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Etude de l'affinement spectral d'un oscillateur paramétrique optique (OPO) en régime nanoseconde par insertion d'un cristal photoréfractif : Modélisation des OPO monomodes.

Stéphane Victori 1
1 Laboratoire Charles Fabry de l'Institut d'Optique / Elsa
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : The first part of the thesis deals with nanosecond Optical Parametric Oscillator (OPO) theory. One introduces non-linear optics and anisotropic optical properties of crystals, leading to the definition of the effective non-linear coupling constant. It is followed by the demonstration of the coupled-wave equations, including or not the refractive index dispersion and the electric field divergence. A state of the art of theoretical models and spectral narrowing techniques concludes this part. The second part presents two numerical methods to integrate the previous equations. The first one is based on the cIassical "split-step" method. It is possible to include parametric fluorescence in order to simulate the starting of the OPO. The second method is based on a transformation of the coupled-wave equations, leading to a direct integration of the non-Iinear Schrödinger set of equations then obtained, using the fix-point method, a finite-difference scheme and a Crank-Nicolson discretization. The third part presents comparisons between experimental and numerical results for experimental setups satisfying or not model hypothesis. Then, it introduces a new spectral-narrowing technique of coherent light sources based on the insertion of a photorefractive crystal in the cavity. This technique is applied to two continuous lasers, two-nanosecond lasers and one nanosecond OPO. In the first two cases, one shows a spectral narrowing of the laser emission becoming longitudinally single-mode and a reduction of the laser Iinewidth. Dealing with the pulsed lasers, one shows a frequency stabilization of the laser emission and a reduction of the laser linewidth. Finally, concerning the nanosecond OPO, one shows a decrease of the number of emitted modes and a good agreement between experimental and numerical results.
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https://pastel.archives-ouvertes.fr/pastel-00714252
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Submitted on : Tuesday, July 3, 2012 - 5:08:55 PM
Last modification on : Wednesday, October 14, 2020 - 4:00:11 AM
Long-term archiving on: : Thursday, December 15, 2016 - 8:22:16 PM

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  • HAL Id : pastel-00714252, version 1

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Stéphane Victori. Etude de l'affinement spectral d'un oscillateur paramétrique optique (OPO) en régime nanoseconde par insertion d'un cristal photoréfractif : Modélisation des OPO monomodes.. Optique [physics.optics]. Université Pierre et Marie Curie - Paris VI, 2001. Français. ⟨pastel-00714252⟩

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