507 research outputs found
Band gap engineering in simultaneous phononic and photonic crystal slabs
Get PDFWe discuss the simultaneous existence of phononic and photonic band gaps in two types of phononic crystals
slabs, namely periodic arrays of nanoholes in a Si membrane
and of Si nanodots on a SiO2 membrane. In the former
geometry, we investigate in detail both the boron nitride
lattice and the square lattice with two atoms per unit cell
(these include the square, triangular and honeycomb lattices
as particular cases). In the latter geometry, some preliminary
results are reported for a square lattice
Phononic crystals and acoustic metamaterials : applications to guiding and filtering phenomena and acoustic isolation
No full textCette thèse est consacrée à l’étude de certaines propriétés nouvelles des cristaux phononiques et des métamatériaux acoustiques. La plupart des simulations numériques a été réalisée à l’aide de la méthode F.D.T.D. Une partie préliminaire a porté sur l’existence de bandes interdites dans un cristal phononique 2D constitué de cylindres d’acier dans l’eau et notamment une application originale au démultiplexage. Dans ce travail, nous nous sommes plus particulièrement intéressés au cas d’un cristal phononique à résonances localisées présentant de multiples gaps basses fréquences, nettement en dessous du gap de Bragg. Le cristal étudié est constitué de cylindres concentriques de matériaux ayant des constantes élastiques très différentes, immergés dans une matrice fluide. Il présente plusieurs zéros de transmission basses fréquences dont on a étudié les comportements en fonction des paramètres physiques et géométriques. Nous avons montré comment élargir ces zéros de transmission pour obtenir des bandes de fréquences interdites. Nous avons calculé les paramètres effectifs autour d’une résonance et montré que la densité effective massique pouvait devenir négative sur une certaine gamme de fréquence. La dernière partie de ce travail est consacrée à l’étude d’une structure originale 3D, constituée de piliers déposés sur une plaque fine, qui permet d’obtenir l’ouverture d’un gap très basse fréquence par rapport au gap de Bragg. Nous avons étudié les conditions d’existence des bandes interdites ainsi que certaines propriétés de guidage et de filtrage. Enfin, nous avons étudié la transmission entre deux substrats par l’intermédiaire d’un réseau périodique de piliers. Nous avons mis en évidence une transmission exaltée, associée à une résonance de Fano.This thesis is devoted to the study of some new properties of phononic crystals and acoustics metamaterials. Most of simulations were carried out using F.D.T.D. method. A preliminary part was devoted to the study of the existence of gaps in a 2D phononic crystal made up of steel cylinders in water and in particular an original application to demultiplexing. In this work, we are more particularly interested by a phononic crystal with localized resonances displaying several low frequencies gaps well below the Bragg gap. The studied crystal consists of concentric cylinders having different elastic constants, immersed in a fluid matrix. It presents several zeros of transmission at low frequencies whose behaviors were studied as a function of the physical and geometrical parameters. We showed how to widen these zeros of transmission to obtain prohibited gaps. We calculated effective parameters around a resonance and showed the possibility of negative effective mass density. The last part of this work is devoted to the study of an original 3D structure, consisted of pillars deposited on a thin plate, which makes it possible to obtain the opening of a very low frequency gap compared to the Bragg gap. We studied the conditions of existence of the forbidden bands as well as guiding and filtering properties of this structure. Finally, we studied the transmission between two substrates across a periodic array of pillars. We highlighted an enhanced transmission, associated to a Fano resonance
Modeling of nano-plasmonic and photonic structures : applications to filtering phenomenon and to the conception of bioplasmonic nanosensors
No full textCe travail porte sur la modélisation et simulation avec la méthode des différences finies (FDTD) de structures plasmonique et photoniques à l’échelle submicronique. Dans une première partie, nous avons modélisé la propagation des ondes électromagnétiques à travers des nano-guides diélectriques (air ou SiO2), pris en sandwich entre deux plaques métalliques (de type Metal-Isolant-Metal). L’excitation des plasmons-polaritons aux interfaces permet le guidage d’ondes lumineuses à une échelle sub-longueur d’onde. Nous avons étudié les propriétés de guidage dans le domaine du visible et de l’infrarouge proche, notamment le couplage du guide avec des nano-résonateurs en vue d’explorer des fonctionnalités telles que le filtrage sélectif ou par réjection ainsi que des dispositifs de démultiplexage. Ces mêmes propriétés ont été étudiées dans une structure photonique submicronique constituée de guides d’ondes d’InP entouré d’air, couplé à un ensemble de cavités. Ces nano et microstructures constituent les briques de base pour la conception de nouveaux circuits intégrés tout-optique. Dans une seconde partie de la thèse, on s’est intéressé à la modélisation de l’interaction des ondes électromagnétiques avec des nanoparticules d’or déposées sur un substrat de SiO2, et recouvertes d’une couche d’un matériau diélectrique. Ce type de structures est prometteur pour réaliser des nano-capteurs bioplasmoniques en vue de caractériser des produits biologiques déposés en faible quantité sur la surface du diélectrique. Nous avons montré que la fréquence de la réponse plasmonique des particules présente une variation oscillatoire périodique en fonction l’épaisseur du diélectrique, avec une amplitude des oscillations qui peut atteindre quelques dizaines de nanomètres. Nous avons étudié ce phénomène en fonction des paramètres géométriques des nanoparticules d’or et de l’indice du diélectrique qui les recouvrent. L’objectif est de comprendre comment ces paramètres influencent la gamme de fréquence plasmonique ainsi que la sensibilité du détecteur. Ce travail théorique a été confronté aux résultats expérimentaux réalisés par l’équipe Bio-Interfaces de L’IRI (Institut de recherche interdisciplinaire, Lille 1).This work concerns the modeling and simulation by the finite difference method (FDTD) of plasmonic and photonic structures at the submicron scale. In the first part of the thesis we studied the propagation of electromagnetic-waves through two different dielectric nanoscale waveguides (made out of air and SiO2), sandwiched between two metallic plates (Metal-insulator-Metal). The excitation of surface plasmon-polariton at the interfaces of such waveguides enables light waveguiding at the subwavelength domain. We did study the waveguiding properties in the visible and near infrared ranges of frequency. Coupling of the main waveguide with a nano-resonatorwas investigated to achieve optical operations as filtering (in rejection and selection) and demultiplexing. These same optical functionalities were studied in a submicron photonic structure which is constituted by waveguides of InP surrounded by air, coupled to several cavities. Such nano and microstructures are essential for the design of new all-optical integrated circuits. The second part of the thesis concerns modeling of electromagnetic-waves interaction with metallic (gold) nanoparticles deposited on a glass substrate (SiO2) and covered with a dielectric layer. These structures are promising for the conception of plasmonic nanosensors, which would be used to characterize small amount of biological molecules deposited on the dielectric layer surface. We have shown that the frequency of the plasmonic resonance of metallic particles exhibits an oscillatory variation with the thickness of the layer, with an amplitude reaching tens of nanometers. One investigated this phenomenon according to geometrical parameters of the gold particles and the refractive index of the dielectric layer covering the particles. The aim of such study is to understand how the physical and geometrical parameters influence the frequency range of the plasmonic resonance of the particles and the sensitivity of the nanosensor. This theoretical work was confronted with experimental results realized by Bio-interfaces team of IRI (Interdisciplinary institute of research, University of Lille 1)
Stopping of acoustic waves by sonic polymer/fluid composites
No full textA two-dimensional periodic array of air cylinders in water is known to have giant acoustic stop bands [M.S. Kushwaha and B. Djafari-Rouhani, J. Appl. Phys. 84 (1998) 4677]. It is shown in the present paper that hollow cylinders made of an elastically-soft polymer containing air inside and arranged on a square lattice in water can still give rise to large acoustic band gaps. Similar properties can also be obtained with a close-packed array of tubes containing water when arranged on a honeycomb lattice in air. The transmission coefficient of films made of such polymer-fluid composites has been calculated by finite difference time domain method. With film thickness not exceeding 75 mm, a deep sonic attenuation band was found with, in the best cases, a lower limit below 1 kHz and an upper limit above 10 kHz
Simultaneous guidance of slow photons and slow acoustic phonons in silicon phoxonic crystal slabs
Get PDFThis 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
Dual phononic and photonic band gaps in a periodic array of pillars deposited on a thin plate
Get PDFWe study theoretically the simultaneous existence of phononic and photonic band gaps in a periodic array of
silicon pillars deposited on a homogeneous thin silica plate. Several lattices, namely, square, triangular, and
honeycomb are investigated for a wide range of geometrical parameters. We discuss the most suitable cases for
dual phononic-photonic band gaps, especially in comparison to the more conventional structures constituted by
a periodic array of holes in a membrane
Rigorous simulation of nonlinear optomechanical coupling in micro- and nano-structured resonant cavities
Get PDFA numerical method aimed to predict the optomechanical dynamics in micro- and nano-structured resonant cavities is introduced here. The rigorousness of it is ensured by exploiting the harmonic version of the transformation optics (TO) technique and by considering all the energy-transduction contributions of electrostriction, radiation pressure, photoelasticity and moving boundaries. Since our full-wave approach implements a multi-modal analysis and also considers material losses, from both a mechanical and an optical point of view, a considerable step further has been made in respect to the standard optomechanical perturbative theory. The efficiency and the versatility of the strategy are tested by analysing the optomechanical behaviour of a corrugated Si-based nanobeam and comparing numerical results to experimental ones from the literature
Fundamental Properties of Phononic Crystal
No full textInternational audiencePhononic crystals are periodic composite structures where the elastic and acoustic properties display a periodic variation in space. They are in general constituted by a periodic array of inclusions in a matrix. Due to their periodicity, they can exhibit absolute band gaps in which the propagation of elastic waves is prohibited in any direction of the space. More generally, tailoring their band structure allows the control and manipulation of elastic waves and pave the way to several functionalities ranging from sound isolation to filtering and signal processing, negative refraction and high resolution imaging, nanoscale thermal transport managing, quantum information processing. In this chapter, we discuss some basic properties of the phononic crystals, in particular the dependence of the band gaps with the nature of the constituent materials (solid or fluid), the contrast between the elastic properties of the constituents, the shape and the filling fraction of the inclusions, the crystal lattice. We discuss the existence of gaps resulting from Bragg interference or from local resonances. The localized modes associated with defects such as cavities and waveguides are presented and their functionalities in filtering and multiplexing applications are discussed
Robustness of conventional and topologically protected edge states in phononic crystal plates
Get PDFMany efforts have been devoted to studying the robustness of topologically protected edge states in acoustics;
however, the robustness of conventional edge states is rarely reported. In this work we theoretically study
interface acoustic states appearing in finite arrays of resonators on a thin plate with topologically protected
and conventional designs. Topologically protected interface states are first analyzed by employing the concept of
breaking inversion symmetry within the unit cell of a honeycomb lattice for cylindrical and spherical resonators;
we further demonstrate the robustness of the wave propagation along a zigzag path containing sharp corners
and defects. In parallel, a conventional interface state is also designed and compared to the same situations.
We found that the conventional interface state suffers backscattering in the zigzag path while it can show a
more confined wave transport in some cases. The presence of a defect along the propagation path scatters the
conventional interface wave and in particular can prohibit full propagation in the presence of a localized state
at the defect. Then, we show that the immunity of the topologically protected design needs the interface to be
surrounded by at least two hexagons of the phononic crystals on both sides, especially at the sharp corners in the
zigzag path, while the conventional design only needs one hexagon of bulk media with the advantage of compact
wave transport. Position and height disorders are further introduced to the interface pillars for both designs. It
is revealed that in both designs, the transmission decreases quasilinearly with position disorder while it exhibits
an abrupt drop with height disorder showing a transition threshold. With high disorder perturbation, waves can
hardly enter the interface for the topologically protected design, while waves are trapped at the interface for the
conventional design. A certain robustness against disorder is exhibited for conventional edge states. This work
provides insight into the interface states in micro- and nanoscale characterization and figures out the behaviors
for both topologically protected and conventional interface states
Gradient index phononic crystals and metamaterials
Get PDFPhononic crystals and acoustic metamaterials
are periodic structures whose effective properties can be
tailored at will to achieve extreme control on wave propagation. Their refractive index is obtained from the homogenization of the infinite periodic system, but it is possible
to locally change the properties of a finite crystal in such
a way that it results in an effective gradient of the refractive index. In such case the propagation of waves can be
accurately described by means of ray theory, and different refractive devices can be designed in the framework of
wave propagation in inhomogeneous media. In this paper
we review the different devices that have been studied for
the control of both bulk and guided acoustic waves based
on graded phononic crystals
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