Tesi sul tema "Fibres optiques à cœur creux"
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Ravaille, Alexia. "Gyromètre optique basé sur une cavité résonante passive en fibre à cœur creux". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS411/document.
Testo completoIn this manuscript, we report the theoretical and experimental developments at TRT, TAV and LAC, aiming the realization of a hollow-core passive resonant fiber optical gyroscope that can achieve navigation grade performances. We mathematically describe the Sagnac effect, which is a relativistic effect used to optically probe mechanical rotations. Then, we detail the state of the art in passive resonant fiber optical gyroscope development. We identify their limitations, and explain why the hollow core fiber seems to be the best solution to cope with the actual limitations of such gyroscopes. We then focus on two different types of hollow core fibers: Kagome and photonic bandgap. We evaluate their performances in terms of transmission, polarization holding and backscattering. We describe the first measurement of a lock in region in a hollow core fiber passive optical gyroscope, i.e the range of rotation rates that cannot be measured because of backscattering. A mathematical model is propounded to link the lock in to the backscattering of the cavity. We then discuss the experimental protocol that we implemented to circumvent this limitation. Finally, we characterize the performances of our gyroscope based on these features
Scol, Florent. "Amplification et transport fibré d’impulsions énergétiques pour les pilotes des installations laser de puissance". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10129/document.
Testo completoCompactness, stability and beam quality are some benefits of fiber lasers. In large scale laser facilities, those systems are already used to generate and amplify pulses but are limited to the nanojoule range. The goal of this thesis consists in building a millijoule range system satisfying large scale laser facility requirements. Amplification and beam delivery systems have been considered. In the first case, an all-fiber MOPA has been realized. Using a 32 µm mode field diameter tapered fiber, we amplified 10 ns pulses up to 500 µJ with excellent temporal, spectral and spatial properties. In a second step, we consider the fiber beam delivery of those pulses over 15 m. In order to minimize nonlinear effects, hollow-core fibers have been used. This way, thanks to a 21 µm mode field diameter fiber, 30 kW peak power nanosecond pulses have been delivered over 15 m with negligible temporal and spectral distortions. In addition of amplification and beam delivery, we also considered technological building blocks which could be used to modified actual fiber seeder architecture. Chirped laser diode has been used to generate pulses and allowed us to finally obtained 1,25 mJ with our MOPA system. Fiber spatial beam shaping has also been performed in the 100 µJ range thanks to a microstructured, single-mode, polarization maintaining fiber which delivers a coherent top-hat beam. Finally, this work confirms the great potential of fiber systems for high energy amplification and beam delivery for the next generation of large scale laser facilities seeder
Scol, Florent. "Amplification et transport fibré d’impulsions énergétiques pour les pilotes des installations laser de puissance". Electronic Thesis or Diss., Lille 1, 2017. http://www.theses.fr/2017LIL10129.
Testo completoCompactness, stability and beam quality are some benefits of fiber lasers. In large scale laser facilities, those systems are already used to generate and amplify pulses but are limited to the nanojoule range. The goal of this thesis consists in building a millijoule range system satisfying large scale laser facility requirements. Amplification and beam delivery systems have been considered. In the first case, an all-fiber MOPA has been realized. Using a 32 µm mode field diameter tapered fiber, we amplified 10 ns pulses up to 500 µJ with excellent temporal, spectral and spatial properties. In a second step, we consider the fiber beam delivery of those pulses over 15 m. In order to minimize nonlinear effects, hollow-core fibers have been used. This way, thanks to a 21 µm mode field diameter fiber, 30 kW peak power nanosecond pulses have been delivered over 15 m with negligible temporal and spectral distortions. In addition of amplification and beam delivery, we also considered technological building blocks which could be used to modified actual fiber seeder architecture. Chirped laser diode has been used to generate pulses and allowed us to finally obtained 1,25 mJ with our MOPA system. Fiber spatial beam shaping has also been performed in the 100 µJ range thanks to a microstructured, single-mode, polarization maintaining fiber which delivers a coherent top-hat beam. Finally, this work confirms the great potential of fiber systems for high energy amplification and beam delivery for the next generation of large scale laser facilities seeder
Vasko, Kostiantyn. "Outil numérique (1+2D)/3D pour modéliser la diffusion de surface de la lumière d'une fibre creuse à couplage inhibé". Electronic Thesis or Diss., Limoges, 2023. http://www.theses.fr/2023LIMO0105.
Testo completoThis work presents the development of a numerical tool based on finite element method to study and optimize the performances of photonic crystal hollow-core fibers (HCPCF). Various loss mechanisms in these fibers were analyzed. Firstly, through a detailed understanding of the influence of geometric parameters on losses and by an approach based on an azimuthal Fourier decomposition, several innovative hollow-core fiber designs have been proposed making it possible to go beyond the current state-of-the-art. In particular, a hybrid hollow-core fiber guiding by inhibited coupling (IC) was designed and then manufactured, combining for the first time ultra-low confinement loss and singlemode guidance. Then, the sources of losses induced by surface roughness within these hollow-core fibers were integrated into the studies by developing a transverse 2D numerical approach and scaling formula. The calculations then confirmed the impact of a new shear process implemented during the fabrication, making it possible to reduce the amplitude of the surface profile of the silica membranes by a factor of three. This results in the demonstration of record losses of HCPCF-CI in the short wavelengths of the visible (< 1 dB/km) and the ultraviolet (< 50 dB/km) found in good agreement with simulations. In parallel, a second process called opto-thermal began, making it possible for the first time to obtain a non-stochastic roughness profile, a result which constitutes a strong perspective of my work. Finally, developments to extend these analyzes to the propagation axis (2D+1 and 3D simulations) have begun. To conclude, all of this work has contributed to the realization of a new generation of hollow-core fibers which could ultimately meet the challenges of both the still inaccessible ultraviolet domain and applications with a strong societal impact such as the optical telecommunications of tomorrow
Chafer, Matthieu. "Sources lasers innovantes à base de micro-capsules photoniques et par nano-structuration de milieux gazeux". Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0042.
Testo completoSince their advent, hollow-core photonic crystal fibers have proved to be highly efficient for frequency conversion, especially via by playing with stimulated Raman scattering. Within the frame work of a CIFRE contract between the firm GLOphotonics and the Xlim research institute, this thesis project has consisted in developing these fibers to enhance their optical performances, in order to target two different field of applications: an industrial one to offer a a compact multi-line laser in the visible and UV and a second more fundamental one to realize a optical wave synthesizer. The amelioration of these performances relies on the exacerbation of the inhibition of the coupling between the air core mode and the silica cladding modes. Two types of micro-structures have been explored, a Kagomé and a tubular lattice. Several fibers have been fabricated demonstrating record performances on all a wavelength range (8.5 dB/km at 1 µm, 7.7 dB/km at 750 nm, 13.8 dB/km at 549 nm, and around 70 dB/km at 355 nm). Concerning the functionalization of the fibers, photonic micro-cells have been designed and realized enabling to overcome the problem the permeability of silica to gas (conversion stability over 12 months) and demonstrate a conversion to 26 lines in the visible. An industrial product coined CombLas has been made and used for flow cytometry in order to study the influence of the repetition rate of the pump laser. This product has also been extended to the UV range with 24 lines generated between 225-400 nm. Also, more fundamental research has been realized consisting in developing an optical wave synthesizer based on Raman generation in hollow core fibres where a new dynamic has been observed demonstrating the trapping of hydrogen molecules by an auto-assembled optical lattice of ultra-deep and nano-metric potential wells. This configuration has enabled to generate a Lamb-Dicke regime of stimulated Raman scattering. Sub-Doppler signatures usually found in cold atoms have been measured with linewidths narrower than 5 orders of magnitude than what is predicted in the literature. Finally, this linewidth has been optmised of an order of magnitude by plaing on the length of the fiber and the pressure of hydrogen
Jamier, Raphaël. "Propriétés linéaires des fibres optiques à cristal photonique à cœur solide". Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/cc01e272-24b8-44b9-b5a1-478b8ebad714/blobholder:0/2007LIMO4044.pdf.
Testo completoThe insertion of photonic crystal in optical fibres made it possible to increase the thresholds of physical phenomena limiting the delivery and the generation of high power. The core size and the effective area (Aeff) of the fundamental mode are drastically increased while preserving a singlemode emission. The photonic crystal fibres studied here are defined by a one-dimensional periodic cladding allowing the light to be guided by the so-called photonic bandgap effect. Their potential is revealed through the study of their linear properties. Results about the design, fabrication and characterisation of fibres exhibiting large Aeff relative to the wavelength are reported. The drastic reduction of confinement loss and bending sensitivity is shown. The possibility of integrating such a fibre as a passive element in an “all fibre” laser source is also shown through an example of dispersion management
Morvan, Pierre-Antoine. "Mesures de déformations par capteurs à fibres optiques au cœur de matériaux composites". Nantes, 2013. http://archive.bu.univ-nantes.fr/pollux/show.action?id=ad04d174-7b51-4ba6-ac5d-495f007179ba.
Testo completoThe use of optical fibers for strain measurements tends to generalize because of its numerous advantages over other sensor technologies. Today strain gauges based on the use of optical fiber are easy and commercially available. However, this can become complex when the fiber is embedded into a material displaying very different mechanical properties from the properties of the silica. The main purpose of this work is to further question the use of fiber optic strain sensors to obtain quantifiable and/or relevant measures inside composite materials. Firstly we present a state of the art of different types of fiber optic sensors by focusing our attention on their use in composite materials. The second part of this work is devoted to optical fibers included in different homogeneous materials. Analytical and numerical models are compared to experimental studies in order to quantify measurement errors eventually made when the sensor is embedded into a material. Then a method is proposed in order to obtain both the longitudinal and the radial strain with only one optical fiber sensor. Finally, the concepts presented in the second part are validated through the study of a specimen made of two materials crossing the sensor’s location. Furthermore we evaluate the use of this sensor in a laminated composite structure under a different configuration than that proposed in the literature : the sensor is inserted across the thickness of the laminate
Gagnon, Pierre-Louis. "Modélisation de la dispersion chromatique et de l'atténuation dans les fibres microstructurées à cœur suspendu". Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27150.
Testo completoArfaoui, Imen. "Fibres optiques à coeur creux comme éléments sélectifs et compensateurs de dispersion pour les systèmes de communication multilongueurs d'onde". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23986/23986.pdf.
Testo completoBeaudou, Benoît. "Conception et réalisation de fibres microstructurées à coeur creux optimisées pour l'émission dans l'infrarouge par diffusion Raman stimulée". Limoges, 2009. https://aurore.unilim.fr/theses/nxfile/default/a6c1f8f1-ff8e-4e2b-9285-b1aeb54e0bec/blobholder:0/2009LIMO4038.pdf.
Testo completoApplications such as pollution control or countermeasures have a need in mid infrared sources (2. 5-5μm). Nowadays, compact, robust sources with a good beam quality are not available in this spectral range. To overcome this limitation, we study the conversion of usual sources by stimulated Raman scattering in hollow-core fibre. A proposal uses a hydrogen-filled tapered hollow-core photonic bandgap fibre as a wavelength converter. First results demonstrate the ability to convert the pump toward fifth Stokes order with a monomode beam profile. Then, large pitch hollow-core fibre allowing air-guiding over a broad spectral range are studied. Characterisation of the fabricated fibres paves the way to stimulated Raman scattering with large shift gases
Bertry, Laure. "Elaboration de nanostructures cœur-couronne or-silice dopées par des ions lanthanides pour l’exaltation de la luminescence dans les fibres optiques de spécialité". Paris 6, 2013. http://www.theses.fr/2013PA066396.
Testo completoThis work is part of the Fenoptic ANR project, which aims at taking advantage of the plasmonic properties of metallic nanoparticles incorporated into optical fibers. Optical signals attenuation occurring for long distances propagation is usually overcome by re-amplification. Optical amplification is based on rare earth ions stimulated emission. This work aims at improving the amplification process in optical fibers by efficiently coupling lanthanide ions with metallic nanoparticles to enhance their luminescence properties. Original multilayer nanostructures made of a gold core coated with sol-gel silica shells, either pure or doped with lanthanide ions, were specifically designed by soft chemistry. The size and shape of the gold nanoparticles, along with the thickness and doping rate of the silica shells, were finely controlled. Stable core-shell suspensions were thus obtained. Optical reference nanostructures were also prepared by gold core dissolution. These nanostructures are then incorporated into sol-gel silica matrices with high optical quality to study their photoluminescence intensities and lifetime decay profiles. Strong europium (III) luminescence quenching is observed for a 2 nm spacer between the gold nanospheres and the lanthanide ions. This extinction slightly decreases as the coupling distance increases, but still occurs for a 28 nm buffer layer thickness. Incorporation of the nanostructures into optical fibers silica cores was evaluated for a high-temperature process patented by Draka. Some preliminary trials were also conducted on a semi-industrial sol-gel process
Delahaye, Frédéric. "Fibre microstructurée à cœur plasma pour la génération de radiations ultraviolettes". Thesis, Limoges, 2019. http://aurore.unilim.fr/theses/nxfile/default/eb8bad31-ba1b-4347-97cc-ea597d1238fb/blobholder:0/2019LIMO0096.pdf.
Testo completoThe generation of microwave micro-plasmas by non-intrusive excitation inside hollow-core photonic crystal fibers (HC-PCF), allowed the emergence of a new platform emitting in the ultraviolet range. Based on the surface wave generation, the observed plasma columns are of 50 mm confined to a micrometric scale. Despite a plasma temperature close to the transforming the microstructured silicat this one is not affected, preserved by a particular plasma dynamics. This work includes a study on the development of inhibited coupling fiber with an expended core (i.e., core diameter> 200 μm) with short wavelength transmission bands. These transmission bands make itpossible to guide the plasma fluorescence in the ultraviolet optimized by ternary gas mixture of argon, oxygen and nitrogen. These two demonstrations are at the origin of the realization of a tunable ultraviolet plasma source with more than 20 lines ranging from 450 nm to 200 nm. With optical outputs of more than 1 μW at 314 nm and 337 nm. A final experimental study on the possibility to use the plasma as an optical amplifier medium opens the way for the realization in the near future of portable ultraviolet laser sources
Bertry, Laure. "Elaboration de nanostructures cœur-couronne or-silice dopées par des ions lanthanides pour l'exaltation de la luminescence dans les fibres optiques de spécialité". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00967580.
Testo completoKudinova, Maryna. "Développement de nouvelles matrices vitreuses pour la fonctionnalisation de fibres optiques par l’exploitation de la technologie Poudre". Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0124/document.
Testo completoThe main part of optical fibers used in the fields of optical sources and sensors are called 'functionalised', i.e. they have new properties, due to their nature and/or structure, compared to standard fibers. To do this, we will use 'Powder' technology for the realization of optical fiber using properties of original vitreous glasses developed during this thesis. Three families of optical fibers will be studied in order to demonstrate the great potential of this association, materials - technology. The first exploit the structuring of the cladding with two vitreous glass rods (Panda type) doped or not with copper oxide. The study of this fiber is done from the synthesis of the material up to the test of this fiber as a sensor. The second fiber leads us to design a novel optical glass matrix, to define the optimal composition and decline form of an optical fiber including the glass for the core. Finally, the optical fiber manufacturing process is used to produce optical fiber with glass-ceramic core, i.e. starting from a vitreous matrix specially developed for this application happen to grow the nano-structures in the core of the fiber and obtain a novel fiber family
Maurel, Martin. "Dynamique propagative d’impulsions optiques ultra-courtes pour un module de compression à base de fibre creuse". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0116.
Testo completoUltra-short pulse laser, hundred femtoseconds, are currently an essential tool for many industrial or academic applications. However, their duration remains limited by the technology which composed this device itself. In addition, development of new microstructured optical fibers offers high-energy pulse guidance in gaseous media, thus allowing the generation of non-linear effects, key parameter for pulse compression and post-compression dynamics. The work of this thesis is therefore part of this context. Studies of ultra-short pulse compression dynamics are presented. Self-compression and post-compression are demonstrated at wavelengths ranging from 343 nm to 1030 nm with energy from few microJoules to several hundred microJoules and average power up to 100 W. Factor 29 of compressions are presented, with solitonic dynamic pulse with duration of 580 fs are compressed down to 19 fs. In addition, this technology has been integrated into an industrial platform installed at various customers' sites
Benoit, Aurélien. "Sources laser fibrées hybrides de haute puissance : Amplification et conversion de fréquences". Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0024/document.
Testo completoHigh-power fiber lasers adress an increasing number of applications since ten years. In the frame of a CIFRE contract between the company Eolite Systems and Xlim (joint laboratory between CNRS and the University of Limoges), the goal of this PhD project was to develop the technological blocs to achieve all-fibre high-power lasers emiting out of the conventional spectral band covered by existing lasers.Modal instabilities in large mode area (LMA) fibers are currently the main limitation of the fiber lasers power scaling. We have experimentally demonstrated the relevance of inner cladding aperiodic structures to efficiently delocalize higher order modes outside the gain region. A systematic study of passive fibers based on such structures has shown the single propagation of the fundamental mode over a wide wavelength range from 1 to 2 µm for dimension of core up to 85 µm. This effective mode delocalization even extends up to a core dimension of 140 µm at a 2 µm wavelength.The combination of high power picosecond fiber laser with an average power of 22.7 W and a hydrogen-filled inhibited coupling Kagome fiber allowed us to generate two Raman combs over five frequency octaves from 321 nm to 12.5 µm. These two combs are controlled by the laser pump polarization and generated an average power of 10.1 W displayed over 70 laser lines for circular pump polarization and 8.6 W over 30 lines for linear polarization. Some laser lines within these combs have been generated for the first time from high-power fiber source in the mid-infrared range. We have also demonstrated the generation of high-power line by optimizing the first vibrational Stokes at 1.8 µm with an average power of 9.3 W and a quantum efficiency of the frequency conversion stage close to 80%
Mulle, Matthieu. "Eprouvettes technologiques instrumentées à cœur par réseau de Bragg pour l'analyse du matériau composite dans la structure". Toulouse 3, 2007. http://www.theses.fr/2007TOU30242.
Testo completo"Fibres optiques à coeur creux comme éléments sélectifs et compensateurs de dispersion pour les systèmes de communication multilongueurs d'onde". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23986/23986.pdf.
Testo completo