We investigate how the microstructure of a colloidal polycrystal influences its linear viscoelasticity. We use thermosensitive copolymer micelles that arrange in water in a cubic crystalline lattice, yielding a colloidal polycrystal. The polycrystal is doped with a small amount of nanoparticles, of size comparable to that of the micelles, which behave as impurities and thus partially segregate in the grain boundaries. We show that the shear elastic modulus only depends on the packing of the micelles and does not vary neither with the presence of nanoparticles nor with the crystal microstructure. By contrast, we find that the loss modulus is strongly affected by the presence of nanoparticles. A comparison between rheology data and small-angle neutron scattering data suggests that the loss modulus is dictated by the total amount of nanoparticles in the grain boundaries, which in turn depends on the sample microstructure.

Nanophotonics is an emerging field where researchers look for potential application of carbon nanotubes (SWNT) in the framework of silicon photonics technology, due to SWNT ability to emit, modulate and detect light in the wavelength range of silicon transparency. In this field of nanotube photonics, a first milestone was to couple light emission from SWNT into silicon waveguides. Current researches focus on coupling SWNT with optical cavities, either for enhancing nanotube photoluminescence (PL) or nonlinear optical phenomena at the nanoscale, using microdisk resonators, or photonic crystal cavities. However, these kinds of cavities could not be easily coupled to silicon waveguides, hindering subsequent integration into more complex photonic devices. Building up on our previous work, we propose to couple SWNT PL with silicon microring resonators in a fully integrated configuration, with an acess waveguide. PL coupled to microring modes could be collected from the access waveguide, with efficient rejection on non-resonant photons. Emission quality factor up to 8000 were observed. This design allow for collinear excitation of SWNT through the access waveguide, leading to efficient excitation and collection of SWNT PL at different wavelengths. The requirement for out-of-the-plane SWNT excitation is lifted, underlining the pertinence of this approach for realistic carbon nanotube based photonic devices.

Single-wall carbon nanotube are considered a fascinating nanomaterial for photonic applications and are especially promising for efficient light emitter in the telecommunication wavelength range. Furthermore, their hybrid integration with silicon photonic structures makes them an ideal platform to explore the carbon nanotube instrinsic properties. Here we report on the strong photoluminescence enhancement from carbon nanotubes integrated in silicon ring resonator circuit under two pumping configurations: surface-illuminated pumping at 735 nm and collinear pumping at 1.26 {\mu}m. Extremely efficient rejection of the non-resonant photoluminescence was obtained. In the collinear approach, an emission efficiency enhancement by a factor of 26 has been demonstrated in comparison with classical pumping scheme. This demonstration pave the way for the development of integrated light source in silicon based on carbon nanotubes.

(Ga,In)N-based light emitting devices are very efficient in producing blue light and to a lesser extent green. Extending their spectral range to longer wavelengths while maintaining high efficiency is a challenge due to material and physical issues related to high-In content (Ga,In) N alloys. We review the current status of yellow and red emitters (light emitting diodes and laser diodes) based on this material system. We also describe the state-of-the-art of devices mixing blue–yellow or red–blue–green coloured light, such as monolithic phosphor-free white light emitting diodes and full-colour micro-displays.

L’état vitreux est un état de la matière que l’on rencontre couramment dans le domaine des matériaux mais aussi dans le domaine de la géologie, du vivant, de la pharmacopée ou encore des procédés alimentaires... La zone de température où un système passe de l’état liquide, pour lequel la mobilité des entités structurales est élevée, à l’état vitreux, pour lequel la structure peut être considérée comme figée sur le temps de l’expérience et la cristallisation empêchée, est qualifié de domaine de transition vitreuse. Ce phénomène est étudié depuis de nombreuses années en sciences de la matière condensée et pourtant il n’existe pas actuellement de consensus quant à sa description théorique. En dehors des aspects thermodynamiques qui accompagnent cette transition, qui n’est pas une transition de phase classique, ce phénomène présente un caractère cinétique marqué. Il est aussi associé à des processus relaxationnels complexes qui s’étendent sur une large gamme de temps. Cet article traite de ces caractéristiques typiques de la transition vitreuse et des matériaux vitrifiables.

There is considerable interest at present in Singular Stochastic PDEs especially in connection with rough path theory in different guises. The mathematical work started with results by Giovanni Jona-Lasinio and myself a long time ago. I will review what was accomplished at the time and the progress that has been made since then. One reason for presenting this to this audience is that there is, in my opinion, considerable scope for rigorous renormalsation group work in this subject as I will explain. I will also attempt to prepare the ground for Jona-Lasinio's talk on our common work on large deviations for singular SPDEs.