Mathias FINK - Institut d'études scientifiques de Cargèse (IESC)

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disordered media leads to substantial changes in the photonic properties, compare to that of bulk materials. Changes in the local density of optical states (LDOS) influence spontaneous emission as well as absorption of light (weak coupling regime or Purcell effect). Disorder also influences the intrinsic spatial coherence that can be described by the concept of cross density of states (CDOS). A reduction of the intrinsic spatial coherence can reveal the spatial localization of modes in a complex system. The strong coupling regime can even be reached between a resonant scatterer (or emitter) and an Anderson localized mode. In the lecture we will focus on the basic concepts used to describe the different interaction regimes, and illustrate the main trends based on numerical simulations and experiments. We will also discuss some analogies between different kind of measurements that are actually driven by the same features of the underlying structure of the optical eigenmodes. Pr. Didier Felbacq Universality and scaling in topological metamaterials The presentation will deal with electromagnetic wave propagation in a model metamaterial made of dielectric rods. The scatterers are such that they present a double resonance (magnetic and electric) in such a way that conduction bands are opened. A low frequency analysis will show that the behavior of the system can be described by resonant (dispersive) electromagnetic parameters ε and μ. The bands have universal features with respect to symmetry and scaling, that will be explored numerically. The link with photonic topological insulators will be discussed as well as the transition to Anderson localization. Dr. Sylvain Gigan Matricial approach to optical wavefront engineering The randomness of the refractive index and/or the position of the scatterers blur the images in biological tissues. OCT by selecting singly backscattered photons is a first approach that allows overcoming this problem. Even with incoherent sources the OCT signal exhibits a speckle distribution. Despite of the speckle in the images the Full Field OCT (FFOCT) approach that we have developed allows to reveal the tissue morphology at the micron scale and starts to be a valuable tool in intra operative surgery. Sometimes the morphology is not enough to characterize the tissue, so we will examine the basic nature of the signal and what kind of supplementary information can be extracted from the OCT data such as local refractive index, density of scatterers and elasticity map. Finally (because we are in Cargese !) I will shows how FFOCT is used to count and characterize, through their Brownian trajectories, viruses in see water. Dr. Stefan Enoch Scaling up the holes : Towards Seismic metamaterials It has been recently suggested that structured media can bend light trajectories the wrong way, making a flat convergent superlens, or even detour light around an objsect, making an invisibility cloak. Such electromagnetic metamaterials introduced by Sir John Pendry during the last decade have counterparts in acoustics. In this talk, I will focus my attention on certain type of surface waves : flexural (Lamb) waves propagating within thin elastic metamaterial plates which have been experimentally studied this year by research groups in Wegener in Karlsruhe, Vandenberghe in Marseille, with applications thought in cloaking, and Sebbah’s group in Paris, where the dynamics of a flat lens for Lamb waves has been unveiled. Interestingly, control of flexural waves opens a route towards seismic metamaterials. First experiments performed by multinational company Menard this year near the French cities of Grenoble and Lyon demonstrate that one can shield or even focus a seismic wave of magnitude 4 on the Richter scale through an array of meter sized
holes drilled in a rather homogeneous soil. Pr. Vincent Laude Phononic crystals for the control of acoustic waves Phononics can be defined as the science of designing artificial acoustic materials with tailored dispersion properties. Of special interest are phononic crystals, two- or three-dimensional periodically structured materials that show a number of amazing properties - but only if properly designed. For instance, strong confinement of wave energy can be obtained inside complete band gaps, i.e., frequency ranges within which no wave propagation is allowed, whatever the incidence and the polarization. Even outside band gaps, the periodic structure leads to very strong spatial dispersion, resulting in properties unavailable with usual homogeneous materials. I will highlight recent achievements in the field of phononics and use them to emphasize that much remains to be achieved. Topics include experimental demonstrations of band gaps, waveguiding and cavity design, crystals for surface acoustic waves, and phononic crystal slabs. Pr. José Sánchez-Dehesa Recent Advances on Acoustic Metamaterials I will start reporting the advances on acoustic cloaking and our experimental demonstration of 2D and 3D acoustic cloaks based on scattering cancellation. Afterwards, I will review the latest results on acoustic metamaterial with negative parameters and density near zero materials. In these topics, the multiple scattering method has been employed as a tool to design building units of artificial structures whose effective parameters can be adjusted. Experiments supporting the theoretical prediction will be also described. Dr. Sergey Skipetrov Quantum optical resources for imaging and wave control in random media Many imaging and adaptive techniques can be realized in very similar ways with different kinds of waves : light, microwaves, sound or elastic waves, for example. Light has, however, an important difference as compared to other waves : it exhibits manifest and readily controllable quantum properties under standard experimental conditions (room temperature, atmospheric pressure, visible wavelength). The purpose of this lecture will be to imagine and explore the possible uses of this new, quantum resource for practical purposes. In particular, we will discuss the use of nonclassical states of light (Fock and squeezed states) to probe turbid media, as well as the potential of quantum entanglement between photons to control their propagation through a random environment.
Page 1 and 2: 2013 27 Mai 31 Mai CONTROLLING WAVE
Page 3 and 4: Speakers • Hui Cao - Yale Univers
Page 5 and 6: Pr. Hui Cao Light transport through
Page 7: Photoacoustic tomography (PAT), com

Mathias FINK - Institut d'études scientifiques de Cargèse (IESC)

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