Optical Gain in Carbon Nanotubes

Semiconducting single-wall carbon nanotubes (s-SWNTs) have proved to be promising material for nanophotonics and optoelectronics. Due to the possibility of tuning their direct band gap and controlling excitonic recombinations in the near-infrared wavelength range, s-SWNT can be used as efficient light emitters. We report the first experimental demonstration of room temperature intrinsic optical gain as high as 190 cm-1 at a wavelength of 1.3 {\mu}m in a thin film doped with s-SWNT. These results constitute a significant milestone toward the development of laser sources based on carbon nanotubes for future high performance integrated circuits.Comment: 4 figure

Prevention of post-mastectomy neuropathic pain with memantine: study protocol for a randomized controlled trial

International audienceBackground: N-methyl-D-aspartate receptor antagonists are potential therapies for neuropathic pain, and memantine has a good tolerance profile. A preclinical study recently reported that presurgery memantine may prevent neuropathic pain development and cognition dysfunction. Considering the high prevalence of breast cancer and of post-mastectomy neuropathic pain, a clinical trial is carried out to evaluate if memantine may prevent neuropathic pain development and maintain cognitive function and quality of life in cancer patients. Methods/Design: A randomized clinical trial (NCT01536314) includes 40 women with breast cancer undergoing mastectomy at the Oncology Hospital, Clermont-Ferrand, France. Memantine (5 to 20 mg/day; n = 20) or placebo (n = 20) is administered for 4 weeks starting 2 weeks before surgery. Intensity of pain, cognitive function, quality of life and of sleep, anxiety and depression are evaluated with questionnaires. The primary endpoint is pain intensity on a 0 to 10) numerical scale at 3 months post-mastectomy. Data analysis is performed using mixed models and the tests are two-sided, with a type I error set at α = 0.05. Discussion: The hypothesis of this translational approach is to confirm in patients the beneficial prophylactic effect of memantine observed in animals. Such a protective action of memantine against neuropathic pain and cognitive dysfunction would greatly improve the quality of life of cancer patients. Trial registration: ClinicalTrials.gov: NCT01536314 on 16 February 201

Optical pump-rejection filter based on silicon sub-wavelength engineered photonic structures

The high index contrast of the silicon-on-insulator (SOI) platform allows the realization of ultra-compact photonic circuits. However, this high contrast hinders the implementation of narrow-band Bragg filters. These typically require corrugations widths of a few nanometers or double-etch geometries, hampering device fabrication. Here we report, for the first time, on the realization of SOI Bragg filters based on sub-wavelength index engineering in a differential corrugation width configuration. The proposed double periodicity structure allows narrow-band rejection with a single etch step and relaxed width constraints. Based on this concept, we experimentally demonstrate a single-etch, $\mathbf{220\,nm}$ thick, Si Bragg filter featuring a corrugation width of $\mathbf{150\,nm}$, a rejection bandwidth of $\mathbf{1.1\,nm}$ and an extinction ratio exceeding $\mathbf{40\,dB}$. This represents a ten-fold width increase compared to conventional single-periodicity, single-etch counterparts with similar bandwidths

Polarization and wavelength agnostic nanophotonic beam splitter

High-performance optical beam splitters are of fundamental importance for the development of advanced silicon photonics integrated circuits. However, due to the high refractive index contrast of the silicon-on-insulator platform, state of the art Si splitters are hampered by trade-offs in bandwidth, polarization dependence and sensitivity to fabrication errors. Here, we present a new strategy that exploits modal engineering in slotted waveguides to overcome these limitations, enabling ultra-wideband polarization-insensitive optical power splitters, with relaxed fabrication tolerances. The proposed splitter relies on a single-mode slot waveguide which is transformed into two strip waveguides by a symmetric taper, yielding equal power splitting. Based on this concept, we experimentally demonstrate -3$\pm$0.5 dB polarization-independent transmission in an unprecedented 390 nm bandwidth (1260 - 1650 nm), even in the presence of waveguide width deviations as large as $\pm$25 nm

Optical microcavity with semiconducting single-wall carbon nanotubes

We report studies of optical Fabry-Perot microcavities based on semiconducting single-wall carbon nanotubes with a quality factor of 160. We experimentally demonstrate a huge photoluminescence signal enhancement by a factor of 30 in comparison with the identical film and by a factor of 180 if compared with a thin film containing non-purified (8,7) nanotubes. Futhermore, the spectral full-width at half-maximum of the photo-induced emission is reduced down to 8 nm with very good directivity at a wavelength of about 1.3 $\mu$m. Such results prove the great potential of carbon nanotubes for photonic applications