Waves are means by which we probe our environment and communicate with one another. Media in which waves propagates are often heterogeneous, scattering, and sometime opaque. In such media, interference plays an essential role.
My current research focuses on wave-matter interaction and the fundamental phenomena resulting from multiple scattering and interference of waves in disordered media.
Anderson localization. Among these phenomena, Anderson localization plays a central role. In certain conditions of scattering, the wave can be trapped in a finite region of space, due to interference. This phenomenon has been proposed in the fifties by Anderson to explain the metal-insulator transition of electrons in metals. Spurred by the analogy with electronic waves, rapid progress has been made in recent years in understanding transport of classical waves in random media in the emerging fields of mesoscopic optics and photon localization.

Random lasers. Pumping energy into an amplifying medium randomly filled with scatterers, a powder for instance, makes a perfect random laser. In such an unconventional laser, the absence of mirrors greatly simplifies laser design, but control over emission directionality or frequency tunability is lost. We proved recently that control over the random laser emission can be regained by active shaping of the spatial pump profile. This novel approach will be used to harness important characteristics of the random laser emission, such as directionality and pulse temporal profile.

Elastic metamaterials. By replacing atoms with man-made elementary structures, new artificial materials may provide novel functionalities. These so-called metamaterials may bend waves in an unusual manner (“negative refraction”), hide objects (“cloaking”), focus light below the diffraction limit,… Flexural waves in thin plates are excellent candidates to test “crazy” ideas proposed by theoreticians. One such idea is transformational optics, a mathematical technique for designing such artificial materials. By using the appropriate coordinate transformation, media containing gradients in optical or elastic properties are designed to mimic curved geometries of space-time to hide objects. One of our project is to investigate the broadband cloaking of objects using a number of active sources located outside the object. The challenge is to cancel the elastic field around the object without interfering with the incident field away from the target. Such a device should give the illusion that the object has disappeared or could show a different object instead.

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