Benoit MOREL : "Modeling and simulation of dielectric ionization by femtosecond pulses"

PhD Works of Benoit MOREL : "Modeling and simulation of dielectric ionization by femtosecond pulses"

The presentation will be in french. Due to the current situation, the defence is public but only available via: https://live.femto-st.fr

Abstract :  Femtosecond lasers are powerful tools to induce modifications, index variations or nano-voids within dielectric materials. The deposited laser energy distribution is usually calculated from models based on quasi-neutrality assumption of electron-hole plasma and while neglecting transport of charge carriers. These assumptions are not necessarily verified in the case of laser illumination by highly focused femtosecond Bessel beams, which can generate nano-voids within dielectrics. In this thesis work, we developed a theoretical two-fluid plasma model describing deposited laser energy at the nanometric scale, by taking into account the transport of electrons and holes, plasma waves, photionization, impact ionization, electron-hole scattering and scattering on phonons. A study of deposited laser energy in sapphire by femtosecond Bessel beams was realized. This study showed that holes dynamic, transport and quasi-neutrality phenomena can strongly affect the generated plasma distribution and laser energy absorption.

Jury Composition :

M. Arnaud Couairon Directeur de recherche CNRS au Centre de Physique Théorique de l’École Polytechnique, Reporter
M. Stéphane Guizard Directeur de Recherche CEA/CNRS/École Polytechnique, Reporter
M. Guy Bonnaud Professeur à l'Institut National des Sciences et Techniques Nucléaires (INSTN), Reviewer
M. Maxime Jacquot Professeur à l'Université de Bourgogne Franche-Comté, Reviewer
M. John M. Dudley Professeur à l'Université de Bourgogne Franche-Comté, PhD Director
M. François Courvoisier Directeur de recherche CNRS à l’Institut FEMTO-ST, PhD Directeur

Localization : 15B avenue des Montboucons 25030 BESANCON cedex - salle Amphithéatre Jean-Jacques GAGNEPAIN