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Marseille, France

Schittny R.,Karlsruhe Institute of Technology | Kadic M.,Karlsruhe Institute of Technology | Guenneau S.,Fresnel Institute | Wegener M.,Karlsruhe Institute of Technology
Physical Review Letters

It was recently shown theoretically that the time-dependent heat conduction equation is form invariant under curvilinear coordinate transformations. Thus, in analogy to transformation optics, fictitious transformed space can be mapped onto (meta)materials with spatially inhomogeneous and anisotropic heat-conductivity tensors in the laboratory space. On this basis, we design, fabricate, and characterize a microstructured thermal cloak that molds the flow of heat around an object in a metal plate. This allows for transient protection of the object from heating while maintaining the same downstream heat flow as without object and cloak. © 2013 American Physical Society. Source

Durt T.,Fresnel Institute
International Journal of Modern Physics B

The role played by time in the quantum theory is still mysterious by many aspects. In particular it is not clear today whether the distribution of decay times of unstable particles could be described by a time operator (TO). As we shall discuss, different approaches to this problem (one could say interpretations) can be found in the literature on the subject. As we shall show, it is possible to conceive crucial experiments aimed at distinguishing the different approaches, by measuring with accuracy the statistical distribution of decay times of entangled particles. Such experiments can be realized in principle with entangled kaon pairs. © 2013 World Scientific Publishing Company. Source

Jang M.,California Institute of Technology | Sentenac A.,Fresnel Institute | Yang C.,California Institute of Technology
Optics Express

Isotropic optical focusing-the focusing of light with axial confinement that matches its lateral confinement, is important for a broad range of applications. Conventionally, such focusing is achieved by overlapping the focused beams from a pair of opposite-facing microscope objective lenses. However the exacting requirements for the alignment of the objective lenses and the method's relative intolerance to sample turbidity have significantly limited its utility. In this paper, we present an optical phase conjugation (OPC)-assisted isotropic focusing method that can address both challenges. We exploit the time-reversal nature of OPC playback to naturally guarantee the overlap of the two focused beams even when the objective lenses are significantly misaligned (up to 140 microns transversely and 80 microns axially demonstrated). The scattering correction capability of OPC also enabled us to accomplish isotropic focusing through thick scattering samples (demonstrated with samples of ∼7 scattering mean free paths). This method can potentially improve 4Pi microscopy and 3D microstructure patterning. © 2013 Optical Society of America. Source

Baffou G.,Fresnel Institute | Rigneault H.,Fresnel Institute
Physical Review B - Condensed Matter and Materials Physics

We investigate theoretically and numerically the thermodynamics of gold nanoparticles immersed in water and illuminated by a femtosecond-pulsed laser at their plasmonic resonance. The spatiotemporal evolution of the temperature profile inside and outside is computed using a numerical framework based on a Runge-Kutta algorithm of the fourth order. The aim is to provide a comprehensive description of the physics of heat release of plasmonic nanoparticles under pulsed illumination, along with a simple and powerful numerical algorithm. In particular, we investigate the amplitude of the initial instantaneous temperature increase, the physical differences between pulsed and cw illuminations, the time scales governing the heat release into the surroundings, the spatial extension of the temperature distribution in the surrounding medium, the influence of a finite thermal conductivity of the gold/water interface, the influence of the pulse repetition rate of the laser, the validity of the uniform temperature approximation in the metal nanoparticle, and the optimum nanoparticle size (~40 nm) to achieve a maximum temperature increase. © 2011 American Physical Society. Source

Guenneau S.,Fresnel Institute | Amra C.,Fresnel Institute | Veynante D.,Ecole Centrale Paris
Optics Express

We adapt tools of transformation optics, governed by a (elliptic) wave equation, to thermodynamics, governed by the (parabolic) heat equation. We apply this new concept to an invibility cloak in order to thermally protect a region (a dead core) and to a concentrator to focus heat flux in a small region. We finally propose a multilayered cloak consisting of 20 homogeneous concentric layers with a piecewise constant isotropic diffusivity working over a finite time interval (homogenization approach). © 2012 Optical Society of America. Source

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