24 research outputs found

    Design, monitoring and performance evaluation of high capacity optical networks

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    Premi Extraordinari de Doctorat, promoció 2018-2019. Àmbit de les TICInternet traffic is expected to keep increasing exponentially due to the emergence of a vast number of innovative online services and applications. Optical networks, which are the cornerstone of the underlying Internet infrastructure, have been continuously evolving to carry the ever-increasing traffic in a more flexible, cost-effective, and intelligent way. Having these three targets in mind, this PhD thesis focuses on two general areas for the performance improvement and the evolution of optical networks: i) introducing further cognition to the optical layer, and ii) introducing new networking solutions revolutionizing the optical transport infrastructure. In the first part, we present novel failure detection and identification solutions in the optical layer utilizing the optical spectrum traces captured by cost-effective coarse-granular Optical Spectrum Analyzers (OSA). We demonstrate the effectiveness of the developed solutions for detecting and identifying filter-related failures in the context of Spectrum-Switched Optical Networks (SSON), as well as transmitter-related laser failures in Filter-less Optical Networks (FON). In addition, at the subsystem level we propose an Autonomic Transmission Agent (ATA), which triggers local or remote transceiver reconfiguration by predicting Bit-Error-Rate (BER) degradation by monitoring State-of-Polarization (SOP) data obtained by coherent receivers. I have developed solutions to push further the performance of the currently deployed optical networks through reducing the margins and introducing intelligence to better manage their resources. However, it is expected that the spectral efficiency of the current standard Single-Mode Fiber (SMF) based optical network approaches the Shannon capacity limits in the near future, and therefore, a new paradigm is required to keep with the pace of the current huge traffic increase. In this regard, Space Division Multiplexing (SDM) is proposed as the ultimate solution to address the looming capacity crunch with a reduced cost-per-bit delivered to the end-users. I devote the second part of this thesis to investigate different flavors of SDM based optical networks with the aim of finding the best compromise for the realization of a spectrally and spatially flexible optical network. SDM-based optical networks can be deployed over various types of transmission media. Additionally, due to the extra dimension (i.e., space) introduced in SDM networks, optical switching nodes can support wavelength granularity, space granularity, or a combination of both. In this thesis, we evaluate the impact of various spectral and spatial switching granularities on the performance of SDM-based optical networks serving different profiles of traffic with the aim of understanding the impact of switching constraints on the overall network performance. In this regard, we consider two different generations of wavelength selective switches (WSS) to reflect the technology limitations on the performance of SDM networks. In addition, we present different designs of colorless direction-less, and Colorless Directionless Contention-less (CDC) Reconfigurable Optical Add/Drop Multiplexers (ROADM) realizing SDM switching schemes and compare their performance in terms of complexity and implementation cost. Furthermore, with the aim of revealing the benefits and drawbacks of SDM networks over different types of transmission media, we preset a QoT-aware network planning toolbox and perform comparative performance analysis among SDM network based on various types of transmission media. We also analyze the power consumption of Multiple-Input Multiple-Output (MIMO) Digital Signal Processing (DSP) units of transceivers operating over three different types of transmission media. The results obtained in the second part of the thesis provide a comprehensive outlook to different realizations of SDM-based optical networks and showcases the benefits and drawbacks of different SDM realizations.Se espera que el tráfico de Internet siga aumentando exponencialmente debido a la continua aparición de gran cantidad de aplicaciones innovadoras. Las redes ópticas, que son la piedra angular de la infraestructura de Internet, han evolucionado continuamente para transportar el tráfico cada vez mayor de una manera más flexible, rentable e inteligente. Teniendo en cuenta estos tres objetivos, esta tesis doctoral se centra en dos áreas cruciales para la mejora del rendimiento y la evolución de las redes ópticas: i) introducción de funcionalidades cognitivas en la capa óptica, y ii) introducción de nuevas estructuras de red que revolucionarán el transporte óptico. En la primera parte, se presentan soluciones novedosas de detección e identificación de fallos en la capa óptica que utilizan trazas de espectro óptico obtenidas mediante analizadores de espectros ópticos (OSA) de baja resolución (y por tanto de coste reducido). Se demuestra la efectividad de las soluciones desarrolladas para detectar e identificar fallos derivados del filtrado imperfecto en las redes ópticas de conmutación de espectro (SSON), así como fallos relacionados con el láser transmisor en redes ópticas sin filtro (FON). Además, a nivel de subsistema, se propone un Agente de Transmisión Autónomo (ATA), que activa la reconfiguración del transceptor local o remoto al predecir la degradación de la Tasa de Error por Bits (BER), monitorizando el Estado de Polarización (SOP) de la señal recibida en un receptor coherente. Se han desarrollado soluciones para incrementar el rendimiento de las redes ópticas mediante la reducción de los márgenes y la introducción de inteligencia en la administración de los recursos de la red. Sin embargo, se espera que la eficiencia espectral de las redes ópticas basadas en fibras monomodo (SMF) se acerque al límite de capacidad de Shannon en un futuro próximo, y por tanto, se requiere un nuevo paradigma que permita mantener el crecimiento necesario para soportar el futuro aumento del tráfico. En este sentido, se propone el Multiplexado por División Espacial (SDM) como la solución que permita la continua reducción del coste por bit transmitido ante ése esperado crecimiento del tráfico. En la segunda parte de esta tesis se investigan diferentes tipos de redes ópticas basadas en SDM con el objetivo de encontrar soluciones para la realización de redes ópticas espectral y espacialmente flexibles. Las redes ópticas basadas en SDM se pueden implementar utilizando diversos tipos de medios de transmisión. Además, debido a la dimensión adicional (el espacio) introducida en las redes SDM, los nodos de conmutación óptica pueden conmutar longitudes de onda, fibras o una combinación de ambas. Se evalúa el impacto de la conmutación espectral y espacial en el rendimiento de las redes SDM bajo diferentes perfiles de tráfico ofrecido, con el objetivo de comprender el impacto de las restricciones de conmutación en el rendimiento de la red. En este sentido, se consideran dos generaciones diferentes de conmutadores selectivos de longitud de onda (WSS) para reflejar las limitaciones de la tecnología en el rendimiento de las redes SDM. Además, se presentan diferentes diseños de ROADM, independientes de la longitud de onda, de la dirección, y sin contención (CDC) utilizados para la conmutación SDM, y se compara su rendimiento en términos de complejidad y coste. Además, con el objetivo de cuantificar los beneficios e inconvenientes de las redes SDM, se ha generado una herramienta de planificación de red que prevé la QoT usando diferentes tipos de fibras. También se analiza el consumo de energía de las unidades DSP de los transceptores MIMO operando en redes SDM con tres tipos diferentes de medios de transmisión. Los resultados obtenidos en esta segunda parte de la tesis proporcionan una perspectiva integral de las redes SDM y muestran los beneficios e inconvenientes de sus diferentes implementacionesAward-winningPostprint (published version

    Design, monitoring and performance evaluation of high capacity optical networks

    Get PDF
    Internet traffic is expected to keep increasing exponentially due to the emergence of a vast number of innovative online services and applications. Optical networks, which are the cornerstone of the underlying Internet infrastructure, have been continuously evolving to carry the ever-increasing traffic in a more flexible, cost-effective, and intelligent way. Having these three targets in mind, this PhD thesis focuses on two general areas for the performance improvement and the evolution of optical networks: i) introducing further cognition to the optical layer, and ii) introducing new networking solutions revolutionizing the optical transport infrastructure. In the first part, we present novel failure detection and identification solutions in the optical layer utilizing the optical spectrum traces captured by cost-effective coarse-granular Optical Spectrum Analyzers (OSA). We demonstrate the effectiveness of the developed solutions for detecting and identifying filter-related failures in the context of Spectrum-Switched Optical Networks (SSON), as well as transmitter-related laser failures in Filter-less Optical Networks (FON). In addition, at the subsystem level we propose an Autonomic Transmission Agent (ATA), which triggers local or remote transceiver reconfiguration by predicting Bit-Error-Rate (BER) degradation by monitoring State-of-Polarization (SOP) data obtained by coherent receivers. I have developed solutions to push further the performance of the currently deployed optical networks through reducing the margins and introducing intelligence to better manage their resources. However, it is expected that the spectral efficiency of the current standard Single-Mode Fiber (SMF) based optical network approaches the Shannon capacity limits in the near future, and therefore, a new paradigm is required to keep with the pace of the current huge traffic increase. In this regard, Space Division Multiplexing (SDM) is proposed as the ultimate solution to address the looming capacity crunch with a reduced cost-per-bit delivered to the end-users. I devote the second part of this thesis to investigate different flavors of SDM based optical networks with the aim of finding the best compromise for the realization of a spectrally and spatially flexible optical network. SDM-based optical networks can be deployed over various types of transmission media. Additionally, due to the extra dimension (i.e., space) introduced in SDM networks, optical switching nodes can support wavelength granularity, space granularity, or a combination of both. In this thesis, we evaluate the impact of various spectral and spatial switching granularities on the performance of SDM-based optical networks serving different profiles of traffic with the aim of understanding the impact of switching constraints on the overall network performance. In this regard, we consider two different generations of wavelength selective switches (WSS) to reflect the technology limitations on the performance of SDM networks. In addition, we present different designs of colorless direction-less, and Colorless Directionless Contention-less (CDC) Reconfigurable Optical Add/Drop Multiplexers (ROADM) realizing SDM switching schemes and compare their performance in terms of complexity and implementation cost. Furthermore, with the aim of revealing the benefits and drawbacks of SDM networks over different types of transmission media, we preset a QoT-aware network planning toolbox and perform comparative performance analysis among SDM network based on various types of transmission media. We also analyze the power consumption of Multiple-Input Multiple-Output (MIMO) Digital Signal Processing (DSP) units of transceivers operating over three different types of transmission media. The results obtained in the second part of the thesis provide a comprehensive outlook to different realizations of SDM-based optical networks and showcases the benefits and drawbacks of different SDM realizations.Se espera que el tráfico de Internet siga aumentando exponencialmente debido a la continua aparición de gran cantidad de aplicaciones innovadoras. Las redes ópticas, que son la piedra angular de la infraestructura de Internet, han evolucionado continuamente para transportar el tráfico cada vez mayor de una manera más flexible, rentable e inteligente. Teniendo en cuenta estos tres objetivos, esta tesis doctoral se centra en dos áreas cruciales para la mejora del rendimiento y la evolución de las redes ópticas: i) introducción de funcionalidades cognitivas en la capa óptica, y ii) introducción de nuevas estructuras de red que revolucionarán el transporte óptico. En la primera parte, se presentan soluciones novedosas de detección e identificación de fallos en la capa óptica que utilizan trazas de espectro óptico obtenidas mediante analizadores de espectros ópticos (OSA) de baja resolución (y por tanto de coste reducido). Se demuestra la efectividad de las soluciones desarrolladas para detectar e identificar fallos derivados del filtrado imperfecto en las redes ópticas de conmutación de espectro (SSON), así como fallos relacionados con el láser transmisor en redes ópticas sin filtro (FON). Además, a nivel de subsistema, se propone un Agente de Transmisión Autónomo (ATA), que activa la reconfiguración del transceptor local o remoto al predecir la degradación de la Tasa de Error por Bits (BER), monitorizando el Estado de Polarización (SOP) de la señal recibida en un receptor coherente. Se han desarrollado soluciones para incrementar el rendimiento de las redes ópticas mediante la reducción de los márgenes y la introducción de inteligencia en la administración de los recursos de la red. Sin embargo, se espera que la eficiencia espectral de las redes ópticas basadas en fibras monomodo (SMF) se acerque al límite de capacidad de Shannon en un futuro próximo, y por tanto, se requiere un nuevo paradigma que permita mantener el crecimiento necesario para soportar el futuro aumento del tráfico. En este sentido, se propone el Multiplexado por División Espacial (SDM) como la solución que permita la continua reducción del coste por bit transmitido ante ése esperado crecimiento del tráfico. En la segunda parte de esta tesis se investigan diferentes tipos de redes ópticas basadas en SDM con el objetivo de encontrar soluciones para la realización de redes ópticas espectral y espacialmente flexibles. Las redes ópticas basadas en SDM se pueden implementar utilizando diversos tipos de medios de transmisión. Además, debido a la dimensión adicional (el espacio) introducida en las redes SDM, los nodos de conmutación óptica pueden conmutar longitudes de onda, fibras o una combinación de ambas. Se evalúa el impacto de la conmutación espectral y espacial en el rendimiento de las redes SDM bajo diferentes perfiles de tráfico ofrecido, con el objetivo de comprender el impacto de las restricciones de conmutación en el rendimiento de la red. En este sentido, se consideran dos generaciones diferentes de conmutadores selectivos de longitud de onda (WSS) para reflejar las limitaciones de la tecnología en el rendimiento de las redes SDM. Además, se presentan diferentes diseños de ROADM, independientes de la longitud de onda, de la dirección, y sin contención (CDC) utilizados para la conmutación SDM, y se compara su rendimiento en términos de complejidad y coste. Además, con el objetivo de cuantificar los beneficios e inconvenientes de las redes SDM, se ha generado una herramienta de planificación de red que prevé la QoT usando diferentes tipos de fibras. También se analiza el consumo de energía de las unidades DSP de los transceptores MIMO operando en redes SDM con tres tipos diferentes de medios de transmisión. Los resultados obtenidos en esta segunda parte de la tesis proporcionan una perspectiva integral de las redes SDM y muestran los beneficios e inconvenientes de sus diferentes implementacione

    Quantum Dash Multi-Wavelength Lasers for Next Generation High Capacity Multi-Gb/s Millimeter-Wave Radio-over-Fiber Wireless Communication Networks

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    The ever-increasing proliferation of mobile users and new technologies with different applications and features, and the demand for reliable high-speed high capacity, pervasive connectivity and low latency have initiated a roadmap for the next generation wireless networks, fifth generation (5G), which is set to revolutionize the existing wireless communications. 5G will use heterogeneous higher carrier frequencies from the plentifully available spectra in the higher microwave and millimeter-wave (MMW) bands, including licensed and unlicensed spectra, for achieving multi-Gb/s wireless connectivity and overcoming the existing wireless spectrum crunch in the sub-6 GHz bands, resulting from the tremendous growth of data-intensive technologies and applications. The use of MMW when complemented by multiple-input-multiple-output (MIMO) technology can significantly increase data capacity through spatial multiplexing, and improve coverage and system reliability through spatial diversity. However, high-frequency MMW signals are prone to extreme propagation path loss and are challenging to generate and process with conventional bandwidth-limiting electronics. In addition, the existing digitized fronthaul for centralized radio access network (C-RAN) architecture is considered inefficient for 5G and beyond. Thus, to fully exploit the promising MMW 5G new radio (NR) resource and to alleviate the electronics and fronthaul bottleneck, microwave photonics with analog radio-over-fiber (A-RoF) technology becomes instrumental for optically synthesizing and processing broadband RF MMW wireless signals over optical links. The generation and distribution of high-frequency MMW signals in the optical domain over A-RoF links facilitate the seamless integration of high-capacity, reliable and transparent optical networks with flexible, mobile and pervasive wireless networks, extending the reach and coverage of high-speed broadband MMW wireless communications. Consequently, this fiber-wireless integration not only overcomes the problem of high bandwidth requirements, transmission capacity and span limitation but also significantly reduces system complexity considering the deployment of ultra-dense small cells with large numbers of 5G remote radio units (RRUs) having massive MIMO antennas with beamforming capabilities connected to the baseband units (BBU) in a C-RAN environment through an optical fiber-based fronthaul network. Nevertheless, photonic generation of spectrally pure RF MMW signals either involves complex circuitry or suffers from frequency fluctuation and phase noise due to uncorrelated optical sources, which can degrade system performance. Thus simple highly integrated and cost-efficient low-noise optical sources are required for next-generation MMW RoF wireless transmission systems. More recently, well-designed quantum confined nanostructures such as semiconductor quantum dash/dot multi-wavelength lasers (QD-MWLs) have attracted more interest in the photonic generation of RF MMW signals due to their simple compact and integrated design with highly coherent and correlated optical signals having a very low phase and intensity noise attributed to the inherent properties of QD materials. The main theme of this thesis revolves around the experimental investigation of such nanostructures on the device and system level for applications in high-speed high-capacity broadband MMW RoF-based fronthaul and wireless access networks. Several photonic-aided high-capacity long-reach MMW RoF wireless transmission systems are proposed and experimentally demonstrated based on QD-MWLs with the remote distribution and photonic generation of broadband multi-Gb/s MMW wireless signals at 5G NR (FR2) in the K-band, Ka-band and V-band in simplex, full-duplex and MIMO configurations over 10 to 50 km optical fiber and subsequent wireless transmission and detection. The QD-MWLs-based photonic MMW RoF wireless transmission systems’ designs and experimental demonstrations could usher in a new era of ultra-high-speed broadband multi-Gb/s wireless communications at the MMW frequency bands for next-generation wireless networks. The QD-MWLs investigated in this thesis include a simple monolithically integrated and highly coherent low-noise single-section semiconductor InAs/InP QD buried heterostructure passively mode-locked (PML) laser-based optical coherent frequency comb (CFC) and a novel monolithic highly correlated low-noise semiconductor InAs/InP buried heterostructure common-cavity QD dual-wavelength distributed feedback laser (QD-DW-DFBL). The performance of each device is thoroughly characterized experimentally in terms of optical phase noise, relative intensity noise (RIN), timing jitter and RF phase noise exhibiting promising results. Based on these devices, different long-reach photonic MMW RoF wireless transmission systems, including simplex single-input-single-output (SISO) and multiple-input-multiple-output (MIMO) and bidirectional configurations, are proposed and experimentally demonstrated with real-time remote electrical RF synthesizer-free all-optical frequency up-conversion, wireless transmission and successful reception of wide-bandwidth multi-level quadrature amplitude modulated (M-QAM) RF MMW wireless signals having bit rates ranging from 4 Gb/s to 36 Gb/s over different hybrid fiber-wireless links comprising of standard single mode fiber (SSMF) and indoor wireless channel. The end-to-end links are thoroughly investigated in terms of error-vector-magnitude (EVM), bit-error-rat (BER), constellations and eye diagrams, realizing successful error-free transmission. Finally, novel high-capacity spectrally efficient MIMO and optical beamforming enabled photonic MMW RoF wireless transceivers design and methods based on QD-MWLs with wavelength division multiplexing (WDM) and space division multiplexing (SDM) are proposed and discussed. A proof-of-concept implementation of the proposed photonic MMW RoF wireless transmission system is also simulated in a simple WDM-based configuration with bidirectional 4×4 MIMO MMW carrier streams

    Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications

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    The rapid proliferation of the Internet has been driving communication networks closer and closer to their limits, while available bandwidth is disappearing due to an ever-increasing network load. Over the past decade, optical fiber communication technology has increased per fiber data rate from 10 Tb/s to exceeding 10 Pb/s. The major explosion came after the maturity of coherent detection and advanced digital signal processing (DSP). DSP has played a critical role in accommodating channel impairments mitigation, enabling advanced modulation formats for spectral efficiency transmission and realizing flexible bandwidth. This book aims to explore novel, advanced DSP techniques to enable multi-Tb/s/channel optical transmission to address pressing bandwidth and power-efficiency demands. It provides state-of-the-art advances and future perspectives of DSP as well

    Microwave Photonic Applications - From Chip Level to System Level

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    Die Vermischung von Mikrowellen- und optischen Technologien – Mikrowellenphotonik – ist ein neu aufkommendes Feld mit hohem Potential. Durch die Nutzung der Vorzüge beider Welten hat die Mikrowellenphotonik viele Anwendungsfälle und ist gerade erst am Beginn ihrer Erfolgsgeschichte. Der Weg für neue Konzepte, neue Komponenten und neue Anwendungen wird dadurch geebnet, dass ein höherer Grad an Integration sowie neue Technologien wie Silicon Photonics verfügbar sind. In diesem Werk werden zuerst die notwendigen grundlegenden Basiskomponenten – optische Quelle, elektro-optische Wandlung, Übertragungsmedium und opto-elektrische Wandlung – eingeführt. Mithilfe spezifischer Anwendungsbeispiele, die von Chipebene bis hin zur Systemebene reichen, wird der elektrooptische Codesign-Prozess veranschaulicht. Schließlich werden zukünftige Ausrichtungen wie die Unterstützung von elektrischen Trägern im Millimeterwellen- und THz-Bereich sowie Realisierungsoptionen in integrierter Optik und Nanophotonik diskutiert.The hybridization between microwave and optical technologies – microwave photonics – is an emerging field with high potential. Benefitting from the best of both worlds, microwave photonics has many use cases and is just at the beginning of its success story. The availability of a higher degree of integration and new technologies such as silicon photonics paves the way for new concepts, new components and new applications. In this work, first, the necessary basic building blocks – optical source, electro-optical conversion, transmission medium and opto-electrical conversion – are introduced. With the help of specific application examples ranging from chip level to system level, the electro-optical co-design process for microwave photonic systems is illustrated. Finally, future directions such as the support of electrical carriers in the millimeter wave and THz range and realization options in integrated optics and nanophotonics are discussed

    Otimização de soluções de fotónica integrada para sistemas óticos de nova geração

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    Next generation optical systems can highly benefit from optimized photonic integrated solutions. Photonic integrated circuits (PIC) appear as a promising technology under the current demand for flexibility/reconfigurability in optical systems and telecommunications networks. PIC-based optical systems offer an efficient and cost-effective solution to data transmission increasing claims. In order to contribute to the development of integrated photonic technology, optimized PIC solutions addressing different steps of the PIC development chain, mainly design, testing, and packaging processes, are investigated. Optical signal data compression techniques are progressing to sustain the fast processing/storing of large amounts of bandwidth demanding data, with the advantage of resorting to photonic integrated solutions for the implementation of optical transforms, e.g., Haar transform (HT). This demand motivated the research of an optimized PIC design solution in silicon nitride (Si3N4) based platform comprising a two-level HT network for compression, and a switching network as a framework that supplies all logical inputs of the HT network for testing/characterization purposes. Optimized design models for the multimode interference key building block structure of the PIC design solution, are proposed. Additionally, a first test and characterization of PIC solutions implementing the HT for compression applications in indium phosphide (InP) based platform and in a new organic-inorganic hybrid material were realized. Taking advantage of a tunable lattice filter dispersion compensator in Si3N4-based integrated platform, it was demonstrated a real-time extended reach PAM-4 transmission over 40 km enabled by the photonic integrated dispersion compensator, with application in data center interconnects. Under photonic integrated high-Q resonators need for accurate performance measurement, a technique based on RF calibrated Mach-Zehnder interferometer, and Brillouin gain measurements through Lorentzian fitting analysis were successfully attained. Finally, as technical and functional requirements of PIC demand a thorough characterization/testing to provide an accurate prediction of its performance, and current testing platforms can be expensive and have low flexibility, a proof of concept of a new soft-packaging flexible platform for photonic integrated processors and spatial division multiplexing systems, based in spatial light modulation operation principle is proposed.Os sistemas óticos de nova geração beneficiam com a otimização de fotónica integrada. Com os circuitos de fotónica integrada (PIC) avançados a surgir como uma tecnologia promissora, dentro da crescente procura por flexibilidade/ reconfigurabilidade dos sistemas óticos e redes de telecomunicações. Os sistemas óticos baseados em PIC oferecem soluções eficientes e rentáveis em resposta às necessidades crescentes de transmissão de dados. De modo a contribuir para o desenvolvimento tecnológico associado à fotónica integrada, são investigados no âmbito desta dissertação diferentes soluções otimizadas de PIC, abordando diferentes estágios do seu desenvolvimento, nomeadamente projeto/design, teste e encapsulamento. Técnicas de compressão de sinais óticos estão a progredir no sentido de apoiar a expansão de velocidade de processamento e quantidade de armazenamento com elevada largura de banda associada. São esperadas vantagens recorrendo a PIC para a implementação de transformadas óticas, e.g., transformada de Haar (HT). Esta necessidade motivou a investigação de soluções de PIC com design otimizado, desenvolvidas em plataforma integrada de nitreto de silício (Si3N4). O PIC desenhado é constituído por uma rede 2D a executar a HT para fins de compressão e uma rede de comutação para produzir todas as entradas lógicas esperadas para teste e caracterização. São propostos modelos de design otimizados para a estrutura elementar que compõe o PIC, i.e., componente de interferência multimodal. Adicionalmente, foi realizado o primeiro teste e caracterização experimental de um PIC implementando a HT para fins de compressão, numa plataforma integrada de fosfato de índio (InP) e num material orgânico-inorgânico híbrido. Tirando partido de um filtro sintonizável para compensação de dispersão, desenvolvido em plataforma integrada de Si3N4, foi demostrado um link de transmissão alargada (40 km) em modulação PAM-4, com possível aplicação em centros de processamento de dados de interconexão. A necessidade de medições precisas de desempenho para a caracterização efetiva de soluções integradas de ressoadores de elevado fator de qualidade, motivou a implementação de uma técnica de medição eficaz. Esta é baseada num interferómetro de Mach-Zehnder calibrado em rádio frequência e na realização de mediações de ganho de Brillouin por análise Lorentziana de ajuste de curva. Por fim, tendo em conta os rigorosos requisitos técnicos e funcionais associados ao teste/caracterização precisa de PIC e o facto de as atuais soluções serem dispendiosas e pouco flexíveis. Uma prova de conceito de uma nova plataforma flexível de encapsulamento por software é proposta com aplicação em processadores PIC e sistemas com multiplexagem por divisão espacial.Programa Doutoral em Telecomunicaçõe

    Optimization, Design, and Analysis of Flexible-Grid Optical Networks with Physical-Layer Constraints

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    The theme of this thesis is the optimization, design, and analysis of flexible-grid optical networks that are constrained by physical-layer impairments (PLIs). We consider three flexible-grid network scenarios. The networks in the first class are static nonlinear transparent backbone networks where physical-layer resources are allocated to each traffic demand. The networks in the second class are traffic-variable nonlinear translucent backbone networks where regenerator sites are necessary to recover optical signals from the accumulated noise in long-distance transmission. The third class is data-center networks based on optical spatial division multiplexing. Within each class, our focus is primarily on an efficient and balanced allocation of network resources. Both optimization formulations and heuristic algorithms are proposed for each class. The contributions of this thesis can thus be categorized into three topics, as outlined below.First, we consider the optimization of network resources in the presence of PLI. The PLI between optical connections is characterized by the Gaussian noise (GN) model and incorporated into resource allocation algorithms. As an example, for a link-level optical communication system, the spectrum usage can be reduced by roughly up to 22% by accurately modelling the PLIs and assigning proper modulation formats and spectrum to optical connections. For resource allocation in the network level, the power spectral density of each optical connection is optimized in addition to the previously mentioned resources.As a second topic, the design of flexible-grid optical networks is studied. Specifically, we consider the regenerator location problem in traffic-variable translucent backbone networks. Due to the constantly changing traffic, the PLIs suffered by optical connections are also stochastic and, thus, have to be handled from a probabilistic perspective. A statistical network assessment process is used to characterize the noise distributions suffered by optical connections on each link, based on which a heuristic algorithm is proposed to select a set of regenerator sites with the minimum blocking probability.Finally, we study the trade-off between the blocking probability and total throughput in the modular data center networks (DCNs) based on different optical spatial division multiplexing switching schemes. This performance trade-off is caused by the coexistence of traffic demands with extremely different data rates and number of requests in DCNs. A heuristic resource allocation algorithm is proposed to enable flexible tuning of the objective function and achieve a balanced network performance

    Telecommunication Systems

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    This book is based on both industrial and academic research efforts in which a number of recent advancements and rare insights into telecommunication systems are well presented. The volume is organized into four parts: "Telecommunication Protocol, Optimization, and Security Frameworks", "Next-Generation Optical Access Technologies", "Convergence of Wireless-Optical Networks" and "Advanced Relay and Antenna Systems for Smart Networks." Chapters within these parts are self-contained and cross-referenced to facilitate further study

    POF 2016: 25th International Conference on Plastic Optical Fibres - proceedings

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