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Caractérisation spatio-temporelle d'une chaîne laser à 32.8 nm par plasma laser et perspectives vers une source ultrabrève et intense

Abstract : Plasma-based soft-x-ray lasers are a promising coherent source complementary to the soft-x-ray free-electron laser. While most of the soft x-ray lasers in the world operate in the ampliifcation of spontaneouse emission regime, we study here a oscillator-amplifier geometry, following the example of power lasers in the VIS/IR range. The amplifier is a 8 times-ionized krypton plasma resulting from optical field ionization of a low-density gaseous target by an intense laser pulse. This amplifier is seeded by a high-order harmonic radiation at the same wavelength. We present here experimental and numerical results focused on the effect of the amplification on the spatial characteristics of the resulting beam (spatial profile, transverse coherence and wavefront) as well as its spectro-temporal properties. We show that, due to spatial filtering of the harmonic beam by the amplifier, the seeded beam exhibits remarkable characteristics such as a strong transverse coherence and a near diffraction-limit wavefront. It is also shown that its spatial profile can be controled from a Gaussian profile to a Bessel profile with several intense rings. This beam is made up of Fourier-limited microjoule picosecond pulses. A lead to enhance this source intensity is to generate the amplifier in a near-critical density plasma. This was achieved by guiding the pump laser pulse in an optically preformed waveguide. Guiding was demonstrated and promising results were obtained in the amplification of spontaneous emission regime.
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https://pastel.archives-ouvertes.fr/pastel-00604362
Contributor : Fabien Tissandier <>
Submitted on : Tuesday, June 28, 2011 - 5:05:17 PM
Last modification on : Thursday, April 2, 2020 - 9:16:06 AM
Long-term archiving on: : Thursday, March 30, 2017 - 12:34:58 PM

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F. Tissandier. Caractérisation spatio-temporelle d'une chaîne laser à 32.8 nm par plasma laser et perspectives vers une source ultrabrève et intense. Physique des plasmas [physics.plasm-ph]. Ecole Polytechnique X, 2011. Français. ⟨pastel-00604362⟩

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