Wavelength division multiplexing passive optical network (WDM-PON) can meet growing bandwidth demand in access network by providing high bandwidth to the end users. Failure in the access network is becoming critical as a large volume of traffic might be affected. Therefore, an effective supervision mechanism to detect and localize the fault is required to shorten the service interruption time. Meanwhile, open access provides a certain freedom for end users to choose the service and hence boosts competition among service/network providers. On the other hand, to offer open access in WDM-PON could result in a substantial change on architectural design, e.g., multiple feeder fibers (FFs) instead of a single one may be required to connect different service/network providers. Consequently, the traditional supervision mechanisms don’t work properly in open WDM-PON. To fill in this gap, several fault supervision mechanisms to support open access in WDMPON are proposed in this thesis. They can be applied to both disjoint and co-located FF layout where the choice of providers is done through wavelength selection. The feasibility of such solutions has been validated by evaluating transmission performance. We have carried out simulations in VPItransmissionMaker for different deployment scenarios. The results have confirmed that no significant degradation of the transmission performance is introduced by the proposed monitoring schemes compared to the benchmark, where no any fault supervision method is implemented.

GMPLS is a still developing protocol family which is indented to assume the role of a control plane in transport networks. GMPLS is designed to provide traffic engineering in transport networks composed of different network technologies such as wavelength switched optical networks, Ethernet networks, point-to-point microwave links, etc. Integrating the different network technologies while using label switched paths to provide traffic engineering poses a challenge. The purpose of integrating multiple technologies under a single GMPLS control plane is to enable rapid service provisioning and efficient traffic engineering. Traffic engineering in networks provides two primary advantages, network resource utilization optimization and the ability to provide Quality of Service. Utilizing network resources more efficiently translates to lower expenditures for the network provider. Quality of Service can be used to provide the customer with for example guaranteed minimum bandwidth packet services. Specifically this thesis focused on the problems of signaling and establishing Forward Adjacency Label Switched Paths (FA-LSPs), and on a experimental method of connecting different network technologies. A testbed integrating an Ethernet network and a wave length division multiplexing network was used to show that the proposed solutions can work in practice. / GMPLS består av en samling protokoll under utveckling, de är tänkta att anta rollen som kontrollplan i transportnätverk. GMPLS är designat för att tillhandahålla trafikplanering i transportnätverk bestående av flera olika nätverksteknologier såsom Ethernet, våglängds switchande nätverk m.fl. Integration av dessa olika nätverksteknologier under ett gemensamt kontrollplan och uppsättning av ”label switched paths” i dataplanet är en utmaning. Syftet med att integrera multipla teknologier under ett ensamt GMPLS kontroll plan är att snabbt kunna tillhandahålla tjänster över nätverket samt möjliggöra advancerad trafikplanering. Trafikplanering i nätverk ger två stora fördelar, optimering av utnyttjandet av nätverksresurser samt ökade möjligheter att erbjuda ”Quality of Service” till kunder. Bättre utnyttjande av nätverksresurser innebär lägre kostnader för nätverksleverantören medans ”Quality of Service” kan ge kunden t.ex. en garanterad bandbredd. Specifikt fokuserar denna avhandling på problemen med att signalera och etablera ”Forwarding Adjaceny Label Switched Paths” samt en experimentell metod som båda sammankopplar olika typer av nätverk. En testbed bestående av ett Ethernet nätverk samt ett optiskt våglängdsswitchande nätverk användes för att visa att lösningarna kan fungera i praktiken.

Un défi majeur dans les réseaux d’aujourd’hui est de combler l’écart entre la haute vitesse de la transmission optique et la vitesse plus limitée du traitement électronique des données. Une option est de commuter les données directement dansle domaine optique. Dans cette thèse, nous proposons plusieurs solutions permettant la commutation dans le domaine optique à une granularité plus fine que la longueur d’onde, technique que nous appelons commutation sous-longueurd’onde. Pour montrer la pertinence des solutions proposées, nous analysons leur performance en termes de capacité de trafic, de débit et de délai. La performance est évaluée à la fois par des simulations et en utilisant des modèles de filesd’attente appropriés. Nous considérons d’abord le cas des réseaux métropolitains (Metropolitan Area Networks, MAN) et nous étudions la performance d’un anneau optique avec multiplexage en longueur d’onde (Wavelength Division Multiplexing, WDM) dans lequel la communication entre les noeuds du réseau se fait par insertion/extraction de données dans des créneaux temporels. Nous présentons un protocole entièrement distribué conçu pour assurer l’équité dansce réseau. Nous proposons également un mécanisme d’assemblage de paquets capable d’assurer des délais faibles ainsi que des taux de remplissage élevés. Nous proposons ensuite des solutions de commutation sous-longueur d’onde qui peuvent être appliquées dans le cas plus général des réseaux asynchrones. D’abord, nous proposons de résoudre le problème des collisions de la commutation optique par rafale (Optical Burst Switching, OBS) par la mise en oeuvre d’un mécanisme de réservation. Afin de maximiser l’utilisation des ressources, nous proposons d’adapter la taille de la rafale optique à la charge du réseau.Ensuite, nous proposons une solution alternative pour construire un réseau coeur tout-optique. A cette architecture, nous associons un protocole d’accès ainsi qu’un algorithme d’allocation dynamique de bande passante et nous analysons les performances de la solution proposée. Par le biais d’une étude de cas, nousmontrons que notre solution est capable de réduire considérablement la consommation énergétique par rapport aux architectures actuelles basées sur des routeurs IP. Enfin, nous proposons un nouveau dispositif optique capable derésoudre la contention directement dans le domaine optique. Nous montrons que ce dispositif simple peut être utilisé pour construire des réseaux optiques dynamiques à courte portée tels que les réseaux d’accès ou les centres de traitement de données. / A key challenge in today’s networks is to bridge the gap between high-speed optical transmission and limited electronic processing. This can be achieved by enabling payload to be switched directly in the optical domain.A simple solutionto provide optical switching is by allocating one wavelength channel to each source-destination pair, a technique called Optical Circuit Switching (OCS). Due to lack of sharing, OCS suffers from limited scalability. To overcome this issue,the capacity of each wavelength channel must be dynamically shared among different source-destination pairs. This requires data to be switched at subwavelength granularity by means of subwavelength switching. In this thesis, wepropose several solutions which enable subwavelength switching in optical networks. To show the relevance of the proposed solutions, we analyse their performance in terms of traffic capacity, flow throughput and packet delay. Performance is evaluated both through simulations and by means of appropriate queueing models. We first consider the case of Metropolitan Area Networks (MAN) and we study the performance of synchronous time-slotted Wavelength DivisionMultiplexing (WDM) ring in which network nodes communicate by inserting and extracting data from time-slots. We present a fully distributedMedia Access Control (MAC) protocol designed to ensure fairness. We also propose a burst assembly mechanism able to ensure low assembly delays and high fill rates of the optical time-slots. We then propose subwavelength switching solutions which can be applied in the more general case of asynchronous wide area networks. We first propose to solve the contention problems of conventional Optical Burst Switching (OBS) and the low utilization issue of wavelength-routed OBS byimplementing a two-way reservation OBS scheme in which the size of the opticalburst increases proportionally with the network load so as to maximize resourceutilization. Next, we propose a solution for building an all-optical wide area network based on multipoint-to-multipoint lightpath sharing. We also design an associated MAC protocol and a dynamic bandwidth allocation algorithm and analyse the performance of the proposed solution. By means of a case study, we show that the proposed solution has the potential to considerably reduce power consumption with respect to current router-based architectures. Finally, we propose a novel optical device able to solve contention directly in the optical domain withoutrequiring any optical buffering, electronic signalling or header processing. We show that thissimple device can be used as a building block for dynamic and power efficient short-range optical networks such as access networks or data centers.

No description available.

Nonlinear fiber devices have been attracting considerable attention in recent years, due to their inherent ultrafast response time and potential applications in optical communication systems. They usually require long fibers to generate sufficient nonlinear phase shifts, since nonlinearities of conventional silica-core silica-clad fibers are too low. These long devices, however, cause the serious problems of pulse walk-off, pulse broadening, and polarization fluctuation which are major limiting factors for response time, switching bandwidth, and maximum transmittable bit-rate. Therefore, short device length is indispensable for achieving ultrafast switching and higher bit-rate data transmission. To shorten the required device length, fiber nonlinearities should be increased. In this dissertation, as a way of increasing fiber nonlinearities, high-nonlinearity materials of Litharge, Bismite, Tellurite, and Chalcogenide glasses have been considered. Although they have high nonlinearities, they also have high group-velocity dispersion and high losses deteriorating the performance of nonlinear fiber devices seriously. The aim of this work is to investigate how these high-nonlinearity glasses affect the performance of nonlinear fiber devices, taking into consideration both the advantages and disadvantages. To achieve it, the critical properties of various nonlinear fiber devices constructed with the different types of high-nonlinearity glasses and different types of fibers have been evaluated. It turned out that the required device lengths of nonlinear fiber devices constructed with the high-nonlinearity glasses were significantly reduced and high group-velocity dispersions and losses could not be major problems due to the extremely short device length. As a result, it would be possible to suppress the problems of pulse walk-off, pulse broadening, and polarization fluctuation in nonlinear fiber devices by introducing high-nonlinearity glasses, thus enabling ultrafast switching and higher bit-rate data transmission. Furthermore, in this dissertation, a new scheme of wavelength-division demultiplexing based on the optical Kerr effect has been proposed for the first time. The new scheme can turn the disadvantage of the extremely high group-velocity dispersion of high-nonlinearity glasses into an advantage of wavelength-division demultiplexing. Finally, it now would be possible to greatly increase maximum transmittable bit-rate in optical communication systems by simultaneously demultiplexing optical time-division-multiplexed signals and wavelength-division-multiplexed signals with an optical Kerr effect-based demultiplexer. / Ph. D.

The performance of fused fiber couplers is wavelength dependent. Wavelength spectral compensation is a technique to decrease the effect of the wavelength dependence, which is an essential task for many applications in fiber optic communication systems. Fiber devices such as wavelength-flattened couplers (WFCs) can be fabricated using wavelength spectral compensation methods. In this dissertation, wavelength spectral compensation techniques in fused biconical taper (FBT) couplers including both multimode and single-mode fiber couplers are studied in detail. In multimode fiber coupler operation, a novel theoretical model based on frustrated total internal reflection (FTIR) has been developed to effectively describe the power coupling and loss mechanism. Experimental results support the theoretical predictions. In single-mode fiber couplers, the conventional technique of fabricating WFCs is discussed. An alternative analytical model has been developed based upon coupled mode theory, which provides a relatively simple and mathematically sound explanation to the wavelength spectral compensation. Aiming to simplify WFC fabrication, a new way of constructing WFCs is proposed and demonstrated by connecting regular single-mode fiber couplers, some of which serve as wavelength spectral compensators. WFCs of various structures including 2x2, 1x3, 1x2ᴺ, and 4x4 have been developed, and the experimental data agree with theoretical predictions of performance. Potential applications and future research directions in wavelength spectral compensation are also presented. / Ph. D.

Nonreciprocity is a fundamental property of networks. Unlike electronic networks theory, optical network theory is still a field to be investigated. Lightwave systems, including fiber optic and integrated optic, are becoming more and more complex, new function blocks ( or components) and networking strategies are very important for future highly integrated lightwave circuits. Several common nonreciprocal optical effects studied in this disseration and several basic applications to fiber components and fiber optic metrology systems analyzed. The common optical nonreciprocal phenomena include the Faraday effect, Sagnac effect, Fresnel drag effect, nonlinearity or asymmetric geometric structure-induced nonreciprocity, and some pseudo nonreciprocity. The best-known application of nonreciprocity to optical components is the isolator, and the known nonreciprocity-based fiber optic sensors are the fiber optic gyroscope and the fiber optic current sensor. The major difficulty in forming a general optical network theory is the complexity of optical signals compared to the electrical signal, because each light signal consists of four independent parameters, all of which changing during transmission. Fortunately, most optical signals can be classified into intensity-based and phase-based systems, and the Jones matrix technique is the ideal tool for describing the intensity-based system. Several reciprocity-insensitive structures designed and analyzed in chapter 3. The performance of the intensity-based reciprocity-insensitive structure (IRIS) was employed successfully in a fiber optic current sensor for stabilizing the signal from birefringence influences in chapter 5. A variable-loop Sagnac interferometer was designed and applied to distributed sensing in chapter 6, and the reciprocity-insensitive property of the Sagnac interferometer was preserved. Polarization independent isolators and wavelength division multiplexers were also realized by employing suitable nonreciprocal effects and were discussed in chapter 2 and chapter 4, and their feasibilities were verified by experiment. The primary contributions of this dissertation are the study of common nonreciprocal optical effects and demonstration of several basic applications to fiber components and fiber metrology systems. / Ph. D.

Dans cette thèse, nous nous intéressons à un problème de fiabilité dans les réseaux multicouches IP-sur-WDM. Etant donné un ensemble de demandes pour lesquelles on connaît une topologie fiable dans la couche IP, le problème consiste à sécuriser la couche optique WDM en y cherchant une topologie fiable. Nous montrons que le problème est NP-complet même dans le cas d'une seule demande. Ensuite, nous proposons quatre formulations en termes de programmes linéaires en nombres entiers pour le problème. La première est basée sur les contraintes de coupes. Nous considérons le polyèdre associé. Nous identifions de nouvelles familles de contraintes valides et étudions leur aspect facial. Nous proposons également des algorithmes de séparation pour ces contraintes. En utilisant ces résultats, nous développons un algorithme de coupes et branchements pour le problème et présentons une étude expérimentale. La deuxième formulation utilise comme variables des chemins entre des terminaux dans le graphe sous-jacent. Un algorithme de branchements et génération de colonnes est proposé pour cette formulation. Par la suite, nous discutons d'une formulation dite naturelle utilisant uniquement les variables de design. Enfin, nous présentons une formulation étendue compacte qui, en plus des variables naturelles, utilise des variables de routage. Nous montrons que cette formulation fournit une meilleure borne inférieure. / This thesis deals with a problem related to survivability issues in multilayer IP-over-WDM networks. Given a set of traffic demands for which we know a survivable logical routing in the IP layer, the aim is determine the corresponding survivable topology in the WDM layer. We show that the problem is NP-hard even for a single demand. Moreover, we propose four integer linear programming formulations for the problem. The first one is based on the so-called cut inequalities. We consider the polyhedron associated with the formulation. We identify several families of valid inequalities and discuss their facial aspect. We also develop separation routines. Using this, we devise a Branch-and-Cut algorithm and present experimental results. The second formulation uses paths between terminals of the underlying graph as variables. We devise a Branch-and-Price algorithm based on that formulation. In addition, we investigate a natural formulation for the problem which uses only the design variables.  Finally, we propose an extended compact formulation which, in addition to the design variables, uses routing variables. We show that this formulation provides a tighter bound for the problem.

A interligação de várias redes de telecomunicação ampliou a cobertura, mas tornou a operabilidade entre elas complexa, principalmente por causa da arquitetura resultante, formada por várias camadas. Estas camadas lidam com protocolos e taxas de transmissão diferentes e com sinais elétricos e ópticos. Diante desse cenário, a alternativa usual de expandir os recursos proporcionalmente ao crescimento da demanda é inviável devido ao elevado custo. Assim, soluções eficientes que agregam os benefícios das tecnologias ópticas e eletrônicas na arquitetura de nós e no gerenciamento de tráfego tornaram-se uma necessidade importante no projeto, expansão e gerenciamento de redes de telecomunicação. Os nós que permitem a comutação de tráfego na camada óptica e eletrônica e a agregação de tráfego em várias granularidades têm sido empregados para fazer o melhor uso possível dos recursos disponíveis nas redes. Esses nós são conhecidos na literatura como MG-OXCs. Nessa pesquisa, foi proposta uma abordagem dos nós MG-OXCs de uma e três camadas com a inclusão de recursos como conversão de comprimento de onda e agregação de tráfego. Também foi proposto um método de cálculo do custo desses nós baseado no volume de utilização das portas. Posteriormente foram inseridos fatores de degradação do sinal óptico para a análise da camada física de redes com os nós MGOXCs. Adicionalmente, para o gerenciamento de tráfego, foi proposto um esquema de escolha de comprimentos de onda chamado de canal específico e um esquema de monitoramento baseado na intensidade de tráfego. A meta principal é a redução da probabilidade de bloqueio de solicitação de conexão. Em redes ópticas, os modelos de nós propostos conseguem diminuir o número de portas dos nós comutadores tradicionais além de realizar a comutação de tráfego de conexões de diferentes valores de largura de banda. O esquema do canal específico consegue melhorar a utilização da largura de banda dos comprimentos de onda e diminui a probabilidade de bloqueio e o esquema do monitoramento diminui o número de conexões bloqueadas devido ao aumento dos recursos. Resultados numéricos apresentados demonstram a potencialidade dos algoritmos propostos para gerenciar recursos e rotear o tráfego das redes de telecomunicação. / Integrating telecommunication networks has enlarged the coverage, but has made operations more complex, mainly because of the architecture, formed by various layers. These layers deal with different protocols and transmission rates, as well as electrical and optical signals. The usual alternative of expanding the resources proportionally to the demand is impractical due to the high cost. Therefore, efficient solutions which add to the benefits of optical and electronic technology in node architecture and traffic management are essential in the design, expansion and management of telecommunications networks. The nodes that enable traffic switching in the optical and electronic layer and traffic grooming have been used to make the best use of the available resources in the networks. These nodes are known as MG-OXCs. In this research, an approach based on MG-OXCs was proposed with one and three layers, which include the wavelength conversion and traffic grooming. Additionally, a method to calculate the node costs based on their use of ports was proposed. The work also considered optical signal impairments in order to analyze the network physical layer with MG-OXCs nodes. For the purpose of traffic management, a scheme which sets specific wavelengths for different bandwidths and a scheme which monitors the flow of traffic were proposed. The main aim is to reduce the blocking probability of connection requests. In optical networks, the node models proposed are able to reduce the number of ports used in usual optical cross connects and switch the traffic connections using different bandwidths. The scheme of setting specific wavelengths for different bandwidths improves the bandwidth use and the blocking probability. The scheme which monitors the flow of traffic achieves blocking probability reduction due to the increase in resources. The numerical results presented show the feasibility of the proposed algorithms to manage resources and switch traffic in telecommunication networks.

As redes ópticas têm evoluído de forma contínua dentro de um paradigma de aumento das taxas de transmissão e extensão dos enlaces, devido à demanda crescente de banda em função do crescimento do tráfego da Internet. Além disso, atualmente, diversas propostas vêm sendo implementadas visando torná-las mais dinâmicas e flexíveis. Uma destas propostas que atualmente está no âmbito de pesquisa e desenvolvimento refere-se às redes ópticas definidas por software (Software Defined Optical Network, SDON). Nas SDONs, o plano de controle é desacoplado do plano de encaminhamento de dados possibilitando que controladores remotos configurem em tempo real diversos parâmetros dos canais ópticos, tais como a taxa de transmissão, o formato de modulação, a largura do espectro, entre outros. Nestas redes, o sistema de controle torna-se bastante complexo, uma vez que diversos parâmetros têm que ser ajustados de forma dinâmica e autônoma, ou seja, com a mínima intervenção humana. O emprego de técnicas de inteligência computacional em tal controle possibilita a configuração autônoma dos parâmetros dos equipamentos com base em dados coletados por monitores de rede e o aprendizado, a partir de eventos passados, visando a otimização do desempenho da rede. Esta arquitetura de controle constitui um novo paradigma na evolução das redes ópticas, as denominadas Redes Ópticas Cognitivas. A escolha de uma técnica de inteligência computacional adequada para tomada de decisão em redes ópticas é importante para se obter vantagens no uso da cognição. Esta técnica deve possibilitar o aprendizado e ainda minimizar a complexidade computacional, uma vez que a configuração dos parâmetros da rede deve ocorrer em tempo real. Neste contexto, esta tese investiga o uso do algoritmo de agrupamento Fuzzy C-Means (FCM) para aprendizado e tomada de decisão em redes ópticas flexíveis de próxima geração. FCM possibilita a geração automática de regras com base na experiência adquirida no meio de operação (aprendizado) e a tomada de decisão a partir destas regras. Uma comparação de desempenho entre os algoritmos FCM e CBR (Case-Based Reasoning) é apresentada. O algoritmo CBR foi escolhido para esta comparação devido a ter sido utilizado recentemente, com sucesso, em redes ópticas cognitivas. Por fim, um conceito de rede óptica cognitiva é apresentado. / Optical networks have evolved continuously increasing the transmission rate and the extension of links due to the increased bandwidth consuming. Moreover, currently, several proposals are under development to make the next generation optical network more dynamic and flexible. The term \"flexible\" refers to the ability of dynamically adjust the parameters of the optical network such as modulation format, transmission rate, optical bandwidth and others, according with the quality of transmission of each lightpath. In this scenario, a Software Defined Optical Network (SDON) emerges as a new optical network paradigm, where the control plane is decoupled from the data plane, enabling remote controllers to configure network equipment from different hardware vendors, which allows a degree of software programmability to the network. In SDON, the control plane needs to include functionalities to operate autonomously, i.e, with minimal human intervention. The use of the computational intelligence techniques in such control plane enables the autonomous operation and learning based on past events, in order to optimize the network performance. This architecture represents a new paradigm in the evolution of optical networks, resulting in so-called Cognitive Optical Networks. The choice of a computational intelligence technique for learning and decisionmaking in such optical networks is essential to bring advantages with the use of cognition. This technique should minimize the computational complexity, since the configuration of the network parameters must occur in real time.In this context, this thesis investigates the use of Fuzzy C-Means clustering algorithm (FCM) for learning and decision-making in the software defined optical networks context. FCM enables the automatic generation of rules, based on the experience gained during the network operation. Then, these rules are used by the control plane to take decisions about the lightpaths\' configuration. A comparison of performance between the FCM and the CBR (Case-Based Reasoning) algorithm. CBR algorithm was chosen because it has been successfully used in cognitive optical networks. Finally, we propose a concept for optical cognitive network.