Academic literature on the topic 'Reconfigurable Optical Add-Drop Multiplexers (ROADMs)'

Le trafic dans les réseaux optiques est en constante augmentation depuis de nombreuses années. CISCO affirme qu'il devrait augmenter d'un facteur 13 en 2020. Ceci induit une augmentation de la consommation énergétique et de l'évolution de la taille des réseaux entrainant un accroissement de la complexité des réseaux. Dans ce contexte, pour répondre à l'augmentation du débit dans les réseaux et procure un réseau de télécommunications fiable, il faut prévoir une planification et une ingénierie de réseaux adaptées. Dans ce but, nous étudions dans cette thèse le design d'un nœud de commutation optique ROADM. nous considérons différentes architectures de nœud, composants et sous-systèmes utilisés dans les configurations de nœud RODM "Broadcast and Select" et "Route and Select". Diverses configurations de modules d'insertion/extraction sont analysées ("Colored/colorless, directional/directionless et contentional/contentionless"). Pour ce faire, nous avons développé un simulateur de nœud ROADM dans une plateforme de trafic dynamique et nous avons proposé une stratégie de gestion offline de la contention à l'intérieur du nœud. Nous avons obtenu une réduction du rapport de blocage intra noeud de l'ordre de 1.5. Ensuite, nous nous sommes focalisés sur la planification des futures générations de réseaux optiques métro cœur. Dans ce but, nous avons étudié la possibilité d'une transmission non cohérente à 100 Gb/s en utilisant le format de modulation PDM-DQPSK. Ensuite, nous avons considéré l'implémentation de la PDM-CS-DQPSK. La qualité de transmission de ces deux systèmes a finalement été évaluée<br>Traffic demand is exponentially increasing in recent years. Cisco forecast claims that by 2020, transport traffic will be 13 times of today's traffic transmission. This incremental traffic demand makes concerns about energy consumption and network scalability as well as increasing the network complexity. In this respect, to adresse the future traffic demand requirement and provide a reliable telecommunication network, precise network planning and engineering are needed. To this aim, we adress the problem of ROADM node design by presenting different architectures, components and subsystems to investigate the Broadcast and Select and Route and Select ROADM node architectures. Colored/colorless, directional/directionless and contentional/contentionless add/drop module configurations are studied. Futhermore, the problem of Intra Node Blocking is investigated by developing a node simulator in a dynamic network traffic platform. In this respect, we propose an offline contention management strategy for an ROADMnode in order to efficiently decrease the Intra Node blocking ration by more than 1.5 order of magnitude. Finally, we focus on network planning by investigating short and medium term network upgrades for metro-core optical network. To this goal, we investigate the possibility of non coherent signal transmission in metro-core segment of hierarchical layered optical network. Quality of transmission for 100 Gbit/s PDM-DQPSK-modulation format is investigated. Then, we propose the implementation of PDM-CS-DQPSK modulation format to transmit 100 Gbit/s signals in ROADM based optical transmission systems

Le trafic dans les réseaux optiques est en constante augmentation depuis de nombreuses années. CISCO affirme qu'il devrait augmenter d'un facteur 13 en 2020. Ceci induit une augmentation de la consommation énergétique et de l'évolution de la taille des réseaux entrainant un accroissement de la complexité des réseaux. Dans ce contexte, pour répondre à l'augmentation du débit dans les réseaux et procure un réseau de télécommunications fiable, il faut prévoir une planification et une ingénierie de réseaux adaptées. Dans ce but, nous étudions dans cette thèse le design d'un nœud de commutation optique ROADM. nous considérons différentes architectures de nœud, composants et sous-systèmes utilisés dans les configurations de nœud RODM "Broadcast and Select" et "Route and Select". Diverses configurations de modules d'insertion/extraction sont analysées ("Colored/colorless, directional/directionless et contentional/contentionless"). Pour ce faire, nous avons développé un simulateur de nœud ROADM dans une plateforme de trafic dynamique et nous avons proposé une stratégie de gestion offline de la contention à l'intérieur du nœud. Nous avons obtenu une réduction du rapport de blocage intra noeud de l'ordre de 1.5. Ensuite, nous nous sommes focalisés sur la planification des futures générations de réseaux optiques métro cœur. Dans ce but, nous avons étudié la possibilité d'une transmission non cohérente à 100 Gb/s en utilisant le format de modulation PDM-DQPSK. Ensuite, nous avons considéré l'implémentation de la PDM-CS-DQPSK. La qualité de transmission de ces deux systèmes a finalement été évaluée<br>Traffic demand is exponentially increasing in recent years. Cisco forecast claims that by 2020, transport traffic will be 13 times of today's traffic transmission. This incremental traffic demand makes concerns about energy consumption and network scalability as well as increasing the network complexity. In this respect, to adresse the future traffic demand requirement and provide a reliable telecommunication network, precise network planning and engineering are needed. To this aim, we adress the problem of ROADM node design by presenting different architectures, components and subsystems to investigate the Broadcast and Select and Route and Select ROADM node architectures. Colored/colorless, directional/directionless and contentional/contentionless add/drop module configurations are studied. Futhermore, the problem of Intra Node Blocking is investigated by developing a node simulator in a dynamic network traffic platform. In this respect, we propose an offline contention management strategy for an ROADMnode in order to efficiently decrease the Intra Node blocking ration by more than 1.5 order of magnitude. Finally, we focus on network planning by investigating short and medium term network upgrades for metro-core optical network. To this goal, we investigate the possibility of non coherent signal transmission in metro-core segment of hierarchical layered optical network. Quality of transmission for 100 Gbit/s PDM-DQPSK-modulation format is investigated. Then, we propose the implementation of PDM-CS-DQPSK modulation format to transmit 100 Gbit/s signals in ROADM based optical transmission systems

碩士<br>國立臺灣科技大學<br>電子工程系<br>92<br>Abstract In this thesis, we design optical add/drop multiplexer (OADM) and study its applications in metropolitian area networks and/or DWDM subsystem. We propose a network architecture using -cell architecture to realize all optical networks architecture, in which the crucial modules of OADMs and optical cross-connects (OXCs) are implemented. Both of them make the network much more flexible and simple then ever. We introduce an example of “Double Ring -cell WDM network” to examine that OADM is indeed an importance part in the -cell architecture. For investigation of OADMs, we integrated them with fiber Bragg gratings (FBGs) and some related optical components such as optical circulators and 1xN optical switches. To prevent the crosstalk and reflection by home made FBGs, the FBGs have high reflectivity of 99.9% and low side lobes. The FBGs also be temperature compensated to avoid them from wavelength misalignment with the corresponding laser source. Temperature coefficient before and after temperature compensated is 15 pm/℃ and 0.7 pm/℃, respectively. The four kinds of OADMs we made are: (1) Two identical OADMs module with the same four channels of 1542.4 nm,1545.6 nm,1547.1 nm and 1552.3 nm and as an add-drop pair in the optical network, (2) a 4-Ch reconfigurable OADM with insertion loss, intrachannel crosstalk and channel spacing of 5 dB, 25 dB and 1.6 nm, respectively, (3) a power compensated OADM with net gain of 5 dB (i.e., virtual insertion loss of 5 dB!) for the pass-through channel, and (4) a bi-directional OADM with 45 dB isolation for either direction. Finally, we conclude our achievements in thesis and suggested future works.

碩士<br>國立臺灣科技大學<br>電子工程系<br>93<br>This thesis investigates several reconfigurable optical add/drop multiplexers (ROADM) with power compensation function. Here, we proposed both unidirectional and bi-directional ROADMs for optical networks applications. The ROADM is constructed by integrating fiber Bragg gratings (FBGs), optical circulators (OCs), optical switches (OSWs) and erbium-doped fiber amplifier. To avoid intraband crosstalk cause the signal deterioration, the home-made FBGs should have above 99.5% reflectivity after annealing. The tunable FBG with tuning range of 17 nm, while the wavelength fixed FBG has wavelength inaccurate less than 0.04 nm and low temperature coefficient of 0.7 pm/oC. We manufacture two kinds of ROADM. Firstly, we investigate a unidirectional ROADM. The channel spacing is based on the ITU-T grid of 100 GHz in 1547.7-, 1548.5- and the 1549.3 nm. The fourth channel is to use a tunable FBG to increase the add/drop feasibility. Insertion loss and gain of the ROADM are 4.3 dB and 14 dB, respectively. In a 25 km standard fiber transmission without dispersion compensation, power penalty is only 0.8 dB at the dropped port for 10 Gb/s, bit error rate (BER) measurement. We also design another three kinds of unidirectional multichannel ROADMs and analyze their characteristics. Secondly, we experimentally demonstrate a bidirectional ROADM including power compensation function. The insertion loss and gain of it are 5.3 dB and 17 dB, respectively. Moreover, we design another kind of bidirectional ROADM and analyze its characteristics. Finally, we conclude our achievements in this thesis and suggested future works.

碩士<br>國立臺灣大學<br>應用力學研究所<br>91<br>With an explosion in the growth of knowledge, and the coming internet era, the demand for bandwidth has increased drastically, making the all-optical network an inevitable trend. In particular, the development of Dense Wavelength Division Multiplexing (DWDM) technology has really emphasized the superiority of the optical networks. Performing the important network resource allocation function is the optical add / drop multiplexer which directly adds or drops wavelengths. It supports flexible provisioning, wavelengths add / drop, and other requirements resulting from a complex and constantly changing environment in the metro-core networks. Such functions enable the add / drop multiplexer to be a key component in the optical networks. The purpose of this study is to take advantage of the bulk micromachining, an innovative approach in the MEMS technology, and to apply it in the optical add/ drop multiplexer used in optical networks to improve optical performance. By use of unique characteristics of vertical crystal planes in bulk micromachining, two-sided mirrors for light reflection can be produced. Its mirror surfaces are of extremely superior quality, with a radius of curvature of 130 meters, and a root-mean-square roughness of below 8 nm. These qualities facilitate its use in optical add / drop multiplexer applications. In terms of mechanical properties, this study begins with the most basic concepts of mechanics, analyzing the static interaction among magnetic, electrostatic, and mechanical force. The actuating mechanism is utilizing the magnetic ability of not being affected by distance and electrostatic force special quality to perform addressable control. In this approach, it may require less electrical and magnetic energy to drive it. The clamping-down voltage requires 100 volts, while the magnetic full field applied is 25 gausses. In addition, the switching times for switch-on and switch-off are measured to be 50 ms and 110 ms, respectively. Test results show that the design concept for this study is feasible. As expected, the two-sided mirrors possess excellent flatness and roughness, and require low driving voltage and magnetic field. For use of flexible, reconfigurable OADM, the switching function has been verified. If additional peripheral functions such as multiplexing and de-multiplexing can also be integrated into the devices in the future, making it a reconfigurable OADM, then it is bound to play an important role in the field of optical networking applications.

The optical network physical layer limitations, in particular, the crosstalk due to imperfect isolation of optical network switching components, such as Reconfigurable Optical Add/Drop Multiplexers (ROADMs), can become a limiting factor in the performance of these networks. In this work, the impact of in-band crosstalk due to M-ary quadrature amplitude modulation (M-QAM) interferers on the performance of 4-QAM and 16-QAM coherent receivers in ROADM based networks is analysed, using Monte Carlo (MC) simulation. Several Wavelength Select Switch (WSS) models, a ROADM component, were studied, and each WSS model had a different optical filter profile. Two crosstalk metrics, unweighted crosstalk and weighted crosstalk, are used to measure the system performance degradation regarding the Optical Signal-to-Noise Ratio (OSNR) penalty at the coherent receiver. The difference between the two, is the fact that weighted crosstalk takes into account that the spectrum content closer to the center of the channel bandwidth has more impact than spectral content closer to the edges of the channel bandwidth. Using unweighted crosstalk metric, it can be concluded that optical filters with a wider rejection bandwidth in the center of the channel, have a better performance in terms of OSNR penalty at the coherent receiver. With the weighted crosstalk metric, it was observed that regardless of the WSS filter profile, the OSNR penalty performances of each WSS were similar. It can be concluded that the weighted crosstalk metric is very reliable at predicting system performances independently of the filter shape present in the WSS.<br>As limitações do nivel físico das redes ópticas, nomeadamente a diafonia (crosstalk) devido ao isolamento imperfeito de elementos de redes de fibra óptica, como os Multiplexadores Ópticos de Adição/Extracção Reconfiguráveis (ROADMs), podem constituir um factor limitativo no desempenho das redes ópticas. Nesta dissertação, foi estudado através de simulação de Monte-Carlo (MC), o impacto do crosstalk homódino devido a sinais interferentes com o formato de modulação em amplitude e em quadratura (M-QAM), no desempenho dos receptores coerentes de sinais 4-QAM e 16-QAM. Foram também estudados vários Selectores de Comprimento de Onda (WSS), um componente dos ROADMs, e em que cada WSS tem um filtro óptico com um perfil diferente. Duas métricas de crosstalk, unweighted crosstalk e weighted crosstalk, foram usadas para estudar a degradação do desempenho do sistema de comunicações ópticas referente à relação de sinal-ruído óptica (OSNR), no receptor coerente. A diferença entre estas duas métricas, é o facto de o weighted crosstalk levar em consideração que o conteúdo espectral perto do centro da largura de banda do canal, tem um impacto maior do que o conteúdo espectral perto das margens da largura de banda do canal. Analisando os resultados com a métrica unweighted crosstalk, foi possível concluir que WSSs com filtros ópticos com a banda de rejeição maior e mais centrada com a largura de banda do canal, obtiveram melhor desempenho em relação à penalidade de OSNR medida no receptor coerente. Usando o weighted crosstalk como métrica, foi observado que todos os WSSs registaram desempenhos semelhantes em termos de penalidade de OSNR. Podemos concluir, que o weighted crosstalk constitui uma métrica bastante fiável a prever desempenhos de sistemas de comunicações ópticos, independentemente do perfil dos filtros usados em cada WSS.