Letteratura scientifica selezionata sul tema "Fibres optiques à cœur creux"
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Tesi sul tema "Fibres optiques à cœur creux"
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