Mise en forme programmable de faisceau laser femtoseconde pour le micro-usinage et la photoinscription de guides d'ondes

Abstract : This work concerns spatial beam shaping of ultrashort pulse lasers, for laser-matter interaction improvement.
The first part presents the conception and the experimental realization of an adaptive optics system, enabling spatial focal spot shaping. This original set-up relies on a liquid-crystal wavefront modulator, used as a programmable phase plate with a high resolution. A precise correction of the phase aberrations is performed : a quasi-flat wavefront is obtained in real-time, and thus a diffraction-limited focal spot. Then, by precisely controlled spatial-phase modulation, programmable beam shaping is performed, matching the arbitrary shapes desired. A wide variety of shapes with a high quality are obtained at the focal point of a lens, with small dimensions (70 µm) : round and square top-hats, doughnut, triangle, rectangle.
In a second part, this set-up is profitably used for femtosecond laser-matter interaction, for which the material is modified essentially in the irradiated zone : surface micro-machining (metals) and micro-structuration in the bulk (transparent dielectrics). Spatial beam shaping makes it possible to perform direct micro-machining of complex shapes, and wavefront correction enables controlled photo-writing of optical waveguides in glass, via refrctive index modification. Subsequent improvement of quality, precision and control is demonstrated, enabling both optimization and extension of femtosecond laser processes.
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Contributor : Nicolas Sanner <>
Submitted on : Thursday, January 4, 2007 - 3:43:04 PM
Last modification on : Wednesday, July 25, 2018 - 2:05:30 PM
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  • HAL Id : tel-00122731, version 1

Citation

Nicolas Sanner. Mise en forme programmable de faisceau laser femtoseconde pour le micro-usinage et la photoinscription de guides d'ondes. Physique Atomique [physics.atom-ph]. Université Jean Monnet - Saint-Etienne, 2005. Français. ⟨tel-00122731⟩

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