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Montée en puissance de lasers et d'amplificateurs à fibres dopées Ytterbium en régime continu et d'impulsions

Abstract : Extraordinary high powers are nowadays available out of fiber lasers and amplifiers (» 10 kW in continuous wave regime and » 1 MW peak power in pulsed regime). Such an increase can initiate the apparition of some undesirable effects.
During this thesis, we have developed and studied some high power Ytterbium doped fiber systems both in continuous wave and pulsed regimes. For this purpose, we have chosen to use the technology of double-clad fibers in association with adapted pumping techniques.
Especially, we have developed an original approach that allows to efficiently amplify wavelengths of small emission cross sections. High output powers, in continuous wave regime, have been achieved experimentally and these results are in good agreement with the theoretical ones.
The spatial and spectral properties of high output power lasers or amplifiers can be significantly degraded compared to those at low power. We have studied and developed an original approach allowing, for a system in pulsed regime, to maintain, up to extreme high output peak powers, the spectral purity of the source.
Moreover, we have computed and theoretically analysed the evolution of the pulse shape in amplification by a high power fiber amplifier. The study of the influence of various parameters of the seed pulse on the output pulse shape allows to significantly decrease the penalties induced by the apparition of non linear effects and to increase their thresholds while output power and energy become important. Comparison between computed results and theoretical ones are of good agreement.
These results, associated with the development of new components, indicate the possibility to achieve even higher output powers while preserving good spectral and spatial properties and retaining the same techniques as those used or demonstrated during this thesis.
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Submitted on : Tuesday, June 13, 2006 - 1:35:58 PM
Last modification on : Tuesday, January 12, 2021 - 4:50:34 PM
Long-term archiving on: : Monday, April 5, 2010 - 10:42:55 PM

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  • HAL Id : tel-00079671, version 1

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Sébastien Grot. Montée en puissance de lasers et d'amplificateurs à fibres dopées Ytterbium en régime continu et d'impulsions. Physique Atomique [physics.atom-ph]. Université Rennes 1, 2006. Français. ⟨tel-00079671⟩

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