Experimental investigation of the optical Kerr effect at large laser intensity: impact on the propagation of a short and intense laser pulse

Talk given by O. Faucher; International audience

Quantifying alignment with transient grating technique

Higher-order Kerr terms allow ionization-free filamentation in gases

Talk given by J. Kasparian; International audience; Higher-order nonlinear indices, rather than plasma, provide the main defocusing contribution to filamentation in gases at 800 nm. Developing generalized Miller formulae, we discuss the generality of this as a function of the laser wavelength

Field-free molecular alignment of ethylene

Talk given by O. Faucher; International audience

Stratégies de contrôle pour la manipulation spatiale de molécules

Talk given by E. Hertz; National audience

Observation d'effets Kerr d'ordres élevés (HOKE) dans les gaz

Talk given by O. Faucher; National audience

Alignement moléculaire sous impulsions laser ultracourtes

Talk given by O. Faucher; National audience

Human Immunodeficiency Virus Continuum of Care in 11 European Union Countries at the End of 2016 Overall and by Key Population: Have We Made Progress?

Abstract Background High uptake of antiretroviral treatment (ART) is essential to reduce human immunodeficiency virus (HIV) transmission and related mortality; however, gaps in care exist. We aimed to construct the continuum of HIV care (CoC) in 2016 in 11 European Union (EU) countries, overall and by key population and sex. To estimate progress toward the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 target, we compared 2016 to 2013 estimates for the same countries, representing 73% of the population in the region. Methods A CoC with the following 4 stages was constructed: number of people living with HIV (PLHIV); proportion of PLHIV diagnosed; proportion of those diagnosed …

Determination of concentrations in ternary and quaternary molecular gas mixtures using femtosecond Raman spectroscopy

European Conference on Nonlinear Optical Spectroscopy MAR 18-19, 2002 VILLIGEN, SWITZERLAND; Measurements of concentrations in gas mixtures of three and four molecular components are presented. They rely on a femtosecond time-resolved pump-probe technique based on Raman-induced polarization spectroscopy. The rotational time response of the molecular gas mixture is measured as a function of the pump-probe time delay. No selective frequency tunability is needed as the molecular rotational spectra are excited within the laser bandwidth. The results obtained from experiments performed at room temperature in N2O-CO2-N2 and N2O-CO2-O2-N2 mixtures are presented and the accuracy of the method is di…

Higher-order Kerr terms allow ionization-free filamentation in gases

International audience; We show that higher-order nonlinear indices (n4 , n6 , n8 , n10) provide the main defocusing contribution to self-channeling of ultrashort laser pulses in air and Argon at 800 nm, in contrast with the previously accepted mechanism of filamentation where plasma was considered as the dominant defocusing process. Their consideration allows to reproduce experimentally observed intensities and plasma densities in self-guided filaments.

Mesure de l'effet Kerr d'ordre élevé des constituants de l'air

Talk given by V. Loriot

Laser induced field-free molecular alignment

Talk given by O. Faucher; International audience

Negative and positive Kerr nonlinearity of air calibrated with transient molecular alignment

Talk given by O. Faucher; International audience; Nonlinear electronic Kerr index of the major air constituents has been measured up to high order terms using transient molecular alignment as a reference. Sign reversal associated to negative nonlinearity is observed above a pulse intensity of 26 TW/cm^.2

TIGER: TIme-Gated Electric field Reconstruction

We present a novel self-referenced method for the complete temporal characterization (phase and amplitude) of ultrashort optical laser pulses. The technique, called TIme-Gated Electric field Reconstruction (TIGER), measures a second-order nonlinear signal (namely, second harmonic generation or two-photon absorption) produced by four time-delayed replicas of the input pulse. The delays are spatially encoded in the beam profile using a four-faced pyramid-like optical element. The presented technique enables single shot measurement and does not require any spectral measurements, in contrast with well-known self-referenced characterization methods. Depending on the chosen geometry, the recorded…

High-order Kerr nonlinearity of air calibrated with transient molecular alignment

Talk given by O. Faucher; International audience; Nonlinear electronic Kerr index of the major air constituents has been measured up to high order terms using transient molecular alignment as a reference. Sign reversal associated to negative nonlinearity is observed above a pulse intensity of 26 TW/cm^2.