[pt] As fibras ópticas são suscetíveis ao estresse mecânico e podem ser danificadas ou quebradas, portanto, a supervisão da camada física é essencial para identificar essas falhas e remediá-las o mais rápido possível. Com o objetivo de agilizar e simplificar o processo de agendamento de unidades de reparo em campo, foi desenvolvido um sistema automatizado de medição de fibras baseado em uma unidade de processamento digital de sinal (DSP) capaz de identificar as posições das falhas de forma autônoma. Combinando esta unidade de DSP com um OTDR de contagem de fótons, é possível criar tal dispositivo. Este trabalho apresenta o desenvolvimento dos blocos de construção para tal dispositivo. / [en] Optical fibers are susceptible to mechanical stress and may be damaged or broken, thus physical layer supervision is essential to identify these failures and remediate them as quickly as possible. In order to hasten and simplify the scheduling process of the in-field repairing units, an automated fiber measurement system based on a digital signal processing (DSP) unit capable of autonomously identifying fault positions was developed. By combining this DSP unit with a Tunable Photon-Counting OTDR, it is possible to create such a device. This work presents the development of the building blocks for such device.

At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the recurring needs for in-depth fiber characterization. The first part of this dissertation details a novel experiment that was demonstrated to achieve modal decomposition with extended capabilities, reaching beyond the limits set by the existing mode analysis techniques. As a result, individual transverse modes carrying between ~0.01% and ~30% of the total light were resolved with unmatched accuracy. Furthermore, this approach was employed to decompose the light guided in Large-Mode Area (LMA) fiber, Photonic Crystal Fiber (PCF) and Leakage Channel Fiber (LCF). The single-mode performances were evaluated and compared. As a result, the suitability of each specialty fiber design to be implemented for power-scaling applications of fiber laser systems was experimentally determined. The second part of this dissertation is dedicated to novel specialty fiber laser systems. First, challenges related to the monolithic integration of novel and complex specialty fiber designs in all-fiber systems were addressed. The poor design and size compatibility between specialty fibers and conventional fiber-based components limits their monolithic integration due to high coupling loss and unstable performances. Here, novel all-fiber Mode-Field Adapter (MFA) devices made of selected segments of Graded Index Multimode Fiber (GIMF) were implemented to mitigate the coupling losses between a LMA PCF and a conventional Single-Mode Fiber (SMF), presenting an initial 18-fold mode-field area mismatch. It was experimentally demonstrated that the overall transmission in the mode-matched fiber chain was increased by more than 11 dB (the MFA was a 250 ?m piece of 50 ?m core diameter GIMF). This approach was further employed to assemble monolithic fiber laser cavities combining an active LMA PCF and fiber Bragg gratings (FBG) in conventional SMF. It was demonstrated that intra-cavity mode-matching results in an efficient (60%) and narrow-linewidth (200 pm) laser emission at the FBG wavelength. In the last section of this dissertation, monolithic Multi-Core Fiber (MCF) laser cavities were reported for the first time. Compared to existing MCF lasers, renown for high-brightness beam delivery after selection of the in-phase supermode, the present new generation of 7-coupled-cores Yb-doped fiber laser uses the gain from several supermodes simultaneously. In order to uncover mode competition mechanisms during amplification and the complex dynamics of multi-supermode lasing, novel diagnostic approaches were demonstrated. After characterizing the laser behavior, the first observations of self-mode-locking in linear MCF laser cavities were discovered.

[pt] Motivado pelos desafios de processar a grande quantidade de dados disponíveis, pesquisas recentes em estatística tem sugerido novas técnicas de modelagem e inferência. Paralelamente, outros campos como processamento de sinais e otimização também estão produzindo métodos para lidar problemas em larga escala. Em particular, este trabalho é focado nas teorias e métodos baseados na regularização l1. Após uma revisão compreensiva da norma l1 como uma ferramenta para definir soluções esparsas, estudaremos mais a fundo o método LASSO. Para exemplificar como o LASSO possui uma ampla gama de aplicações, exibimos um estudo de caso em processamento de sinal esparso. Baseado nesta idea, apresentamos o l1 level-slope filter. Resultados experimentais são apresentados para uma aplicação em transmissão de dados via fibra óptica. Para a parte final da dissertação, um novo método de estimação é proposto para modelos em alta dimensão com variância periódica. A principal ideia desta nova metodologia é combinar esparsidade, induzida pela regularização l1, com o método de máxima verossimilhança. Adicionalmente, esta metodologia é utilizada para estimar os parâmetros de um modelo mensal estocástico de geração de energia eólica e hídrica. Simulações e resultados de previsão são apresentados para um estudo real envolvendo cinquenta geradores de energia renovável do sistema Brasileiro. / [en] Motivated by the challenges of processing the vast amount of available data, recent research on the ourishing field of high-dimensional statistics is bringing new techniques for modeling and drawing inferences over large amounts of data. Simultaneously, other fields like signal processing and optimization are also producing new methods to deal with large scale problems. More particularly, this work is focused on the theories and methods based on l1-regularization. After a comprehensive review of the l1-norm as tool for finding sparse solutions, we study more deeply the LASSO shrinkage method. In order to show how the LASSO can be used for a wide range of applications, we exhibit a case study on sparse signal processing. Based on this idea, we present the l1 level-slope filter. Experimental results are given for an application on the field of fiber optics communication. For the final part of the thesis, a new estimation method is proposed for high-dimensional models with periodic variance. The main idea of this novel methodology is to combine sparsity, induced by the l1-regularization, with the maximum likelihood criteria. Additionally, this novel methodology is used for building a monthly stochastic model for wind and hydro inow. Simulations and forecasting results for a real case study involving fifty Brazilian renewable power plants are presented.

В данной работе представлены исследования характеристик металлического круглого волновода с неоднородным диэлектрическим заполнением и одномодового оптического волокна. Были построены и проанализированы частотные зависимости постоянной распространения для следующих диэлектрических структур круглого волновода: стержень, втулка, цилиндр, цилиндр с зазором, стержень с параболическим профилем изменения относительной диэлектрической проницаемости. Были рассмотрены одномодовые оптические волокна с разным профилем преломления и изучены материальная и хроматическая дисперсия одномодового волокна. / This work contains researches of characteristics of inhomogeniously filled metal circular waveguide and single-mode optical fiber. Frequency dependences of propagation constant of following dialectic structures in circular waveguide were calculated and analyzed: rod, plug, cylinder, cylinders with air gap, rod with parabolic permittivity profile. Characteristics of single-mode optical fiber with different refractive index profiles were considered, alsomaterial and chromatic dispersions were explored.

[ES] Las comunicaciones ópticas inalámbricas (OWC) constituyen una tecnología muy prometedora para el desarrollo de futuras comunicaciones inalámbricas. De hecho, ha despertado un interés creciente entre los investigadores y varias empresas de todo el mundo trabajan actualmente en el desarrollo de redes inalámbricas de muy alta velocidad. Las comunidades científica e industrial consideran la OWC como una tecnología complementaria en sus diversas formas: comunicaciones ópticas en el espacio libre (FSO), comunicaciones de luz visible (VLC) o fidelidad de la luz (Li-Fi). El espectro óptico ha sido considerado durante muchos años como una gran oportunidad para las comunicaciones inalámbricas, especialmente debido a la saturación del espectro de radiofrecuencia (RF). Esta disertación trata del uso de fuentes de banda ancha en sistemas de transmisión de luz visible (VLC), así como en sistemas de transmisión en el espectro infrarrojo por fibra óptica. En el trabajo de investigación realizado se pueden distinguir tres partes: En la primera parte, se considera el estudio y la simulación de componentes de Diodos Emisores de Luz (LED) con el software WIEN2k centrándose en las propiedades ópticas y eléctricas de los elementos II-VI. La segunda parte trata del diseño, la implementación y las pruebas de diferentes prototipos de comunicación VLC para la transmisión analógica y digital en modo simplex y semidúplex. Hemos demostrado un sistema OWC empleando una fuente de banda ancha (LED) para la transmisión no sólo de datos, sino también para la transmisión inalámbrica de energía. Además, se aborda el problema de la sincronización y la detección del nivel "1" o "0" de un bit en los sistemas de comunicación inalámbrica óptica implementados que surge como consecuencia de la atenuación de la luz a lo largo de la distancia y al problema de la pérdida de línea de visión (NLOS) entre el emisor y el receptor. Para hacer frente a este problema, se ha proporcionado un protocolo de comunicación que garantiza la transmisión fiable de datos digitales con un algoritmo de detección de nivel de bits adaptativo y se ha demostrado su eficacia mediante la transmisión de textos e imágenes. Además, esta tesis aporta una solución para la implementación de transmisores multiplexados en redes con división de longitud de onda (WDM) para formatos de modulación con multiplexación por división de frecuencia ortogonal (OFDM) basados en el uso de fuentes de banda ancha en el espectro infrarrojo para redes de fibra bidireccionales centralizadas. A pesar de las limitaciones impuestas por la dispersión cromática en el uso de este tipo de fuentes ópticas, la inclusión de ciertas estructuras antes de la detección permite la transmisión de señales OFDM en enlaces ópticos. En este trabajo se ha demostrado experimentalmente la reutilización de portadoras, la asignación dinámica de ancho de banda y la transmisión de señales OFDM multibanda mediante el uso de fuentes ópticas de banda ancha en redes WDM. Los principales resultados obtenidos en cada parte de esta tesis doctoral muestran los procedimientos de estudio, la eficacia de las soluciones propuestas y las limitaciones encontradas. / [CA] Les comunicacions òptiques sense fils (OWC) constitueixen una tecnologia molt prometedora per al desenvolupament de futures comunicacions sense fils. De fet, ha despertat un interés creixent entre els investigadors i diverses empreses de tot el món treballen actualment en el desenvolupament de xarxes sense fils de molt alta velocitat. Les comunitats científica i industrial consideren la OWC com una tecnologia complementària en les seues diverses formes: comunicacions òptiques en l'espai lliure (FSO), comunicacions de llum visible (VLC) o fidelitat de la llum (Li-Fi). L'espectre òptic ha sigut considerat durant molts anys com una gran oportunitat per a les comunicacions sense fils, especialment a causa de la saturació de l'espectre de radiofreqüència (RF). Aquesta dissertació tracta de l'ús de fonts de banda ampla en sistemes de transmissió de llum visible (VLC), així com en sistemes de transmissió en l'espectre infraroig per fibra òptica. En el treball de recerca realitzat es poden distingir tres parts: ¿ En la primera part, es considera l'estudi i la simulació de components de Díodes Emissors de Llum (LED) amb el software WIEN2k centrant-se en les propietats òptiques i elèctriques dels elements II-VI. ¿ La segona part tracta del disseny, la implementació i les proves de diferents prototips de comunicació VLC per a la transmissió analògica i digital de manera simplex i semidúplex. Hem demostrat un sistema OWC emprant una font de banda ampla (LED) per a la transmissió no sols de dades, sinó també per a la transmissió sense fil d'energia. A més, s'aborda el problema de la sincronització i la detecció del nivell "1" o "0" d'un bit en els sistemes de comunicació sense fil òptica implementats, que sorgeix a conseqüència de l'atenuació de la llum al llarg de la distància i al problema de la pèrdua de línia de visió (NLOS) entre l'emissor i el receptor. Per a fer front a aquest problema, s'ha proporcionat un protocol de comunicació que garanteix la transmissió fiable de dades digitals amb un algorisme de detecció de nivell de bits adaptatiu i s'ha demostrat la seua eficàcia mitjançant la transmissió de textos i imatges. ¿ A més, aquesta tesi aporta una solució per a la implementació de transmissors multiplexats en xarxes amb divisió de longitud d'ona (WDM) per a formats de modulació amb multiplexació per divisió de freqüència ortogonal (OFDM) basats en l'ús de fonts de banda ampla en l'espectre infraroig per a xarxes de fibra bidireccionals centralitzades. Malgrat les limitacions imposades per la dispersió cromàtica en l'ús d'aquest tipus de fonts òptiques, la inclusió d'unes certes estructures abans de la detecció permet la transmissió de senyals OFDM en enllaços òptics. En aquest treball s'ha demostrat experimentalment la reutilització de portadores, l'assignació dinàmica d'amplada de banda i la transmissió de senyals OFDM multibanda mitjançant l'ús de fonts òptiques de banda ampla en xarxes WDM. Els principals resultats obtinguts en cada part d'aquesta tesi doctoral mostren els procediments d'estudi, l'eficàcia de les solucions proposades i les limitacions trobades. / [EN] Optical wireless communication (OWC) is a very promising technology for future wireless communications developments. It has attracted increasing interest from researchers and several companies around the world are currently working on the development of very high-speed wireless networks. The scientific and industrial communities believe that OWC will be a complementary technology in its various forms: Free Space Optical communications (FSO), Visible Light Communications (VLC), Light Fidelity (Li-Fi). In fact, the optical spectrum has been considered for many years as a great opportunity for wireless communications especially due to the saturation of the radio frequency (RF) spectrum. This dissertation deals with the use of broadband sources in visible light transmission systems (VLC) as well as fiber optic systems. To carry out the research, three parts can be distinguished: In the first part, we consider the study and simulation of Light Emitting Diode (LED) components with the WIEN2k software by focusing on the optical and electrical properties of elements II-VI. The second part deals with the design, implementation and testing of different VLC communication prototypes for analog and digital transmission in simplex and half-duplex mode. We have demonstrated that an OWC system using a broadband source (i.e. an LED) can be used not only for data transmission, but also for wireless power transmission. Moreover, the synchronization problem and the detection of level "1" or "0" of a bit often arise in the optical wireless communication systems. This is a result of the attenuation nature of the light over the distance and the problem of Non Line-Of-Sight (NLOS) between the emitter and the receiver. To deal with this problem, a communication protocol ensuring reliable digital data transmission with an adaptive bit level detection algorithm has been provided and its effectiveness has been demonstrated by the transmission of texts and images. In addition, this thesis provides a solution for the implementation of wavelength division multiplexed - orthogonal frequency division multiplexed (WDM-OFDM) transmitters based on the use of broadband sources in the infrared spectrum for centralized bidirectional fiber networks. Despite the chromatic dispersion that avoids the use of this type of optical sources, the inclusion of certain structures before detection allows the transmission of OFDM signals in optical links. Carrier reuse, dynamic bandwidth allocation and multiband OFDM signals transmission will be experimentally demonstrated by using optical broadband sources in WDM networks. The main results obtained during this thesis work demonstrate the study procedures, for each part, the effectiveness of the proposed solutions as well as the constraints encountered. / Sekkiou, I. (2021). Design of communication systems based on broadband sources for fiber and free space optical links [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172542

[ES] Las fibras de multiplexación por división espacial surgieron en la última década como solución al cuello de botella en la capacidad en las redes de comunicación de fibra óptica monomodo. Utilizan el espacio, la última técnica de multiplexación en comunicaciones ópticas, para aumentar la capacidad total en comunicaciones digitales al tiempo que reducen las necesidades de espacio. Las fibras multinúcleo, un tipo de fibras de multiplexación por división espacial compuestas por varios núcleos individuales dentro de la misma cubierta, son prometedoras para las comunicaciones de largo alcance por su compatibilidad inmediata con las redes de fibra actuales. Además, las fibras multinúcleo han despertado interés en otros campos de aplicación, como las interconexiones de centros de datos, las comunicaciones cuánticas, las redes de acceso radio y la Fotónica de Microondas. Además, estas fibras presentan un gran potencial no sólo para la distribución de señales, sino también para su procesado. Las funcionalidades de procesado de señal pueden beneficiarse significativamente del uso de estas fibras en términos de compacidad y peso, garantizando al mismo tiempo versatilidad, reconfigurabilidad y rendimiento estable de banda ancha. En esta Tesis, proponemos la explotación del paralelismo inherente que se encuentra en las fibras multinúcleo para implementar el procesado distribuido de señales ópticas y de microondas. En primer lugar, estudiamos la realización de un componente óptico clave en el procesado de señales en Fotónica de Microondas, la línea de retardo en tiempo real muestreada, con fibras multinúcleo heterogéneas. Esto comprende la validación del rendimiento de una fibra heterogénea de 7 núcleos previamente fabricada, la demostración experimental de las funcionalidades de procesado de señales de microondas; incluyendo el filtrado de señales, la conformación óptica de haces y la generación de formas de onda arbitrarias; y el diseño y fabricación de una fibra heterogénea de 19 núcleos que se comporta como una línea de retardo en tiempo real sintonizable. Esta fibra se fabricó escalando 3 preformas diferentes, cada una con un perfil de índice refractivo específico, para obtener núcleos con unas características de propagación determinadas. Por último, proponemos diferentes diseños de fibras multinúcleo heterogéneas específicos para aplicaciones novedosas de distribución y procesado de señales ópticas, incluyendo la distribución de claves cuánticas, la compensación paralela de la dispersión cromática y los efectos Talbot temporales paralelos. / [CA] Les fibres de multiplexació per divisió espacial van sorgir en la darrera dècada per a solucionar el coll de botella en la capacitat de les xarxes de comunicació de fibra òptica monomode. Utilitzen l'espai, l'última tècnica de multiplexació en comunicacions òptiques, per a incrementar la capacitat total en comunicacions digitals al mateix temps que redueixen les necessitats espacials. Les fibres multinucli, un tipus de fibres de multiplexació per divisió espacial compostes per diversos nuclis individuals situats dins la mateixa coberta, són prometedores per a les comunicacions de llarg abast per la immediata compatibilitat amb les xarxes de fibra òptica actuals. Per aquest motiu, les fibres multinucli han despertat interès en altres àmbits d'aplicació, com les interconnexions de centres de dades, les comunicacions quàntiques, les xarxes d'accés radio i la Fotònica de Microones. A més, aquestes fibres presenten un gran potencial no només per a la distribució de senyals, sinó també per al seu processament. Les funcionalitats de processament de senyals poden beneficiar-se significativament del seu ús en relació a la compacitat i al pes, mentre garanteixen versatilitat, reconfigurabilitat i rendiment estable de banda ampla. En aquesta Tesi, proposem l'explotació del paral·lelisme inherent de les fibres multinucli per a implementar processament distribuït de senyals òptiques i de microones. En primer lloc, estudiem la realització d'un component òptic clau en el processament de senyals en la Fotònica de Microones, la línia de retard en temps real mostrejada, amb fibres multinucli heterogènies. Això comprèn la validació del rendiment d'una fibra de heterogènia 7 nuclis fabricada prèviament, la demostració experimental de les funcionalitats de processament de senyals de microones sobre aquesta mateixa fibra; la qual cosa inclou el filtrat de senyals, la conformació òptica de feixos i la generació de formes d'ona arbitràries; i el disseny i fabricació d'una fibra heterogènia de 19 nuclis que es comporta com una línia de retard en temps real sintonitzable. Aquesta fibra es va fabricar escalant 3 preformes diferents, cadascuna amb un perfil d'índex refractiu específic, per obtindre nuclis amb característiques de propagació determinades. Per últim, proposem diversos dissenys específics de fibres multinucli heterogènies per a aplicacions innovadores de distribució i processament de senyals òptiques, incloent la distribució de claus quàntiques, la compensació paral·lela de la dispersió cromàtica i els efectes Talbot temporals en paral·lel. / [EN] Space-division multiplexing fibers emerged in the last decade as a solution to the capacity bottleneck in single-mode optical fiber communication networks. They utilize space, the last multiplexing technique in optical communications, to increase the total capacity in digital communications whilst reducing space needs. Multicore fibers, a type of space-division multiplexing fibers comprised of multiple individual cores within the same cladding, are promising for long-reach communications because of their immediate compatibility with current fiber networks. Moreover, multicore fibers have raised interest in other fields of application such as data-center interconnects, quantum communications, radio access networks and Microwave Photonics. Apart from that, these fibers exhibit great potential not only for signal distribution but also for signal processing. Signal processing functionalities can benefit significantly from using these fibers in terms of compactness and weight, while assuring broadband versatility, reconfigurability, and performance stability. In this Thesis, we propose the exploitation of the inherent parallelism found in multicore fibers to implement distributed signal processing for optical and microwave signals. First, we study the realization of a key optical component in Microwave Photonics signal processing, the sampled true-time delay line, with heterogeneous multicore fibers. This comprises the performance validation of a previously fabricated heterogeneous 7-core fiber, the experimental demonstration of microwave signal processing functionalities including signal filtering, optical beamforming, and arbitrary waveform generation, and the design and fabrication of a heterogeneous 19-core fiber that behaves as a tunable true-time delay line. This fiber was fabricated by scaling down 3 different preforms, each with a specific refractive index profile, with a different ratio to obtain cores with determined propagation characteristics. Lastly, we propose different custom heterogeneous multicore fiber designs for novel optical signal distribution and processing applications, including quantum key distribution, parallel chromatic dispersion compensation and parallel temporal Talbot effects. / Ureña Gisbert, M. (2023). Novel Multicore Optical Fibers for Signal Distribution and Processing [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196862

Cavity ring-down spectroscopy has been used over the last twenty years as a highly sensitive absorption spectroscopic technique to measure light attenuation in gases, liquids, and solid samples. An optical cavity is used as a multi-pass cell, and the decay time of the light intensity in the cavity is measured, thereby rendering the techniques insensitive to light intensity fluctuations. Optical waveguides are used to build the optical cavities presented in this work. The geometries of such waveguides permit the use of very small liquid sample volumes while retaining the advantages of cavity ring-down spectroscopy. In this thesis cavity ring-down measurements are conducted, both, in the time domain and by measuring phase-shifts of sinusoidally modulated light, and the two methods are theoretically connected using a simple mathematical model, which is then experimentally confirmed. A new laser driver, that is compatible with high powered diode lasers, has to be designed to be able to switch from time domain to frequency domain measurements. A sample path length enhancement within the optical cavity is explored with the use of liquid core waveguides. The setup was optimised with respect to the matrix liquid, the geometrical matching of waveguide geometries, and the shape of liquid core waveguide ends. Additionally, a new technique of producing concave lenses at fibre ends has been developed and the output of a general fibre lens is simulated. Finally, liquid core waveguides are incorporated into a fibre-loop ring-down spectroscopy setup to measure the attenuation of two model dyes in a sample volume of <1 µL. The setup is characterized by measuring concentrations of Allura Red AC and Congo Red from 1 µM to a limit of detection of 5 nM. The performance of the setup is compared to other absorption techniques measuring liquid samples. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-04-23 14:08:16.33

La nécessité de prouver l’existence de nouvelles particules comme les quarks et le boson de Higgs a entrainé le développement de deux nouveaux pans de la recherche : la physique des hautes énergies ou physique des particules, dédiée à prouver expérimentalement l'existence de ces particules puis à étudier leurs propriétés et la physique des accélérateurs, dédiée au développement de nouveaux instruments pour la physique des hautes énergies.Dans ce contexte, des collisionneurs linéaires électrons/positrons polarisés de forte luminosité dont l'énergie serait connue et accordable pourrait permettre d’étudier plus finement des particules se situant dans des énergies autour du TeV telles que le Boson de Higgs. C'est dans ce sens que le projet International Linear Collider (ILC) est conçu et c'est dans le cadre du développement de ce collisionneur linéaire de particules que cette thèse de doctorat se situe. Un des points critiques de l'ILC est la source de positrons polarisés. Sans entrer dans des explications sur la physique du processus de création de positrons polarisés, nous précisons simplement que ceux-ci sont créés lorsque des rayons gamma polarisés circulairement interagissent avec la matière. Le point critique est donc la source de rayons gamma polarisés circulairement. Une alternative pour cette source est la diffusion Compton inverse et c'est finalement dans le cadre de la recherche et du développement de systèmes lasers de fortes puissances moyennes asservis à des cavités Fabry-Perot pour la production de rayons gamma polarisés par diffusion Compton inverse que se situe cette thèse.Dans un premier temps, nous posons plus précisément le contexte de cette thèse, le principe de la diffusion Compton inverse ainsi que le choix d’une architecture optique basée sur un laser fibré et une cavité Fabry-Perot. Nous finissons sur une énumération des différentes applications possibles de la diffusion Compton inverse montrant que les travaux présentés pourraient bénéficier de transfert technologique vers d’autres domaines. Dans un second temps, nous présentons les différentes architectures d’amplification laser fibrée étudiées ainsi que les résultats obtenus. Dans un troisième temps, nous faisons un rappel du principe de fonctionnement d’une cavité Fabry-Perot et présentons celle utilisée pour notre expérience ainsi que ses spécificités. Dans un quatrième temps, nous abordons l’expérience de diffusion Compton inverse qui nous a permis de présenter pour la première fois à notre connaissance l’utilisation conjointe d’un laser à fibre optique et d’une cavité Fabry-Perot dans le cadre d’un accélérateur de particules pour générer des rayons gamma. Le dispositif expérimental ainsi que les résultats obtenus sont alors présentés. Finalement, nous résumons les résultats présentés dans ce manuscrit et proposons différentes possibilités d’évolution pour le système dans une conclusion générale. / The requirement to prove the existence of news particles like quarks and the Higgs boson has led the development of two news branches for the research: the high energy physics or particle physics, dedicated to experimentally prove the existence of these new particles then to study their properties and the accelerator physics, dedicated to develop particles accelerators for the high energy physic. In this context, polarized electrons/positrons high luminosity linear collider of known and scalable energy might enable more precise studies of particles with energy around the TeV such as the Higgs boson. To that end, the International Linear Collider (ILC) project is being designed and it is in this framework that this PhD thesis takes place. One of the critical points of the ILC is the polarized positrons source. Without going through further explanation on the physical process of polarized positrons production, we point out that they are produced when circularly polarized gamma rays interact with mater. Thus, the critical point is the circularly polarized gamma-ray source. A technical solution for this source is the Compton backscattering and in the end, this thesis takes place in the framework of R&D for high average power laser systems enslaved to Fabry-Perot cavities for polarized gamma-ray production by Compton backscattering. In the first part, we present this thesis context, the Compton backscattering principle and the choice for an optical architecture based on a fiber laser and a Fabry-Perot cavity. We finish by enumerating several possible applications for Compton backscattering which shows that the work presented here might benefits from technology transfer through others research fields. In the second part, we present the different fiber laser architecture studied as well as the results obtained. In the third part, we remind the operating principle of a Fabry-Perot cavity and present the one used for our experiment as well as its specificities. In the fourth part, we address the Compton backscattering experiment which enables us to present the joint utilization of a fiber laser and a Fabry-Perot cavity in a particles accelerator to generate gamma rays for the first time to our knowledge. The experimental apparatus as well as the results obtained are thus presented. In the end, we summarize the results presented in this manuscript and propose different evolution possibilities for the system in a general conclusion.

O trabalho tem por objetivo o estudo e o desenvolvimento de interferômetros recuperadores com baixa tensão de meia onda utilizando moduladores eletro-ópticos para serem aplicados em sistemas Interferométricos de luz branca. Ele dá continuidade às pesquisas do autor em seu mestrado, em que foi desenvolvido e testado um sistema de sensoriamento eletro-óptico capaz de medir diretamente tensões de até 69,4 kVRMS. Desta forma aperfeiçoa-se o sistema de processamento de sinais ópticos desenvolvendo um novo interferômetro recuperador, baseado em óptica integrada. Para o desenvolvimento do tema proposto, inicialmente foi feito uma revisão da literatura/bibliografia, baseada em livros, artigos e teses, visando identificar o \"estado da arte\" relacionado aos moduladores eletro-ópticos para definir o tipo de modulador mais adequado à aplicação em vista. O estudo resultou na escolha de um componente em óptica integrada que foi aplicado numa configuração inédita em um protótipo de transformador de potencial óptico para medição de elevados níveis de tensão elétrica. As características de desempenho deste protótipo foram comparadas com as do protótipo previamente construído. Como resultado deste trabalho, amplia-se o conhecimento e fixa-se em âmbito nacional o domínio sobre as técnicas de construção de interferômetros recuperadores baseados em óptica integrada aplicáveis à recuperação de sinais ópticos em sistemas interferométricos para medição de altas tensões. / This work has as objective the study and development of low half-wave voltage recovery interferometers using electro-optical modulators to be applied to white light interferometric systems. This work is a continuation in the research carried out by the author to obtain his master degree, in which it was developed and tested an electro- optic sensing system capable to measure direct voltage to 69.4 kVrms. In the present work the optical signals processing system is improved by developing a new recovery interferometer based on integrated optics. To develop the proposed subject, initially a review of the literature, based on books, articles and thesis, has been done aiming to identify the State of the Art related to electro-optic modulators and helping to define the most suitable type of modulator for the desired application. The study resulted in the selection of an integrated optical device arranged in an unpublished configuration that was applied to a prototype of optical voltage transformer, intended to measure high voltage levels. The performance of this prototype was compared with a previous version. The results of this work increase the knowledge of the construction techniques of recovery interferometers based on integrated optic devices applicable to the recovering of optical signals in interferometric systems for high voltage measurement.

L’objectif principal de cette thèse était d’examiner dans quelle mesure il est possible d’étendre l’approche de la courbe maîtresse à des composants complexes afin de déterminer des conditions de déverminage et de réaliser une prédiction de durée de vie en fonction de ces conditions de déverminage. Nous avons considéré la stabilité d’un réseau dit élémentaire (réseau carré, à pas constant et droit) puis le problème de la stabilité (selon des critères spécifiques) des composants complexes: les CDC et les monofiltres GFF. Cette thèse a permis de décrire de façon rigoureuse, puis d'utiliser le cadre de travail VAREPA pour résoudre des problèmes issus de l'industrie de télécoms. A cet effet, des séries d’études de vieillissement accéléré sur des réseaux simples et complexes ont été menées. Un protocole de mesure permettant de déterminer les incertitudes de mesure a été mis au point afin de déterminer de façon fiable des intervalles de confiance sur les prédictions de durée de vie.Nous avons étudié les cinétiques de croissance des réseaux inscrits dans une fibre dédiée à l’inscription des CDC (Coreactive). Cette étude nous a permis de montrer que la réaction prédominante à l’origine des changements d’indice de réfraction est activée par une absorption à 1 photon. D’autre part, nous avons étendu le cadre de travail utilisé pour prédire l’effacement des réseaux (VAREPA) afin de rendre compte de leurs cinétiques d’inscription. Puis nous avons cherché à déterminer les conditions de passivation et à prédire la durée de vie des réseaux déverminés en présence d’hydrogène résiduelle (procédé industriel actuel). Pour cela, nous avons établi la courbe maîtresse de réseaux photoinscrits non déverminés puis nous avons validé les conditions de déverminage et les prédictions de durée de vie en construisant une nouvelle courbe maîtresse sur des réseaux déverminés.Nous avons étudié la stabilité thermique des réseaux inscrits dans une fibre hydrogénée dédiée aux futurs monofiltres GFF dans des conditions d’inscription similaires à celles de ces composants. Nous avons utilisé les courbes maîtresses établies à partir des réseaux élémentaires (mais apodisés) simplement dégazés « à froid » (ici 2jours à 50°C puis 2 jours à 110°C). Puis, nous avons fait vieillir le profil d’indice (cœur et gaine) d’un monofiltre GFF. Puis, nous avons recalculé la réponse spectrale de ce filtre vieilli (e.g. 30jours à 200°C) et nous l’avons comparé à des mesures expérimentales. Cette approche reste générale et permet de changer les conditions de déverminage au besoin. Cette étude nous a permis de mettre en évidence que la stabilité des variations d’indice photo-induites dans le cœur dépend peu de l’amplitude initiale de la modulation pour des valeurs comprises entre quelques 10-5 et 10-3. Du fait de la présence d’une gaine optique fortement photosensible (car fortement dopée en Ge), nous avons établi les courbes maîtresses des variations d’indice photo-inscrites dans le cœur et la gaine optique pour des valeurs allant jusque 10-3 dans le cœur et 3.10-3 dans la gaine. Nous avons ainsi obtenu des courbes maîtresses présentant le même k0 (fréquence d'essai, i.e facteur pré exponentiel) mais dont la forme est légèrement différente. La stabilité des variations d’indice est meilleure dans le cœur (moins dopé en Ge) que dans la gaine photosensible. Dans un second temps, nous avons cherché à déterminer les conditions de passivation et à prédire la durée de vie des réseaux déverminés à partir des réseaux de Bragg qualifiés d’élémentaires. Pour la première fois à notre connaissance, nous avons validé de façon fiable les conditions de passivation et les prédictions de durée de vie en construisant une nouvelle courbe maîtresse sur des monofiltres GFF préalablement déverminés. Conformément à la théorie, cette courbe maîtresse présente le même k0 et une forme similaire à celle établie au moyen de réseaux non déverminés, ce qui valide la fiabilité de nos prédictions. / The main objective of this thesis was to investigate how it is possible to extend the master curveapproach to complex components, in order to calculate annealing conditions and giving a life timeprediction according those annealing conditions. We studied the stability of a simple Bragg grating (noapodisation, constant pitch, no tilt). Then, we have been able to study the problem of the stability(according to specific criteria) of complex components: CDC and GFF monofilters. This thesis allowed toshow precisely what is the VAREPA framework and how to apply it to optical telecommunicationsproblems. To give an answer to the question of the possibility of extending the master curve approach tocomplex components, series of accelerate aging studies have been carried out. For this purpose, ameasurement protocol including the determination of the measurement uncertainty was developed. Thisprotocol allow, to determine confidence intervals on the life time prediction.We studied the kinetics of photo induced index growth in the optical fiber dedicated forfabrication of CDC (Coreactive). This study allowed us to demonstrate that the predominant reaction atthe origin of changes in refractive index is activated by a one photon absorption. On the other hand wehave extended the VEREPA framework used to predict the Bragg gratings erasure to take into account thegrowing kinetics. In a second step we tried to calculate annealing conditions in the presence of residualmolecular hydrogen and associated Bragg grating life time prediction. For that purpose we established themaster curve of photo-induced Bragg gratings without annealing, then we validated the annealingconditions and lifetime predictions by building a new master curve from aging of annealed Bragg gratings(in presence of residual hydrogen).We studied the thermal stability of hydrogenated fiber Bragg gratings dedicated to futuremonofiltres GFF in similar conditions to those components. We used master curves from basic Bragggratings (ie no apodisation, constant pitch, no tilt) simply out-gazed at "cold" temperature (here 2 days at50 ° C and 2 days at 110 ° C). Then the aging of the index profile of a GFF monofilter have beensimulated (index profile of the core and of the cladding, each of them having a different master curve).For that purpose the profile have been separated into 35 "basic" filters. Then the spectral response of thisaged monofilter (e.g. 30 days at 200°C) have been calculated and compared with experimentalmeasurements. The advantage of this approach is that it is general and allow to change the annealingconditions if needed. Firstly, this study allowed to highlight that the stability of photo-induced indexchanges in the core depend little on the initial amplitude modulation for values between several 10-5 and10-3. Secondly, due to the presence of a highly sensitive optical cladding (and therefore highly Ge doped),Master curves, of photo-induced index change in the core and the cladding have been established forvalues ranging up to 10-3 in the core and 3.10-3 in the cladding. Master Curves with the same k0 havebeen obtained but the elbow and the slopes are different. Stability of index variations in the core is better(less Ge doped) than in the photosensitive cladding. In a second step, from the basic Bragg gratings, theannealing conditions and the lifetime have been determined. For the first time to our knowledge, thereliably of the annealing conditions and the life time predictions have been validated by building a newmaster curve on annealed GFF monofilters. According to the theory, this master curve show the same k0as the one determined using non-annealed gratings. More beyond the elbow, the two curves are same,which validates the reliability of our predictions.