Tesi: "All-optical routing and switching"

1

Mokhtar, Ahmed. "Routing, switching, and multiaccess in all-optical networks /". Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5942.

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2

Yuan, Xiaochun, e 袁小春. "Routing protocols in all-optical packet switched networks". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243885.

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3

Yuan, Xiaochun. "Routing protocols in all-optical packet switched networks /". Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25100725.

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4

Santos, Blanco María Concepción. "Optical solitons in quadratic nonlinear media and applications to all-optical switching and routing devices". Doctoral thesis, Universitat Politècnica de Catalunya, 1998. http://hdl.handle.net/10803/6913.

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Esta tesis constituye un estudio detallado y exhaustivo de las propiedades de una variedad específica de ondas ópticas solitarias. Observadas experimentalmente por primera vez en 1995, estas ondas estan formadas por un haz óptico a frecuencia fundamental y su segundo armónico que están ligados entre sí y viajan juntos en el material cuadrático; y son debidas al equilibrio entre la difracción lineal que sufre el haz al propagarse y un término no lineal de segundo orden en la susceptibilidad del medio. Las llamamos por eso solitones ópticos en medios cuadráticos o simplemente 'solitones cuadráticos'. También se les conoce como 'Solitones Multicolor' aludiendo al hecho de que requieren de haces a diferentes frecuencias para formarse.
Un medio no-lineal cuadrático tiene por fuerza que ser no-centrosimétrico, lo cual es una variedad de anisotropía. Una gran parte de los materiales no-lineales cuadráticos (los que tienen mayor interés para la industria) son uniaxiales lo que significa que presentan un eje de simetría que suele llamarse eje óptico. De la dirección de un haz relativa a ese eje óptico dependen las características de la propagación del haz en el medio cuadrático no-lineal. Una consecuencia de eso en configuraciones de interés es un desvío ('walk-off') sufrido por el haz respecto a su dirección de propagación inicial al entrar en el material no-lineal.
Las propiedades de los solitones cuadráticos 'caminantes' son también estudiadas en la tesis, estableciendo que existe una relación entre la potencia inyectada en el medio y el ángulo de desvío (walking angle).
Una parte importante de la tesis está dedicada al estudio a través de exhaustivos experimentos numéricos del potencial de estas ondas solitarias para constituir la base de dispositivos de conmutación y encaminamiento totalmente ópticos que puedan hacer realidad la promesa de la red transparente totalmente óptica. Los experimentos han permitido identificar varias configuraciones de interés con niveles de potencia y dimensiones que permiten plantearse el diseño y construcción de dispositivos comerciales de conmutación y encaminamiento totalmente ópticos basados en solitones ópticos cuadráticos.
This thesis is a comprehensive study of the fundamental properties of a specific kind of optical spatial solitary waves. First observed experimentally in 1995, these solitary waves are formed by an optical beam at a fundamental frequency and its second harmonic which propagate together and are mutually entangled; and are due to a balanced interplay between the beams' linear diffraction and a second-order nonlinear susceptibility of the medium. They are thereby referred as 'Optical Solitons in Quadratic Nonlinear Media' or simply 'Quadratic Solitons', They are also known as 'Multicolor Solitons' recalling that they are formed by beams at different frequencies.
A quadratic nonlinear media needs to be non centrosymmetric which is a special kind of anisotropy. A great deal of quadratic nonlinear materials (the most used by industry such as lithim niobate, KTP, etc.) are uniaxial meaning that they feature a symmetry axis known as 'optical axis'. The direction of propagation of an optical beam relative to that axis determines the characteristics of the beam's propagation through the quadratic nonlinear material. A main result of that in some configurations of interest is a walk-off suffered by the beam as it enters the quadratic material.
The properties of the families of quadratic solitons in the presence of a linear walk-off (quadratic walking solitons) are studied as well in the thesis stating that there is a relationship between the power injected into the medium and the walking angle, suitable to applications of all-optical switching and routing.
An important last part of the thesis is devoted to the study from a practical viewpoint and through extensive numerical experiments of the potential of these solitary waves as the basis of practical all-optical switches and routers which could take the all-optical transparent network to a reality. The experiments have allowed to identify several configurations of interest with power level and dimensions suited to practical applications which could allow the production of commercial all-optical switching and routing devices based on quadratic solitons.

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5

Hawkins, William Cory. "Evaluation of the Data Vortex Photonic All-Optical Path Interconnection Network for Next-Generation Supercomputers". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14519.

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Todays supercomputers employ the fastest processors incorporating the latest VLSI technology. Unfortunately, usable system performance is often limited by excessive interprocessor latency. To overcome this bottleneck, this thesis explores the use of all-optical path interconnection networks using a new topology defined by Coke Reed [31]. This work overcomes limitations of previous optical networks through a novel use of defection routing to minimize latency and allow more processors to collaborate on the same application and dataset. In this thesis research, the data vortex is formally characterized and tested for performance. Extra angles serve as virtual buffers to provide required system performance, even under asymmetric mode operation. The data vortex is compared to two well-known interconnection networks (omega and butterfly) using metrics of average latency and message acceptance rate. The data vortex is shown to outperform the comparison networks, with a 20-50% higher acceptance rate and comparable average latency. The impact of angle size is also studied, and a new, synchronous mode of operation is proposed where additional angles are added to increase the virtual buffering of the network. The tradeoff between virtual buffering and angle resolution backpressure is explored, and an optimal point is found at the 1:6 I/O to non-I/O (virtual buffering) angle ratio. The new mode and optimal angle count are used to form data vortex networks that perform as well as larger networks with fewer total nodes. Finally, hierarchical layering with data vortex clusters is proposed and compared to a single-level data vortex. In todays technology, similar performance is attained at high network communication locality loads (> 2/3), and a 19% latency reduction is obtained at the highest locality loads (> 95%) for current optical switching technology. For projected future technology, the clustered system is shown to yield up to a 55% reduction in latency for applications with 2/3 or better locality.

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6

Chiang, Ming Feng. "High speed all-optical packet switching router employing single and multiple PPM based routing tables". Thesis, Northumbria University, 2009. http://nrl.northumbria.ac.uk/2384/.

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All-optical packet switched networks with flexibility and capability to deal with the bursty traffic is one solution to deal with the ever increasing demand for bandwidth. To fully utilise the potential of such networks and to ensure that high-speed packets, passed through a number of nodes, are faithfully delivered to their intended destination with minimum delay times, packet header processing and routing decision needs to be carried out in the optical domain not in the electrical domain. This is to avoid the speed bottleneck imposed by the slow response of currently available electronic devices beyond 40 Gb/s. At present, packet header recognition is carried out by sequentially correlating the incoming packet header address with every entry of a local routing table. For a small size network, with a reasonable size routing table, sequential correlation is viable both in terms of processing speed and implementation complexity. However, for a large size network with a very large size routing table of hundreds or thousands of entries, the cost, complexity and processing time does become a real issue. The latter will lead to a noticeable increase in the packet processing time at every router, which could be significantly reduced by a non- conventional signal formatting. In this thesis, an all-optical 3-input AND gate and an all-optical 1 x2 switch with high contrast ratio are proposed as an essential element in all-optical routers. New routing schemes employing pulse position modulation (PPM) packet header format as well as single and multiple PPM based routing tables (PPRTs) are proposed and investigated. The main advantage of the proposed scheme is reduced size routing table leading to a faster router processing time compared to the routers with conventional routing tables (CRTs). The correlation-time gains offered by the proposed schemes are given by theoretical calculations. For optical packets with 4-bit binary address, all-optical 1x3 routers employing single and multiple PPRTs with an entry slot of 6.25 ps offer — 100 and — 400 times faster processing times when compared to the routers employing CRT, respectively. The performance of the proposed routers employing single and multiple PPRTs are assessed in terms of optical signal-to-noise ratio (OSNR) in multi-hop routing by means of numerical simulations and theoretical analysis. It is shown that predicted and simulated OSNR decreases by —2 dB after each hop. New packet header address formats proposed offers reduced complexity of nodes by employing single or multiple PPM based routing tables. Adopting a hybrid header address format, it is shown that routers with multiple PPRTs can operate at 160 Gb/s with the output intra-channel crosstalk of -18 dB and with output packet power fluctuation of 2 dB. Finally, a WDM router employing a single PPRT, capable of processing packets at different wavelengths simultaneously, is proposed and its inter-channel crosstalk performance is investigated. At 160 Gb/s, results obtained show an inter-channel crosstalk of — -27 dB at a channel spacing of greater than 0.4 THz and a demultiplexer bandwidth of 500 GHz.

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7

He, Jenny Jing. "Optical flow routing : a routing and switching paradigm for the core optical networks". Thesis, University of Essex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248654.

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8

GARRICH, ALABARCE MIQUEL. "Optical architectures for high performance switching and routing". Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506247.

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This thesis investigates optical interconnection networks for high performance switching and routing. Two main topics are studied. The ﬁrst topic regards the use of silicon microring resonators for short reach optical interconnects. Photonic technologies can help to overcome the intrinsic limitations of electronics when used in interconnects, short-distance transmissions and switching operations. This thesis considers the peculiarasymmetric losses of microring resonators since they pose unprecedented challenges for the design of the architecture and for the routing algorithms. It presents new interconnection architectures, proposes modiﬁcations on classical routing algorithms and achieves a better performance in terms of fabric complexity and scalability with respect to the state of the art. Subsequently, this thesis considers wavelength dimension capabilities of microring resonators in which wavelength reuse (i.e. crosstalk accumulation) presents impairments on the system performance. To this aim, it presents different crosstalk reduction techniques, a feasibility analysis for the design of microring resonators and a novel wavelength-agile routing matrix. The second topic regards ﬂexible resource allocation with adaptable infrastructure for elastic optical networks. In particular, it focus on Architecture on Demand (AoD), whereby optical node architectures can be reconﬁgured on the ﬂy according to trafﬁc requirements. This thesis includes results on the ﬁrst ﬂexible-grid optical spectrum networking ﬁeld trial, carried out in a collaboration with University of Essex. Finally, it addresses several challenges that present the novel concept AoD by means of modeling and simulation. This thesis proposes an algorithm to perform automatic architecture synthesis, reports AoD scalability and power consumption results working under the proposed synthesis algorithm. Such results validate AoD as a ﬂexible node concept that provides power efﬁciency and high switching capacity.

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9

Hawkins, William Cory. "Evaluation of the data vortex photonic all-optical path interconnection network for next-generation supercomputers". Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-12182006-155304/.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.
Dr. Henry L. Owen III, Committee Member ; Dr. David Keezer, Committee Member ; Dr. D. Scott Wills, Committee Chair.

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10

Sato, Ken-ichi. "Future directions in optical networking technology development — Optical fast circuit switching and multilevel optical routing". IEEE, 2009. http://hdl.handle.net/2237/13986.

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11

Gao, Xingbo. "DESIGN AND ANALYSIS OF EFFECTIVE ROUTING AND CHANNEL SCHEDULING FOR WAVELENGTH DIVISION MULTIPLEXING OPTICAL NETWORKS". Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2810.

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Optical networking, employing wavelength division multiplexing (WDM), is seen as the technology of the future for the Internet. This dissertation investigates several important problems affecting optical circuit switching (OCS) and optical burst switching (OBS) networks. Novel algorithms and new approaches to improve the performance of these networks through effective routing and channel scheduling are presented. Extensive simulations and analytical modeling have both been used to evaluate the effectiveness of the proposed algorithms in achieving lower blocking probability, better fairness as well as faster switching. The simulation tests were performed over a variety of optical network topologies including the ring and mesh topologies, the U.S. Long-Haul topology, the Abilene high-speed optical network used in Internet 2, the Toronto Metropolitan topology and the European Optical topology. Optical routing protocols previously published in the literature have largely ignored the noise and timing jitter accumulation caused by cascading several wavelength conversions along the lightpath of the data burst. This dissertation has identified and evaluated a new constraint, called the wavelength conversion cascading constraint. According to this constraint, the deployment of wavelength converters in future optical networks will be constrained by a bound on the number of wavelength conversions that a signal can go through when it is switched all-optically from the source to the destination. Extensive simulation results have conclusively demonstrated that the presence of this constraint causes significant performance deterioration in existing routing and wavelength assignment (RWA) algorithms. Higher blocking probability and/or worse fairness have been observed for existing RWA algorithms when the cascading constraint is not ignored. To counteract the negative side effect of the cascading constraint, two constraint-aware routing algorithms are proposed for OCS networks: the desirable greedy algorithm and the weighted adaptive algorithm. The two algorithms perform source routing using link connectivity and the global state information of each wavelength. Extensive comparative simulation results have illustrated that by limiting the negative cascading impact to the minimum extent practicable, the proposed approaches can dramatically decrease the blocking probability for a variety of optical network topologies. The dissertation has developed a suite of three fairness-improving adaptive routing algorithms in OBS networks. The adaptive routing schemes consider the transient link congestion at the moment when bursts arrive and use this information to reduce the overall burst loss probability. The proposed schemes also resolve the intrinsic unfairness defect of existing popular signaling protocols. The extensive simulation results have shown that the proposed schemes generally outperform the popular shortest path routing algorithm and the improvement could be substantial. A two-dimensional Markov chain analytical model has also been developed and used to analyze the burst loss probabilities for symmetrical ring networks. The accuracy of the model has been validated by simulation. Effective proactive routing and preemptive channel scheduling have also been proposed to address the conversion cascading constraint in OBS environments. The proactive routing adapts the fairness-improving adaptive routing mentioned earlier to the environment of cascaded wavelength conversions. On the other hand, the preemptive channel scheduling approach uses a dynamic priority for each burst based on the constraint threshold and the current number of performed wavelength conversions. Empirical results have proved that when the cascading constraint is present, both approaches would not only decrease the burst loss rates greatly, but also improve the transmission fairness among bursts with different hop counts to a large extent.
Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Science PhD

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12

Yu, Wing Wa. "Routing and time-slot assignment in photonic circuit switching networks /". View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20YUW.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.
Includes bibliographical references (leaves 68-70). Also available in electronic version. Access restricted to campus users.

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13

Chevalier, Franck. "Performance evaluation of the Clockwork routing scheme in optical packet switching networks". Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248602.

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14

SATO, Ken-ichi, Hiroshi HASEGAWA e Takahiro OGAWA. "Optical Fast Circuit Switching Networks Employing Dynamic Waveband Tunnel". 電子情報通信学会, 2012. https://search.ieice.org/.

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15

Komolafe, Olufemi O. "High-speed optical packet switching over arbitrary physical topologies using the Manhattan Street Network". Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366847.

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16

Masi, Marco. "Modeling of sequences of Silicon micro-Resonators for On-Chip Optical Routing and Switching". Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/369141.

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Abstract (sommario):

The purpose of this thesis is to focus on the aspect of passive devices allowing for WDM, routing, switching and filtering of optical signals, investigating novel routing concepts based on micro optical side coupled resonators to achieve large bandwidth by multiple cascading and/or multiple coupling (low group velocity) periodicity effects. We will describe some technical aspects necessary for the design and fabrication of some passive circuitry, and usually neglected in purely theoretical approaches, including optical routers based on racetrack resonators and novel SCISSOR and CROW devices.

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17

Masi, Marco. "Modeling of sequences of Silicon micro-Resonators for On-Chip Optical Routing and Switching". Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/462/1/Tesi_finale.pdf.

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Abstract (sommario):

The purpose of this thesis is to focus on the aspect of passive devices allowing for WDM, routing, switching and filtering of optical signals, investigating novel routing concepts based on micro optical side coupled resonators to achieve large bandwidth by multiple cascading and/or multiple coupling (low group velocity) periodicity effects. We will describe some technical aspects necessary for the design and fabrication of some passive circuitry, and usually neglected in purely theoretical approaches, including optical routers based on racetrack resonators and novel SCISSOR and CROW devices.

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18

Klinkowski, Miroslaw. "Offset time-emulated architecture for optical burst switching-modelling and performance evaluation". Doctoral thesis, Universitat Politècnica de Catalunya, 2008. http://hdl.handle.net/10803/6000.

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L'evolució de les xarxes publiques de transport de dades destaca per el continu augment de la demanda de tràfic a la que estan sotmeses. La causa és la imparable popularització d'Internet i del seu ús per a tot tipus d'aplicacions. Les xarxes de commutació de ràfegues òptiques (OBS: Optical Bursts Switching) són una solució extraordinàriament prometedora per la pròxima generació de xarxes, tant per la flexibilitat que ofereixen com per el seu alt rendiment fruit de l'explotació de la multiplexació estadística en el domini òptic.

Aquesta tesi presenta l'anàlisi, modelització i avaluació de les xarxes de commutació de ràfegues òptiques basades en l'emulació del temps de compensació (emulated offset time: E-OBS). El concepte d'E-OBS defineix una arquitectura de xarxa OBS per al transportar i commutar ràfegues òptiques en una xarxa troncal en la que, al contrari de l'arquitectura convencional (C-OBS) en la que el temps de compensació s'introdueix des dels nodes d'accés, el temps de compensació s'introdueix en cadascun dels nodes de la xarxa per mitjà d'un retardador de fibra addicional. L'arquitectura E-OBS permet superar algunes de les desavantatges inherents a arquitectures C-OBS, però la seva gran virtut és la compatibilitat amb les xarxes de commutació de circuits òptics (OCS: Optical Circuit Switching) actuals i les futures xarxes de commutació de paquets òptics (OPS: Optical Packet Switching), de manera que les xarxes OBS basades en una arquitectura E-OBS) poden facilitat enormement la transició de unes a les altres.

A ala vista dels principals requeriments de disseny de les xarxes OBS, que són la resolució de contencions en el domini òptic, la provisió de qualitat de servei (QoS) i l'òptim encaminament de les ràfegues per tal de minimitzar la congestió de la xarxa, . en aquesta tesi es proposa un disseny de l'arquitectura E-OBS basada en (i) un mètode viable per a la provisió del temps de compensació, (ii) una qualitat alta global de servei, i (iii) un mecanisme d'encaminament que minimitzi congestió de xarxa.

- La primera part d'aquesta tesi proporciona la informació documental necessària per al disseny d'E-OBS.

- La segona part se centra en l'estudi de la funcionalitat i viabilitat de l'arquitectura E-OBS. S'introdueixen els principis d'operació d'E-OBS i s'identifiquen els principals esculls que presenten les arquitectures C-OBS i que deixen de ser-ho en una arquitectura E-OBS. Alguns d'aquests esculls són la dificultat d'utilitzar un algorisme d'encaminament amb rutes alternatives, la complexitat dels algoritmes de reserva de recursos i la seva falta d'equitat, la complexitat en la provisió de la QoS, etc. En aquesta segona part es constata que l'arquitectura E-OBS redueix la complexitat dels de reserva de recursos i es verifica la viabilitat d'operació i de funcionament de la provisió del tremps de compensació en aquesta arquitectura a partir de figures de comportament obtingudes amb retardadors de fibra comercialment disponibles.

- La tercera part encara el problema de la provisió de la QoS. Primer s'hi revisen els conceptes bàsics de QoS així com els mecanismes de tractament de la QoS per a xarxes OBS fent-ne una comparació qualitativa i de rendiment de tots ells. Com a resultat s'obté que el mecanisme que presenta un millor comportament és el d'avortament de la transmissió de les ràfegues de més baixa prioritat quan aquestes col·lisionen amb una de prioritat més alta (es l'anomenat Burst Preemption mechanism), el qual en alguns casos presenta un problema de senyalització innecessària. Aquesta tercera part es conclou amb la proposta d'un mecanisme de finestra a afegir al esquema de Burst Preemption que només funciona sobre una arquitectura E-OBS i que soluciona aquest problema.

- En la quarta part s'afronta el problema de l'encaminament en xarxes OBS. S'estudia el comportament dels algoritmes d'encaminament adaptatius, els aïllats amb rutes alternatives i els multicamí distribuïts, sobre xarxes E-OBS. A la vista dels resultats no massa satisfactoris que s'obtenen, es planteja una solució alternativa que es basa en model d'optimització no lineal. Es formulen i resolen dos models d'optimització per als algoritmes encaminament de font multicamí que redueixen notablement la congestió en les xarxes OBS.

Finalment, aquesta tesi conclou que l'arquitectura E-OBS és factible, que és més eficient que la C-OBS, que proveeix eficaçment QoS, i que és capaç d'operar amb diverses estratègies d'encaminament i de reduir eficaçment la congestió de xarxa.
The fact that the Internet is a packet-based connection-less network is the main driver to develop a data-centric transport network. In this context, the optical burst switching (OBS) technology is considered as a promising solution for reducing the gap between transmission and switching speeds in future networks.

This thesis presents the analysis, modelling, and evaluation of the OBS network with Emulated offset-time provisioning (E-OBS). E-OBS defines an OBS network architecture to transport and switch optical data bursts in a core network. On the contrary to a conventional offset-time provisioning OBS (C-OBS) architecture, where a transmission offset time is introduced in the edge node, in an E-OBS network the offset time is provided in the core node by means of an additional fibre delay element. The architecture is motivated by several drawbacks inherent to C-OBS architectures. It should be pointed out that the E-OBS has not been studied intensively in the literature and this concept has been considered rather occasionally.

Due to the limitations in optical processing and queuing, OBS networks need a special treatment so that they could solve problems typical of data-centric networks. Contention resolution in optical domain together with quality of service (QoS) provisioning for quality demanding services are, among other things, the main designing issues when developing OBS networks. Another important aspect is routing problem, which concerns effective balancing of traffic load so that to reduce burst congestion at overloaded links. Accounting for these requirements, the design objectives for the E-OBS architecture are (i) feasibility of offset-time provisioning, (ii) an overall high quality of service, and (iii) reduction of network congestion. These objectives are achieved by combining selected concepts and strategies, together with appropriate system design as well as network traffic engineering.

The contributions in this thesis can be summarized as follows.

- At the beginning, we introduce the principles of E-OBS operation and we demonstrate that C-OBS possesses many drawbacks that can be easily avoided in E-OBS. Some of the discussed issues are the problem of unfairness in resources reservation, difficulty with alternative routing, complexity of resources reservation algorithms, efficiency of burst scheduling, and complexity in QoS provisioning. The feasibility of E-OBS operation is investigated as well; in this context, the impact of congestion in control plane on OBS operation is studied. As a result, we confirm the feasibility of E-OBS operation with commercially available fibre delay elements.

- Then, we provide both qualitative and quantitative comparison of the selected, most addressed in the literature, QoS mechanisms. As an outcome a burst preemption mechanism, which is characterized by the highest overall performance, is qualified for operating in E-OBS. Since the preemptive mechanism may produce the overbooking of resources in an OBS network we address this issue as well. We propose the preemption window mechanism to solve the problem. An analytical model of the mechanism legitimates correctness of our solution.

- Finally, we concern with a routing problem - our routing objective is to help the contention resolution algorithms in the reduction of burst losses. We propose and evaluate two isolated alternative routing algorithms designed for labelled E-OBS networks. Then we study multi-path source routing and we use network optimization theory to improve it. The presented formulae for partial derivatives, to be used in a non-linear optimization problem, are straightforward and very fast to compute. It makes the proposed non-linear optimization method a viable alternative for linear programming formulations based on piecewise linear approximations.

Concluding, E-OBS is shown to be a feasible OBS network architecture of profitable functionality, to support efficiently the QoS provisioning, and to be able to operate with different routing strategies and effectively reduce the network congestion.

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19

Guan, Kyle Chi. "Cost-effective optical network architecture : a joint optimization of topology, switching, routing and wavelength assignment". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38678.

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Abstract (sommario):

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (p. 279-285).
To provide end users with economic access to high bandwidth, the architecture of the next generation metropolitan area networks (MANs) needs to be judiciously designed from the cost perspective. In addition to a low initial capital investment, the ultimate goal is to design networks that exhibit excellent scalability - a decreasing cost-per-node-per-unit-traffic as user number and transaction size increase. As an effort to achieve this goal, in this thesis we search for the scalable network architectures over the solution space that embodies the key aspects of optical networks: fiber connection topology, switching architecture selection and resource dimensioning, routing and wavelength assignment (RWA). Due to the inter-related nature of these design elements, we intended to solve the design problem jointly in the optimization process in order to achieve over-all good performance. To evaluate how the cost drives architectural tradeoffs, an analytical approach is taken in most parts of the thesis by first focusing on networks with symmetric and well defined structures (i.e., regular networks) and symmetric traffic patterns (i.e., all-to-all uniform traffic), which are fair representations that give us suggestions of trends, etc.
(cont.) We starts with a examination of various measures of regular topologies. The average minimum hop distance plays a crucial role in evaluating the efficiency of network architecture. From the perspective of designing optical networks, the amount of switching resources used at nodes is proportional to the average minimum hop distance. Thus a smaller average minimum hop distance translates into a lower fraction of pass-through traffic and less switching resources required. Next, a first-order cost model is set up and an optimization problem is formulated for the purpose of characterizing the tradeoffs between fiber and switching resources. Via convex optimization techniques, the joint optimization problem is solved analytically for (static) uniform traffic and symmetric networks. Two classes of regular graphs - Generalized Moore Graphs and A-nearest Neighbors Graphs - are identified to yield lower and upper cost bounds, respectively. The investigation of the cost scalability further demonstrates the advantage of the Generalized Moore Graphs as benchmark topologies: with linear switching cost structure, the minimal normalized cost per unit traffic decreases with increasing network size for the Generalized Moore Graphs and their relatives.
(cont.) In comparison, for less efficient fiber topologies (e.g., A-nearest Neighbors) and switching cost structures (e.g., quadratic cost), the minimal normalized cost per unit traffic plateaus or even increases with increasing network size. The study also reveals other attractive properties of Generalized Moore Graphs in conjunction with minimum hop routing - the aggregate network load is evenly distributed over each fiber. Thus, Generalized Moore Graphs also require the minimum number of wavelengths to support a given uniform traffic demand. Further more, the theoretical works on the Generalized Moore Graphs and their close relatives are extended to study more realistic design scenarios in two aspects. One aspect addresses the irregular topologies and (static) non-uniform traffic, for which the results of Generalized Moore networks are used to provide useful estimates of network cost, and are thus offering good references for cost-efficient optical networks. The other aspect deals with network design under random demands. Two optimization formulations that incorporate the traffic variability are presented.
(cont.) The results show that as physical architecture, Generalized Moore Graphs are most robust (in cost) to the demand uncertainties. Analytical results also provided design guidelines on how optimum dimensioning, network connectivity, and network costs vary as functions of risk aversion, service level requirements, and probability distributions of demands.
by Kyle Chi Guan.
Ph.D.

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20

Toku, Hadi Alper. "A New Feedback-based Contention Avoidance Algorithm For Optical Burst Switching Networks". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610165/index.pdf.

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In this thesis, a feedback-based contention avoidance technique based on weighted Dijkstra algorithm is proposed to address the contention avoidance problem for Optical Burst Switching networks. Optical Burst Switching (OBS) has been proposed as a promising technique to support high-bandwidth, bursty data traffic in the next-generation optical Internet. Nevertheless, there are still some challenging issues that need to be solved to achieve an effective implementation of OBS. Contention problem occurs when two or more bursts are destined for the same wavelength. To solve this problem, various reactive contention resolution methods have been proposed in the literature. However, many of them are very vulnerable to network load and may suffer severe loss in case of heavy traffic. By proactively controlling the overall traffic, network is able to update itself in case of high congestion and by means of this method
contention avoidance can be achieved efficiently. The performance analysis of the proposed algorithm is presented through network simulation results provided by OMNET++ simulation environment. The simulation results show that the proposed contention avoidance technique significantly reduces the burst loss probability as compared to networks without any contention avoidance techniques.

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21

Mendoça, Pedroso Pedro Miguel. "GMPLS-OBS interoperability and routing acalability in internet". Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/52565.

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The popularization of Internet has turned the telecom world upside down over the last two decades. Network operators, vendors and service providers are being challenged to adapt themselves to Internet requirements in a way to properly serve the huge number of demanding users (residential and business). The Internet (data-oriented network) is supported by an IP packet-switched architecture on top of a circuit-switched, optical-based architecture (voice-oriented network), which results in a complex and rather costly infrastructure to the transport of IP traffic (the dominant traffic nowadays). In such a way, a simple and IP-adapted network architecture is desired. From the transport network perspective, both Generalized Multi-Protocol Label Switching (GMPLS) and Optical Burst Switching (OBS) technologies are part of the set of solutions to progress towards an IP-over-WDM architecture, providing intelligence in the control and management of resources (i.e. GMPLS) as well as a good network resource access and usage (i.e. OBS). The GMPLS framework is the key enabler to orchestrate a unified optical network control and thus reduce network operational expenses (OPEX), while increasing operator's revenues. Simultaneously, the OBS technology is one of the well positioned switching technologies to realize the envisioned IP-over-WDM network architecture, leveraging on the statistical multiplexing of data plane resources to enable sub-wavelength in optical networks. Despite of the GMPLS principle of unified control, little effort has been put on extending it to incorporate the OBS technology and many open questions still remain. From the IP network perspective, the Internet is facing scalability issues as enormous quantities of service instances and devices must be managed. Nowadays, it is believed that the current Internet features and mechanisms cannot cope with the size and dynamics of the Future Internet. Compact Routing is one of the main breakthrough paradigms on the design of a routing system scalable with the Future Internet requirements. It intends to address the fundamental limits of current stretch-1 shortest-path routing in terms of RT scalability (aiming at sub-linear growth). Although "static" compact routing works fine, scaling logarithmically on the number of nodes even in scale-free graphs such as Internet, it does not handle dynamic graphs. Moreover, as multimedia content/services proliferate, the multicast is again under the spotlight as bandwidth efficiency and low RT sizes are desired. However, it makes the problem even worse as more routing entries should be maintained. In a nutshell, the main objective of this thesis in to contribute with fully detailed solutions dealing both with i) GMPLS-OBS control interoperability (Part I), fostering unified control over multiple switching domains and reduce redundancy in IP transport. The proposed solution overcomes every interoperability technology-specific issue as well as it offers (absolute) QoS guarantees overcoming OBS performance issues by making use of the GMPLS traffic-engineering (TE) features. Keys extensions to the GMPLS protocol standards are equally approached; and ii) new compact routing scheme for multicast scenarios, in order to overcome the Future Internet inter-domain routing system scalability problem (Part II). In such a way, the first known name-independent (i.e. topology unaware) compact multicast routing algorithm is proposed. On the other hand, the AnyTraffic Labeled concept is also introduced saving on forwarding entries by sharing a single forwarding entry to unicast and multicast traffic type. Exhaustive simulation campaigns are run in both cases in order to assess the reliability and feasible of the proposals.

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22

Chen, Jiajia. "Design, analysis and simultion for optical access and wide-area networks". Doctoral thesis, KTH, Mikroelektronik och tillämpad fysik, MAP, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10348.

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Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks. Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost. Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack. Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++.
QC 20100707

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23

Sato, Ken-ichi, e Hiroshi Hasegawa. "Optical Networking Technologies That Will Create Future Bandwidth-Abundant Networks [Invited]". IEEE, 2009. http://hdl.handle.net/2237/13919.

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24

Nascimento, Luiz Henrique Bonani do 1977. "Proposta de arquitetura inovadora para redes de pacotes opticos baseadas em chaveamento fotonico". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260716.

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Orientadores: Edson Moschim, Felipe Rudge Barbosa
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-07T06:09:06Z (GMT). No. of bitstreams: 1 Nascimento_LuizHenriqueBonanido_D.pdf: 2297657 bytes, checksum: b04918af9ef98f4cae4bd6c3d6d4c0ca (MD5) Previous issue date: 2006
Resumo: Hoje em dia, como uma multiplicidade muito grande de tecnologias converge para as redes fotônicas, a demanda por vazão cresce. Os protocolos para acesso múltiplo e simultâneo às portas de entrada da rede, bem como a abordagem do formato dos pacotes fotônicos e a arquitetura das redes, são considerados como alternativas tecnológicas para a melhora do desempenho das redes fotônicas. Deste modo, apresenta-se aqui uma proposta para a arquitetura de redes fotônicas,utilizando topologias em malha otimizadas para que os pacotes atinjam seus respectivos nós de destino no menor número de hops possível, com nós de rede 2x2. Além disso, utiliza-se o roteamento por deflexão para a resolução de contenda entre pacotes ópticos, bem como buffers eletrônicos na entrada da rede óptica para evitar problemas de perdas de inserção. Além disso, a estrutura de rede permite hierarquização e também se propõe um modelo para o funcionamento do nó que faz a ligação entre hierarquias diferentes dentro da rede óptica. Esta arquitetura de rede é então avaliada quanto à sua capacidade de prover requisitos para QoS em termos de perdas de pacotes, atrasos e inversão de ordem de pacotes, para a qual é proposta uma heurística para uma avaliação quantitativa. Os resultados mostram que uma arquitetura nos moldes apresentados é capaz de prover ganhos de desempenho, oferecendo condições para a garantia de QoS, provida por protocolos de rede em nível superior, até cerca de 70% de carga
Abstract: Nowadays, as a multiplicity of technologies converges upon the optical network, the demand for throughput increases. The protocols for multiple and simultaneous access to network ports, as well as the optical packet approach should be considered as technological alternatives to optical network performance upgrade. Thus, we present here a new proposal to the architecture of optical packet networks, using mesh topologies optimized in such a way that the packets reach their respective destination nodes with the smaller possible number of hops, and using 2x2 network nodes. Besides, we use deflection routing to solve the contention between optical packets, as well as electronical buffers at the optical network input to prevent problems with insertion losses. The structure of the network also allows hierarchization, performing the link between different hierarchies on the optical network. The performance of the proposed architecture is evaluated by the capacity of providing requirements of QoS, in terms of packet losses, delays and the amount of out of order packets, for which is presented a heuristic to get a quantitative estimation. The results show that the proposed architecture is able to provide performance gains, giving conditions to guarantee some levels of QoS, which is done by the specific protocols of superior network layers, up to 70% of network load
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica

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25

Vikrant, Nikam. "Design and Performance Evaluation of Resource Allocation Mechanisms in Optical Data Center Networks". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198163.

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A datacenter hosts hundreds of thousands of servers and a huge amount of bandwidth is required to accommodate communication between thousands of servers. Several packet switched based datacenter architectures are proposed to cater the high bandwidth requirement using multilayer network topologies, however at the cost of increased network complexity and high power consumption. In recent years, the focus has shifted from packet switching to optical circuit switching to build the data center networks as it can support on demand connectivity and high bit rates with low power consumption. On the other hand, with the advent of Software Defined Networking (SDN) and Network Function Virtualization (NFV), the role of datacenters has become more crucial. It has increased the need of dynamicity and flexibility within a datacenter adding more complexity to datacenter networking. With NFV, service chaining can be achieved in a datacenter where virtualized network functions (VNFs) running on commodity servers in a datacenter are instantiated/terminated dynamically. A datacenter also needs to cater large capacity requirement as service chaining involves steering of large aggregated flows. Use of optical circuit switching in data center networks is quite promising to meet such dynamic and high capacity traffic requirements. In this thesis work, a novel and modular optical data center network (DCN) architecture that uses multi-directional wavelength switches (MD-WSS) is introduced. VNF service chaining use case is considered for evaluation of this DCN and the end-to-end service chaining problem is formulated as three inter-connected sub-problems: multiplexing of VNF service chains, VNFs placement in the datacenter and routing and wavelength assignment. This thesis presents integer linear programming (ILP) formulation and heuristics for solving these problems, and numerically evaluate them.
Ett datacenter inrymmer hundratusentals servrar och en stor mängd bandbredd krävs för att skicka data mellan tusentals servrar. Flera datacenter baserade på paketförmedlande arkitekturer föreslås för att tillgodose kravet på hög bandbredd med hjälp av flerskiktsnätverkstopologier, men på bekostnad av ökad komplexitet i nätverken och hög energiförbrukning. Under de senaste åren har fokus skiftat från paketförmedling till optisk kretsomkoppling for att bygga datacenternätverk som kan stödja på-begäran-anslutningar och höga bithastigheter med låg strömförbrukning. Å andra sidan, med tillkomsten av Software Defined Networking (SDN) och nätverksfunktionen Virtualisering (NFV), har betydelsen av datacenter blivit mer avgörande. Det har ökat behovet av dynamik och flexibilitet inom ett datacenter, vilket leder till storre komplexitet i datacenternätverken. Med NFV kan tjänstekedjor åstadkommas i ett datacenter, där virtualiserade nätverksfunktioner (VNFs) som körs på servrar i ett datacenter kan instansieras och avslutas dynamiskt. Ett datacenter måste också tillgodose kravet på stor kapacitet eftersom tjänstekedjan innebär styrning av stora aggregerade flöden. Användningen av optisk kretsomkoppling i datacenternätverk ser ganska lovande ut for att uppfylla sådana trafikkrav dynamik och hög kapacitet. I detta examensarbete, har en ny och modulär optisk datacenternätverksarkitektur (DCN) som använder flerriktningvåglängdsswitchar (MD-WSS) införs. Ett användningsfall av VNF-tjänstekedjor noga övervägd för utvärdering av denna DCN och end-to-end-servicekedjans problem formuleras som tre sammankopplade delproblem: multiplexering av VNF-servicekedjor, VNF placering i datacentret och routing och våglängd uppdrag. Denna avhandling presenterar heltalsprogrammering (ILP) formulering och heuristik för att lösa dessa problem och numeriskt utvärdera dem.

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Sathyan, Saju. "All Optical Switching Architectures". Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-253.

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In communication systems, the need for high bandwidth interconnects and

efficient distribution of large amount of data is very essential. This thesis work

addresses all-optical packet switching issues in the field of reconfigurable optical

interconnection networks for high performance embedded systems. The recent

research conducted at the Halmstad University, on high performance embedded

systems, focuses on the optical interconnection techniques to achieve ultra high

throughputs and reconfigurability at the system level.

Recent research in the field of optical interconnection networks for applications

like switches and routers for data and telecommunication industry and parallel

computing architectures for embedded signal processing use optical to electrical

conversion to switch packets. This conversion scales down the enormous bandwidth

capacity of the optical communication channels to electronic processing rates. To

maintain the high throughputs all over the interconnection networks, the optical

packets need to be maintained in optical state and switched to different part of the

interconnection network. To achieve this goal, all-optical packet switching

architectures are studied. The study is concluded with a positive outlook towards alloptical

switching technologies, and it will play a very important role in the near

future in the field of optical communication, telecommunication and embedded

systems.

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27

Reis, Cláudia Sofia Marcos Machado. "All-optical routing functionalities". Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/12865.

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Doutoramento em Engenharia Eletrotécnica
All-optical solutions for switching and routing packet-based traffic are crucial for realizing a truly transparent network. To meet the increasing requirements for higher bandwidth, such optical packet switched networks may require the implementation of digital functions in the physical layer. This scenario stimulated us to research and develop innovative high-speed all-optical storage memories, focusing mainly on bistables whose state switching is triggered by a pulsed clock signal. In clocked devices, a synchronization signal is responsible for controlling the enabling of the bistable. This thesis also presents novel solutions to implement optical logic gates, which are basic building blocks of any processing system and a fundamental element for the development of complex processing functionalities. Most of the proposed schemes developed in this work are based on SOA-MZI structures due to their inherent characteristics such as, high extinction ratio, high operation speed, high integration capability and compactness. We addressed the experimental implementation of an all-optical packet routing scheme, with contention resolution capability, using interconnected SOAMZIs. The impact on the system performance of the reminiscent power of the blocked packets, from the non ideal switching performed by the SOA-MZIs, was also assessed.
As soluções totalmente óticas para a comutação e encaminhamento de pacotes de tráfego são cruciais para a realização de uma rede verdadeiramente transparente. Para atender às exigências crescentes de maior largura de banda, tais redes de comutação de pacotes óticos exigem a implementação de funções digitais na camada física. Este cenário estimulou-nos a investigar e a desenvolver memórias totalmente óticas, focando-nos principalmente na implementação de flip-flops óticos síncronos, cujo estado de comutação é accionado por um sinal de relógio. Esta tese também apresenta novas soluções para implementar portas lógicas óticas, visto estas serem um elemento fundamental para o desenvolvimento de funcionalidades complexas de processamento. A maioria dos esquemas propostos neste trabalho são baseados em estruturas interferométricas activas Mach-Zehnder (SOA-MZI) devido às suas características intrínsecas, nomeadamente, razão de extinção elevada bem como elevada capacidade de integração. A implementação experimental de um sistema de encaminhamento de pacotes totalmente ótico foi realizada usando cascatas de SOA-MZIs. O impacto da potência residual, devido à comutação não ideal dos SOA-MZIs, foi também analisado.

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28

Le, Dinh Danh. "All-Optical Multicast Routing under Optical Constraints". Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS214/document.

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Au cours de la dernière décennie, le trafic dans les réseaux a connu une croissance explosive en double environ tous les trente trois mois. Les sources à l'origine de cette croissance proviennent de nombreuses applications à grande vitesse qui impliquent la transmission de données dans des groupes de multicast. Pour réaliser la multicast optique, les routeurs optiques peuvent avoir des répartiteurs de lumière spéciaux pour diviser des signaux lumineux et des convertisseurs de longueur d'onde pour modifier les longueurs d'onde où c'est nécessaire. Cependant, la division réduit l'énergie du signal qui nécessite alors une amplification ou une régénération qui nécessitent du matériel coûteux. Les convertisseurs de longueurs d'onde aussi ne sont pas suffisamment matures pour être largement déployés dans les technologies optiques actuelles. Par conséquent, dans les réseaux tout-optique, les unités de transformation des routeurs sont souvent hétérogènes et les algorithmes de routage doivent en tenir compte tout en parvenant à des solutions de compromis coût-performances qui satisfassent les exigences de bande passante et les contraintes optiques.Dans cette thèse, nous étudions les problème de routage multicast tout-optique (AOMR) dans les réseaux tout-optique hétérogènes. L'hétérogénéité provient principalement de l'absence / présence de séparateurs de lumière et de convertisseurs de longueur d'onde et de la répartition inégale des longueurs d'onde dans les liens du réseau. En général, les problèmes de AOMR sont NP-difficiles. L'objectif de la thèse est d'analyser et de formuler les problèmes sous différentes contraintes optiques, pour rechercher des solutions optimales ou proposer des heuristiques efficaces. Les deux contextes possibles, la demande unique ou multiple de multicast, sont examinés. Toutes les propositions présentées dans la thèse sont validées par des simulations approfondies. Les principales contributions peuvent être résumées comme il suit.1) Nous identifions les structures des routes optimales pour les problèmes de l'AOMR dans les réseaux WDM hétérogènes. Comme indiqué dans la thèse, les solutions optimales ne sont plus basées sur des arbres de lumière classiques, mais sur une structure arborescente plus générale appelée hiérarchie. Certaines formes de hiérarchie pour la multicast WDM sont des parcours optiques, des hiérarchies optiques, des hiérarchies-araignée optiques ou encore des ensembles de ces routes optiques. Les algorithmes exacts et les heuristiques proposés dans la thèse sont principalement basés sur les hiérarchies.2) Dans le cas du problème de multicast avec une seule demande dans des réseaux partiellement équipés de diviseurs de lumière, nous proposons une heuristique efficace dont les résultats font le compromis entre la consommation de longueur d'onde, le coût total, et le délai de bout-en-bout.3) Dans le même cas mais dans des réseaux non équipés de diviseurs de lumière, nous prouvons la NP-difficulté, exprimons les problèmes au moyen d'un programme linéaire (ILP) pour trouver les solutions exactes et proposons plusieurs heuristiques pour calculer de bonnes solutions.4) Pour le cas de demandes multicast multiples, nous nous concentrons sur les modèles de trafic statiques dans des réseaux partiellement équipés de diviseurs mais sans convertisseurs de longueur d'onde. Tout d'abord nous proposons une formulation ILP sur la base de hiérarchies optiques afin de rechercher la solution optimale. Ensuite, utilisant un modèle de graphe en couches, nous développons plusieurs heuristiques adaptatives pour calculer des hiérarchies optiques de solutions approximatives. Ces algorithmes adaptatifs surpassent les techniques de routage existants pour minimiser la probabilité de blocage.Dans l'ensemble, la thèse souligne que les solutions optimales pour les problèmes de l'AOMR considérés correspondent à des hiérarchies, que ce soit pour une seule demande ou des demandes multiples
Over the past decade, network traffic levels experienced an explosive growth at about double amount in approximately every thirty months. The sources accounting for this growth come from numerous high-speed applications (e.g., video-on-demand, high-definition television) which involve the data transmission in multicast groups. To realize optical multicasting, optical routers should have light splitters to split light signals and wavelength converters to change the wavelengths wherever needed. However, the splitting reduces the energy of the output signal which in turn requires the costly power amplification or regeneration. Wavelength converters are also immature to be deployed widely in current optical technologies. Consequently, in all-optical networks, routers are often heterogeneous in their processing units, which challenges the routing. Therefore, it is crucial to design efficient multicast routing strategies at the backbone optical networks, in order to achieve cost-performance tradeoff solutions while satisfying the ever-increasing bandwidth demands and optical constraints.In this thesis, we investigate the all-optical multicast routing (AOMR) problems in heterogeneous optical networks. The heterogeneity mainly comes from the absence/presence of light splitters and wavelength converters and the uneven distribution of wavelengths in the network links. In general, AOMR problems are often NP-hard. The objective of the thesis is to analyze and formulate the problems, to search for the optimal solutions, and to propose efficient heuristics to solve the problems under different optical constraints. Both possible contexts, i.e., single-multicast request and multiple-multicast requests, are examined. All the reported results in the thesis are supported by extensive and careful simulations. The major contributions can be summarized as follows.1) We identify the optimal route structures for AOMR problems under heterogeneous mesh WDM networks. As shown in the thesis, the optimal solutions are no longer based on conventional light-trees, but a more general tree-like structure called hierarchy. Some forms of hierarchy realized for WDM multicasting are light-trails, light-hierarchies, light-spider hierarchies and a set of these light-structures. The exact and heuristic algorithms proposed in the thesis are mainly based on hierarchy. 2) For single-multicast with sparse-splitting case, we propose an efficient heuristic algorithm to produce a good tradeoff solution among wavelength consumption, channel total cost and end-to-end delay.3) For single-multicast with non-splitting case, we prove the NP-hardness, identify the optimal solution as a set of light-spider hierarchies, formulate the problems by means of Integer Linear Program (ILP) formulations to find the exact solution, and propose several cost-effective heuristic algorithms to compute the approximate solutions. 4) For the case with multiple-multicast requests, we focus on static traffic patterns under sparse-splitting without wavelength conversion case. First, an ILP formulation based on light-hierarchies is proposed to search for the optimal solution. By applying the layered graph model, we then develop several adaptive heuristic algorithms to compute light-hierarchies for approximate solutions. These adaptive algorithms outperform the existing fixed routing ones in minimizing the blocking probability. Overall, the thesis points out that the optimal solutions for heterogeneously constrained AOMR problems correspond to hierarchies, regardless of request multiplicity consideration

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29

Barry, Richard A. "Wavelength routing for all-optical networks". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12508.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.
Includes bibliographical references (p. 171-176).
by Richard A. Barry.
Ph.D.

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30

Chai, Yue. "Nonlinear propagation of unconventional beams in a photorefractive crystal". Electronic Thesis or Diss., CentraleSupélec, 2024. http://www.theses.fr/2024CSUP0005.

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La thèse explore l'étude de la propagation et de l'interaction des faisceaux de Bessel non conventionnels dans un cristal photoréfractif (PR), en se penchant sur les technologies clés des communications optiques avancées. Cette thèse se divise en deux parties : la photo-inscription des guides d'ondes et la modulation des modes OAM. Premièrement, notre étude démontre qu'un seul faisceau de Bessel diffractant peut inscrire plusieurs guides d'ondes couplés dans le cristal PR en raison de ses profils en anneaux. En manipulant les paramètres optiques de notre plateforme optique, il est possible d'obtenir un contrôle flexible. Ces configurations permettent la réalisation de fonctions de routage complexe en optique. De plus, l'introduction d'un deuxième faisceau contra- propageant permet d'induire des guides d'ondes dynamiques, démontrant ainsi la possibilité de contrôle dans différents régimes. Deuxièmement, il est démontré que l'OAM d'un faisceau de Bessel polarisé de manière arbitraire peut être continuellement modulé par un champ électrique appliqué au matériau PR pour activer sa non-linéarité. Ensuite, des paramètres optimaux sont confirmés pour une plage de modulation en régime stable. Nous montrons également que l'OAM peut être modulé dans des conditions de non-linéarité très élevées, permettant ainsi d'étendre l'intervalle de modulation. Ces résultats offrent des perspectives prometteuses pour le développement de nouvelles technologies dans les domaines des composants passifs et dynamiques pour les communications tout-optiques ou quantiques
The thesis focuses on the propagation of Bessel beams in a photorefractive crystal, involving technologies used in advanced optical communications, such as the all-optical router, switcher, mode multiplexing and demultiplexing using orbital angular momentum (OAM). The work is in two parts: the photo-inscription of waveguides and the modulation of OAM modes. In the first part, we demonstrate numerically and experimentally that a single diffracting Bessel beam can induce complex waveguides under the PR effect. In addition, by manipulating the parameters of our optical platform, we achieve flexible control of the induced waveguides’ characteristics. By testing these photo-induced waveguides using Gaussian probe beams, we confirm their complex routing functions. Furthermore, by introducing the second counter-propagating beam, we induce dynamic waveguides and demonstrate the control in any regime. In the second part, we demonstrated in simulations and experiments that the OAM of an arbitrarily polarized Bessel beam can be continuously modulated in the PR crystal by the applied electric field. By discussing parameter, we confirm optimal parameters to obtain the broadest modulation range in the steady state. We propose temporal plateaux long enough on which the OAM exceeds its initial value, thus enabling the extension of the OAM modulation range, even in the unstable regime. All the results in this thesis open up promising prospects for developing new technologies in all-optical or quantum communications

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31

Pegg, Steven Ian. "All-optical switching in semiconductor laser devices". Thesis, University of Essex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324237.

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32

Matres, Abril Joaquín. "Ultrafast, CMOS compatible, integrated all optical switching". Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/37984.

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El proyecto consistirá en implementar funcionalidades fotónicas avanzadas sobre silicio tales como conmutación ultra rápida o la realización de puertas lógicas todo ópticas. Para ello se emplearán efectos no lineales del silicio basados en el efecto Kerr, producido por el coeficiente no lineal de tercer orden chi(3) .Los dispositivos deberán funcionar al menos a 40Gbps para que sean competitivos con los dispositivos actuales de última generación. También deberán ser compatibles con tecnología CMOS, lo cual es crucial para que la fabricación se pueda realizar a gran escala a precios competitivos.
Matres Abril, J. (2014). Ultrafast, CMOS compatible, integrated all optical switching [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/37984
TESIS

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33

Almeida, Paulo Jorge dos Santos. "Novel all-optical switching and processing techniques for optical networking". Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/46857/.

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In this thesis, the possibility of processing optical time-division multiplexing (OTDM) signals in both the temporal and spectral domains is investigated. The technique relies on the conversion of high-speed OTDM signals into a mixed time and wavelength division multiplexing (TDM-WDM) format. Depending on the specific network function, it may be advantageous to process the signal in one rather than the other domain. For example, channel add/drop multiplexing can be performed directly by passive filtering in the spectral domain. An investigation into the switching of the linearly-chirped pulses in a nonlinear optical loop mirror (NOLM) revealed that the product of the control-pulse duration and the chirprate of the linearly-chirped pulse should be above a minimum value to ensure a one-to-one relation between the temporal and spectral waveforms after the switching. Below this minimum value, severe spectral distortion of the mixed TDM-WDM signal was observed. The physics behind this distortion is unveiled and shown to be related to the interference between the spectral content in the switched pulse and the unavoidable residual components of the linearly-chirped pulse transmitted through the NOLM switch. These effects were identified in experiments which aimed at compressing/expanding waveforms at 40Gb/s by control of the group delay of the converted TDM-WDM signal in a dispersive medium. Apart from the packet compression/expansion experiments, demultiplexing and channel add/drop multiplexing of 40-Gb/s OTDM signals were also experimentally demonstrated. The technological challenges of implementing this technique at higher repetition rates are discussed.

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34

Borrero-Molina, Armando. "Simulation of all-optical networks with deflection routing". Versailles-St Quentin en Yvelines, 2004. http://www.theses.fr/2004VERS0021.

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Dans ce travail de recherche, nous avons développé un simulateur pour les réseaux tout-optique, qui utilise une stratégie de routage par déflexion. La topologie choisie dans notre modèle est un réseau en grille 2D, principalement en raison de la simplicité pour sa mise en forme et de son approche à une topologie réelle. La taille du réseau modélisé est 10 x 10, en prenant en considération que notre réseau est du type "Core Network". Nous avons prouvé un algorithme distribué qui déflecte le plus petit nombre de paquets dans chaque noeud du réseau. Nous l'avons appelé Algorithme de Déflexion Minimal et nous avons évalué ses performances dans un réseau tout optique. Chaque noeud essaie d'envoyer les paquets à leur route optimale, au plus court chemin à leur destination, le chemin avec le nombre minimum de deflexions. Nous avons développé aussi un autre algorithme de routage par deflection qui essaye de faire, une minimisation globale sur tout le parcours des paquets, et nous l'avons appelé Routage Escalier. Nous avons mis en parallèle notre simulateur et nous avons mis en place un simulateur distribué afin d'obtenir de meilleurs temps d'exécution, pour exécuter des problèmes plus grands. Nous avons aussi développé quelques Contrôles d'Access aux réseaux, dans le but de contrôler le flux d'entrée des paquets au réseau, améliorer les performances du temps de transport et contrôler la charge pour offrire diverses Qualités de Service
In this work, we hâve developed an aU-optical networks simulator, that uses a deflection routing method. The chosen topology for our rnodel is a 2D grid network, mainly because of its simplicity of implementation and its approach to a real topology. The size of thé modèle network is 10x10. We hâve considered this size, taking in considération that our network is of thé type "Core Network". We hâve proved a distributed algorithm that deflects thé smaltest number of customers in every node of thé net. We hâve called it Minime Deflection Algorithm and we hâve evaluated its performances in an all-optical network. Every node attempts to send thé packets to theirs optimal routes, to thé shortest hop path to their destination, thé path with thé minimum number of deflections. We hâve also developed another deflection routing algorithm that does a gtobal minimization on thé packets route, and we hâve called it, Scate Routing Algorithm. We hâve paralleled our simulator and we hâve imptemented a distributed simulator in order to obtain better exécution times, with thé intention of decrease thé exécution time and to run bigger problems, this is, to exécute thé simulator with bigger values of thé arrivai rate or bigger simulation times, bigger number of hops. We hâve also developed some Network Access Controls, in order to central thé input networks flow, to central thé load to offer diverse types of Quality of Service and to improve thé time transport performances

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35

Robinson, Bryan S. (Bryan Shawn) 1975. "Semiconductor-based all-optical switching for optical time-division multiplexed networks". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17590.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
Includes bibliographical references.
All-optical switching will likely be required for future optical networks operating at data rates which exceed electronic processing speeds. Switches utilizing nonlinearities in semiconductor optical amplifiers (SOA) are particularly attractive due to their compact size, low required switching energies, and high potential for integration. In this dissertation we investigate the practical application of such semiconductor-based all-optical switches in next-generation optical networks. We present both theoretical and experimental studies of SOA-based interferometric switches. A detailed numerical model for the dynamic response of an SOA to an intensity-modulated optical signal is described. The model is validated using novel pump-probe techniques to measure the time-domain response of an SOA subject to various levels of saturation. The model is then used to evaluate the performance of three common SOA-based interferometric all-optical switches. The use of SOAs in optical transmission systems has been limited due to the deleterious effects of pattern-dependent gain saturation. We develop a statistical model to study the system impact of variations of the SOA optical gain in response to a random intensity-modulated optical signal. We propose the use of pulse-position modulation (PPM) as a means for mitigating gain saturation effects in SOA-based optical processors. We present techniques for modulation and detection of optical PPM signals at data rates in excess of 100 Gbit/s. We demonstrate demultiplexing, wavelength conversion, and format conversion of optical PPM signals at data rates as high as 80 Gbit/s. Finally, we report on experimental demonstrations of an optical interface for slotted OTDM networks.
(cont.) We implement head-end and transmitter nodes capable of producing fully loaded optical slots at an aggregate network data rate of 112.5 Gbit/s. We demonstrate a fully functional receiver node which utilizes semiconductor-based all-optical logic for synchronization, address processing, and rate conversion.
by Bryan S. Robinson.
Ph.D.

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36

Jaques, Stuart Roland. "A TLM analysis of an all-optical switching device". Thesis, University of Hull, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363266.

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37

Evans, Ivan. "Nonlinearities and all-optical switching in semiconductor laser amplifiers". Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325471.

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38

Robinson, Bryan S. (Bryan Shawn) 1975. "All-optical switching using semiconductor amplifiers biased at transparency". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/28194.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (leaves 99-106).
by Bryan S. Robinson.
M.Eng.

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39

Cheney, Glenn P. (Glenn Peter) Carleton University Dissertation Engineering Electrical. "All-optical gain switching of erbium-doped fibre amplifiers". Ottawa, 1992.

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40

Ikeda, Kazuhiro. "All-optical nonlinear switching in optical micro-resonators on a silicon chip". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3335615.

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Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed December 11, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 98-104).

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41

Bickel, Nathan. "ELECTRO-OPTICAL AND ALL-OPTICAL SWITCHING IN MULTIMODE INTERFERENCE WAVEGUIDES INCORPORATING SEMICONDUCTOR NANOSTRUCTURES". Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2977.

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The application of epitaxially grown, III-V semiconductor-based nanostructures to the development of electro-optical and all-optical switches is investigated through the fabrication and testing of integrated photonic devices designed using multimode interference (MMI) waveguides. The properties and limitations of the materials are explored with respect to the operation of those devices through electrical carrier injection and optical pumping. MMI waveguide geometry was employed as it offered advantages such as a very compact device footprint, low polarization sensitivity, large bandwidth and relaxed fabrication tolerances when compared with conventional single-mode waveguide formats. The first portion of this dissertation focuses on the characterization of the materials and material processing techniques for the monolithic integration of In0.15Ga0.85As/GaAs self-assembled quantum dots (SAQD) and InGaAsP/InGaAsP multiple quantum wells (MQW). Supplemental methods for post-growth bandgap tuning and waveguide formation were developed, including a plasma treatment process which is demonstrated to reliably inhibit thermally induced interdiffusion of Ga and In atoms in In0.15Ga0.85As/GaAs quantum dots. The process is comparable to the existing approach of capping the SAQD wafer with TiO2, while being simpler to implement along-side companion techniques such as impurity free vacancy disordering. Study of plasma-surface interactions in both wafer structures suggests that the effect may be dependent on the composition of the contact layer. The second portion of this work deals with the design, fabrication, and the testing of MMI switches which are used to investigate the limits of electrical current control when employing SAQD as the active core material. A variable power splitter based on a 3-dB MMI coupler is used to analyze the effects of sub-microsecond electrical current pulses in relation to carrier and thermal nonlinearities. Electrical current controlled switching of the variable power splitter and a tunable 2 x 2 MMI coupler is also demonstrated. The third part of this dissertation explores the response of In0.15Ga0.85As/GaAs SAQD waveguide structures to photogenerated carriers. Also presented is a simple, but effective, design modification to the 2 x 2 MMI cross-coupler switch that allows control over the carrier distribution within the MMI waveguide. This technique is combined with selective-area bandgap tuning to demonstrate a compact, working, all-optical MMI based switch.
Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD

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42

Born, Brandon. "Photonic architectures for ultrafast all-optical switching and retro-modulation". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63851.

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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

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43

Loka, Hany. "Ultrafast all-optical switching using low-temperature-grown gallium arsenide". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41462.pdf.

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44

Lambert, Charles-Henri. "All-Optical Helicity dependent switching effect in magnetic thin films". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0091/document.

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Depuis une quinzaine d’années, de nombreuses solutions différentes ont été proposés afin de modifier l’aimantations de matériaux sans aucun champ magnétique extérieur appliqué. La manipulation d’aimantation à moindre coût énergétique, de préférence à des échelles de temps ultracourtes, est devenu un enjeu fondamental avec des implications pour les technologies d’enregistrement magnétique et de nouvelles sortes de stockage. Sur ce chemin, le type d’interaction découverte par Stanciu et al. ouvre la voie à l’utilisation de la lumière comme moyen d’exciter et de sonder directement les matériaux magnétiques. La description des théories et modèles existants dans ce domaine permet de nous rendre attentif sur les différents paramètres impliqués par l’interaction des lasers ultrarapides et matériaux magnétiques. L’entrelacement spécifique des impulsions de chaleur et de moment angulaire propre aux lasers ultrarapides est mise en avant afin de discuter de leur rôle dans les phénomènes observés. Le délai des interactions responsables de l’état final de l’aimantation est abordé et notamment la manière dont celle-ci ont un impact sur la façon dont le système se stabilise après une excitation laser. En outre, nous nous sommes intéressés à la relation entre les paramètres matériels et l’état final de l’aimantation obtenue avec un laser ultrarapide. Grâce aux nombreuses classes de matériaux magnétiques existantes les paramètres magnétiques peuvent être ajustés dans une grande gamme de valeurs et de manière entièrement contrôlés. Notre installation d’imagerie magnétique est alors capable de sonder les caractéristiques optiques et la stabilité des domaines après l’excitation. Nous avons finalement démontré que le retournement optique dépendent de l’hélicité peut être observée non seulement dans un grand nombre de couches minces d’alliages de terre rare-métaux de transition (RE-TM) mais aussi dans une variété beaucoup plus large de matériaux, y compris les multicouches et hétérostructures de RE-TM. Nous montrons en outre que les hétérostructures ferrimagnétiques dépourvues de terres rares présentent également un retournement optique. Nous avons en plus développé le contrôle optique de multicouches ferromagnétiques dont des films granulaires actuellement explorés pour l’enregistrement magnétique ultra-haute densité de demain. Notre découverte montre que la manipulation de l’aimantation dans des matériaux magnétiques est un phénomène beaucoup plus général que précédemment suspecté et peut avoir un impact majeur sur l’enregistrement magnétique et le stockage de l’information grâce à l’intégration nouvelle de ce type de contrôle optique dans des bits ferromagnétiques
The possibilities of modifying magnetization without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. In particular the interplay of laser and magnetism recently discovered by Stanciu et al. opens up new way for light to be used as an excitation and a probe of magnetic materials. A description of the current models and frameworks developed in the field requires a careful look at the different parameters involved through the interaction of ultrafast lasers and magnetic materials. The specific and complex interplay between heat and angular momentum transfer is highlighted in order to discuss the role of each of them in the phenomena observed. The timescales of the different interactions responsible for the final state of magnetization are presented and will impact the way the system recovery after a laser excitation. Besides we were interested in exploring the relation between the material parameters such as anisotropy, ordering temperature and exchange coupling on the final state of magnetization obtained with a laser. Indeed thanks to the many different magnetism classes existing the magnetic parameters can be tuned widely and in a controlled manner. Our imaging setup then is able to probe the optical characteristics and domain stability after the laser excitation. We finally demonstrated that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. We further developed the optical control of ferromagnetic materials ranging from magnetic thin films to multilayers and even granular films being explored for ultra-high-density magnetic recording. Our finding shows that optical control of magnetic materials is a much more general phenomenon than previously assumed and may have a major impact on data memory and storage industries through the integration of optical control of ferromagnetic bits

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45

Hadri, Mohammed Salah El. "Magnetization reversal mechanism leading to all-optical helicity-dependent switching". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0107/document.

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Le contrôle de l’aimantation sans application de champ magnétique externe est un domaine de recherche en plein essor, étant prometteur pour les applications technologiques d’enregistrement magnétique et de spintronique. En 2007, Stanciu et al. ont découvert la possibilité de retourner l’aimantation dans un film fait d’alliage ferrimagnétique de GdFeCo en utilisant des impulsions laser femtoseconde. Longtemps cantonné aux alliages de GdFeCo, ce retournement tout-optique s’avère un phénomène plus général, puisqu’il a été mesuré plus récemment dans une large variété de matériaux ferrimagnétiques et ferromagnétiques. Cette découverte a ainsi ouvert la voie à l’intégration de l’écriture tout-optique dans l’industrie des mémoires magnétiques. Néanmoins, l’ensemble des modèles théoriques expliquant le retournement tout-optique dans le GdFeCo ne semblent pas s’appliquer aux autres matériaux magnétiques, mettant ainsi en question l’unicité de l’origine microscopique de ce phénomène. Au cours de cette thèse, nous avons étudié la réponse aux impulsions laser femtoseconde des alliages ferrimagnétiques et des multicouches ferromagnétiques, dans l'objectif d'élucider divers aspects du mécanisme du retournement optique. Nous avons élucidé expérimentalement les paramètres magnétiques gouvernant le retournement tout-optique. Nous avons montré que l’observation du retournement tout-optique nécessite des domaines magnétiques plus grands que la taille du faisceau laser pendant le processus de refroidissement, un critère qui est commun à la fois aux matériaux ferrimagnétiques et ferromagnétiques. En outre, nous nous sommes intéressés à l’intégration du retournement tout-optique dans des dispositifs de spintronique. Grâce à une caractérisation temporelle de l’aimantation dans des croix de Hall via l’effet Hall extraordinaire, nous avons distingué entre deux types de mécanismes du retournement optique. Le premier type est un retournement purement thermique obtenu avec une impulsion unique dans les alliages ferrimagnétiques de GdFeCo, tandis que le deuxième type est un retournement cumulative et à deux régimes dans les alliages ferrimagnétiques de TbCo et les multicouches ferromagnétiques de Co/Pt. Ce dernier consiste en une formation indépendante de l’hélicité de multidomaines magnétiques suivie d'une ré-aimantation dépendante de l'hélicité sur plusieurs dizaines de millisecondes
The control of magnetization without external magnetic fields is an emergent field of research due to the prospect of impacting many technological applications such as magnetic recording and spintronics. In 2007, Stanciu et al. discovered an intriguing new possibility to switch magnetization in a ferrimagnetic GdFeCo alloy film using femtosecond laser pulses. This all-optical switching of magnetization had long been restricted to GdFeCo alloys, though it turned out to be a more general phenomenon for a variety of ferromagnetic and ferromagnetic materials. This discovery paved the way for an integration of the all-optical writing in storage industries. Nevertheless, the theoretical models explaining the switching in GdFeCo alloys films do not appear to apply in the other materials, thus questioning the uniqueness of the microscopic origin of all-optical switching. In this thesis, we have investigated the response of femtosecond laser pulses in ferrimagnetic alloys and ferromagnetic multilayers to the action of femtosecond laser pulses, in order to elucidate several aspects of the all-optical switching mechanism. We have experimentally studied the magnetic parameters governing the all-optical switching. We showed that the observation of all-optical switching requires magnetic domains larger than the laser spot size during the cooling process; such a criterion is common for both ferrimagnets and ferromagnets. Furthermore, we have investigated the integration of all-optical switching in spintronic devices via the anomalous Hall effect. Through a time-dependent electrical investigation of the magnetization in Hall crosses, we distinguished between two types of all-optical switching mechanisms. The first type is the single-pulse helicity-independent switching in ferrimagnetic GdFeCo alloy films as shown in previous studies, whereas the second is a two regimes helicity-dependent switching in both ferrimagnetic TbCo alloys and ferromagnetic Co/Pt multilayers. The latter consists in a step-like helicity-independent multiple-domain formation followed by a helicity-dependent remagnetization on several tens of milliseconds

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46

Day, Ian Edward. "All-optical nonlinearities in semiconductor multi-quantum well waveguides for optical switching at 1.55μm". Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760675.

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47

Kim, Dug Young. "Interferometric measurements of nonlinear optical properties for all optical switching applications in dielectric waveguides". Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186968.

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The successful implementation of nonlinear devices, for example for all-optical switching, depends critically on the availability of appropriate nonlinear optical materials. Most of the currently used methods to measure optical nonlinearities of materials are either indirect or inadequate for separating the fast electronic effects from slow thermo-optic processes. The motivation of this Ph.D. research was to develop a direct and accurate measurement method to evaluate the nonlinear optical properties of various, recently available waveguide materials for all-optical switching applications. A pulse modulated Mach-Zehnder scanning interferometer was built and revised to obtain a resolution of π/100 for nonlinear phase measurements. The evolution of this instrument included the development of single pulse extraction from a mode-locked pulse train, intensity modulation of single pulses, numerical Hilbert transformation of fringe data set, mode profile calculation inside waveguides with a numerical Fourier method, and a careful study of pulse breakup effect associated with instantaneous nonlinear phase shift. Electronic and thermal nonlinear refractive indices of various newly developed materials, especially DANS channel waveguides, DAN single crystal fibers, LiNbO₃ channel waveguide were examined with this method at the 1.32 μm wavelength. For the DAN single crystal cored fibers, the physical origin of the exceptionally large nonlinear phase changes in single crystal fibers was identified to be the cascading of two second order nonlinear processes. In the LiNbO₃ waveguide, cascaded nonlinear phase changes near the second harmonic phase matching temperature were demonstrated for the first time. Based on the results above, single crystal organic fibers appear very promising for ultrafast all optical switching applications. This demonstrates that the interferometric measurement method based on a scanning pulse modulated Mach-Zehnder Interferometer has proven to be one of the best methods for identifying nonlinear materials for all-optical switching applications at the 1.32 μm communications wavelength.

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48

Patel, Naimish S. (Naimish Sanjay). "High speed all-optical switching based on a single-arm interferometer". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38806.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (leaves 125-133).
by Naimish S. Patel.
M.Eng.

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49

Yang, Michael C. H. "SUBPECOSECOND ALL OPTICAL SWITCHING IN A POLYMERIC ONE-DIMENSIONAL PHOTONIC CRYSTAL". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1154013496.

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50

DeLong, Kenneth Wayne. "Two-photon absorption and color centers: Effects on all-optical switching". Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185023.

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This dissertation explores the effects of two-photon absorption and color center induced absorption on all-optical switching devices. The amount of allowable two-photon absorption was quantified by the parameter T = 2βλ/n₂, where λ is the operating wavelength, β is the two-photon absorption coefficient, and n₂ is the nonlinear refractive index coefficient, the latter two being measured at λ. If the value of T exceeds unity, the operation of all-optical switching devices is in general degraded beyond usable regimes. This result was demonstrated by numerical experiments on systems of equations modelling a nonlinear directional coupler, a prototypical all-optical switching device. The value of T was measured in two fibers, one made of lead silicate glass, and one made of TiO₂-doped silica. We find the value of T to be greater than unity at a wavelength of 1.06 μm in both fibers. Significant color center formation was seen in the lead glass fiber. These color centers were created through two-photon absorption and destroyed through one-photon absorption. Color center induced absorption was seen to mimic two-photon absorption in certain regimes. The nonlinear optical response of semiconductor-doped glasses, an example of a one-photon resonant nonlinearity, was studied. A relaxation time which is dependent on the carrier density was found to be important when modelling the response of these glasses.

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Tesi sul tema "All-optical routing and switching"

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