182 research outputs found
Surface coupled phononic resonators
No full textCes travaux de thèse visent à étudier des résonateurs mécaniques capables de confiner, contrôler et transporter l’énergie acoustique à l’échelle du micromètre. L’approche proposée consiste à exploiter la surface sur laquelle reposent les résonateurs et les phénomènes d’hybridation entre les ondes élastiques se propageant sur cette surface et les modes propres des résonateurs pour créer un couplage entre résonateurs. Dans un premier temps, les travaux entrepris prouvent, numériquement et expérimentalement, la capacité d’exciter un micro-résonateur sub-longueur d’onde grâce aux ondes de surface. Une seconde partie est consacrée à l’étude des mécanismes de couplage entre résonateurs adjacents.Au travers de caractérisations optiques donnant notamment accès à la forme des modes excités et de simulations numériques fondées sur la méthode des éléments finis, la présence de couplage entre résonateurs voisins et la possibilité de contrôler ce couplage en modifiant les paramètres géométriques des paires de résonateurs sont démontrées. En particulier, deux types de couplage sont mis en évidence en fonction de l’écartement entre les résonateurs : un couplage évanescent, s’apparentant au couplage dans un dimère plasmonique, et un couplage de type mécanique. Les études réalisées soulignent aussi la réciprocité des systèmes étudiés : il est possible de modifier le couplage en changeant les conditions d’excitation des résonateurs et réciproquement, les vibrations des résonateurs couplés peuvent affecter la vibration de la surface les supportant à des échelles très sub-longueurs d’onde.In the field of Phononics, most of the works reported up to now investigate the collective behaviour of periodic or aperiodic structures in order to control the propagation of elastic waves. In this thesis work, we propose to focus on the individual character of surface-coupled mechanical resonators with the aim to control and manipulate vibrations at the micron-scale. We investigate numerically and experimentally the coupling mechanisms involved between surface acoustic waves propagating on a substrate surface and mechanical modes of sub-wavelength phononic microresonators. Experimental investigations are conducted on isolated resonators and on pairs of neighboring resonators. The microresonator motion is measured using a laser scanning heterodyne interferometer which allows obtaining the frequency response and observing the vectorial behaviour of the elastic field both in the resonator and at the substrate surface.In the first part of this thesis work, we demonstrate the possibility to excite the first flexural natural mode of a resonator with surface acoustic waves. Then, the reported investigations reveal the existence of two coupling regimes in pairs of resonating pillars, depending on the separation distance between two resonators: an evanescent coupling regime, much reminiscent of what can be observed in a plasmonic dimer, and a classical mechanical coupling. Measurements performed at the substrate surface also highlight the interaction through the surface between the resonators.The obtained results prove that it is possible to control the elastic energy distribution at a deep sub-wavelength scale with isolated resonators, and reciprocally, that mechanical resonator systems can be manipulated by propagating surface acoustic waves, hence opening prospects for the dynamic and coherent control of mechanical vibrations at the micron-scale
Trames = Threads
No full text"Threads features the works of five artists: Myriam Dion, Surabhi Ghosh, Diane Meyer, Shelley Miller and Sarah Thibault. Using textile techniques and patterns, the artists featured in this exhibition bring fabric out of its traditional domestic use and use it as a voice for modern-day social concerns. Drawing inspiration from social issues, cultural characteristics and feminism, the artists explore the fine line between craft and great art." -- Publisher's website
Guidage et filtrage des ondes dans les cristaux phononiques
No full textThis thesis has been conducted within the département LPMO of the institut FEMTO-ST, under the supervisionof Vincent Laude and Abdelkrim Khelif. It has been devoted to the study of wave propagation in elastic band gap materials, the so-called phononic crystals.In the first part of this work, filtering, guiding and coupling phenomena in low operating frequency bulk wave phononic crystals consisting of an arrangement of millimeter-sized steel rods immersed in water have been investigated. Complex functions like band gap tunability or wavelength demultiplexing have proven to be achievable in such structures.The second part has been aiming at demonstrating the possibility of implementing band gap properties for surface waves in two-dimensional phononic crystals with an operating frequency of the order of a few hundreds of megahertz. Micron-sized holes have been etched both in lithium niobate and in silicon using clean room processes to allow for the fabrication of the periodical structures which have been characterised by electrical as well as by optical techniques. A full band gap for surface acoustic waves has been found, in close agreement with the theoretical predictions.Eventually, the third part of this thesis has dealt with a preliminary theoretical study of acousto-optical interactionsin artificial materials exhibiting both photonic and phononic band gap properties. This study has highlighted the formalism-pertaining issues encountered when dealing with highly and simultaneously confined acoustic and optical modes.Cette thèse, réalisée au sein du département de Physique et de Métrologie des Oscillateurs de l'institut FEMTO-ST sous la direction de Vincent Laude et d'Abdelkrim Khelif, s'inscrit dans le courant de recherche dédié depuis quelques années à l'étude de la propagation des ondes dans les matériaux à bandes interdites pour les ondes élastiques, ou cristaux phononiques.La première partie de ces travaux a consisté à mettre expérimentalement en évidence l'existence de phénomènes de filtrage, guidage et couplage des ondes dans des structures périodiques de dimension millimétrique constituées de tiges d'acier dans de l'eau, opérant à une fréquence de l'ordre de la dizaine de kilohertz.La seconde partie de cette thèse a été consacrée à la fabrication et à la caractérisation de cristaux phononiques à l'échelle de la dizaine de microns en niobate de lithium pour des applications aux ondes de surface à plus haute fréquence (quelques centaines de mégahertz). La caractérisation électrique comme optique des cristaux phononiques a permis de mettre en évidence l'existence d'une bande interdite complète pour les ondes de surface dans cette structure périodique. Des expériences similaires menées sur des structures en silicium ont encore confirmé ces résultats expérimentaux.Enfin, la dernière partie de ces travaux a été dédiée à l'étude théorique des interactions acousto-optiques dans des matériaux présentant des bandes interdites à la fois photoniques et phononiques. Elle a permis de révéler l'importance du formalisme mathématique employé, dans cette configuration particulière où ondes optiques et élastiques sont fortement confinées
Simultaneous guidance of slow photons and slow acoustic phonons in silicon phoxonic crystal slabs
No full textThis paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.19.009690. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] We demonstrate theoretically that photons and acoustic phonons can be simultaneously guided and slowed down in specially designed nanostructures. Phoxonic crystal waveguides presenting simultaneous phononic and photonic band gaps were designed in perforated silicon membranes that can be conveniently obtained using silicon-on-insulator technology. Geometrical parameters for simultaneous photonic and phononic band gaps were first chosen for optical wavelengths around 1550 nm, based on the finite element analysis of a perfect phoxonic crystal of circular holes. A plain core waveguide was then defined, and simultaneous slow light and elastic guided modes were identified for some waveguide width. Joint guidance of light and elastic waves is predicted with group velocities as low as c/25 and 180 m/s, respectively. © 2011 Optical Society of America.This research has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement number 233883 (TAILPHOX).Laude, V.; Beugnot, J.; Benchabane, S.; Pennec, Y.; Djafari-Rouhani, B.; Papanikolaou, N.; Escalante Fernández, JM.... (2011). Simultaneous guidance of slow photons and slow acoustic phonons in silicon phoxonic crystal slabs. Optics Express. 19(10):9690-9698. https://doi.org/10.1364/OE.19.009690S969096981910Kushwaha, 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.71.2022Maldovan, M., & Thomas, E. L. (2006). Simultaneous localization of photons and phonons in two-dimensional periodic structures. Applied Physics Letters, 88(25), 251907. doi:10.1063/1.2216885Maldovan, M., & Thomas, E. L. (2006). Simultaneous complete elastic and electromagnetic band gaps in periodic structures. Applied Physics B, 83(4), 595-600. doi:10.1007/s00340-006-2241-yAkimov, A. V., Tanaka, Y., Pevtsov, A. B., Kaplan, S. F., Golubev, V. G., Tamura, S., … Bayer, M. (2008). Hypersonic Modulation of Light in Three-Dimensional Photonic and Phononic Band-Gap Materials. Physical Review Letters, 101(3). doi:10.1103/physrevlett.101.033902Sadat-Saleh, S., Benchabane, S., Baida, F. I., Bernal, M.-P., & Laude, V. (2009). Tailoring simultaneous photonic and phononic band gaps. Journal of Applied Physics, 106(7), 074912. doi:10.1063/1.3243276Papanikolaou, N., Psarobas, I. E., & Stefanou, N. (2010). Absolute spectral gaps for infrared light and hypersound in three-dimensional metallodielectric phoxonic crystals. Applied Physics Letters, 96(23), 231917. doi:10.1063/1.3453448Mohammadi, S., Eftekhar, A. A., Khelif, A., & Adibi, A. (2010). Simultaneous two-dimensional phononic and photonic band gaps in opto-mechanical crystal slabs. Optics Express, 18(9), 9164. doi:10.1364/oe.18.009164Pennec, Y., Rouhani, B. D., El Boudouti, E. H., Li, C., El Hassouani, Y., Vasseur, J. O., … Martinez, A. (2010). Simultaneous existence of phononic and photonic band gaps in periodic crystal slabs. Optics Express, 18(13), 14301. doi:10.1364/oe.18.014301Safavi-Naeini, A. H., & Painter, O. (2010). Design of optomechanical cavities and waveguides on a simultaneous bandgap phononic-photonic crystal slab. Optics Express, 18(14), 14926. doi:10.1364/oe.18.014926El Hassouani, Y., Li, C., Pennec, Y., El Boudouti, E. H., Larabi, H., Akjouj, A., … Djafari Rouhani, B. (2010). Dual phononic and photonic band gaps in a periodic array of pillars deposited on a thin plate. Physical Review B, 82(15). doi:10.1103/physrevb.82.155405Khelif, A., Aoubiza, B., Mohammadi, S., Adibi, A., & Laude, V. (2006). Complete band gaps in two-dimensional phononic crystal slabs. Physical Review E, 74(4). doi:10.1103/physreve.74.046610Hussein, M. I. (2009). Reduced Bloch mode expansion for periodic media band structure calculations. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 465(2109), 2825-2848. doi:10.1098/rspa.2008.0471Johnson, S. G., Fan, S., Villeneuve, P. R., Joannopoulos, J. D., & Kolodziejski, L. A. (1999). Guided modes in photonic crystal slabs. Physical Review B, 60(8), 5751-5758. doi:10.1103/physrevb.60.5751Xu, T., Wheeler, M. S., Nair, S. V., Ruda, H. E., Mojahedi, M., & Aitchison, J. S. (2008). Highly confined mode above the light line in a two-dimensional photonic crystal slab. Applied Physics Letters, 93(24), 241105. doi:10.1063/1.3046124Laude, V., Achaoui, Y., Benchabane, S., & Khelif, A. (2009). Evanescent Bloch waves and the complex band structure of phononic crystals. Physical Review B, 80(9). doi:10.1103/physrevb.80.092301Laude, V., Khelif, A., Benchabane, S., Wilm, M., Sylvestre, T., Kibler, B., … Maillotte, H. (2005). Phononic band-gap guidance of acoustic modes in photonic crystal fibers. Physical Review B, 71(4). doi:10.1103/physrevb.71.045107Dainese, P., Russell, P. S. J., Joly, N., Knight, J. C., Wiederhecker, G. S., Fragnito, H. L., … Khelif, A. (2006). Stimulated Brillouin scattering from multi-GHz-guided acoustic phonons in nanostructured photonic crystal fibres. Nature Physics, 2(6), 388-392. doi:10.1038/nphys31
Surface acoustic wave generation in ZX-cut LiNbO3 superlattices using coplanar electrodes
No full textWe report on a configuration to generate surface acoustic waves (SAWs) in acoustic superlattices based on ZX -cut periodically poled lithium niobate. The coplanar electrode configuration allows inducing Rayleigh type SAWs with the elastic energy mainly concentrated in between the electrodes gap and under the crystal surface. With respect to standard interdigitated transducers using the same crystal orientation, the efficiency of the SAW generation in the proposed designs are similar, while, for the same grating period, the resonance frequency that can be achieved is two times larger
Band gaps and cavity modes in dual phononic and photonic strip waveguides
No full text[EN] We discuss theoretically the simultaneous existence of phoxonic, i.e., dual phononic and photonic, band gaps in a periodic silicon strip waveguide. The unit-cell of this one-dimensional waveguide contains a hole in the middle and two symmetric stubs on the sides. Indeed, stubs and holes are respectively favorable for creating a phononic and a photonic band gap. Appropriate geometrical parameters allow us to obtain a complete phononic gap together with a photonic gap of a given polarization and symmetry. The insertion of a cavity inside the perfect structure provides simultaneous confinement of acoustic and optical waves suitable to enhance the phonon-photon interaction. © 2011 Copyright 2011 Author(s).This work was supported by the European Commission Seventh Framework Programs (FP7) under the FET-Open project TAILPHOX No 233883.Pennec, Y.; Rouhani, BD.; Li, C.; Escalante Fernández, JM.; Martínez Abietar, AJ.; Benchabane, S.; Laude, V.... (2011). Band gaps and cavity modes in dual phononic and photonic strip waveguides. AIP Advances. 1(4):41901-41908. https://doi.org/10.1063/1.3675799S41901419081
Guidage et filtrage des ondes dans les cristaux phononiques
No full textBESANCON-BU Sciences Staps (250562103) / SudocSudocFranceF
Surface acoustic wave-driven mechanical resonators for phononic circuitry
No full textInternational audienceGuided elastic waves are powerful information carriers standing at the core of modern telecommunication devices. Surface acoustic waves (SAW), in particular, have been industrially used as radio-frequency filters or delay lines since the 1970s and remain relevant in all current connectivity standard technologies. More recently, the scope of their potential application fields has expanded covering fields as diverse as life science and quantum information technology: SAWs are mechanical vibrations, and as such, can coherently couple to a number of physical systems. This intrinsic property has recently pushed towards the development of hybrid electromechanical or phonon-based devices. In this contexte, the implementation of scalable phononic circuits has become an appealing prospect in view of increasing the versatility of electro-acoustic devices. Recent demonstrations have made convincing steps towards this objective by proposing phononic architectures inspired by photonic integrated circuits or combining the rich dynamics of micro- and nano-electromechanical (M/NEMS) resonators with propagating elastic waves. <br>Here, we propose to exploit the interaction between surface acoustic waves (SAW) and locally-resonant, micron-scale mechanical resonators in order to achieve coherent driving of the resonator motion with SAW and, reciprocally, to control the elastic energy distribution at a deep sub-wavelength scale. We investigate the proposed physical system both in the linear and non-linear regimes and reveal that the elastic field behavior can be further controlled through resonator-to-resonator coupling, leading to a variety of interaction schemes affecting both the frequency response and the polarization of the resonating structures. The proposed devices, that operate in the 70-MHz range, are readily scalable to higher frequencies. They illustrate the potential of SAW-based architectures for the implementation of densely integrated phononic circuits with complex dynamics operating at gigahertz frequencies. <br&g
Simultaneous Existence of Phononic and Photonic Band Gaps in Phoxonic Crystal Slabs
No full textWe discuss the simultaneous existence of phononic and photonic
band gaps in a periodic array of holes drilled in a Si membrane. We investigate in detail both the centered square lattice and the boron nitride (BN) lattice with two atoms per unit cell which include the simple square, triangular and honeycomb lattices as particular cases. We show that complete phononic and photonic band gaps can be obtained from the
honeycomb lattice as well as BN lattices close to honeycomb. Otherwise, all investigated structures present the possibility of a complete phononic gap together with a photonic band gap of a given symmetry, odd or even, depending on the geometrical parameters
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