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Propagation de vortex optiques en milieu photoréfractif: application à la génération de guides optiques

Abstract : This work deals with the generation and handling of optical vortices, ie laser beams holders of a phase singularity providing an orbital angular momentum. The aim is to induce optical waveguides in photorefractive materials such as lithium niobate while also understanding the physical interactions between vortices and the non linear environment. The layout and manipulation of optical vortices are used here to achieve waveguides in massive materials. New technologies-wise, they could process information through new interconnections components. Our solution is based on the principle of spatial optical solitons, invariably propagating beams which can be obtained via an appropriate nonlinear interaction. Photorefractive spatial solitons are associated with a refractive index modulation by the Pockels effect that induces a waveguide in an optical material with the same profile as the soliton's. We propose here to use an efficient material in the field of optoelectronics, the lithium niobate (LiNbO3).

We first introduce the basics and the state of the art on solitons and on optical vortices and their applications are also featured. Then the principles involved in this work are detailed. On one hand, the mathematical formalism defining vortices and methods for obtaining them are described. On the other hand, the different physical mechanisms participating to the formation of solitons in photorefractive materials are described. We then expose the well-known numerical models describing the phenomenons, detailing their strengths and imperfections. A new three dimensional and time numerical model incorporating variables previously neglected is proposed for a better understanding of the behavior of vortices in lithium niobate doped iron. In Chapter Four, we highlight the good agreement between this new model and the experimental observation of the influence of crystal anisotropy on the propagation of a vortex in a photorefractive-photovoltaic according to parameters such as the orbital momentum of the vortex and the directions of propagation and polarization with respect to crystallographic axes of LiNbO3. In the last chapter, the results obtained in the previous one are used to define the optimal experimental conditions to form a quasi-vortex soliton in two dimensions, inducing a structure confining light in the material. In addition, the first experimental complex structures optically induced by vortices with multiple charges are presented.
The new numerical model developed in this thesis may be used to go into details of dislocation mechanisms and dynamics of optical vortex related to the presence of multiple phase singularities.
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https://tel.archives-ouvertes.fr/tel-00400383
Contributor : Bélinda Lafon <>
Submitted on : Tuesday, June 30, 2009 - 4:04:57 PM
Last modification on : Thursday, November 12, 2020 - 9:42:03 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 7:08:58 PM

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  • HAL Id : tel-00400383, version 1

Citation

R. Passier. Propagation de vortex optiques en milieu photoréfractif: application à la génération de guides optiques. Sciences de l'ingénieur [physics]. Université de Franche-Comté, 2009. Français. ⟨tel-00400383⟩

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