Plasmon-enhanced diffraction in nanoparticle gratings fabricated by in situ photo-reduction of gold chloride doped polymer thin films by laser interference patterning

International audienc

Ligand-Induced Anisotropy of the Two-Photon Luminescence of Spherical Gold Particles in Solution Unraveled at the Single Particle Level

Here we report on the visible luminescence properties of individual spherical gold particles in solution, obtained by two-photon excited fluorescence correlation spectroscopy and by an original dual Rayleigh-fluorescence method, correlating the Rayleigh scattering and the luminescence fluctuations of the same particle. The results demonstrate that the power needed to observe the two-photon excited visible luminescence depends on the illuminated particle and that the corresponding emission is anisotropic at low power. These observations combined with the evolution of the dynamics of the luminescence with respect to excitation power are interpreted by the presence of unique emissive surface states that are randomly switched off and on by the heat-induced movement of the molecular coating. These characteristics, which remain hidden in macroscopic experiments, have important implications with respect to the potential use of the particles as labels in two-photon imaging in aqueous samples

Intérêt de la télévision en couleur en fibroscopie digestive

Les auteurs exposent leurs essais de télévision endoscopique digestive en couleur, technique rendue possible par la transmission satisfaisante de l'intensité lumineuse grâce aux fibres de verre et par les progrès des caméras de télévision en couleur. Les résultats obtenus avec une caméra Thomson-CSF sont satisfaisants. L'image a une bonne définition et un bon rendu des couleurs. L'endoscope étant en place et la caméra étant fixée à son oculaire, tout l'examen est conduit ensuite sous le contrôle du moniteur de télévision. Toutes les manoeuvres (biopsie, rétrovision, etc.) sont possibles. Cet appareillage a un grand intérêt. Il permet l'enregistrement des images sur bande magnétique, la transmission à distance (salle voisine, ondes herziennes) des images endoscopiques, ce qui a en particulier un immense intérêt pour l'enseignement. L'obstacle actuel au développement de cette endoscopie télévisée en couleur est son prix très élevé

Influence of surface plasmon propagation on leakage radiation microscopy imaging

International audienceWe study in this Letter, the effect of the surface plasmon (SP) propagation and coherence on the images obtained by leakage radiation microscopy. The studied system is a set of nanocrystals deposited on a thin silver film supporting surface plasmon modes. More than 70% of the emission in this typical system comes from non-local emission. The diameter of the influence circle around the detection point is of the order of magnitude of the plasmon propagation length. We also present an original method to measure the propagation length (L-spp) of surface plasmons in complex systems by a two Young's slits experiment. This method can be useful for complex systems with a very short propagation length

Vertical Plasmonic Nanoantenna for Emission and Redirection

International audienc

Organic Exciton in Strong Coupling with Long-Range Surface Plasmons and Waveguided Modes

International audienc

Localization of plasmon modes in a 2D photonic nanostructure with a controlled disorder

International audienceIn this paper, we focus on the optical properties of disordered hole arrays etched in a gold thin film. The disorder is induced and controlled using hole displacements following a Gaussian distribution and starting from a periodic array. The nanostructures present a transition from ordered arrays to short-range ordered arrays and random arrays by increasing the disorder amount. The associated optical properties are characterized in far and near fields by complementary approaches (absorption spectroscopy, classical scanning near field optical microscopy (SNOM) and Finite Difference Time Domain (FDTD) simulations). By increasing the disorder, a broadened absorption up to 30% in the far-field is achieved. Experiments in agreement with FDTD simulations point out the energy localization induced by the disorder and the dependence on the amount of disorder and on the excitation wavelength. By using a controlled disorder, we also show that the effect of these two parameters is also closely linked