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Nouveaux matériaux laser dopés à l'ytterbium : performances en pompage par diode et étude des effets thermiques.

Sébastien Chenais 1
1 Laboratoire Charles Fabry de l'Institut d'Optique / Elsa
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : This thesis is a study of new ytterbium-doped crystals, made for the development of efficient (and sometimes broadly tunable) lasers emitting around 1 µm. The first part presents the laser performance, under high power diode pumping, of new crystals: Yb:GGG, Yb:GdCOB, Yb:BOYS (and Yb:CaBOYS), Yb:SYS and Yb:YSO. The efficiency, tunability and thermal behaviour of these materials is discussed, and illustrated (when pertinent) by a comparison between materials of similar properties. Thermal effects limit the scaling toward higher powers in most of these materials: a comprehensive study of these effects is performed in the second part of this thesis. We begin this part by setting the theoretical background necessary to understand thermal and thermomechanical effects in solid state lasers. After a description of the classical techniques employed to investigate thermal effects, we describe the experimental setup we used. It is based on a commercially available Shack-Hartmann wavefront sensor, and enables the measurement of the thermal lens (including its aberrations) in end-pumped laser, under lasing and nonlasing conditions. We emphasize on the characteristics and limitations of this technique. Thermal lensing measurements are then reported, for the first time, in ytterbium-doped materials. Significant nonradiative effects have been demonstrated, whereas it is generally admitted that such effects are purely absent. We then explain how, thanks to a simple analytical model, it is possible to derive the quantum efficiency and the thermo-optical coefficient from these measurements. We also demonstrated the influence of the lasing wavelength on the thermal load, the reduction of thermal effects by the use of composite crystals, as well as the major role played by the photoelastic effect in the thermally-induced lens in Yb:GdCOB.
Complete list of metadatas

https://pastel.archives-ouvertes.fr/tel-00119661
Contributor : Sebastien Chenais <>
Submitted on : Monday, December 11, 2006 - 4:20:06 PM
Last modification on : Friday, October 23, 2020 - 4:51:24 PM
Long-term archiving on: : Wednesday, April 7, 2010 - 12:25:44 AM

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  • HAL Id : tel-00119661, version 1

Citation

Sébastien Chenais. Nouveaux matériaux laser dopés à l'ytterbium : performances en pompage par diode et étude des effets thermiques.. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 2002. Français. ⟨tel-00119661⟩

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