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61	Fabrication et caractérisation de fibres optiques en silice dopées au thulium : Influence de l'environnement des terres rares sur l'amplification dans la bande S Faure, Basile 24 November 2005 (has links) (PDF) Cette thèse rapporte les premières études exploratoires menées en vue de réaliser un amplificateur optique fonctionnant dans la bande S des télécommunications (autour de 1470 nm) dans une fibre en silice dopée au thulium dans le but d'augmenter la bande passante utilisable par le procédé de multiplexage en longueur d'onde (WDM) des réseaux optiques en silice standard. Pour permettre d'amplifier un signal optique à l'aide des ions de thulium dans une fibre composé d'un verre à haute énergie de phonon comme la silice, nous avons adapté les processus de fabrication des préforme par MCVD de manière à modifier de moins de 10% mol la composition du cœur de silice de la fibre. Ainsi, l'apport d'Al2O3 permet, en modifiant l'environnement des terres rares, de réduire les désexcitations non radiatives entre les niveaux 3H4 et 3H5 des ions de thulium. Le temps de vie du niveau 3H4 est ainsi multiplié par 3, de 14us pour la silice pure à 50us pour 8,7 %mol d'al2O3. L'efficacité quantique passe alors de 2% à plus de 8%. Grâce à cette amélioration du matériau et à l'optimisation des paramètres optogéométriques de la fibre optique à l'aide d'un modèle numérique, nous avons pu mesurer l'amplification en bande S d'un signal lumineux sur un échantillon majoritairement composé de silice fabriqué au laboratoire. Ce gain, de plus de 1dB pour 1400mW de puissance de pompe optique, est un résultat de premier ordre pour ce type de dispositif, validant l'approche de la modification de l'environnement du thulium dans la silice. De plus les simulations numériques prédisent un gain supérieur à 20 dB pour 1W de puissance de pompe pour le matériau élaboré, avec un schéma de pompage plus efficace. Transmission sur fibre optique Multiplexage en longueur d'onde MCVD Amplification optique Matériau : verre de silice Thulium Désexcitations non radiatives Phonon
62	Power Scaling Of Large Mode Area Thulium Fiber Lasers In Various Spectral And Temporal Regimes McComb, Timothy 01 January 2009 (has links) High power thulium fiber lasers are interesting for a myriad of applications due to their potential for high average output power, excellent beam quality, compactness, portability, high operating efficiency and broad, eye-safe spectral range from 1.8-2.1 microns. Currently, the majority of thulium laser research effort is being invested into scaling average output powers; however, such output powers are being scaled with no degree of control on laser system output spectrum or temporal behavior. Thulium fiber laser technology is not useful for many of its most important applications without implementation of techniques enabling tunable, narrow spectral widths with appropriate pulse durations for particular applications. This work outlines several techniques for spectral control of thulium fiber lasers and investigates scaling of average laser powers while using these techniques to maintain a desired spectral output. In addition, an examination of operation in both nanosecond and picosecond pulsed regimes and scaling of average powers and pulse energies in these regimes to useful power levels is conducted. The demonstration of thulium fiber laser systems for applications in frequency conversion and spectral beam combination is also discussed. In addition to the experimental results, theoretical modeling of thulium fiber amplifier operation, simple thermal management analysis, as well as practical fiber and system design considerations for future power scaling are presented. Experimental and theoretical results of this work will enable the successful design of future extremely high power spectrally and temporally controlled thulium fiber laser systems. laser fiber laser thulium fiber laser eye safe laser large mode area fiber laser 2 micron fiber laser Electromagnetics and Photonics Optics
63	Caracterizacao espectroscopica e dinamica temporal dos processos de transferencia de energia entre os ions Tm sup(3+) - Ho sup(3+) e Yb sup(3+) - Tm sup(3+) em cristais de LiYF sub(4) e LiLuF sub(4) TARELHO, LUIZ V.G. 09 October 2014 (has links) Made available in DSpace on 2014-10-09T12:46:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:21Z (GMT). No. of bitstreams: 1 07543.pdf: 4162108 bytes, checksum: fea345edb32c7ebb6b06110c513a47b1 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:95/03214-1 Lasers energy transfer crystal doping energy-level transitions lithium fluorides diode-pumped solid state lasers yttrium fluorides gadolinium fluorides lutetium fluorides holmium absorption spectra luminescence excited states czochralski method cross sections RARE EARTHS THULIUM IONS YTERBIUM IONS EXPERIMENTAL DATA
64	Caracterizacao espectroscopica e dinamica temporal dos processos de transferencia de energia entre os ions Tm sup(3+) - Ho sup(3+) e Yb sup(3+) - Tm sup(3+) em cristais de LiYF sub(4) e LiLuF sub(4) TARELHO, LUIZ V.G. 09 October 2014 (has links) Made available in DSpace on 2014-10-09T12:46:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:21Z (GMT). No. of bitstreams: 1 07543.pdf: 4162108 bytes, checksum: fea345edb32c7ebb6b06110c513a47b1 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:95/03214-1 lasers energy transfer crystal doping energy-level transitions lithium fluorides diode-pumped solid state lasers yttrium fluorides gadolinium fluorides lutetium fluorides holmium absorption spectra luminescence excited states czochralski method cross sections rare earths thulium ions ytterbium ions experimental data
65	Investigation of Specialized Laser and Optical Techniques to Improve Precision Atomic Spectroscopy of Helium Currey, Ronnie 05 1900 (has links) The aim of this thesis is to develop both Yb and Tm fiber laser sources with all fiber cavities. Both wavelength ranges provide useful laser sources for optical pumping of helium. The goal is to develop Tm laser sources operating at 2058 nm to optically quench 3He (2058.63 nm) and 4He (2058.69 nm) singlets (21S0). We also have developed Yb laser sources at 1083 nm to optical pump the triplet states of helium and laser cool an atomic beam of helium. lasers fiber lasers optical fiber thulium fiber lasers ytterbium fiber lasers fiber amplifiers ytterbium fiber amplifiers high energy laser optical pumping single frequency fiber amplifier Atomic spectroscopy. Optical pumping. Lasers in physics. Helium -- Spectra.
66	Broad Bandwidth, All-fiber, Thulium-doped Photonic Crystal Fiber Amplifier for Potential Use in Scaling Ultrashort Pulse Peak Powers Sincore, Alex 01 January 2014 (has links) Fiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be simultaneously attained using photonic crystal fibers. Thulium-doped fiber lasers are attractive for high peak power ultrashort pulse systems. They offer a broad gain bandwidth, capable of amplifying sub-100 femtosecond pulses. The longer center wavelength at 2 ?m theoretically enables higher peak powers relative to 1 [micro]m systems since nonlinear effects inversely scale with wavelength. Also, the 2 [micro]m emission is desirable to support applications reaching further into the mid-IR. This work evaluates the performance of a novel all-fiber pump combiner that incorporates a thulium-doped photonic crystal fiber. This fully integrated amplifier is characterized and possesses a large gain bandwidth, essentially single-mode propagation, and high degree of polarization. This innovative all-fiber, thulium-doped photonic crystal fiber amplifier has great potential for enabling high peak powers in 2 [micro]m fiber systems; however the current optical-to-optical efficiency is low relative to similar free-space amplifiers. Further development and device optimization will lead to higher efficiencies and improved performance. Photonic crystal fiber ultrashort pulse thulium all fiber pump combiner pcf tm:pcf broad bandwidth large mode area peak power 2 micron 2 [micro]m infrared laser amplifier Electromagnetics and Photonics Optics
67	Lanthanide Doped Wide Band Gap Semiconductors: Intra-4f Luminescence and Lattice Location Studies / Lanthanid-dotierte Halbleiter mit großer Bandlücke: Intra-4f Lumineszenz- und Gitterplatzuntersuchungen Vetter, Ulrich 15 July 2003 (has links) No description available. Mathematics and Computer Science Lanthanide Kathodoluminesznez intra-4f Elektronenübergänge Europium Thulium Gadolinium Halbleiter mit großer Bandlücke Aluminiumnitrid kubisches Bornitrid Siliziumkarbid Diamant dünne Schichten tetraedrischer amorpher Kohlenstoff Lichtemitter Starkniveau-Spektroskopie Kristallfeldanalyse Kathodolumineszenz Energiematrix Judd-Ofelt-Theorie Ionenimplantation massenselektierte Ionenstrahldeposition Emissionschanneling Gitterplatz Mössbauerspektroskopie radioaktive Lanthanidisotope 530 Physik lanthanides cathodoluminescence intra-4f electron transitions europium thulium gadolinium wide band gap semiconductors aluminum nitride cubic boron nitride silicon carbide diamond thin films tetrahedral amorphous carbon light emitters Stark level spectroscopy crystal field analysis energy matrix Judd-Ofelt theory ion implantation mass-selected ion beam deposition emission channeling lattice location Mössbauer spectroscopy radioactive lanthanide isotopes 33.60 33.30 33.07 33.06 33.43 33.72 RTF 400: Ionenimplantation {Physik} RTG 400: Anregung von Atomen atomare Energiezustände {Atomphysik} RRJ 000: Emissions- Absorptionsspektroskopie {Physik} RVQ 000: Halbleiter {Physik}

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