58 research outputs found
Multi-spectroscopic investigation of the structure of single-wall carbon nanotubes
We present a multispectroscopic structural study of various nanotube samples
with different tube diameters. We determine for each sample the mean bundle and
tube diameter as well as the tube diameter distribution. The possibility to
work on SWNT of various structural characteristics opens new opportunities to
correlate the nanotube structure and their physical properties.Comment: Conf\'{e}rence : 8 au 15 mars 200
Raman studies of suspensions and solutions of singlewall carbon nanotubes
Raman spectroscopy is used to probe the structure and electronic properties
of nanotubes dispersed in a liquid phase. We show that the radial breathing
modes are upshifted in suspensions due to the molecular pressure of the
solvent. On the other hand, we directly probe charge transfer in solutions of
nanotube polyelectrolytes and its reversibility after oxydation in air
Nanotube-based systems for broadband optical limiting: towards an operational system
Nanotube-based systems are good candidates for optical limiting against
broadband laser pulses. We explore new routes to improve their limiting
performances. We show that the diameter of the nanotubes is a key factor to
control the performances. On the other hand, we demonstrate that chemically
modified nanotubes can be mixed with organic chromophores, leading to high
performance composite limiting systems which are particularly efficient in the
nanosecond regime due to the cumulative effects of nonlinear scattering and
multiphoton absorption
Light Emission in Silicon from Carbon Nanotubes
The use of optics in microelectronic circuits to overcome the limitation of
metallic interconnects is more and more considered as a viable solution. Among
future silicon compatible materials, carbon nanotubes are promising candidates
thanks to their ability to emit, modulate and detect light in the wavelength
range of silicon transparency. We report the first integration of carbon
nanotubes with silicon waveguides, successfully coupling their emission and
absorption properties. A complete study of this coupling between carbon
nanotubes and silicon waveguides was carried out, which led to the
demonstration of the temperature-independent emission from carbon nanotubes in
silicon at a wavelength of 1.3 {\mu}m. This represents the first milestone in
the development of photonics based on carbon nanotubes on silicon
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
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
m. Such results prove the great potential of carbon nanotubes for photonic
applications
Broadband optical limiting optimisation by combination of carbon nanotubes and two-photon absorbing chromophores in liquids
International audienceWe report here on the optical limiting studies performed with nanosecond laser pulses on several families of multiphoton absorbers in chloroform, with carbon nanotubes suspended in solutions. Performances of these samples are compared with those of simple multiphoton absorber solutions and carbon nanotube suspensions, and the differences observed are interpreted in terms of cumulative NLO effects and adverse aggregation phenomenon
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