Evidences of evanescent Bloch waves in Phononic Crystals

We show both experimentally and theoretically the evanescent behaviour of modes in the Band Gap (BG) 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 (EPWE). The calculated and measured acoustic field of a localized mode out of the point defect inside the PC presents also evanescent behaviour. The correct understanding of evanescent modes is fundamental for designing narrow filters and wave guides based on Phononic Crystals with defects.Comment: 8 pages, 3 figure

Limits of flexural wave absorption by open lossy resonators: reflection and transmission problems

The limits of flexural wave absorption by open lossy resonators are analytically and numerically reported in this work for both the reflection and transmission problems. An experimental validation for the reflection problem is presented. The reflection and transmission of flexural waves in 1D resonant thin beams are analyzed by means of the transfer matrix method. The hypotheses, on which the analytical model relies, are validated by experimental results. The open lossy resonator, consisting of a finite length beam thinner than the main beam, presents both energy leakage due to the aperture of the resonators to the main beam and inherent losses due to the viscoelastic damping. Wave absorption is found to be limited by the balance between the energy leakage and the inherent losses of the open lossy resonator. The perfect compensation of these two elements is known as the critical coupling condition and can be easily tuned by the geometry of the resonator. On the one hand, the scattering in the reflection problem is represented by the reflection coefficient. A single symmetry of the resonance is used to obtain the critical coupling condition. Therefore the perfect absorption can be obtained in this case. On the other hand, the transmission problem is represented by two eigenvalues of the scattering matrix, representing the symmetric and anti-symmetric parts of the full scattering problem. In the geometry analyzed in this work, only one kind of symmetry can be critically coupled, and therefore, the maximal absorption in the transmission problem is limited to 0.5. The results shown in this work pave the way to the design of resonators for efficient flexural wave absorption

More than a magazine: exploring the links between lads’ mags, rape myth acceptance and rape proclivity

Exposure to some magazines aimed at young male readers – lads’ mags – has recently been associated with behaviors and attitudes that are derogatory towards women, including sexual violence. In the present study, a group of Spanish adult men were exposed to the covers of a lads’ mag while a second group was exposed to the covers of a neutral magazine. Results showed that, compared to participants in the second group, participants who were exposed to covers of lads’ mags who also showed high rape myth acceptance (RMA) and legitimized the consumption of such magazines reported higher rape proclivity in a hypothetical situation. These findings suggest the need to further explore the possible detrimental effects of some sexualized media that are widely accepted in many Western countries

Evanescent modes in Sonic Crystals: Complex relation dispersion and supercell approximation

Evanescent modes in complete sonic crystals (SC) and SC with point defects are reported both theoretically and experimentally in this paper. Plane wave expansion (PWE) and, in general, $\omega(k)$ methods have been used to calculate band structures showing gaps that have been interpreted as ranges of frequencies where no real $k$ exists. In this work, we extend PWE to solve the complex $k(\omega)$ problem applied to SC, introducing the supercell approximation for studying one vacancy. Explicit matrix formulation of the equations is given. This $k(\omega)$ 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 $k(\omega)$, and the evanescent modes related with imaginary values of $k(\omega)$. 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 $k(\omega)$ method.Comment: 15 pages, 3 figure

Stealth Acoustic Materials

[EN] We report the experimental design of a one-dimensional stealth acoustic material, namely a material that suppresses the acoustic scattering for a given set of incident wave vectors. The material consists of multiple scatterers, rigid diaphragms, located in an air-filled acoustic waveguide. The position of the scatterers has been chosen such that in the Born approximation a suppression of the scattering for a broad range of frequencies is achieved and thus a broadband transparency. Experimental results are found in excellent agreement with the theory despite the presence of losses and the finite size of the material, features that are not captured in the theory. This robustness as well as the generality of the results motivates realistic potential applications for the design of transparent materials in acoustics and other fields of wave physics.This work has been funded by RFI Le Mans Acoustique (Region Pays de la Loire) in the framework of the APA-MAS project, by the project HYPERMETA funded under the program Etoiles Montantes of the Region Pays de la Loire as well as by the Ministerio de Economia y Competitividad (Spain) and European Union FEDER through project FIS2015-65998-C2-2-P. V. Romero-Garcia and L. M. Garcia-Raffi acknowledge the short-term scientific mission (STSM) funded by the COST (European Cooperation in Science and Technology) Action DENORMS - CA15125.Romero-García, V.; Lamothe, N.; Theocharis, G.; Richoux, O.; García-Raffi, LM. (2019). Stealth Acoustic Materials. Physical Review Applied. 11(5):1-9. https://doi.org/10.1103/PhysRevApplied.11.054076S19115Shen, C., Xu, J., Fang, N. X., & Jing, Y. (2014). Anisotropic Complementary Acoustic Metamaterial for Canceling out Aberrating Layers. Physical Review X, 4(4). doi:10.1103/physrevx.4.041033Jiménez, N., Cox, T. J., Romero-García, V., & Groby, J.-P. (2017). Metadiffusers: Deep-subwavelength sound diffusers. Scientific Reports, 7(1). doi:10.1038/s41598-017-05710-5Shen, H., Lu, D., VanSaders, B., Kan, J. J., Xu, H., Fullerton, E. E., & Liu, Z. (2015). Anomalously Weak Scattering in Metal-Semiconductor Multilayer Hyperbolic Metamaterials. Physical Review X, 5(2). doi:10.1103/physrevx.5.021021Asadchy, V. S., Faniayeu, I. A., Ra’di, Y., Khakhomov, S. A., Semchenko, I. V., & Tretyakov, S. A. (2015). Broadband Reflectionless Metasheets: Frequency-Selective Transmission and Perfect Absorption. Physical Review X, 5(3). doi:10.1103/physrevx.5.031005Martin, P. A. (2006). Multiple Scattering. doi:10.1017/cbo9780511735110Engheta, N., & Ziolkowski, R. W. (Eds.). (2006). Metamaterials. doi:10.1002/0471784192Alù, A., & Engheta, N. (2005). Achieving transparency with plasmonic and metamaterial coatings. Physical Review E, 72(1). doi:10.1103/physreve.72.016623Chen, P.-Y., Farhat, M., Guenneau, S., Enoch, S., & Alù, A. (2011). Acoustic scattering cancellation via ultrathin pseudo-surface. Applied Physics Letters, 99(19), 191913. doi:10.1063/1.3655141Yablonovitch, E. (1987). Inhibited Spontaneous Emission in Solid-State Physics and Electronics. Physical Review Letters, 58(20), 2059-2062. doi:10.1103/physrevlett.58.2059John, S. (1987). Strong localization of photons in certain disordered dielectric superlattices. Physical Review Letters, 58(23), 2486-2489. doi:10.1103/physrevlett.58.2486Sigalas, M. M., & Economou, E. N. (1992). Elastic and acoustic wave band structure. Journal of Sound and Vibration, 158(2), 377-382. doi:10.1016/0022-460x(92)90059-7Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0Deymier, P. A. (Ed.). (2013). Acoustic Metamaterials and Phononic Crystals. Springer Series in Solid-State Sciences. doi:10.1007/978-3-642-31232-8Sánchez-Pérez, J. V., Caballero, D., Mártinez-Sala, R., Rubio, C., Sánchez-Dehesa, J., Meseguer, F., … Gálvez, F. (1998). Sound Attenuation by a Two-Dimensional Array of Rigid Cylinders. Physical Review Letters, 80(24), 5325-5328. doi:10.1103/physrevlett.80.5325Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2011). Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems. Journal of Applied Physics, 110(1), 014904. doi:10.1063/1.3599886Pérez-Arjona, I., Sánchez-Morcillo, V. J., Redondo, J., Espinosa, V., & Staliunas, K. (2007). Theoretical prediction of the nondiffractive propagation of sonic waves through periodic acoustic media. Physical Review B, 75(1). doi:10.1103/physrevb.75.014304Khelif, A., Wilm, M., Laude, V., Ballandras, S., & Djafari-Rouhani, B. (2004). Guided elastic waves along a rod defect of a two-dimensional phononic crystal. Physical Review E, 69(6). doi:10.1103/physreve.69.067601Sigalas, M. M. (1998). Defect states of acoustic waves in a two-dimensional lattice of solid cylinders. Journal of Applied Physics, 84(6), 3026-3030. doi:10.1063/1.368456Khelif, A., Choujaa, A., Djafari-Rouhani, B., Wilm, M., Ballandras, S., & Laude, V. (2003). Trapping and guiding of acoustic waves by defect modes in a full-band-gap ultrasonic crystal. Physical Review B, 68(21). doi:10.1103/physrevb.68.214301Romero-García, V., Sánchez-Pérez, J. V., Castiñeira-Ibáñez, S., & Garcia-Raffi, L. M. (2010). Evidences of evanescent Bloch waves in phononic crystals. Applied Physics Letters, 96(12), 124102. doi:10.1063/1.3367739Baba, T. (2008). Slow light in photonic crystals. Nature Photonics, 2(8), 465-473. doi:10.1038/nphoton.2008.146Kaya, O. A., Cicek, A., & Ulug, B. (2012). Self-collimated slow sound in sonic crystals. Journal of Physics D: Applied Physics, 45(36), 365101. doi:10.1088/0022-3727/45/36/365101Theocharis, G., Richoux, O., García, V. R., Merkel, A., & Tournat, V. (2014). Limits of slow sound propagation and transparency in lossy, locally resonant periodic structures. New Journal of Physics, 16(9), 093017. doi:10.1088/1367-2630/16/9/093017Groby, J.-P., Pommier, R., & Aurégan, Y. (2016). Use of slow sound to design perfect and broadband passive sound absorbing materials. The Journal of the Acoustical Society of America, 139(4), 1660-1671. doi:10.1121/1.4945101Wiersma, D. S. (2013). Disordered photonics. Nature Photonics, 7(3), 188-196. doi:10.1038/nphoton.2013.29Hu, H., Strybulevych, A., Page, J. H., Skipetrov, S. E., & van Tiggelen, B. A. (2008). Localization of ultrasound in a three-dimensional elastic network. Nature Physics, 4(12), 945-948. doi:10.1038/nphys1101Sperling, T., Bührer, W., Aegerter, C. M., & Maret, G. (2012). Direct determination of the transition to localization of light in three dimensions. Nature Photonics, 7(1), 48-52. doi:10.1038/nphoton.2012.313Fan, Y., Percus, J. K., Stillinger, D. K., & Stillinger, F. H. (1991). Constraints on collective density variables: One dimension. Physical Review A, 44(4), 2394-2402. doi:10.1103/physreva.44.2394Kuhl, U., Izrailev, F. M., Krokhin, A. A., & Stöckmann, H.-J. (2000). Experimental observation of the mobility edge in a waveguide with correlated disorder. Applied Physics Letters, 77(5), 633-635. doi:10.1063/1.127068Torquato, S. (2002). Random Heterogeneous Materials. Interdisciplinary Applied Mathematics. doi:10.1007/978-1-4757-6355-3Uche, O. U., Stillinger, F. H., & Torquato, S. (2004). Constraints on collective density variables: Two dimensions. Physical Review E, 70(4). doi:10.1103/physreve.70.046122Kuhl, U., Izrailev, F. M., & Krokhin, A. A. (2008). Enhancement of Localization in One-Dimensional Random Potentials with Long-Range Correlations. Physical Review Letters, 100(12). doi:10.1103/physrevlett.100.126402Batten, R. D., Stillinger, F. H., & Torquato, S. (2008). Classical disordered ground states: Super-ideal gases and stealth and equi-luminous materials. Journal of Applied Physics, 104(3), 033504. doi:10.1063/1.2961314Florescu, M., Torquato, S., & Steinhardt, P. J. (2009). Designer disordered materials with large, complete photonic band gaps. Proceedings of the National Academy of Sciences, 106(49), 20658-20663. doi:10.1073/pnas.0907744106Dietz, O., Kuhl, U., Hernández-Herrejón, J. C., & Tessieri, L. (2012). Transmission in waveguides with compositional and structural disorder: experimental effects of disorder cross-correlations. New Journal of Physics, 14(1), 013048. doi:10.1088/1367-2630/14/1/013048Man, W., Florescu, M., Williamson, E. P., He, Y., Hashemizad, S. R., Leung, B. Y. C., … Steinhardt, P. J. (2013). Isotropic band gaps and freeform waveguides observed in hyperuniform disordered photonic solids. Proceedings of the National Academy of Sciences, 110(40), 15886-15891. doi:10.1073/pnas.1307879110Man, W., Florescu, M., Matsuyama, K., Yadak, P., Nahal, G., Hashemizad, S., … Chaikin, P. (2013). Photonic band gap in isotropic hyperuniform disordered solids with low dielectric contrast. Optics Express, 21(17), 19972. doi:10.1364/oe.21.019972Torquato, S. (2016). Hyperuniformity and its generalizations. Physical Review E, 94(2). doi:10.1103/physreve.94.022122Torquato, S., Zhang, G., & Stillinger, F. H. (2015). Ensemble Theory for Stealthy Hyperuniform Disordered Ground States. Physical Review X, 5(2). doi:10.1103/physrevx.5.021020Leseur, O., Pierrat, R., & Carminati, R. (2016). High-density hyperuniform materials can be transparent. Optica, 3(7), 763. doi:10.1364/optica.3.000763Gkantzounis, G., Amoah, T., & Florescu, M. (2017). Hyperuniform disordered phononic structures. Physical Review B, 95(9). doi:10.1103/physrevb.95.094120Torquato, S., & Stillinger, F. H. (2003). Local density fluctuations, hyperuniformity, and order metrics. Physical Review E, 68(4). doi:10.1103/physreve.68.041113Song, B. H., & Bolton, J. S. (2000). A transfer-matrix approach for estimating the characteristic impedance and wave numbers of limp and rigid porous materials. The Journal of the Acoustical Society of America, 107(3), 1131-1152. doi:10.1121/1.42840