062. doi:10.1103/physrevlett.58.2059 ; John, S. (1987). Strong localization of photons in certain disordered dielectric superlattices. Physical Review Letters, 58(23), 2486-2489. doi:10.1103/physrevlett.58.2486 ; Sigalas, M. M., & Economou, E. N. (1992). Elastic and ...

The use of sonic crystals (SCs) as environmental noise barriers has certain advantages from both the acoustical and the constructive points of view with regard to conventional ones. However, the interaction between the SCs and the ground has not been studied yet. In this work we are reporting a semi-analytical model, based on the multiple scattering theory and on the method of images, to study this interaction considering the ground as a finite impedance surface. The results obtained here show that this model could be used to design more effective noise barriers based on SCs because the excess attenuation of the ground could be modelled in order to improve the attenuation properties of the array of scatterers. The results are compared with experimental data and numerical predictions thus finding good agreement between them. © 2011 IOP Publishing Ltd. ; The authors would like to thank The Open University (UK) for the use of their facilities. This work was supported by the MEC (Spanish Government) and FEDER funds, under Grant No MAT2009-09438. ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2011). Analytical model to predict the effect of a finite impedance surface on the propagation properties of 2D Sonic Crystals. Journal of Physics D: Applied Physics. 44:1-12. https://doi.org/10.1088/0022-3727/44/26/265501 ; S ; 1 ; 12 ; 44 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Sanchez-Perez, J. V., Rubio, C., Martinez-Sala, R., Sanchez-Grandia, R., & Gomez, V. (2002). Acoustic barriers based on periodic arrays of scatterers. Applied Physics Letters, 81(27), 5240-5242. doi:10.1063/1.1533112 ; Sánchez-Dehesa, J., Garcia-Chocano, V. M., Torrent, D., Cervera, F., Cabrera, S., & Simon, F. (2011). Noise control by sonic crystal barriers made of recycled materials. The Journal of the Acoustical Society of America, 129(3), 1173-1183. doi:10.1121/1.3531815 ; Krynkin, A., ...

Evanescent modes in complete sonic crystals (SCs) and SC with point defects are reported both theoretically and experimentally in this paper. Plane wave expansion (PWE) and in general, ω(k)ω(k) methods have been used to calculate band structures showing gaps that have been interpreted as ranges of frequencies where no real kk exists. In this work, we extend PWE to solve the complex k(ω)k(ω) problem applied to SC, introducing the supercell approximation for studying one vacancy. Explicit matrix formulation of the equations is given. This k(ω)k(ω) method enables the calculation of complex band structures, as well as enabling an analysis of the propagating modes related with real values of the function k(ω)k(ω), and the evanescent modes related with imaginary values of k(ω)k(ω). This paper shows theoretical results and experimental evidences of the evanescent behavior of modes inside the SC band gap. Experimental data and numerical results using the finite elements method are in very good agreement with the predictions obtained using the k(ω)k(ω) method. ; The authors would like to thank Dr. E. A. Sanchez-Perez for his comments and suggestions and thank Daniel Fenollosa and Talleres Ferriols for their help in building the mechanical part of 3DReAMS. This work was supported by MEC (Spanish government) and the European Regional Development Fund, under Grant Nos. MAT2009-09438 and MTM2009-14483-C02-02. ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2010). Evanescent modes in sonic crystals: complex dispersion relation and supercell approximation. Journal of Applied Physics. 108(4):449071-4490716. doi:10.1063/1.3466988 ; S ; 449071 ; 4490716 ; 108 ; 4 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Kushwaha, M. S., Halevi, P., Dobrzynski, L., & Djafari-Rouhani, B. (1993). Acoustic band structure of periodic elastic composites. Physical Review Letters, 71(13), ...

Complex band structures and multiple scattering theory have been used in this paper to analyze the overlapping of the evanescent waves localized in point defects in sonic crystals (SCs). The extended plane wave expansion (EPWE) with supercell approximation gives the imaginary part of the Bloch vectors that produces the decay of the localized modes inside the periodic system. Double cavities can present a coupling between the evanescent modes localized in the defect, showing a symmetric or antisymmetric mode. When point defects are close, the complex band structures reveal a splitting of the frequencies of the localized modes. Both the real part and the imaginary values of k of the localized modes in the cavities present different values for each localized mode, which gives different properties for each mode. The novel measurements, in very good agreement with analytical data, show experimental evidence of the symmetric and antisymmetric localized modes for a double-point defect in SCs. The investigation of the localization phenomena and the coupling between defects in periodic systems has fundamental importance in both pure and applied physics. ; This work was supported by MEC (the Spanish Government) and FEDER funds through grants MAT2009-09438 and MTM2009-14483-C02-02. ; Romero García, V.; Sánchez Pérez, JV.; García-Raffi, LM. (2010). Propagating and evanescent properties of duble-point defect in sonic crystals. New Journal of Physics. 12:1-14. doi:10.1088/1367-2630/12/8/083024 ; S ; 1 ; 14 ; 12

The complex band structures calculated using the extended plane wave expansion (EPWE) reveal the presence of evanescent modes in periodic systems, never predicted by the classical ω(kE) methods, providing novel interpretations of several phenomena as well as a complete picture of the system. In this work, we theoretically and experimentally observe that in the ranges of frequencies where a deaf band is traditionally predicted, an evanescent mode with excitable symmetry appears, changing drastically the interpretation of the transmission properties. On the other hand, the simplicity of the sonic crystals in which only the longitudinal polarization can be excited is used to interpret, without loss of generality, the level repulsion between symmetric and antisymmetric bands in sonic crystals as the presence of an evanescent mode connecting both repelled bands. These evanescent modes, obtained using EPWE, explain both the attenuation produced in this range of frequencies and the transfer of symmetry from one band to the other in good agreement with both experimental results and multiple scattering predictions. Thus, the evanescent properties of the periodic system have been revealed to be necessary for the design of new acoustic and electromagnetic applications based on periodicity. ; VRG and LMGR are grateful for the hospitality and the facilities provided by the Institut d'Electronique, de Microelectronique et de Nanotechnologie (IEMN UMR CNRS 8520). LMGR thanks the Universidad Politecnica de Valencia for the grant 'Programa de Apoyo a la Investigacion y Desarrollo (PAID-00-11)'. VRG is grateful for the support provided by 'Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)'. This work was supported by MCI Secretaria de Estado de Investigacion (the Spanish government) and FEDER funds under grant no. MAT2009-09438. ; Romero García, V.; Vasseur, J.; García-Raffi, LM.; Hladky-Hennion, A. (2012). Theoretical and experimental evidence of level repulsion states and evanescent modes in sonic crystal ...

[EN] We report the optimal focusing of acoustic vortex beams by using flat lenses based on a Fresnelspiral diffraction grating. The flat lenses are designed by spiral-shaped Fresnel zone plates composed of one or several arms. The constructive and destructive interferences of the diffracted waves by the spiral grating result in sharp acoustic vortex beams, following the focal laws obtained in analogy with the Fresnel zone plate lenses. In addition, we show that the number of arms determines the topological charge of the vortex, allowing the precise manipulation of the acoustic wave field by flat lenses. The experimental results in the ultrasonic regime show excellent agreement with the theory and full-wave numerical simulations. A comparison with beam focusing by Archimedean spirals also showing vortex focusing is given. The results of this work may have potential applications for particle trapping, ultrasound therapy, imaging, or underwater acoustic transmitters. ; This work was supported by the Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through Project Nos. FIS2015-65998-C2-1 and FIS2015-65998-C2-2. N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD-2017-042. ; Jimenez, N.; Romero García, V.; García-Raffi, LM.; Camarena Femenia, F.; Staliunas, K. (2018). Sharp acoustic vortex focusing by Fresnel-spiral zone plates. Applied Physics Letters. 112(20):204101-1-204101-5. https://doi.org/10.1063/1.5029424 ; S ; 204101-1 ; 204101-5 ; 112 ; 20 ; J. Nye and M. Berry ,Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences(The Royal Society, 1974), Vol.336, pp. 165–190. ; Grier, D. G. (2003). A revolution in optical manipulation. Nature, 424(6950), 810-816. doi:10.1038/nature01935 ; Volke-Sepúlveda, K., Santillán, A. O., & Boullosa, R. R. (2008). Transfer of Angular Momentum to Matter from Acoustical Vortices in Free Space. Physical Review Letters, 100(2). doi:10.1103/physrevlett.100.024302 ; Anhäuser, A., ...

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Applied Physics Letters 107, 204103 (2015); doi:10.1063/1.4935917 and may be found at http://dx.doi.org/10.1063/1.4935917. ; We report the nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating immersed in water. In the linear regime, the system presents high focal gain (32 dB), with a narrow beam-width and intense side lobes as it is common in focusing by Fresnel-like lenses. Activating the nonlinearity of the host medium by using high amplitude incident waves, the focusing properties of the lens dramatically change. Theoretical predictions show that the focal gain of the system extraordinary increases in the strongly nonlinear regime (Mach number of 6.1 x 10(-4)). Particularly, the harmonic generation is locally activated at the focal spot, and the second harmonic beam is characterized by strongly reduced side-lobes and an excellent beam profile as experiments show in agreement with theory. The results can motivate applications in medical therapy or second harmonic imaging. (c) 2015 AIP Publishing LLC. ; The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through Projects FIS2011-29734-C02-01 and -02, MTM2012-36740c02-02, and PAID 2012/253. ; Jimenez, N.; Romero García, V.; Picó Vila, R.; García-Raffi, LM.; Staliünas, K. (2015). Nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating embedded in water. Applied Physics Letters. 107(20). doi:10.1063/1.4935917 ; S ; 204103 ; 107 ; 20 ; Farnow, S. A., & Auld, B. A. (1974). Acoustic Fresnel zone plate transducers. Applied Physics Letters, 25(12), 681-682. doi:10.1063/1.1655359 ; Sleva, M. Z., Hunt, W. D., & Briggs, R. D. (1994). Focusing performance of epoxy‐ and air‐backed polyvinylidene fluoride Fresnel zone plates. The Journal of the Acoustical Society of America, 96(3), 1627-1633. doi:10.1121/1.410242 ; Wang, ...

An acoustic metamaterial made of a two-dimensional (2D) periodic array of multi-resonant acoustic scatterers is analyzed both experimentally and theoretically. The building blocks consist of a combination of elastic beams of low-density polyethylene foam (LDPF) with cavities of known area. Elastic resonances of the beams and acoustic resonances of the cavities can be excited by sound producing several attenuation peaks in the low frequency range. Due to this behavior the periodic array with long wavelength multi-resonant structural units can be classified as a locally multi-resonant acoustic metamaterial (LMRAM) with strong dispersion of its effective properties. The results presented in this paper could be used to design effective tunable acoustic filters for the low frequency range. (C) 2012 Elsevier Ltd. All rights reserved. ; This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and FEDER funds, under Grants MAT2009-09438 and MTM2009-14483-C02-02. V.R.G. is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)". A.K. and O.U. are grateful for the support of EPSRC (UK) through research Grant EP/E063136/1. ; Romero García, V.; Krynkin, A.; García-Raffi, LM.; Umnova, O.; Sánchez Pérez, JV. (2013). Multi-resonant scatterers in sonic crystals: Locally multi-resonant acoustic metamaterial. Journal of Sound and Vibration. 332(1):184-198. doi:10.1016/j.jsv.2012.08.003 ; S ; 184 ; 198 ; 332 ; 1

Copyright (2010) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics along with the following message: The following article appeared in "Romero García, V.; Sánchez Pérez, JV.; Castiñeira Ibáñez, S.; García-Raffi, LM. (2010). Evidences of evanescent Bloch waves in phononic crystals. Applied Physics Letters. 96:1241021-1241021. doi:10.1063/1.3367739" and may be found at http://dx.doi.org/10.1063/1.3367739. Authors own version of final article on e-print servers ; We show both experimentally and theoretically the evanescent behavior of modes in the band gap of finite phononic crystal (PC). Based on experimental and numerical data we obtain the imaginary part of the wave vector in good agreement with the complex band structures obtained by the extended plane wave expansion. The calculated and measured acoustic field of a localized mode out of the point defect inside the PC presents also evanescent behavior. The correct understanding of evanescent modes is fundamental for designing narrow filters and waveguides based on PCs with defects. ; This work was supported by MEC (Spanish Government) and FEDER funds, under Grant Nos. MAT2009-09438 and MTM2009-14483-C02-02. The authors would like to thank J. M. Herrero, S. Garcia-Nieto, and X. Blasco for their work in the control and acquisition system of 3DReAMS. ; Romero García, V.; Sánchez Pérez, JV.; Castiñeira Ibáñez, S.; García-Raffi, LM. (2010). Evidences of evanescent Bloch waves in phononic crystals. Applied Physics Letters. 96(12):1241021-1241021. doi:10.1063/1.3367739 ; S ; 1241021 ; 1241021 ; 96 ; 12 ; Sigalas, M., & Economou, E. N. (1993). Band structure of elastic waves in two dimensional systems. Solid State Communications, 86(3), 141-143. doi:10.1016/0038-1098(93)90888-t ; Kushwaha, M. S., Halevi, P., Martínez, G., Dobrzynski, L., & Djafari-Rouhani, B. (1994). Theory of acoustic band structure of periodic elastic composites. ...

The transmission of acoustic waves in a fractal distribution of rigid scatterers embedded in air is reported in this work. The Sierpinsky fractal is used to produce a compact small device containing several periodicities, therefore the fractal distribution contains several finite sonic crystals. The attenuation band produced by the fractal distribution results from the sum of the Bragg peaks of each periodicity. On the other hand, bandgaps of sonic crystal depend on the well-known filling fraction, thus the radii of the scatterers in the fractal distribution has been optimized using genetic algorithm in order to overlap the bandgaps of each periodicity obtaining a wide and full attenuation band. ; This work was supported by MCI (Spanish Government) and FEDER funds, under Grant Nos. MAT2009-09438 and MTM2009-14483-C02-02. The authors would like to thank Prof. K. ATTENBOROUGH and Dr. E. A. SANCHEZ-PEREZ for their suggestions and for the revision of the manuscript. ; Castiñeira Ibáñez, S.; Romero García, V.; Sánchez Pérez, JV.; García-Raffi, LM. (2010). Overlapping of acoustic bandgaps using fractal geometries. EPL. 92(2):240071-240073. doi:10.1209/0295-5075/92/24007 ; S ; 240071 ; 240073 ; 92 ; 2

We propose and experimentally demonstrate a mechanism of sound wave concentration based on soft reflections in chirped sonic crystals. The reported controlled field enhancement occurs at around particular (bright) planes in the crystal and is related to a progressive slowing down of the sound wave as it propagates along the material. At these bright planes, a substantial concentration of the energy (with a local increase up to 20 times) was obtained for a linear chirp and for frequencies around the first band gap. A simple couple mode theory is proposed that interprets and estimates the observed effects. Wave concentration energy can be applied to increase the efficiency of detectors and absorbers. ; The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through projects FIS2011-29734-C02-01 and -02 and GVA/2011/055. V. R.-G. is grateful for the support of post-doctoral contracts of the UPV CEI-01-11. K. S. acknowledges the grant of UPV PAID-02-01. We acknowledge the CTFAMA and the Sonic Crystal Technologies Research Group at UPV for the use of the anechoic chamber and the 3DReAMS, respectively. ; Romero García, V.; Picó Vila, R.; Cebrecos Ruiz, A.; Sánchez Morcillo, VJ.; Staliünas, K. (2013). Enhancement of sound in chirped sonic crystals. Applied Physics Letters. 102(919):1-3. https://doi.org/10.1063/1.4793575 ; S ; 1 ; 3 ; 102 ; 919 ; Kushwaha, M. S., Halevi, P., Dobrzynski, L., & Djafari-Rouhani, B. (1993). Acoustic band structure of periodic elastic composites. Physical Review Letters, 71(13), 2022-2025. doi:10.1103/physrevlett.71.2022 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Zhang, X., & Liu, Z. (2004). Negative refraction of acoustic waves in two-dimensional phononic crystals. Applied Physics Letters, 85(2), 341-343. doi:10.1063/1.1772854 ; Lu, M.-H., Zhang, C., Feng, L., Zhao, J., Chen, Y.-F., Mao, Y.-W., … Ming, ...

Phononic crystals are artificial materials made of a periodic distribution of solid scatterers embedded into a solid host medium with different physical properties. An interesting case of phononic crystals, known as sonic crystals (SCs), appears when the solid scatterers are periodically embedded in a fluid medium. In SCs only longitudinal modes are allowed to propagate and both the theoretical and the experimental studies of the properties of the system are simplified without loss of generality. The most celebrated property of these systems is perhaps the existence of spectral band gaps. However, the periodicity of the system can also affect to the spatial dispersion, making possible the control of the diffraction inside these structures. In this work we study the main features of the spatial dispersion in SCs from a novel point of view taking into account the evanescent properties of the system, i.e., studying the complex spatial dispersion relations. The evanescent behavior of the propagation of waves in the angular band gaps are theoretically and experimentally observed in this work. Both the numerical predictions and the experimental results show the presence of angular band gaps in good agreement with the complex spatial dispersion relation. The results shown in this work are independent of the spatial scale of the structure, and in principle the fundamental role of the evanescent waves could be also expected in micro- or nanoscale phononic crystals. ; This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant Nos. MAT2009-09438, FIS2011-29734-C02-02, and from Generalitat Valencia through Project No. GV/2011/055. V.R.G. is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)." We acknowledge the Centro de Tecnologias Fisicas: Acustica, Materiales y Astrofisica and the Sonic Crystal Technologies Research Group of the Universitat Politecnica de Valencia for the use of the anechoic chamber and the ...