Depot des Theses - Advanced microstructured fibers design for a robust singlemode high power laser operation

The development of tailored micro-structured optical fibers has known a real infatuation during the last two decades allowing an outstanding management of optical properties. In particular, this approach was beneficial to the emission of a robust singlemode beam from large mode area fibers whose the core size exceeds 40 μm. This ability has made fiber lasers serious and competitive candidates for widespread applications such as micro-machining or surgery. In this purpose, several fiber structures have been devised (Large Pitch Fibers and Distributed Mode Filtering fibers for instance), pushing further the performances of high-power fiber lasers and amplifiers. However, new detrimental phenomena impact their operation at high-power regime. Indeed, a degradation of the beam quality is noticed when the emitted power overcomes a certain threshold, because of the inherent capability of state-of-the-art fibers to sustain several guided modes into their core. In this context, I first investigated thoroughly the behavior of guided modes in state-ofthe- art ultra large-mode-area fibers and highlighted several milestones allowing to get an efficient selective amplication. Hence, I benefited from these statements to propose novel kinds of all-solid micro-structured fibers exhibiting an enhancement of the singlemode robustness. I demonstrated a record modal discrimination in a so-called Spiral LPF whose the inner cladding pattern is totally asymmetry. The first fabrications of these all-solid fibers are also reported, contributing to clearly define the prospect of this work as well as the fabrication hurdles. Créé par DAULIAT Romain 3 oct. 2014 Version 0.1

Nature

Thèse de doctorat

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Disciplines Doctorat/Électronique des Hautes Fréquences et Optoélectronique

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3 oct. 2014

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3 oct. 2014

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DAULIAT Romain

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