CArbon nanotube LASEr (Reloaded) – Ca (Re-)Lase !

SWNT synthesis techniques are numerous, but all will produce a mixture of metallic and semiconducting SWNT. It is not possible today to speciofically synthesis a single SWNT species. The presence of metallic SWNT really hamper optical application, and in particular photonics, because they quench photoluminescence.
Therefore, it is of great importance to obtain samples constituted only by semiconducting SWNT, without metallic tubes. This is one of the blocking point that this project will solve: extraction of semiconducting nanotubes, with optical emission at 1.5 µm.
An other challenge is the electrical pumping of SWNT, which necessite efficient carriers injection inside nanotubes. It is envisioned to engineer the contact nanotube/metal. At last, an integrated source need to have an efficient design to integrate SWNT with silicon waveguide. Various photonic structures are under study, such as Bragg resonnator or ring cavities.

The project just started but show great potential.

This project open perspectives in two fields:
- Photonics: a silicon integrated electrically driven carbon nanotube laser source will be a great breakthrough for photonics, with the possibility to achieve an optical link with a single material. Consequences for industry are great.
- Nanotube research: the methodology employed in this project open perspectives to study non linear phenomenon in nanotubes, such Stark and Kerr effects

* 1 conference proceeding + 1 oral communication : A. Noury et al. « Light Emission at Telecom Wavelengths from Single-Walled Carbon Nanotubes », SPIE Microtechnologies, 24 au 26 avril 2013, Grenoble, France
* 1 oral communication, A. Noury et al., « s-SWNT based silicon photonic devices : coupling nanotubes' photoluminescence with passive waveguides and Bragg micro-resonators », GDR-i GNT, 8 au 12 avril 2013, Lorient, France

These two communications presents first results obtained on integration of carbon nanotubes with photonic structures

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.