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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Conception et caractérisation de nouvelles fibres optiques à cristal photonique dites hybrides et applications à l'optique non linéaire / Conception and Caracterisation of new photonic bandgap optical fibers

Bétourné, Aurélie 10 December 2010 (has links)
Les fibres à cristaux photoniques sont constituées d’un réseau périodique transverse de diélectriques. En introduisant un défaut dans ce réseau, il est possible de guider la lumière par un effet de bandes interdites photoniques, dont les propriétés diffèrent fondamentalement du guidage par réflexion totale interne qui a lieu dans les fibres conventionnelles. Nous étudions en particulier les fibres à bandes interdites photoniques solides, comportant des inclusions dont l’indice de réfraction est supérieur à celui de la matrice. En insérant des trous d’air dans cette structure solide, on observe une forte diminution des pertes par confinement et par courbure. De plus, la présence de trous d’air entre les inclusions de haut indice rend possible l’accord de phase entre deux modes fondamentaux, pour la génération du 2nd ou 3ème harmonique. Il est également possible dans ces fibres de générer efficacement un supercontinuum et d’en contrôler l’étendue spectrale grâce aux propriétés de dispersion particulières. / This thesis focuses both on theoretical and experimental studies of a recent class of Photonic Crystal Fibers (PCF): the solid-core PCF which guide light thanks to a Photonic BandGap (PBG) effect. The main goal of this work is then to better understand their propagation mechanisms (in order to improve their transmission properties) as well as to explore their potentials for non linear purposes. The study of these fibers (dispersion diagrams interpretation, emphasis of a scaling law and also of a light level of bend losses restrictive for their practical uses) leads us to develop a new kind of PCF for which wave guidance is a combination of PBG effect and more common Total Internal Reflexion (TIR). These fibers, called hybrid PCF, are made here by adding air holes in the all-solid structures previously studied. Particularly, two hybrid structures are proposed and fabricated, exhibiting a huge reduction of confinement and bend losses. Finally, we show that their unique disoersive properties enable to obtain a phase index matching between two fundamental modes (one is guided by PBG and the other by TIR) for second or third harmonic generation, and to effectively generate a supercontinuum for which the spectral broadening can be controlled by the opto-geometrical properties of the structure.

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