We report on the first THz magnetospectroscopy of double HgTe quantum well in magnetic fields up to 16 T. Very recently, specific metal phase, which holds some properties of natural bilayer graphene, was predicted in this system. In this work, we focus on the double HgTe QW with parameters, corresponding to such `bilayer graphene' phase. In our experiments we clearly observe THz optical transitions from double-degenerated zero-mode Landau level. A good agreement between experimental and theoretical transition energies confirms previous prediction of `bilayer graphene' phase in double HgTe quantum wells.

Genome processing relies on the intracellular localization and dynamic assembly of higher-order nucleoprotein complexes. In bacteria, the mechanism of assembly for the most widespread partition systems, ParABS, responsible for active DNA segregation remains elusive. We have combined super-resolution, genome-wide, biochemical and modeling approaches to investigate quantitatively the formation of the nucleoprotein complex organized around the centromere-like sequences, parS. We found that the active confinement of nearly all ParB proteins around parS, observed at the single molecule resolution, relies on a network of synergistic interactions involving protein-protein and protein-DNA interactions. Our physico-mathematical modeling of ParB binding pattern revealed that ParB binds stochastically in the vicinity of parS over long distances. Based on our findings, and consistent with previous data, we propose a new model that relies on a nucleation and looping mechanism leading to the formation of a dynamic lattice for the partition complex assembly. We thus provide new bases to model the DNA segregation process. Our original assembly model may also apply to many unrelated proteins that self-assemble in superstructures through nucleation centers.

Les nanotubes de carbone monofeuillets (SWNT) présentent des propriétés physiques originales dues à leur composition –ils sont constitués uniquement d’atomes de carbone– et à leur faible dimensionnalité. En ce qui concerne leurs propriétés optiques, les SWNT semi-conducteurs émettent de la lumière dans le proche infrarouge –on parle de photoluminescence ou de fluorescence– à des longueurs d’onde qui dépendent de leur structure et de leur environnement diélectrique. Cet article traitera des phénomènes physiques à l’origine de la photoluminescence des SWNT, et en particulier leurs propriétés excitoniques, l’influence de la structure et de l’environnement sur le spectre de photoluminescence, ainsi que les perspectives d’applications en photonique.

The rise of efficient extraction techniques triggered a renewal of interest in semiconducting carbon nanotube (s-SWNT) research. It represents a great interest for optoelectronics, with outstanding properties in field-effect transistor, and s-SWNT ability to efficiently emit light in the near-IR range. In particular, the hybrid system polyfluorene (PFO) wrapped s‑SWNT (s-SWNT@PFO) display strong photoluminescence, and could be coupled with photonic devices such as microring resonators to control photoluminescence linewidth and enhance photoluminescence intensity.The main challenge for using s-SWNT@PFO in optoelectronics lies in the difficulty to establish good electrical contact with a PFO embedded carbon nanotube, and existing studies only focused on optical pumping of carbon nanotube networks, without addressing issues of electrical driving.We propose to investigate these issues using suspended s-SWNT@PFO networks. The network formation process allow to control nanotube density, while the amount of remaining metallic nanotube in the network could be adjusted at the extraction phase. A selective annealing process under low pressure is used to tune PFO wrapping around the nanotubes. The resulting s-SWNT@PFO networks are then probed by AFM, Raman spectroscopy, absorption, photoluminescence and electrical experiments.

Silicon photonics, due to its compatibility with the CMOS platform and unprecedented integration capability, has become the preferred solution for the implementation of next generation optical interconnects. However, current Si photonics require on-chip integration of several materials, including III-V for lasing, doped silicon for modulation and Ge for detection. The very different requirements of these materials result in complex fabrication processes that offset the cost-effectiveness of the Si photonics approach. We are developing an alternative route towards the integration of optoelectronic devices in Si photonic, relying on the use of single wall carbon nanotubes (SWNTs). SWNTs can be considered as a Si compatible material able to emit, modulate and detect near-infrared light. Hence, they hold a unique potential to implement all active devices in the Si photonics platform. In addition, solution processed SWNTs can be integrated on Si using spin-coating techniques, obviating the need of complex epitaxial growth or chip bonding approaches. Here, we report on our recent progress in the coupling of SWNTs light emission into optical resonators implemented on the silicon-on-insulator (SOI) platform.

Silicon photonics has emerged as a very promising technology platform for the implementation of high-performance, low-cost, ultra-compact circuits that can monolithically cointegrate electronic, opto-electronic and optic functionalities. However, Si neither has efficient light emission or detection in the telecom wavelength range, nor exhibits efficient electro-optic Pockels effect, hindering the implementation of integrated active devices like sources, detectors, or modulators. Current approaches relay on different materials to provide active functionalities in Si photonics, resulting in highly complex integration schemes that compromise cost-effectiveness. Semiconducting single-wall carbon nanotubes (SWNTs) are capable of emitting and detecting near-infrared light at room temperature and exhibit intrinsically fast electro-optic effects. They have also proven promising uses in micro-electronic devices, making them an ideal material to provide active functionalities in the Si photonic platform. In this work, we propose and experimentally validate the possible use of slot photonic waveguides to improve interaction between SWNTs and Si waveguide modes. Fabricated Si slot micro-ring shown an experimental ~ 60% photo-luminescence improvement compared to previous demonstration based on Si strip waveguide resonators. These results prove the potential of Si slot waveguides for the implementation of efficient SWNT-based Si photonic devices.

We report on the strong photoluminescence enhancement from carbon nanotubes integrated in silicon microring resonators under two pumping configuration: surface-illuminated pumping and collinear pumping. Extremely efficient rejection of non-resonant photoluminescence is observed.