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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Fabrication and characterization of thermo-plasmonic routers for telecom applications

Hassan, Karim 12 July 2013 (has links) (PDF)
The Dielectric Loaded Surface Plasmon Polariton Waveguides (DLSPPWs) have recently emerged as a possible solution to carry both optical and electrical signals on- chip. However, in the particular context of optical interconnects, advanced functionalities such as filtering, switching, and routing are required in order to replace in the future the equivalent electronic components which are too much power consumer and also to reduce their footprints. After presenting the interest and limitation of the leakage radiation microscopy method used all along this work, we show several active devices using thermo-sensitive polymers as the dielectric load driven electrically by Joule heating. Then we demonstrate the feasibility of all-optical systems by either doping the dielectric with metallic nanoparticles or by plasmo-thermal eect of a second plasmonic mode providing a localized heating of controlled shape. The dynamic activation of our thermo- optical devices is performed using a homemade fiber-to-fiber setup which allows us to investigate the response time of a plasmo-thermal heating as well as true datacom transmission. Some improvements of the original DLSPPWs performances are proposed by adding a metallic wall on one side of the polymer ridge. This system can act as a compact and athermal polarization converter
72

Physical Layer Impairments Aware Transparent Wavelength Routed and Flexible-Grid Optical Networks

Krishnamurthy, R January 2015 (has links) (PDF)
Optical WDM network is the suitable transport mechanism for ever increasing bandwidth intensive internet applications. The WDM technique transmits the data over several different wavelengths simultaneously through an opticalfiber and the switching is done at wavelength level. The connection between the source and destination is called the light path. Since the WDM network carries huge amount of tra c, any failure can cause massive data loss. Therefore protecting the network against failure is an important issue. Maintaining high level of service availability is an important aspect of service provider. To provide cost effective service, all-optical network is the suitable choice for the service provider. But in all optical network, the signals are forced to remain in optical domain from source to destination. In the firrst part of the thesis, we deal the physical layer impairments (PLIs) aware shared-path provisioning on a wavelength routed all-optical networks. As the signal travels longer distances, the quality of the signal gets degraded and the receiver may not be able to detect the optical signal properly. Our objective is to establish a light path for both the working path and protection path with acceptable signal quality at the receiver. We propose an impairment aware integer linear programming (ILP) and impairment aware heuristic algorithm that takes into account the PLIs. The ILP provides the optimal solution. It is solved using IBM ILOG CPLEX solver. It is intractable for large size net-work. Therefore we propose the heuristic algorithm for large size network. It is evaluated through discrete-event simulation. But the algorithm provides only the suboptimal solution. To know the performance of this algorithm, the simulation result is compared with the optimal solution. We compute total blocking probability, restoration delay, computation time, and connection setup delay with respect to network load for the heuristic algorithm. We compare the performance of shared-path protection with dedicated-path protection and evaluate the percentage of resource saving of shared-path protection over the dedicated-path protection. In the second and third part of the thesis, we address the issues related to flexible-grid optical networks. In wavelength routed optical network, the bandwidth of each wavelength is fixed and rigid. It supports coarse grained tra c grooming and leads to ancient spectrum utilization. To overcome this, flexible-grid optical networks are proposed. It supports flexible bandwidth, and ne grained tra c groom In the second part of the thesis, we address the routing and spectrum allocation (RSA) algorithm for variable-bit-rate data tra c for flexible-grid optical networks. The RSA problem is NP-complete. Therefore a two-step heuristic approach (routing and spectrum allocation) is proposed to solve the RSA problem. The first step is solved by using a classical shortest path algorithm. For the second step we propose two heuristic schemes for frequency-slot allocation: (i) largest number of free frequency-slot allocation scheme and (ii) largest number of free frequency-slot maintaining scheme. As the network load increases, the spectrum is highly fragmented. To mitigate the fragmentation of the spectrum, we propose a xed-path least-fragmentation heuristic algorithm which fragments the spectrum minimally. It also supports varying-bit-rate tra c and also supports dynamic arrival connection requests. Through extensive simulations the proposed algorithms have been evaluated. Our simulation results show that the algorithms perform better in terms of spectrum utilization, blocking probability, and fraction of fragmentation of the spectrum. The spectrum utilization can reach up to a maximum of 92% and that only 71% of the spectrum is fragmented under maximum network load condition. Finally in the third part of the thesis, we discuss PLIs-aware RSA for the transparent exible-grid optical network. In this network, not only the optical signal expected to travel longer distance, but also to support higher line rates, i.e., data rate is increased up to 1 Tb/s. In such a high data rate, the optical signals are more prone to impairments and noises. As the transmission distance increases, optical signals are subject to tra-verse over many bandwidth-variable wavelength cross connects (BV-WXC) and multiple fibber spans due to which the PLIs get accumulated and are added to the optical signal. These accumulated impairments degrades the signal quality to an unacceptable level at the receiver, the quality of transmission falls below the acceptable threshold value, and the receiver may not be able to detect the signal properly. Therefore our objective is to develop an impairment aware RSA algorithm which establishes the QoT satisfied empathy based on the available resources and the quality of the signal available at the receiver. We formulate the PLIs-RSA problem as an ILP that provides an optimal solution. The optimal solution is obtained by solving the ILP using IBM ILOG CPLEX optimization solver. Since ILP is not efficient for large-size networks, we propose a heuristic algorithm for such a large-size networks. The signal power is measured at the receiver and the connection is established only when the signal power lies above the threshold value. The heuristic algorithm is evaluated through discrete-event simulation. It gives the sub-optimal solution. The simulation result is compared with optimal solution. The result shows that heuristic algorithm performs closer to the ILP. We compute the total blocking probability versus the network load for different spectrum allocation schemes. Total blocking probability is the sum of frequency-slot blocking probability and QoT blocking probability. We compute spectrum efficiency for the proposed algorithm. We also compare our algorithm with the existing routing and spectrum allocation algorithm, and the result shows that our algorithm outperforms the existing algorithms in terms of blocking probability and spectrum utilization.
73

Estudo de algoritmos RWA em redes GMPLS sobre DWDM

Feres, Mariana Massimino 08 June 2009 (has links)
Made available in DSpace on 2016-06-02T19:05:45Z (GMT). No. of bitstreams: 1 3190.pdf: 9507279 bytes, checksum: 8c55bfbb567b6057f6f56e7a27fb7164 (MD5) Previous issue date: 2009-06-08 / Financiadora de Estudos e Projetos / The increase in the number of users and the emergence of sophisticated network applications motivate the research to improve the data-communication technologies, and thus to meet the requirement for bandwidth. In optical networks, one of the main advances is wavelength division multiplexing (WDM). An essential issue in designing of optical networks is how the network will be controlled, that is, which type of signaling will be used for resources reservation, routing and wavelength assigning, and how physical impairments will be dealfish. This implies in the necessity of several devices to guarantee the good functioning of the network. The diversity and complexity of administration of these devices stimulate the creation of GMPLS (Generalized Multiprotocol Label Switching), in order to provide control, for domains not only based on packages (as it makes the MPLS - Multiprotocol Label Switching), but also on time slots, wavelength and fiber. However, the labels switching on the wavelength multiplexing can generate a NP-complete problem involving the routing and wavelength assignment: if both do no succeed, the connection blocking will occur with and loss of network performance. Another relevant question is that, in all-optical networks, there is some physical impairment that influence the blocking probability e must be taken in consideration in algorithms RWA. This work presents the study of the control plan GMPLS and RWA algorithms for the setting up of connections in alloptical WDM networks. Moreover, the study of two physical impairments (polarization mode dispersion and optical signal noise rate) was done, inserting them in RWA algorithm to reduce the blocking probability due them. The results had shown that the MostUsed algorithm has better performance than the BestFit and the Random one when considered the connection blocking due to resources (lambdas). Moreover, the use of impairments-aware algorithms influence significantly in the reduction of the blocking probability. Therefore, the more advantageous performance was observed in the use of impairment-aware algorithms simultaneously with the MostUsed algorithm. / O aumento de usuários e o surgimento de aplicações de redes sofisticadas impulsionam as pesquisas para aprimorar as tecnologias de transmissão de dados, e assim suprir a exigência por largura de banda. Em redes ópticas, um dos principais avanços é o surgimento da multiplexação de comprimento de onda (WDM). Desta forma, uma questão essencial no projeto de redes ópticas compreende na definição de como a rede será controlada, isto é, qual tipo de sinalização será utilizado para reserva de recursos, definição de rotas, tratamento de falhas, entre outras funções formadoras do plano de controle. Isso implica na necessidade de diversos dispositivos para garantir o bom funcionamento da rede. A diversidade e complexidade de administração desses dispositivos incentivam a criação do GMPLS (Generalized Multiprotocol Label Switching), a fim de prover controle, não somente para domínios baseados em pacotes (como faz o MPLS - Multiprotocol Label Switching), mas também em tempo, comprimento de onda e fibra. Porém, a comutação de rótulos sobre a multiplexação de comprimento de onda pode gerar um problema NP-Completo envolvendo o roteamento e a associação de comprimento de onda, uma vez que se ambas não obtiverem sucesso, ocorrerá o bloqueio da conexão e perda de desempenho da rede. Outra questão relevante é que, em redes totalmente ópticas, existem problemas inerentes da camada física os que influenciam na probabilidade de bloqueio e devem ser levados em consideração em algoritmos RWA (roteamento por associação de comprimento de onda). O presente trabalho realiza o estudo do plano de controle GMPLS e de algoritmos RWA para o estabelecimento de conexões em redes WDM transparentes. Além disso, é feito um estudo de duas restrições da camada física (dispersão por modo de polarização e relação sinal ruído óptica) inserindo-as no algoritmo RWA para diminuir a probabilidade de bloqueio devido a elas. Os resultados mostraram que o algoritmo MostUsed possui melhor desempenho em relação ao BestFit e ao Random quando considerado bloqueio por falta de recursos (lambdas). Além disso, o uso de algoritmos cientes de restrições da camada física influencia significamente na diminuição da probabilidade de bloqueio. Portanto, o melhor desempenho foi observado no uso de algoritmos cientes de restrições físicas juntamente com o algoritmo MostUsed.
74

Fabrication and characterization of thermo-plasmonic routers for telecom applications / Fabrication et caractérisation de routeurs thermo-plasmoniques pour les applications telecom

Hassan, Karim 12 July 2013 (has links)
Les guides d’ondes plasmoniques à rubans dielectriques (DLSPPW) sont récemment apparus comme une des solutions possible pour le transport de signaux optiques et électriques sur puce. Néanmoins, dans le contexte particulier des interconnections optiques, des fonctionalitées avancées telles que filtrage, commutation, et routage sont nécessaires afin de remplacer dans le futur les composants electroniques équivalents trop gourmands en énergie et aussi réduire leur empreinte. Après une présentation des intérêts et limitations de la technique de micro- scopie à fuite radiative, nous montrons plusieurs composants actifs utilisant pour diélectrique des polymères thermo-sensibles controlés électriquement par eet Joule. Par la suite nous démontrons la faisabilité de systèmes tout optique que ce soit par dopage du polymère par des nanoparticules metalliques ou par eet thermo-plasmonique d’un second mode plasmon permettant un échauement localisé de forme choisie. L’activation dynamique de nos composants thermo-optiques est réalisée grâce à un montage fibre-à-fibre créé spécialement nous permettant d’investiguer le temps de réponse d’un chauage plasmonique ainsi que la transmission de signal télécom. Des améliorations de performances du concept DLSPPW original sont proposées par l’ajout d’un mur métallique sur le côté du ruban de polymère. Ce système peut alors fonctionner comme un convertisseur de polarisation compacte et athermique / The Dielectric Loaded Surface Plasmon Polariton Waveguides (DLSPPWs) have recently emerged as a possible solution to carry both optical and electrical signals on- chip. However, in the particular context of optical interconnects, advanced functionalities such as filtering, switching, and routing are required in order to replace in the future the equivalent electronic components which are too much power consumer and also to reduce their footprints. After presenting the interest and limitation of the leakage radiation microscopy method used all along this work, we show several active devices using thermo-sensitive polymers as the dielectric load driven electrically by Joule heating. Then we demonstrate the feasibility of all-optical systems by either doping the dielectric with metallic nanoparticles or by plasmo-thermal eect of a second plasmonic mode providing a localized heating of controlled shape. The dynamic activation of our thermo- optical devices is performed using a homemade fiber-to-fiber setup which allows us to investigate the response time of a plasmo-thermal heating as well as true datacom transmission. Some improvements of the original DLSPPWs performances are proposed by adding a metallic wall on one side of the polymer ridge. This system can act as a compact and athermal polarization converter
75

[pt] MULTIPLEXAÇÃO ÓPTICA NO DOMÍNIO DO TEMPO EM SISTEMA STM-16, STM-64, STM-256 / [en] TIME-DOMAIN OPTICAL MULTIPLEXING IN STM-16, STM-64 AND STM-256 SYSTEMS

28 February 2002 (has links)
[pt] Este trabalho tem como foco o up-grade da taxa de bits em enlaces ópticos através da tecnologia OTDM. Os sistemas analisados contemplam os up-grades das taxas de 2,48 Gbps para 10 Gbps e também da taxa de 10 Gbps para 40 Gbps. Para tal, foram introduzidos módulos de transmissão e recepção, capazes de utilizar arquiteturas quase totalmente ópticas. É avaliado então, através de simulações, o comportamento da arquitetura proposta em infra-estruturas de enlaces já instalados no Brasil, destacando os pontos mais críticos. No que se refere ao up-grade de 10 Gbps para 40 Gbps, foi dado enfoque especial para as penalidades relativas à PMD (Polarization Mode Dispersion). / [en] This work aims at up grading the bit rate of optical links through the OTDM technology. The analyzed up-grades change the bit rate of 2,48 Gbps up to 10 Gbps and also from the bit rate of 10 Gbps up to 40 Gbps. To reach these objectives, transmission and reception modules were introduced, using all optical networks topologies. The performance of the proposed architecture was simulated using a infrastructure of links already installed in Brazil. The most critical issues were pointed out. Concerning the up-grade from 10 Gbps to 40 Gbps, a special focus was given to the penalties due to PMD (Polarization Mode Dispersion).
76

Μελέτη των RWA και IA-RWA μέσω γενετικών αλγορίθμων

Μονογιός, Δημήτρης 26 August 2009 (has links)
Η πρόσφατη τεχνολογική ανάπτυξη των οπτικών ενισχυτών, πολυπλεκτών/αποπλεκτών, οπτικών διακοπτών καθώς και άλλων οπτικών συσκευών μας οδηγεί στο να ελπίζουμε ότι σύντομα στο μέλλον θα υλοποιηθεί ένα πλήρες οπτικό (all optical), WDM (wavelength division multiplexing) δίκτυο που να ικανοποιεί και την ανάγκη για μεγάλα μεγέθη χωρητικότητας. Σε ένα τέτοιο δίκτυο η μετατροπή του οπτικού σήματος σε ηλεκτρονικό και εκ νέου στο οπτικό (ΟΕΟ) δεν θα χρησιμοποιείται στους ενδιάμεσους κόμβους, και αυτό συμβάλει σε οικονομικότερες υλοποιήσεις των οπτικών δικτύων. Σε ένα WDM δρομολογούμενο δίκτυο, τα δεδομένα μεταφέρονται μέσω ενός οπτικού καναλιού, lightpath, στους κόμβους του δικτύου που συνδέονται με οπτικές ίνες. Στις πλείστες των περιπτώσεων, κατά την άφιξη ενός lightpath σε κάποιο κόμβο, εφαρμόζεται σε αυτό οπτικό-ηλεκτρονική μετατροπή και αντίστροφα, ούτως ώστε το σήμα να αναδημιουργηθεί λόγω των απωλειών που υπέστη κατά την μεταφορά, ή ακόμη για να αναλυθεί από ενδιάμεσες ηλεκτρονικές συσκευές. Στα μη πλήρη οπτικά δίκτυα, η μεταφορά των δεδομένων γίνεται από κόμβο σε κόμβο κατά μήκος του δικτύου, ούτως ώστε το οπτικό σήμα να ενισχύεται και να αναγεννάτε μέσω της OEO επεξεργασίας. Παρ’ όλα αυτά, η κάθε ενδιάμεση ανάλυση του θέματος σε ένα τέτοιο δίκτυο προϋποθέτει πολύ μεγάλα κόστη λόγω των πολλών συσκευών που απαιτούνται για τη OEO επεξεργασία. Το γεγονός αυτό μας οδηγεί στα ημί-πλήρη δίκτυα όπου η ενίσχυση και αναγέννηση του θέματος δε γίνεται σε όλους τους ενδιάμεσους κόμβους αλλά σε μερικούς από αυτούς. Ο τελικός στόχος όμως είναι η απαλοιφή της ηλεκτρονικής μετατροπής και αυτό οδηγεί στην υλοποίηση των πλήρως οπτικών δικτύων. Στα πλήρη οπτικά δίκτυα, ένα σήμα που μεταδίδεται παραμένει, για όλο το lightpath, στο οπτικό επίπεδο. Έτσι, το πλήρες οπτικό δίκτυο μπορεί να απαλείψει την ασύμφορη OEO μετατροπή. Η αναζήτηση των κατάλληλων μονοπατιών με τα κατάλληλα μήκη κύματος που θα ικανοποιούσε ένα πλήρες οπτικό δίκτυο το οποίο δρομολογείται από ligthpaths, ονομάζεται Routing and Wavelength Assignment (RWA) και αποτελεί ένα από τα σημαντικότερα ζητήματα για το σωστό σχεδιασμό των οπτικών δικτύων τέτοιου είδους. Το πρόβλημα γίνεται ιδιαίτερα πολύπλοκο όταν στην τελική απόφαση θα πρέπει να συμπεριληφθούν και τα χαρακτηριστικά του φυσικού επιπέδου του δικτύου, όπως εξασθένιση του σήματος, μη γραμμικά φαινόμενα, διασπορά κ.ά, η συμβολή των οποίων στην τελική δρομολόγηση δεν θεωρείται αμελητέα (Impairment Aware Routing and Wavelength Assignment, ΙΑ-RWA). Σε αυτή την εργασία μελετάται το RWA πρόβλημα και προτείνεται ένας μονού στόχου γενετικός αλγόριθμος (Single Objective Genetic Algorithm - SOGA), ο οποίος επιλύει ικανοποιητικά το πρόβλημα θεωρώντας στατική κίνηση. Επιπλέον τονίζεται η σημασία των φυσικών παραμέτρων του προβλήματος και πως αυτές επηρεάζουν την απόδοση του πλήρους οπτικού δικτυου. Στη συνέχεια προτείνεται ένας νέος, πολλαπλών στόχων γενετικός αλγόριθμος (multi objective genetic algorithm – MOGA) ο οποίος βελτιστοποιεί τις λύσεις του προβλήματος ικανοποιητικά λαμβάνοντας ταυτόχρονα υπόψη, με έμμεσο τρόπο, και τις φυσικές παραμέτρους. Επίσης προτείνεται και ένας μονού στόχου γενετικός αλγόριθμος οποίος χρησιμοποιεί ένα εργαλείο αποτίμηση της ποιότητας μετάδοσης (Q-TOOL) σαν μέτρο κατά τη διαδικασία εύρεσης ικανοποιητικής λύσης. Το υπόλοιπο της εργασίας οργανώνεται ως ακολούθως: Στην ενότητα 2 παρουσιάζεται μια σύντομη αναφορά στα WDM δίκτυα καθώς και η περιγραφή του RWA και IA-RWA προβλήματος, ενώ στην ενότητα 3 παρουσιάζεται η πρόταση επίλυσης του RWA προβληματος με τη χρήση γενετικών αλγορίθμων. Ακολουθεί στην ενότητα 4 η πρότασή μας για επίλυση του IA-RWA προβλήματος με τη χρήση Multi-objective διαδικασιών βελτιστοποίησης, καθώς και η βελτιστοποίηση του προβλήματος με τη χρήση του Q-TOOL. Τέλος στην ενότητα 5 συνοψίζουμε την εργασία και παρουσιάζουμε τα συμπεράσματα. / The recent development of optical amplifiers, multiplexers / de-multiplexers, optical switches and other optical devices leads us to hope that soon in future all optical, WDM (wavelength division multiplexing) networks will be implemented which that will satisfy the needs for large capacity. In such networks a viable conversion of the optical -> Electronic and back to optical (OEO) will not be used at intermediate nodes, and this will contribute to efficient and economical implementation. The search for the appropriate paths with the appropriate wavelengths that meet the requirement in all optical networks is called Routing and Wavelength Assignment (RWA) and is one of the most important issues for proper design of such optical networks. The problem becomes particularly complex when the final decision should include the characteristics of the physical layer of the network, such as attenuation of the signal, nonlinear effects, dispersion, etc., whose contribution to the final result is not considered negligible (Impairment Aware Routing and Wavelength Assignment,IA-RWA). This work studies the RWA problem considering static traffic, and proposes a single-objective genetic algorithm (Single Objective Genetic Algorithm - SOGA), which resolves the problem satisfactorily. Furthermore the work stresses the importance of physical parameters of the problem and how these affect the performance of the all optical networks, and proposes a new, multi-objective genetic algorithm (MOGA) which optimizes the solution of IA-RWA problem adequately taking into account indirectly, and the physical impairments that affect the quality of the signal. In addition, a single objective genetic algorithm is proposed that uses a tool to assess the quality of the transmission signal (Q-TOOL), as a benchmark, in the process of optimization of the solution to the IA-RWA problem.
77

Mélange à quatre ondes multiple pour le traitement tout-optique du signal dans les fibres optiques non linéaires / Multiple four wave mixing for all-optical signal processing in nonlinear optical fibers

Baillot, Maxime 15 December 2017 (has links)
Le mélange à quatre ondes est un effet non linéaire sensible à la phase qui suscite de nombreux intérêts dans le domaine de la génération de peignes de fréquences et du traitement tout optique du signal par exemple. Un peigne de fréquences peut en effet s'obtenir par effet de mélange à quatre ondes 1en cascade. Dans ce cas, un nombre N d'ondes interagissent entre elles via l'effet Kerr et la modélisation d'un tel processus doit tenir compte de tous les couplages possibles entre les ondes. Au cours de mes travaux de thèse, je me suis intéressé, dans un premier temps, à la modélisation du mélange à quatre ondes dit multiple pour lequel un nombre quelconque N d'ondes interagissent entre elles. J'ai proposé une formulation générale permettant d'identifier simplement tous les termes de mélange à quatre ondes issus de toutes les combinaisons possibles de couplage entre les ondes et leur désaccord de phase associé. J'ai validé cette approche en proposant une étude théorique et expérimentale d'un processus de mélange à quatre ondes multiple dans une fibre optique non linéaire. Dans une deuxième partie, j'ai proposé, grâce au modèle élaboré précédemment, une étude théorique du phénomène de conversion de fréquence sensible à la phase, permettant la décomposition des composantes en quadrature d'un signal optique. Dans la littérature, cette expérience fut démontrée initialement avec quatre ondes pompes et dans plusieurs types de composants non linéaires. J'ai pu démontrer, au cours de mes travaux, que trois pompes étaient suffisantes pour réaliser l'expérience et j'ai déterminé des relations analytiques simples permettant de choisir les paramètres expérimentaux (notamment l'amplitude et la phase des pompes) rendant possible la décomposition des composantes en quadrature d'un signal. J'ai validé cette étude par la démonstration expérimentale d'un convertisseur de fréquence sensible à la phase avec uniquement trois pompes et j'ai étudié théoriquement les effets de la dispersion chromatique sur les performances du convertisseur de fréquence. Enfin, dans une dernière partie, j'ai caractérisé des fibres optiques microstructurées en verre de chalcogénure fabriquées dans le cadre d'une collaboration avec Perfos, l'Institut des Sciences Chimiques de Rennes et SelenOptics. Dans ce cadre, j'ai mis en place un banc de mesure de la dispersion chromatique et du coefficient non linéaire des fibres optiques basé sur le mélange à quatre ondes. / Four-wave mixing is a phase-sensitive nonlinear effect that arouses interest, particularly in the fields of frequency comb generation and all-optical signal processing. As an example, frequency combs can be produced thanks to a cascaded four-wave mixing process. In this case, N waves can interact with each other through the optical Kerr effect, and one has to take into account all the possible interactions to be able to adequately model the process. During my PhD thesis, I was interested in modeling the so-called multiple four-wave mixing process, in which any number N of waves can interact with each other. I proposed a general formulation that allows to easily identify all the four-wave mixing terms originating from all the possible combinations of wave coupling and their associated phase-mismatch terms. I validated this approach through the theoretical and experimental study of a multiple four-wave mixing process in a nonlinear optical fiber. Thanks to the developed model, I then proposed a theoretical study of the phase-sensitive frequency conversion process, which permits to demultiplex the quadrature components of an optical signal. In the literature, this process was first experimentally demonstrated in several nonlinear devices using four pump waves. I demonstrated that only three pump waves were required to successfully perform the experiment, and I determined the simple analytical relations from which the adequate experimental parameters (namely, the amplitudes and phases of the pump waves) could be deduced. I finally validated this study by experimentally demonstrating a phase-sensitive frequency conversion process with only three pump waves, and I theoretically studied the influence of chromatic dispersion on the performance of this frequency converter. Finally, I characterized some chalcogenide microstructured optical fibers that were fabricated in the framework of a collaboration with Perfos, the Institut des Sciences Chimiques de Rennes, and SelenOptics. I set up a test bench based on the four-wave mixing process in order to measure the chromatic dispersion and nonlinear coefficient of some optical fibers.
78

Theoretical and experimental study of optical solutions for analog-to-digital conversion of high bit-rate signals / Étude théorique et expérimentale de techniques optiques pour la conversion analogique-numérique de signaux de communication à très haut débit

Nguyen, Trung-Hiên 19 November 2015 (has links)
Les formats de modulation bidimensionnels (i.e. basés sur l’amplitude et la phase de l’onde porteuse) ont gagné depuis peu le domaine des transmissions par fibre optique grâce aux progrès conjoints de l’électronique rapide et du traitement du signal, indispensables pour réaliser les récepteurs opto-électroniques utilisant la détection cohérente des signaux optiques. Pour pallier les limites actuelles en rapidité de commutation des circuits intégrés électroniques, une voie de recherche a été ouverte il y a quelques années, consistant à utiliser des technologies optiques pour faciliter la parallélisation du traitement du signal, notamment dans l’étape d’échantillonnage ultra-rapide du signal rendu possible par des horloges optiques très performantes. Le thème principal de cette thèse concerne l’étude théorique et expérimentale de la fonction de conversion analogique-numérique (ADC) de signaux optiques par un récepteur opto-électronique cohérent, associant les étapes d’échantillonnage optique linéaire, de conversion analogique-numérique et de traitement du signal. Un prototype, utilisant une solution originale pour la source d’échantillonnage, est modélisé, réalisé et caractérisé, permettant la reconstruction temporelle de signaux optiques modulés selon divers formats : NRZ, QPSK, 16-QAM. Les limitations optiques et électroniques du système sont analysées, notamment l’impact sur la reconstruction des signaux de divers paramètres : le taux d’extinction de la source optique, les paramètres de l’ADC (bande passante BW, temps d’intégration et nombre effectif de bits ENOB). Par ailleurs, de nouveaux algorithmes de traitement du signal sont proposés dans le cadre de la transmission optique cohérente à haut débit utilisant des formats de modulation bidimensionnels (amplitude et phase) : deux solutions sont proposées pour la compensation du déséquilibre de quadrature IQ dans les transmissions mono-porteuses: une méthode originale de l’estimation du maximum du rapport signal sur bruit ainsi qu’une nouvelle structure de compensation et d’égalisation conjointes; ces deux méthodes sont validées expérimentalement et numériquement avec un signal 16-QAM. Par ailleurs, une solution améliorée de récupération de porteuse (décalage de fréquence et estimation de la phase), basée sur une décomposition harmonique circulaire de la fonction de maximum de vraisemblance logarithmique, est validée numériquement pour la première fois dans le contexte des transmissions optiques (jusqu’à une modulation de 128-QAM). Enfin les outils développés dans ce travail ont finalement permis la démonstration d’une transmission sur 100 km d’un signal QPSK à 10 Gbaud fortement limité par un bruit de phase non linéaire et régénéré optiquement à l’aide d’un limiteur de puissance préservant la phase basé sur une nanocavité de cristal photonique. / Bi-dimensional modulation formats based on amplitude and phase signal modulation, are now commonly used in optical communications thanks to breakthroughs in the field of electronic and digital signal processing (DSP) required in coherent optical receivers. Photonic solutions could compensate for nowadays limitations of electrical circuits bandwidth by facilitating the signal processing parallelization. Photonic is particularly interesting for signal sampling thanks to available stable optical clocks. The heart of the present work concerns analog-to-digital conversion (ADC) as a key element in coherent detection. A prototype of linear optical sampling using an original solution for the optical sampling source, is built and validated with the successful equivalent time reconstruction of NRZ, QPSK and 16-QAM signals. Some optical and electrical limitations of the system are experimentally and numerically analyzed, notably the extinction ratio of the optical source or the ADC parameters (bandwidth, integration time, effective number of bits ENOB). Moreover, some new DSPs tools are developed for optical transmission using bi-dimensional modulation formats (amplitude and phase). Two solutions are proposed for IQ quadrature imbalance compensation in single carrier optical coherent transmission: an original method of maximum signal-to-noise ratio estimation (MSEM) and a new structure for joint compensation and equalization; these methods are experimentally and numerically validated with 16-QAM signals. Moreover, an improved solution for carrier recovery (frequency offset and phase estimation) based on a circular harmonic expansion of a maximum loglikelihood function is studied for the first time in the context of optical telecommunications. This solution which can operate with any kind of bi-dimensional modulation format signal is numerically validated up to 128-QAM. All the DSP tools developed in this work are finally used in a demonstration of a 10 Gbaud QPSK 100 km transmission experiment, featuring a strong non-linear phase noise limitation and regenerated using a phase preserving and power limiting function based on a photonic crystal nanocavity.
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Impairment-aware design and performance evaluation of all-optical wavelength convertible networks / Conception et évaluation des performances des réseaux à conversion de longueur d'onde tout-optique gérant les dégradations du signal

Chouman, Hussein 22 March 2019 (has links)
La croissance continue du trafic Internet implique une augmentation de la consommation d'énergie en raison des nombreuses conversions optique à électronique(OEO) requises par les routeurs et les commutateurs. L'utilisation de réseaux transparents pourraient freiner cette croissance incontrôlée, mais le maintien des données dans le domaine optique a deux conséquences néfastes: une accumulation du bruit et des non-linéarités de l'amplification qui dégrade fortement les performances au niveau de la couche physique. et la contrainte de continuité de longueur d'onde (WCC) reflétant la conservation de la longueur d'onde du signal optique dans les réseaux optiques multiplexés en longueur d'onde (WDM) qui dégradent les performances du réseau, notamment sa probabilité de blocage. Les convertisseurs de longueur d'onde (WC) peuvent pallier la contrainte WCC, mais les seuls dispositifs suffisamment matures disponibles dans le commerce sont les WC basés sur OEO (OEO-WC). Cependant, leur coût augmente avec les débits binaires. D'autre part, des convertisseurs de longueur d'onde tout optique (AO-WC) ont été démontrés dans des laboratoires de recherche, avec toutefois une plage de conversion limitée et une dégradation du signal converti.Dans cette thèse, nous concevons la couche de transmission en utilisant deux ensembles de formats de modulation différents avec des plages de débits différentes; et par conséquent différents modèles d'estimation de performance. Au niveau du réseau, nos analyses montrent que la contribution des WC dépend des demandes de trafic servant à l’ordre dans un scénario de planification du réseau; qu'en utilisant des algorithmes fixed-alternate-routing (FAR) ou least-loaded-routing (LLR) et un algorithme d'affectation de longueur d'onde first-fit (FF), les AO-WCs offrent les mêmes améliorations de performances que les OEO-WC. De plus, nous identifions une plage de conversion et une cascadabilité optimale d’AO-WC qui montre que le LLR nécessite un nombre de conversions par canal inférieur au FAR. / The continuous growth of Internet traffic implies an increased power consumption due to the many optical-to-electronic (OEO) conversions required by routers and switches. Transparent networks could curb this uncontrolled growth, but keeping the data in the optical domain has two adverse consequences: physical layer impairments accumulation which strongly degrades the performance due to amplication noise and non-linearities; and the wavelength continuity constraint (WCC) to keep the opticalsignal's wavelength unchanged in wavelength-division-multiplexed (WDM) optical networks which degrades network blocking performance. Wavelength converters (WCs) can alleviate the WCC constraint, but the only commercially available devices are the OEO-based WCs (OEO-WCs), however, their cost increases with bit-rates. On the other hand, all-optical wavelength converters (AO-WCs) have been demonstrated in research laboratories albeit with a limited conversion range and a performance that degrades converted signal's quality.In this thesis, we design the transmission layer using two different modulation formats sets with different bit-rates ranges; and consequently different performance estimation models. At the network level, our analyses show that WCs' contribution depends on traffic demands serving ordering in the online traffic assumption; that using xed-alternate routing (FAR) or least-loaded routing (LLR) algorithms and first-fit (FF) wavelength assignment algorithm, AO-WCs give the same performance enhancement as OEO-WCs. Moreover, we identify an optimum AO-WC conversion range and cascadability which shows that LLR requires lower number of conversions per channel compared to FAR.
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Toward a new generation of photonic devices based on the integration of metal oxides in silicon technology

Parra Gómez, Jorge 22 December 2022 (has links)
[ES] La búsqueda de nuevas soluciones e ideas innovadoras en el campo de la fotónica de silicio mediante la integración de nuevos materiales con prestaciones únicas es un tema de alta actualidad entre la comunidad científica en fotónica y con un impacto potencial muy alto. Dentro de esta temática, esta tesis pretende contribuir hacia una nueva generación de dispositivos fotónicos basados en la integración de óxidos metálicos en tecnología de silicio. Los óxidos metálicos elegidos pertenecen a la familia de óxidos conductores transparentes (TCO), concretamente el óxido de indio y estaño (ITO) y el óxido de cadmio (CdO), y materiales de cambio de fase (PCM) como el dióxido de vanadio (VO2). Dichos materiales se caracterizan especialmente por una variación drástica de sus propiedades optoelectrónicas, tales como la resistividad o el índice de refracción, frente a un estímulo externo ya sea en forma de temperatura, aplicación de un campo eléctrico o excitación óptica. De esta forma, nuestro objetivo es diseñar, fabricar y demostrar experimentalmente nuevas soluciones y dispositivos clave tales como dispositivos no volátiles, desfasadores y dispositivos con no linealidad óptica. Tales dispositivos podrían encontrar potencial utilidad en diversas aplicaciones que comprenden las comunicaciones ópticas, redes neuronales, LiDAR, computación, cuántica, entre otros. Las prestaciones clave en las que se pretende dar un salto disruptivo son el tamaño y capacidad para una alta densidad de integración, el consumo de potencia, y el ancho de banda. / [CA] La recerca de noves solucions i idees innovadores al camp de la fotònica de silici mitjançant la integració de nous materials amb prestacions úniques és un tema d'alta actualitat entre la comunitat científica en fotònica i amb un impacte potencial molt alt. D'aquesta temàtica, aquesta tesi pretén contribuir cap a una nova generació de dispositius fotònics basats en la integració d'òxids metàl·lics en tecnologia de silici. Els òxids metàl·lics elegits pertanyen a la família d'òxids conductors transparents (TCO), concretament l'òxid d'indi i estany (ITO) i l'òxid de cadmi (CdO), i materials de canvi de fase (PCM) com el diòxid de vanadi (VO2). Aquests materials es caracteritzen especialment per una variació dràstica de les propietats optoelectròniques, com ara la resistivitat o l'índex de refracció, davant d'un estímul extern ja siga en forma de temperatura, aplicació d'un camp elèctric o excitació òptica. D'aquesta manera, el nostre objectiu és dissenyar, fabricar i demostrar experimentalment noves solucions i dispositius clau com ara dispositius no volàtils, desfasadors i dispositius amb no-linealitat òptica. Aquests dispositius podrien trobar potencial utilitat en diverses aplicacions que comprenen les comunicacions òptiques, xarxes neuronals, LiDAR, computació, quàntica, entre d'altres. Les prestacions clau en què es pretén fer un salt disruptiu són la grandària i la capacitat per a una alta densitat d'integració, el consum de potència i l'amplada de banda. / [EN] The search for new solutions and innovative ideas in the field of silicon photonics through the integration of new materials featuring unique optoelectronic properties is a hot topic among the photonics scientific community with a very high potential impact. Within this topic, this thesis aims to contribute to a new generation of photonic devices based on the integration of metal oxides in silicon technology. The chosen metal oxides belong to the family of transparent conducting oxides (TCOs), namely indium tin oxide (ITO) and cadmium oxide (CdO), and phase change materials (PCMs) such as vanadium dioxide (VO2). These materials are characterized by a drastic variation of their optoelectronic properties, such as resistivity or refractive index, in response to an external stimulus either in the form of temperature, application of an electric field, or optical excitation. Therefore, our objective is to design, fabricate and experimentally demonstrate new solutions and key devices such as non-volatile devices, phase shifters, and devices with optical nonlinearity. Such devices could find potential utility in several applications, including optical communications, neural networks, LiDAR, computing, and quantum. The key features in which we aim to take a leapfrog are footprint and capacity for high integration density, power consumption, and bandwidth. / This work is supported in part by grants ACIF/2018/172 funded by Generaliltat Valenciana, and FPU17/04224 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”. / Parra Gómez, J. (2022). Toward a new generation of photonic devices based on the integration of metal oxides in silicon technology [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/190883

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