IEEE has recently finished its ratification of the IEEE Standard 802.3ba in June 2010 which set the target Ethernet speed as 100 Gbps. The studies on the future trends of the ever-increasing demands for higher speed optical fiber communications show that there is no sign of decline in the demand. Constantly increasing internet traffic and the bandwidth-hungry multimedia services like HDTV, YouTube, voice-over-IP, etc. can be shown as the main driving forces. Indeed, the discussions over the future upgrades on the Ethernet speeds have already been initiated. It is predicted that the next upgrade will enable 400 Gbps Ethernet and the one after will be toward enabling the astounding 1 Tbps Ethernet.Although such high and ultra high transmission speeds are unprecedented over any transmission medium, the bottlenecks for achieving them over the optical fiber remains to be fundamental. At such high operating symbol rates, the signal impairments due to inter- and intra-channel fiber nonlinearities and polarization mode dispersion get exacerbated to the levels that cripple the high-fidelity communication over optical fibers. Therefore, efforts should be exerted to provide solutions that not only answer the need for high-speed transmission but also maintain low operating symbol rates.In this dissertation, we contribute to these efforts by proposing nonbinary-LDPC-coded modulation (NB-LDPC-CM) schemes as enabling technologies that can meet both the aforementioned goals. We show that our proposed NB-LDPC-CM schemes can outperform their prior-art, binary counterparts called bit-interleaved coded modulation (BI-LDPC-CM) schemes while attaining the same aggregate bit rates at a lower complexity and latency. We provide comprehensive analysis on the computational complexity of both schemes to justify our claims with solid evidence. We also compare the performances of both schemes by using amplified spontaneous emission (ASE) noise dominated optical fiber transmission and short to medium haul optical fiber transmission scenarios. Both applications show outstanding performances of NB-LDPC-CM schemes over the prior-art BI-LDPC-CM schemes with increasing gaps in coding gain as the transmission speeds increase. Furthermore, we present how a rate-adaptive NB-LDPC-CM can be employed to fully utilize the resources of a long haul optical transport network throughout its service time.

Les oscillateurs sont présents dans tous les systèmes de communications que nous utilisons. Ils nous permettent de faire la synchronisation entre l’émetteur et le récepteur d’un message. La qualité de cette synchronisation dépend de la stabilité de l’oscillateur. Afin de caractériser cette stabilité dans le domaine fréquentiel, le bruit de phase est utilisé comme paramètre de référence. Un oscillateur qui délivre un signal avec une faible valeur de bruit de phase est un oscillateur de grande pureté spectrale. Les oscillateurs électroniques ont une bonne performance à basse fréquence. En mesure de la demande des systèmes de très haut débit, les oscillateurs électroniques ne sont pas capables de produire signaux qu’avec l’utilisation de multiplicateurs de fréquence qui ajoutent plusieurs éléments à la chaine de communication. Les systèmes hybrides permettent de prendre d’avantage la bonne performance de composants optiques en haute fréquence afin de les intégrer dans les systèmes électroniques et surmonter de cette façon-là les limitations fréquentielles des systèmes électroniques. Ce travail vise l’utilisation de la technique de verrouillage optique par injection du faisceau d’un laser maître vers la cavité d’un VCSEL sous modulation directe dans la boucle d’oscillation. La technique du verrouillage optique du VCSEL permets d’élargir la bande passante de modulation directe du VCSEL et réduire son bruit d’intensité (Relative Intensity Noise - RIN). La réduction du RIN a comme effet secondaire la réduction de la contribution du bruit additif dans l’oscillateur et, en conséquence, la réduction du bruit de phase de l’oscillateur. / Oscillators are present in all telecommunication systems. They synchronize the emitter and receiver of a message. The quality of the synchronization depends on the oscillator stability. To characterize the frequency domain oscillator stability, the phase noise of the carrier is used as figure of merit. An oscillator delivering a low phase noise carrier is a high spectral purity oscillator. Electronic oscillators are high performing at low frequencies. As communications systems require high data rate transmission, the electronic oscillators uses frequency multipliers that degrades the spectral purity of the carrier. The hybrid systems take advantage of the good performance of optical components at high frequency with the goal to be integrated in the electronic systems to overcome frequency limitation issues. This work use the optical injection locking technique by injecting the laser beam of a master laser inside the cavity of a VCSEL under direct modulation. The optical injection locking technique enlarges the direct modulation bandwidth of the VCSEL and reduces the Relative Intensity noise of the laser (RIN). The RIN reduction has as side effect the reduction of the additive noise inside the oscillator and, in consequence, reducing the oscillator phase noise.

Nos dias de hoje o controle e monitoração de sistemas biológicos relacionados ao controle ambiental tem sido considerado importante para o diagnóstico e biorremediação de sistemas aquosos como rios e lagos. A eficácia dos processos de controle está diretamente relacionada aos processos de medição \"in-situ\" em tempo real. Nesse sentido o presente trabalho apresenta o desenvolvimento de sistemas multiespectrais portáteis para monitoramento, \"in-situ\" e em tempo real, da dinâmica do crescimento microbiano utilizados em processos de biorremediação. Assim, para este fim foram desenvolvidos dois sistemas, um para monitorar a concentração de oxigênio dissolvido (OD) em meio aquoso e outro para monitorar a absorção óptica do meio de cultura. O sensor óptico para monitorar a concentração de OD está baseado em uma fibra óptica na qual em uma de suas pontas (extremidades) foi depositado um filme fino de Poli (cloreto de vinila) (PVC) dopado com moléculas de octaetilporfirina de platina (PtOEP) como parte sensível do dispositivo. O sensor mostrou resposta linear em regiões entre 4 e 18 mg/L de OD em meio aquoso, tendo como tempo de resposta de 8 s e tempo de recuperação de 236 s. O sistema de medida de absorção óptica do meio de cultura foi projetado e fabricado utilizando-se um fotodetector multiespectral e um diodo LED (600nm) como fonte de excitação. A aquisição, controle e processamento de sinais deste sistema está baseado em uma placa de aquisição NI modelo myRIO-1900 fabricado pela National Instruments, utilizando-se tecnologia Field Programmable Gate Array (FPGA). Os resultados obtidos com este sistema mostram ter o mesmo nível de desempenho se comparado ao de um sistema biofotométrico comercial na faixa de concentração entre 1,13 mg/ml à 2,11mg/ml. / Nowadays, the controlling and monitoring biological systems related to environmental control has been considered important for the diagnosis and bio-remediation of aqueous systems like rivers and lakes. The effectiveness of this control processes are directly related to \"in-situ\" and real-time measurement processes. In this sense the present work presents the development of portable multispectral systems for monitoring, \"in-situ\" and in real time, the dynamics of microbial growth used in bio-remediation processes. So, for this purpose were fabricated two systems, one to monitor the concentration of dissolved oxygen (DO) in aqueous medium and another to monitor the optical absorption of culture medium. The optical sensor to monitor the DO is based on an optical fiber in which in one of its ends was deposited a poly(vinyl chloride) (PVC) thin film doped with Platinum octaethylphorphyrin molecules (PtOEP) as part of the device. The sensor showed linear response in regions between 4 and 18 mg/L of DO in aqueous medium, with response time of 8s and the recovery time of 236s. The system of measurement of optical absorption of culture medium was designed and manufactured using a multispectral photodetector and a diode LED (600nm) as a source of excitation. The acquisition, signal processing and control of this system are based on an acquisition card NI myRIO-1900 model manufactured by National Instruments, using FPGA technology. The results obtained with this system shows to have the same level of performance to that of a commercial biophotometric system in the concentration range of 1.13 mg/mL to 2.11 mg/mL.

Amplificadores a fibra dopada com érbio de dupla passagem (DP-EDFA) contendo fibras compensadoras de dispersão (DCF) são estudados nesta tese. Os DP-EDFAs são uma alternativa para amplificadores de baixo custo e bom desempenho, sobretudo para utilização em redes metropolitanas. Devido a sua estrutura de dupla passagem, outras funções podem ser facilmente inseridas em seu circuito óptico, incrementando sua funcionalidade e reduzindo o custo envolvido. Considerando ainda que a compensação da dispersão é crítica para sistemas WDM de alta velocidade, um interessante tópico de investigação, que será bastante explorado nesta tese, refere-se a embutir uma fibra compensadora de dispersão dentro no circuito do DP-EDFA. Estudos experimentais são conduzidos, mostrando as vantagens e os problemas associados a algumas topologias de circuitos de DP-EDFAs. Um circuito original de DP-EDFA contendo DCF é proposto e caracterizado em termos de ganho e figura de ruído para diversas aplicações multicanal e multibanda dentro do espectro de transmissão da fibra óptica. Caracterizações sistêmicas em termos de taxa de erro de bit são também conduzidas / Double pass erbium doped fiber amplifiers (DP-EDFA) with an embedded dispersion compensation fiber are studied in this work. DP-EDFA is a cost-effective alternative for optical amplifiers, yet preserving good optical performance, mainly for use in metropolitan networks. Due to its double pass circuit, others functions beyond amplification can be inserted within the amplification circuit, increasing its capabilities and decreasing the involved cost. Considering that dispersion compensation is very critical for high-speed DWDM systems operating with standard single mode fiber, a timely topic of investigation concerns the embedding of the high insertion loss DCFs (dispersion compensating fibers) into optical amplifier configurations. Experimental studies are conducted first showing the advantages and impairments associated with DP-EDFAs circuits using DCFs. Next, a DP-EDFA proposed in this work is characterized in terms of gain and noise figure for several applications in multichannel and multiband network topologies. Systemic characterization in terms of bit error rate is also conducted, evaluating the performance of the proposed DP-EDFA using DCF

Este trabalho de doutoramento propôs investigar novas configurações geométricas para as fibras ópticas microestruturadas a base de sílica. Aproveitando-se da flexibilidade que sua geometria proporciona, diferentes das fibras ópticas convencionais, foram propostas fibras ópticas microestruturadas com perfil tipo D atuando, especificamente, em duas aplicações distintas: fibras compensadoras de dispersão ou fibras altamente birrefringentes. Para o estudo teórico das fibras ópticas microestruturadas foram utilizados dois métodos numéricos: o método da Sobre-Relaxação Sucessiva (SOR) e o método de Arnoldi Implicitamente Reiniciado (IRAM). Foi necessário implementar o método IRAM para determinar os modos de mais alta ordem presentes em guias de onda multimodos, uma vez que o método SOR fornece apenas a solução para o modo fundamental. Neste contexto, as fibras ópticas microestruturadas com perfil D, propostas e investigadas neste trabalho, demonstraram ser extremamente promissoras para atuar na compensação da dispersão cromática ou no aumento do efeito da birrefringência. Foram projetadas fibras capazes de compensar a dispersão em banda larga, cobrindo as bandas de telecomunicações S, C e L, ou, ainda, fibras com um alto coeficiente de dispersão negativo em torno do comprimento de onda de 1550nm. Adicionalmente, verificou-se também que com as novas configurações propostas foi possível projetar fibras com elevado grau de birrefringência, sendo atrativas no projeto de fibras mantedoras do estado de polarização. / This work proposed to investigate new geometric configurations for the silica microstructured optical fibers. Based on their design flexibility, not usually found in conventional silica fibers, D-shape microstructured optical fibers were designed, specifically, for two different applications: dispersion compensation or high birefringence. For the theoretical analysis two numerical methods were used: the finite difference Successive Over Relaxation (SOR) method, and the Implicitly Restarted Arnoldi Method (IRAM). It was necessary to develop the IRAM method to determine the higher order modes inside the multimodo optical waveguide, since the SOR method is able to yield only the fundamental mode. In this framework, the D-shape microstructured optical fibers, which have been proposed and investigated in this work, proved to be extremely efficient for chromatic dispersion compensation and increasing the birefringent effect. Fibers have been designed in order to compensate the wideband dispersion, covering three entire telecommunication bands, namely: S-, C- and L- bands, simultaneously. Additionally, with these new proposed configurations it is possible to design high birefringent fibers, which are very attractive in polarization maintaining applications.

The growing demand for faster connection to the Internet service and wireless multimedia applications has motivated the development of broadband wireless access technologies in recent years. WiMAX has enabled convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. Scheduling is a fundamental component in resource management in WiMAX networks and plays the main role in meeting QoS requirements such as delay, throughput and packet loss for different classes of service. In this dissertation work, the performance of uplink schedulers at the fixed WiMAX MAC layer has been considered, we proposed an Adaptive Hierarchical Weighted Fair Queuing Scheduling algorithm, the new scheduling algorithm adapts to changes in traffic, at the same time; it is able to heuristically enhance the performance of WiMAX network under most circumstances. The heuristic nature of this scheduling algorithm enables the MAC layer to meet the QoS requirements of the users. The performance of this adaptive WiMAX Uplink algorithm has been evaluated by simulation using MATLAB. Results indicate that the algorithm is efficient in scheduling the Base Stations’ traffic loads, and improves QoS. The utilization of relay stations is studied and simulation results are compared with the case without using relay stations. The results show that the proposed scheduling algorithm improves Quality of Service of WiMAX system. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Des méthodes de modulation et de détection de la lumière originales ont été étudiées afin d’améliorer la performance des systèmes de transmission optique longue distance. Des formats de modulation multiplexés en polarisation, utilisant plusieurs niveaux de phase ont été étudiés en particulier. La détection cohérente associée à un traitement numérique du signal a également été choisie au niveau de la réception afin d’optimiser la performance du système. Cela permet notamment de compenser de façon très efficace les distorsions linéaires introduites par la propagation dans le fibre optique, telles que la dispersion chromatique et la dispersion modales de polarisation. Après propagation sur grande distance, le rapport signal à bruit devient une limitation importante. L’autre limitation provient des interactions non linéaire entre la lumière et la fibre optique qui limitent la puissance maximale que l’on peut injecter dans la fibre optique.La première transmission multiplexée en longueur d’onde sur grandes distances (>1000km) utilisant la détection cohérente a notamment été démontrée.Afin de minimiser l’impact de ces effets non linéaires, différentes stratégies ont été proposées et investiguées. L’impact du multiplexage de polarisation a notamment été quantifié dans des configuration où la dispersion chromatique de la fibre est compensée régulièrement dans la liaison et dans le cas où elle n’est compensée qu’en fin de liaison de façon numérique.La proposition d’utiliser un format de modulation à 2 niveaux de phase ainsi que les algorithmes permettant de le détecter ont été fait. Le gain de performance obtenu par rapport à la solution conventionnelle à 4 niveaux de phase a été montré.Au débit de 100Gb/s, la démonstration de la première transmission sur des distances transocéanique a également été faite.Ces travaux de recherche ont été notamment utilisés pour définir puis développer des produits Alcatel-Lucent qui sont maintenant commercialisés, à 40Gb/s en utilisant un format de modulation multiplexé en polarisation à deux niveaux de phase, et à 100Gb/s en utilisant un format multiplexé en polarisation à quatre niveaux de phase. / Modulation and detection methods have been studied to improve the performance of optical long distance communication systems. Polarization division multiplexed modulation and multilevel phase modulation format have been evaluated. Coherent detection associated with digital signal processing has been selected at the receiver side to optimize system performance. This receiver design allows especially to compensate linear distortions induced by fiber optics propagation very efficiently. After long distance propagation, optical signal to noise ratio is a major limitation. The other main limitation comes from non linear interactions of light and fiber optics which put a limit on the maximum power to be injected within fiber optics.The first wavelength division multiplexed transmission over long distances (>1000km) using coherent detection has been demonstrated.Various strategies have been proposed to minimize the impact of non linear effect. The impact of polarisation multiplexing has been quantified in configuration where chromatic dispersion is either regularly optically compensated within the line or digitally compensated at the receiver end.The proposition to use a polarization multiplexed format using only 2 phase levels as well as the algorithms capable to detect them has been done. The performance gain obtained compared to the convention solution using 4 phase levels has been demonstrated.At 100Gb/s bit rate, the demonstration of the first transmission over trans-oceanic distance has also been done.These research work have been used to define and then develop Alcatel-Lucent products which are now commercialized, at 40Gb/s by using a polarization multiplexed and 2 phase levels modulation format, and at 100Gb/s by using a polarization multiplexed 4 phase levels format.

Neste trabalho é investigada uma nova classe de fibras ópticas, baseada no conceito de cristais fotônicos, denominada fibra microestruturada. Sua geometria particular, com materiais de diferentes índices de refração estruturados de forma periódica, permite uma alta flexibilidade de projeto. Consegue-se, portanto, ajustar, conforme a necessidade, as propriedades de dispersão, área efetiva, perdas por confinamento, entre outras, o que torna estas fibras especialmente úteis para aplicações em comunicações ópticas. Para o estudo das propriedades das fibras microestruturadas foi implementado, em diferenças finitas, o método numérico da sobre relaxação sucessiva - SOR com as três aproximações possíveis para a equação de Helmholtz: escalar, semivetorial e vetorial completa. Adicionalmente, no intuito de melhorar alguns aspectos do formalismo SOR, como precisão e velocidade de convergência, foi proposta a aproximação em diferenças finitas de quarta ordem. / This work investigates a new class of optical fibers based on the photonic crystal concept. The main advantage of these fibers is the flexibility offered by their particular geometry, which is formed by materials of different refractive index periodically arranged in a specific pattern. The dispersion properties of these microstructured optical fibers are analyzed by using the finite difference Successive Over Relaxation (SOR) method, where three different formalisms are implemented under the scalar, semivectorial and full vectorial approximations. Finally, a fourth order approximation for the SOR method is proposed in order to improve the convergence and precision.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Serà estudado nesta dissertaÃÃo o comportamento da propagaÃÃo de trÃs tipos de pulsos Ãpticos (Solitons, Quasisolitons e Gaussianos) ultracurtos na regiÃo de 1.55μm e a eficiÃncia de conversÃo destes na geraÃÃo de pulsos por meio do fenÃmeno nÃo-linear de mistura de quatro ondas (FWM) em uma fibra comum e em fibras com dispersÃo decrescente em sistemas multiplexados por divisÃo de comprimento de onda (WDM). Para tal usamos seis diferentes perfis de dispersÃo; Constante, Linear, LogarÃtmico, Gaussiano, Exponencial e HiperbÃlico; nas simulaÃÃes da propagaÃÃo dos pulsos atravÃs de 100 Km de fibras.Na anÃlise dos resultados observamos que a eficiÃncia de conversÃo decai quando aumentamos a separaÃÃo entre os canais independentemente do perfil. Dentre estes perfis para os trÃs tipos de pulsos quando na separaÃÃo de canal de 0.2nm o HiperbÃlico apresentou a maior eficiÃncia, sendo de aproximadamente 1000 vezes maior em magnitude se comparada aos perfis Constante, Linear e LogarÃtmico.Para o pulso Gaussiano, exceto pelo perfil HiperbÃlico todos os outros perfis apresentaram a mesma eficiÃncia a partir da separaÃÃo de 0.675nm. Os pulsos Soliton e Quasisoliton tambÃm apresentam tal exceÃÃo no perfil Exponencial. A eficiÃncia de conversÃo ao longo do comprimento da fibra foi analisada para os trÃs tipos de pulsos em cada um dos seis perfis. Em todos os tipos de pulsos os perfis que apresentaram maior eficiÃncia de conversÃo, em ordem decrescente foram o HiperbÃlico, o Exponencial e o Gaussiano. Os outros trÃs, Constante, Linear e LogarÃtmico, apresentaram eficiÃncias muito prÃximas nos trÃs tipos de pulsos. Durante a propagaÃÃo observamos a presenÃa de pulsos gerados pela instabilidade modulacional para os trÃs tipos de pulsos nos perfis Constante, Linear, LogarÃtmico, Gaussiano e Exponencial. Entretanto apÃs percorrido aproximadamente 20Km a instabilidade modulacional desaparece nos trÃs primeiros perfis e nos outros dois o fenÃmeno permanece atà o final da propagaÃÃo na maioria dos casos. Em todos os casos estudados houve um aumento da eficiÃncia de conversÃo do pulso no canal 3 quando do incremento da potÃncia dos pulsos incidentes nos canais 1 e 4. A anÃlise do fator de compressÃo mostrou que os pulsos Soliton e Quasisoliton no canal 1 apresentaram alargamento na maioria dos perfis. E o pulso Gaussiano no canal 1 sà apresentou alargamento no perfil HiperbÃlico. No canal 4 o pulso Soliton sà apresentou compressÃo no perfil HiperbÃlico, o pulso Quasisoliton apresentou alargamento somente nos perfis Exponencial e Constante, no pulso Gaussiano todos os perfis apresentaram compressÃo, exceto o Constante que ao fim da propagaÃÃo obteve o mesmo valor que no inÃcio desta. A compressÃo do pulso gerado no canal 3 em todos os casos apresentou uma forte oscilaÃÃo nos primeiros 20 Km propagados e nos pulsos Soliton e Quasisoliton o perfil Gaussiano apresentou uma variaÃÃo brusca depois de percorrido 60 Km e estabilizando-se antes do fim da propagaÃÃo. / This dissertation will study the behavior of the propagation of three types of optical pulses (Solitons, Quasisolitons and Gaussianos, short ultra in the area of 1.55μm) and their efficiencies of conversion in the generation of pulses through the non linear phenomenon of four waves mixture (FWM) in a common fiber and in fibers with decreasing dispersion in systems multiplexados by wavelength division (WDM). Six different dispersion profiles were used during the simulations of propagation of the pulses through 100km of fibers: Constant, Linear, Logarithmic, Gaussiano, Exponential and Hyperbolic. The analysis of the results concluded that the efficiency of conversion declines when he/she increases the separation of the channels independently of the profile. The Hyperbolic profiles presented the largest efficiency when in the separation of channel of 0.2nm, being of approximately 1000 times larger in magnitude if compared to the other profiles Constant, Lineal and Logarithmic. In the pulse Gaussiano all profiles presented the same efficiency starting from the separation of 0.675nm, except for the Hyperbolic profile. While in the Soliton and Quasisoliton pulses, the Exponential profiel also presents such exception. The conversion efficiency along the length of the fiber was analyzed for the three types of pulses for each one of the six profiles. For all of the types of pulses the profiles that presented larger efficiency in decreasing order were, the Hyperbolic, the Exponential and Gaussiano. The other three, Constant, Lineal and Logarithmic, presented very close efficiencies for the three types of pulses. The presence of pulses generated by the instability modulacional for the three types of pulses in the profiles Constant, Lineal, Logarithmic, Gaussiano and Exponential was observed during the propagation. After travelling approximately 20Km the instability modulacional disappears in the first three profiles in all types of pulses while in the other two profiles the phenomenon stays until the end of the propagation in most of the cases. There was an increase of the efficiency of the conversion of the pulse in the channel 3 when of the increment of the potency of the incident pulses in the channels 1 and 4 in all the three types of pulses in each one of the six profiles. The analysis of the compression factor indicated that the pulse generated in the channel 3 by mixture of four waves (FWM) and the incident pulse in the channel 4 always presented compression during the propagation. The incident pulse in the channel 1 also presented compression in most of the profiles and in the Hyperbolic profile it presented strong enlargement attributed to the loss of energy. In the pulse generated in the channel 3 in all of the cases a strong oscillation was observed in the first 20 Km while in the Soliton and Quasisoliton pulses the Gaussian profile presented an abrupt variation after traveling 60 Km and being stabilized before the end of the propagation. This analysis concludes that the control of the efficiency of conversion and of the compression factor in the generation of mixture of four waves is made possible by the use of fiber optic with decreasing dispersion.

Dans le domaine du nucléaire, les techniques actuelles de mesure de radiation n’offrent pas la possibilité d’effectuer un contrôle le long d’un objet filaire. Le projet Droïd a pour but de développer un dosimètre linéique utilisant une fibre optique comme élément sensible. L’atténuation radio-induite (ARI) du guide d’onde, lue par réflectométrie optique, permet non seulement de quantifier, mais également de localiser le dépôt de dose le long de la fibre. Chaque portion du câble fait alors office de capteur de rayonnement. Il est envisageable d’effectuer des mesures réparties sur de longues distances (plusieurs dizaines de mètres) et d’obtenir des cartographies de dose en une, deux ou trois dimensions selon la disposition de l’objet dans l’espace. Le projet se structure en deux volets. Le premier est le développement d’une fibre optique hautement sensible aux radiations. En effet, les technologies commerciales standard ne le sont pas suffisamment pour des applications comme la radioprotection du personnel dans le milieu du nucléaire. Définir la composition chimique de la fibre permet de maîtriser sa réponse aux rayonnements. Le second volet du projet concerne la modélisation liant l’atténuation radio-induite à la dose reçue par le guide d’onde. Dans le cas général d’une fibre avec fading, le développement et l’inversion d’un modèle non linéaire sont primordiaux pour le bon fonctionnement du dosimètre et constituent un verrou scientifique majeur à lever. / In the nuclear domain, current radiation monitoring techniques do not offer the possibility to locally determine the dose received by a wire along its path. The purpose of the Droïd project is to develop a linear dosimeter based on an optical fiber as a sensitive element. The Radiation-Induced Attenuation (RIA) of the waveguide, read by optical reflectometry, can be used not only to quantify, but also to locate the dose deposition along the fiber. Each portion of the cable acts as a radiation sensor. It becomes possible to make measurements over long distances (several tens of meters) and to obtain dose maps in one, two or three dimensions depending on the spatial arrangement of the fiber. The project is structured in two parts. The first one is the development of an optical fiber that is highly sensitive to radiation. Indeed, standard commercial technologies are not reactive enough for applications such as staff radioprotection. Defining the chemical composition of the fiber permits to master its behavior under radiation. The second part of the project deals with modeling the non-linear relationship between the RIA and the dose received by the waveguide. In the general case of a sensor with fading, building and inverting such a model are a requirement for the final device and constitute a major scientific challenge.