We report the observation of the biexciton in semiconducting single-wall carbon nanotubes by means of nonlinear optical spectroscopy. Our measurements reveal the universal asymmetric line shape of the Fano resonance intrinsic to the biexciton transition. For nanotubes of the (9,7) chirality, we find a biexciton binding energy of 106 meV. From the calculation of the χ(3) nonlinear response, we provide a quantitative interpretation of our measurements, leading to an estimation of the characteristic Fano factor q of 7±3. This value allows us to extract the first experimental information on the biexciton stability and we obtain a biexciton annihilation rate comparable to the exciton-exciton annihilation one.

Heat transfer between two plates of polar materials at nanoscale distance is known to be enhanced by several orders of magnitude as compared with its far-field value. In this article, we derive accu- rate analytical expressions to quantitatively predict heat fluxes in the near-field. These analytical expressions reveal the physical mechanisms responsible for the enhancement. For two dielectric polar materials and for gaps smaller than 75nm at room temperature the heat transfer is dominated by the surface phonon polariton contribution. Between 75nm and 500 nm, the enhancement is mostly due to frustrated total internal reflection. The paper reports accurate analytical expressions for both contributions. Our analytical results highlight two differences between radiation flux at the nanoscale and in the far field: i)the heat flux spectrum depends on the gap distance, ii) the temperature dependence of the heat transfer coefficient deviates strongly from the T3 law valid for gray bodies in the far-field

Controlling the launching efficiencies and the directionality of surface plasmon polaritons (SPPs) and their decoupling to freely propagating light is a major goal for the development of plasmonic devices and systems. Here, we report on the design and experimental observation of a highly efficient unidirectional surface plasmon launcher composed of eleven subwavelength grooves, each with a distinct depth and width. Our observations show that, under normal illumination by a focused Gaussian beam, unidirectional SPP launching with an efficiency of at least 52% is achieved experimentally with a compact device of total length smaller than 8 μm. Reciprocally, we report that the same device can efficiently convert SPPs into a highly directive light beam emanating perpendicularly to the sample.

This talk will present the physics of the heat transfer at the nanoscale. Experimental realizations and measurements such as coherent emission from thermal sources and radiative heat transfer enhancement will be presented.

It has been predicted theoretically that for distances smaller than the peak wavelength of the blackbody spectrum, radiative heat transfer can be increased by the contribution of evanescent waves [1]. These effects have already been observed but a quantitative comparison is still missing. We measure the heat flux between a sphere and a plate as a function of the sphere-plate distance. We find a good agreement between the experimental and theoretical results . Particularly, the distance dependence is well reproduced by the theory in a large range of gap widths: 50nm-2μm.