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Theses

Caractérisation des effets de lentille de population dans les lasers à solide

Abstract : In ion-doped solid-state laser materials, the pump-induced refractive index changes (RIC) have an electronic component, the so-called population lens effect, which can be related to the change in excited state population and to the polarizability difference between the excited and ground states. These population effects have a tremendous influence upon the spatiotemporal characteristics of laser resonators and it is thus a challenging problem to have sensitive techniques for measuring them. Hence, this PhD thesis is focused on the metrology of the RIC for a better understanding of the solid-state lasers behavior and in order to be able to use these effects for various applications. The first part of this manuscript consists in measuring the population effects in Chromium and Ytterbium-doped laser crystals with the Z-scan technique. For doing so, a time-resolved experiment has been designed in order to discriminate between thermal and electronic effects. In a second part, we have developed a new efficient technique, called Baryscan, able to measure very weak RIC and to reach among the highest sensitivity levels to date. This method is based upon the measurement of optical nonlinearities by means of beam centroid displacements with a Position Sensitive Detector. Besides, interesting results about the diffractive focusing of laser beams with a cascade of phase plates are presented and two beam shaping techniques for forcing a laser to oscillate on a high-order mode are detailed.
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https://tel.archives-ouvertes.fr/tel-00745389
Contributor : Thomas Godin <>
Submitted on : Thursday, October 25, 2012 - 2:25:42 PM
Last modification on : Friday, March 5, 2021 - 2:59:31 PM
Long-term archiving on: : Saturday, January 26, 2013 - 3:55:17 AM

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  • HAL Id : tel-00745389, version 1

Citation

Thomas Godin. Caractérisation des effets de lentille de population dans les lasers à solide. Optique [physics.optics]. Université de Caen, 2012. Français. ⟨tel-00745389⟩

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