The Bridgman technology details of growing up to 100 mm-length Cr3+:LiCaAlF6 crystals are reported. The spectral-kinetic luminescence and laser properties for the pulse lamp-pumped laser are discussed.
We report the experimental study of the ultra-fast modification of the dielectric function of pure water by an intense
femtosecond laser pulse. Using a time-resolved optical interferometric technique, we measured the variation of the
phase shift, which is proportional to the modification of the real part of the refractive index, as well as the variation of
the fringes contrast, proportional to the modification of the absorption coefficient. We first observe a positive phase
shift due to Kerr effect and immediately followed a negative one. After 200 fs, the phase shift becomes positive and
remains so for at least 3 ps. Using the simple Drude -Lorentz model, we interpret this evolution as the result of
electron self-trapping.
We report the experimental study of the ultra-fast modification of the dielectric function of pure water by an intense femtosecond laser pulse. Using a time-resolved optical interferometric technique, we measured the variation of the phase shift, which is proportional to the modification of the real part of the refractive index, as well as the variation of the fringes contrast, proportional to the modification of the absorption coefficient. We first observe a positive phase shift due to Kerr effect and immediately followed a negative one. After 200 fs, the phase shift becomes positive and
remains so for at least 3 ps. Using the simple Drude - Lorentz model, we interpret this evolution as the result of electron self-trapping.
The interaction of intense femtosecond laser pulse with model samples containing gold nanoparticales embedded in dielectrics is studied in order to understand the role played by nanodefects in optical breakdown of dielectrics. A theoretical study of the conduction electrons dynamics in the laser field predicts an efficient injection of carriers from the metallic inclusion to the conuction band of the dielectric, which leads to a strong local increase of the optical
absorption in the initially transparent matrix. This prediction is tested experimentally by using time -resolved spectral interferometry to measure excitation densities as a function of the laser intensity in silica and samples doped with gold nanoparticles, which are compared with similar measurements in pure silica.
Interaction of a cluster jet with a very intense laser pulse generates x-rays in the keV domain. Many features of this type of source are well characterized and understood but their temporal structure is still being discussed. We performed experiments on photoelectron emission of a pure copper metallic sample irradiated by such a source of x-rays. We determined the best laser and gas jet parameters in order to enhance the photoemission yield. The maximum signal was obtained with 30 bars of xenon irradiated by 250 fs 75 mJ pulse at 800 nm, corresponding to an intensity of 2.1016 W/cm2. We were able to observe a peak of Auger electrons at 62 eV in the photoelectron spectrum. This suggests that pulse duration measurements based on the Laser Assisted Auger Decay (LAAD) technique are possible.
Alexandre Semerok, Catherine Chaleard, Vincent Detalle, Sylvain Kocon, Jean-Luc Lacour, Patrick Mauchien, Pierre Meynadier, Corinne Nouvellon, Pavel Palianov, Michel Perdrix, Guillaume Petite, Beatrice Salle
Laser ablation of pure metals by femtosecond, picosecond and nanosecond pulses is studied experimentally in air at atmospheric pressure. Craters created by interaction of visible and UV laser pulses with the targets are investigated. The dependence of the ablation efficiency in terms of ablated volume per unit of energy on the pulse duration and wavelength is discussed.
Catherine Chaleard, Vincent Detalle, Sylvain Kocon, Jean-Luc Lacour, Patrick Mauchien, Pierre Meynadier, Corinne Nouvellon, Pavel Palianov, Michel Perdrix, Guillaume Petite, Beatrice Salle, Alexandre Semerok
Laser ablation of pure metals by femtosecond, picosecond and nanosecond pulses is studied in air at atmospheric pressure. Craters created after interaction of visible and UV laser pulses with the targets are investigated. The dependence of the ablation efficiency in terms of ablated volume per unit of energy on the pulse duration is discussed.
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