Jeux de Miroir. Réflexions sur MSF et l’action humanitaire

Depuis la fin de la décennie 1990, la plupart des États occidentaux ont modifié leur doctrine militaire en incorporant l’aide humanitaire dans les missions de leurs forces armées. La dénomination de « guerre humanitaire », utilisée pour la première fois au Kosovo en 1999, fait désormais partie intégrante de la rhétorique des gouvernements afin de conférer une légitimité à leurs engagements militaires. Forces armées et ONG humanitaires évoluent donc de plus en plus simultanément sur un même te..

80-Gb/s OTDM system analysis of a vertical microcavity-based saturable absorber for the enhancement of pulse pedestal suppression

In future high-speed optical time-division-multiplexed (OTDM) systems, an important factor that needs to be considered for optical pulse generation schemes is the impact of pulse pedestals on the overall system performance. The results presented in this letter are two-fold; first, the impact due to the height of pulse pedestals in an 80-Gb/s OTDM system are established. Second, a solution is provided to overcome these high pedestal levels through the use of a vertical microcavity saturable absorber, which can significantly reduce the pulse pedestal level and give enhanced system performanc

Resonant nonlinear spectroscopy in strong fields

A method is presented to describe multiple resonant nonlinear spectra in the presence of strong laser fields. The Liouville equation for the d. operator of the mol. system is transformed to a time-independent linear equation system. This can be easily solved rigorously by numerical methods or, after partitioning into a strong-field part and a perturbation, the soln. can be obtained anal. by a novel perturbative approach. The results account for power broadening. Rabi splitting of signals, and power-induced extra resonances, the latter being related to the pure dephasing-induced resonances in the weak-field limit. The method can be applied to a large no. of multiple resonant nonlinear spectroscopies, esp. CARS, CSRS, coherent Rayleigh scattering and sum- or difference-frequency generation

Bis{4-[(E)-2-(1H-indol-3-yl)ethen­yl]-1-methyl­pyridinium} 4-fluoro­benzene­sulfonate nitrate 0.25-hydrate1

In the title compound, 2C16H15N2 +·C6H4FO3S−·NO3 −·0.25H2O, the two cations are nearly planar, with dihedral angles of 1.34 (14) and 4.6 (2)°, respectively, between the pyridinium and indole rings. The cations each adopt E configurations with respect to the C=C bonds and are inclined to each other with a dihedral angle of 77.66 (5)°. The ethenyl group of one cation is disordered over two sites with occupancies of 0.685 (12) and 0.315 (12), and the sulfonate group of the 4-fluoro­benzene­sulfonate anion is also disordered with occupancies of 0.535 (10) and 0.465 (10) for the two sets of O atoms. The anion is also inclined to the two cations, with dihedral angles between the mean planes of the benzene ring and the π-conjugated systems of the cations of 24.72 (11) and 79.83 (11)°. In the crystal structure, the cations are stacked in an anti­parallel fashion into columns approximately along the a axis and are further linked through the anions into a three-dimensional network via N—H⋯O and C—H⋯O inter­actions. The water mol­ecule forms O—H⋯O hydrogen bonds to the nitrate anion and C—H⋯π inter­actions are also observed

Traitement tout-optique d'un Signal RZ DPSK à 42,7 Gbit/s en utilisant Absorbant Saturable en Micro-Cavité

session orale 8 : « Systèmes et réseaux de Télécommunication »National audienceDans ce papier, nous présentons une technique de traitement tout-optique à base d'absorbant saturable limitant les fluctuations d'intensité d'un signal RZ DPSK à 42,7 Gbit/s tout en préservant sa phase. Des mesures de taux d'erreur binaire et de facteur de qualité démontrent le potentiel du dispositif pour le traitement tout-optique d'un signal DPSK dans un régime où le bruit de phase non-linéaire est dominant