For several years, silicon photonics is a very active research field, first to overcome metallic interconnects problem in CMOS microchip, and more and more to reduce component cost in telecommunications. The realization of an “optical link” involves developing basic key components, such as optical laser source, optical modulator or photodetectors, that could be easily integrated over silicon. Numerous solutions were developed (III-V, Germanium, nc-silicon), but their monolithic integration on silicon still presents difficulties, due to different materials used for optical source, modulator and detector. The use of carbon nanotubes could allow monolithic integration of these components. In this context, “Ça (Re-)Lase !” proposal aims at focus on the laser optical source, and to realize an electrically driven silicon integrated carbon nanotube laser source. Carbon nanotube is a pertinent choice for this project. Indeed, carbon nanotubes present, among other originalities, semiconductor or metallic behavior, leading to a great variety of electrical and optical properties depending on carbon nanotubes structure. This behavior generates a great interest in carbon nanotubes for nano-electronics and nano-optoelectronics. At the electronic level, carbon nanotubes based field effect transistors displays promising performances, and their compatibility with microelectronics technology is under study. ITRS, the industrial consortium defining the future of microelectronics, started to be interested in carbon nanotubes for possible use as an ultimate channel in MOSFET transistors and as metallic vias. At the optoelectronic level, carbon nanotube displays strong photo- and electro-luminescence, in the NIR-MIR range (from 1 µm to 5 µm), tunable by choosing a precise carbon nanotube diameter and chirality. The possibility to use electric pumping to generate luminescence is extremely favorable for the developing of nanotube based laser sources. Moreover, a breakthrough was recently performed at IEF by the first observation of optical gain in semiconductor carbon nanotubes, and this is an important first step towards carbon nanotubes based laser sources. Thus, the use of the same carbon nanotubes for both optical and electronic functions, as proposed by “Ça (Re-)Lase !” offers very innovatives perspectives for monolithically integration of electronic and optical function in future microchips. From the context presented above, one could see that carbon nanotubes are a very polyvalent material, displaying at the same time very rich optical and electronic properties. Carbon nanotubes are good candidates for the realization of optical light source. All of this illustrates “Ça (Re-)Lase !” pertinent choice of carbon nanotubes for the realisation of an electrically driven laser integrated on silicon. Outcomes of “Ça (Re-)Lase !” will be broader than the carbon nanotube laser source. The research theme of carbon nanotube photonics is an emerging field, and potentialities of carbon nanotubes for optical modulation, photodetection, bio-photonics or medical or environmental applications are great.