Quasi-static stop band with flexural metamaterial having zero rotational stiffness

Metamaterials realizing stop bands have attracted much attentions recently since they can break-through the well-known mass law. However, achieving the stop band at extremely low frequency has been still a big challenge in the fields of elastic metamaterials. In this paper, we propose a new metamaterial based on the idea of the zero rotational stiffness, to achieve extremely low frequency stop band for flexural elastic waves. Unlike the previous ways to achieve the stop band, we found that the zero rotational stiffness can provide a broad stop band at extremely low frequency, which starts from even almost zero frequency. To achieve the zero rotational stiffness, we propose a new elastic metamaterial consisting of blocks and links with the hinge connection. Analytic developments as well as numerical simulations evidence that this new metamaterial can exhibit extremely low and broad stop band, even at the quasi-static ranges. In addition, the metamaterial is shown to exhibit the negative group velocity at extremely low frequency ranges, as well as the quasi-static stop band, if it is properly designed.ope

Cavity modes and optomechanic interactions in strip waveguide

Phoxonic crystals can exhibit dual phononic/photonic band gaps. Therefore, the confinement of both acoustic and optical waves in a phoxonic cavity can allow the enhancement of their interaction. In this paper, we discuss our recent theoretical works on the strength of the optomechanic coupling, based on both photoelastic and moving interfaces mechanisms, in nanobeam phoxonic crystals cavities

Optomechanic interaction in a corrugated phoxonic nanobeam cavity

[EN] The interaction between phonons and photons is investigated theoretically in a phoxonic cavity inside a corrugated nanobeam waveguide presenting band gaps for both electromagnetic and elastic waves. The structure is made by drilling periodic holes on a silicon nanobeam with lateral periodic stubs and the tapered cavity is constructed by changing gradually the geometrical parameters of both the holes and stubs. We show that this kind of cavity displays localized phonons and photons inside the gaps, which can enhance their interaction and also promotes the presence of many optical confined modes with high quality factor. Using the finite-element method, we demonstrate that with appropriate design of the tapering construction, one can control the cavity modes frequency without altering significantly the quality factor of the photonic modes. By changing the tapering rates over the lattice constants, we establish the possibility of shifting the phononic cavity modes frequency to place them inside the desired gap, which enhances their confinement and increases the mechanical quality factor while keeping the strength of the optomechanic coupling high. In our calculations, we take account of both mechanisms that contribute to the acousto-optic interaction, namely photoelastic and interface motion effects. We show that in our case, these two effects can contribute additively to give high coupling strength between phononic and photonic cavity modes. The calculations of the coupling coefficient which gives the phonon-photon coupling strength give values as high as 2 MHz while photonic cavity modes display quality factor of 105 and even values up to 3.4 MHz but with smaller photonic quality factors.The authors acknowledge the support of the European Commission Seventh Framework Programs (FP7) under the FET-Open project TAILPHOX N 233883.Oudich, M.; El-Jalla, S.; Pennec, Y.; Djafari-Rouhani, B.; Gomis Bresco, J.; Navarro-Urrios, D.; Sotomayor Torres, CM.... (2014). Optomechanic interaction in a corrugated phoxonic nanobeam cavity. Physical Review B. 89:245122-245130. https://doi.org/10.1103/PhysRevB.89.245122S2451222451308

Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam

[EN] We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of vertical bar g(o, OM)vertical bar= 1.8 MHz (vertical bar g(o, OM)vertical bar/2 pi=0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high go, OM values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.This work was supported by the EU through the FP7 project TAILPHOX (ICT-FP7-233883) and the ERC Advanced Grant SOULMAN (ERC-FP7-321122) and the Spanish projects TAPHOR (MAT2012-31392). D.N-U and J.G-B acknowledge support in the form of postdoctoral fellowships from the Catalan (Beatriu de Pinos) and the Spanish (Juan de la Cierva) governments, respectively.Navarro-Urrios, D.; Gomis-Bresco, J.; El-Jallal, S.; Oudich, M.; Pitanti, A.; Capuj, N.; Tredicucci, A.... (2014). Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam. AIP Advances. 4(12). https://doi.org/10.1063/1.4902171S412Aspelmeyer, M., Kippenberg, T. J., & Marquardt, F. (Eds.). (2014). Cavity Optomechanics. doi:10.1007/978-3-642-55312-7Kippenberg, T. J., Rokhsari, H., Carmon, T., Scherer, A., & Vahala, K. J. (2005). Analysis of Radiation-Pressure Induced Mechanical Oscillation of an Optical Microcavity. Physical Review Letters, 95(3). doi:10.1103/physrevlett.95.033901Hossein-Zadeh, M., Rokhsari, H., Hajimiri, A., & Vahala, K. J. (2006). Characterization of a radiation-pressure-driven micromechanical oscillator. Physical Review A, 74(2). doi:10.1103/physreva.74.023813Eichenfield, M., Chan, J., Camacho, R. M., Vahala, K. J., & Painter, O. (2009). Optomechanical crystals. Nature, 462(7269), 78-82. doi:10.1038/nature08524Pennec, Y., Laude, V., Papanikolaou, N., Djafari-Rouhani, B., Oudich, M., El Jallal, S., … Martínez, A. (2014). Modeling light-sound interaction in nanoscale cavities and waveguides. Nanophotonics, 3(6). doi:10.1515/nanoph-2014-0004Chan, J., Alegre, T. P. M., Safavi-Naeini, A. H., Hill, J. T., Krause, A., Gröblacher, S., … Painter, O. (2011). Laser cooling of a nanomechanical oscillator into its quantum ground state. Nature, 478(7367), 89-92. doi:10.1038/nature10461Safavi-Naeini, A. H., Alegre, T. P. M., Chan, J., Eichenfield, M., Winger, M., Lin, Q., … Painter, O. (2011). Electromagnetically induced transparency and slow light with optomechanics. Nature, 472(7341), 69-73. doi:10.1038/nature09933Pennec, Y., Rouhani, B. D., Li, C., Escalante, J. M., Martinez, A., Benchabane, S., … Papanikolaou, N. (2011). Band gaps and cavity modes in dual phononic and photonic strip waveguides. AIP Advances, 1(4), 041901. doi:10.1063/1.3675799Gomis-Bresco, J., Navarro-Urrios, D., Oudich, M., El-Jallal, S., Griol, A., Puerto, D., … Torres, C. M. S. (2014). A one-dimensional optomechanical crystal with a complete phononic band gap. Nature Communications, 5(1). doi:10.1038/ncomms5452Oudich, M., El-Jallal, S., Pennec, Y., Djafari-Rouhani, B., Gomis-Bresco, J., Navarro-Urrios, D., … Makhoute, A. (2014). Optomechanic interaction in a corrugated phoxonic nanobeam cavity. Physical Review B, 89(24). doi:10.1103/physrevb.89.245122Chan, J., Safavi-Naeini, A. H., Hill, J. T., Meenehan, S., & Painter, O. (2012). Optimized optomechanical crystal cavity with acoustic radiation shield. Applied Physics Letters, 101(8), 081115. doi:10.1063/1.4747726Safavi-Naeini, A. H., Hill, J. T., Meenehan, S., Chan, J., Gröblacher, S., & Painter, O. (2014). Two-Dimensional Phononic-Photonic Band Gap Optomechanical Crystal Cavity. Physical Review Letters, 112(15). doi:10.1103/physrevlett.112.153603Johnson, S. G., Ibanescu, M., Skorobogatiy, M. A., Weisberg, O., Joannopoulos, J. D., & Fink, Y. (2002). Perturbation theory for Maxwell’s equations with shifting material boundaries. Physical Review E, 65(6). doi:10.1103/physreve.65.066611Navarro-Urrios, D., Gomis-Bresco, J., Capuj, N. E., Alzina, F., Griol, A., Puerto, D., … Sotomayor-Torres, C. M. (2014). Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects. Journal of Applied Physics, 116(9), 093506. doi:10.1063/1.4894623Barclay, P. E., Srinivasan, K., & Painter, O. (2005). Nonlinear response of silicon photonic crystal micresonators excited via an integrated waveguide and fiber taper. Optics Express, 13(3), 801. doi:10.1364/opex.13.000801J. Chan, Ph.D. thesis, California Institute of Technology, Los Angeles, 2014.Gorodetsky, M. L., Schliesser, A., Anetsberger, G., Deleglise, S., & Kippenberg, T. J. (2010). Determination of the vacuum optomechanical coupling rate using frequency noise calibration. Optics Express, 18(22), 23236. doi:10.1364/oe.18.02323

General analytical approach for sound transmission loss analysis through a thick metamaterial plate

International audienceWe report theoretically and numerically on the sound transmission loss performance through a thick plate-type acoustic metamaterial made of spring-mass resonators attached to the surface of a homogeneous elastic plate. Two general analytical approaches based on plane wave expansion were developed to calculate both the sound transmission loss through the metamaterial plate (thick and thin) and its band structure. The first one can be applied to thick plate systems to study the sound transmission for any normal or oblique incident sound pressure. The second approach gives the metamaterial dispersion behavior to describe the vibrational motions of the plate, which helps to understand the physics behind sound radiation through air by the structure. Computed results show that high sound transmission loss up to 72 dB at 2 kHz is reached with a thick metamaterial plate while only 23 dB can be obtained for a simple homogeneous plate with the same thickness. Such plate-type acoustic metamaterial can be a very effective solution for high performance sound insulation and structural vibration shielding in the very low-frequency range

Acoustic superfocusing by solid phononic crystals

International audienceWe propose a solid phononic crystal lens capable of acoustic superfocusing beyond the diffraction limit. The unit cell of the crystal is formed by four rigid cylinders in a hosting material with a cavity arranged in the center. Theoretical studies reveal that the solid lens produces both negative refraction to focus propagating waves and surface states to amplify evanescent waves. Numerical analyses of the superfocusing effect of the considered solid phononic lens are presented with a separated source excitation to the lens. In this case, acoustic superfocusing beyond the diffraction limit is evidenced. Compared to the fluid phononic lenses, the solid lens is more suitable for ultrasonic imaging applications

Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic metamaterials

International audienceWe present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of lambda/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging

On the Bi2O3-Al2O3-PbO system

39th Edition of the Joint European Days on Equilibrium between Phases (JEEP), Nancy, FRANCE, MAR 19-21, 2013International audienceThe present work is dedicated to the description of the pseudo - binary Al 2 O 3 - Bi 2 O 3 and the isothermal section at 600°C of the system Al 2 O 3 - Bi 2 O 3 - PbO according to a Calphad approach. It takes part of the complete description of the complex system Pb - Bi - Fe - (Al,Cr) - O. Such study is of hig h interest for the nuclear community that aims to develop protective coatings for the MEGAPIE s pa l lation t arget to prevent the T91 steel from corrosion due to contact with lead - bismuth eutectic liquid

Love wave biosensor to diagnose modification of cell viscoelasticy

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