Dissertations / Theses on the topic 'Optical switche'
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1
Branč, Martin. "Media konvertory a optické switche." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218967.
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This Master´s thesis provides an overview of wired networks, its parameters, used standards and the deployment possibilities. Moreover, it includes the overall overview about optical networks, its parameters, maximum bandwidth, reachable distances as well as the advantages and disadvantages in comparition with wired networks. The project describes network elements which are used in the optical access network such as media convertors, optical switches etc. The practical part includes results of testing of the network devices in various scenarios. To get a comparable result, the real throughput, the power of each device and compatibility of devices from different producers were measured. At the end I have suggested few scenarios with the usage of optical switches and media convertors for extension of the current optical network. The calculation of costs for building and operation of the network is also included.
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Rossek, Sacha J. "Direct optical control of a microwave phase shifter using GaAs field-effect transistors." Thesis, Middlesex University, 1995. http://eprints.mdx.ac.uk/10682/.
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The design and analysis of a novel optical-to-microwave transducer based upon direct optical control of microwave gallium arsenide (GaAs) field-effect transistor (FET) switches is the subject of this thesis. The switch is activated by illuminating the gate depletion region of the FET device with laser light having a photon energy and wavelength appropriate to the generation of free carriers (electron-hole pairs) within GaAs. The effects of light on the DC and microwave properties of the GaAs FET are explored and analyzed to permit the characterization of the switching performance and transient response of a reflective microwave switch. The switch is novel in that it utilizes direct optical control, whereby the optically controlled GaAs FET is directly in the path of the microwave signal and therefore relies on optically-induced variations in the microwave characteristics of the switch. This contrasts with previous forms of optically controlled switches which rely on indirect methods with the optical stimulus inducing variations in the DC characteristics of the GaAs FET, such that there is no direct interaction between the optically illuminated GaAs FET and the microwave signal. Measured and simulated results relating to the switching performance and transient response of the direct optically controlled microwave switch have been obtained and published as a result of this work. For the first time, good agreement is achieved between the measured and simulated results for the rise and fall times associated with the transient response of the gate photovoltaic effect in optically controlled GaAs FET switches. This confirms that the GaAs FET, when used as an optically controlled microwave switch, has a transient response of the order of several micro-seconds. An enhanced model of the GaAs FET switch has been developed, which represents a more versatile approach and leads to improved accuracy in predicting switching performance. This approach has been shown to be valid for both optical and electrical control of the GaAs FET. This approach can be used to model GaAs FET switches in discrete or packaged forms and predicts accurately the occurrence of resonances which may degrade the switch performance in both switching states. A novel method for tuning these resonances out of the switch operating band has been developed and published. This allows the switch to be configured to operate over the frequency range 1 to 20 GRz. The agreement between the models and measured data has been shown to hold for two very different GaAs FET structures. The results of the direct optically controlled microwave GaAs FET switch have been used as the basis for the design of a novel direct optically controlled microwave phase shifter circuit; Measured and simulated results are in good agreement and verify that the performance of the optically controlled phase shifter is comparable with previously published results for electrically controlled versions of the phase shifter. The 10 GRz phase shifter was optically controlled over a 1 GRz frequency range and exhibited a mid-band insertion loss of 0.15 dB. The outcome of the work provides the basis for directly controlling the phase of a microwave signal using the output of an optical sensor, with the GaAs FET acting as an optical-to-microwave transducer through a monolithic interface.
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Ding, Minsheng. "Energy efficient high port count optical switches." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275326.
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The advance of internet applications, such as video streaming, big data and cloud computing, is reshaping the telecommunication and internet industries. Bandwidth demands in datacentres have been boosted by these emerging data-hungry internet applications. Regarding inter- and intra-datacentre communications, fine-grained data need to be exchanged across a large shared memory space. Large-scale high-speed optical switches tend to use a rearrangeably non-blocking architecture as this limits the number of switching elements required. However, this comes at the expense of requiring more sophisticated route selection within the switch and also some forms of time-slotted protocols. The looping algorithm is the classical routing algorithm to set up paths in rearrangeably non-blocking switches. It was born in the electronic switch era, where all links in the switches are equal. It is, therefore, not able to accommodate loss difference between optical paths due to the different length of waveguides and distinct numbers of crossings, and bends, leading to sub-optimal performance. We, therefore, propose an advanced path-selection algorithm based on the looping algorithm that minimises the path-dependent loss. It explores all possible set-ups for a given connection assignment and selects the optimal one. It guarantees that no individual path would have a sufficiently substantial loss, therefore, improve the overall performance of the switch. The performance of the proposed algorithm has been assessed by modelling switches using the VPI simulator. An 8×8 Clos-tree switch demonstrates a 2.7dB decrease in loss and 1.9dB improvement in IPDR with 1.5 dB penalty for the worst case. An 8×8 dilated Beneš shows more than 4 dB loss reduction for the lossiest path and 1.4 dB IPDR improvement for 1 dB power penalty. The improved algorithm can be run once for each switch design and store its output in a compact lookup table, enabling rapid switch reconfiguration. Microelectromechanical systems (MEMS) based optical switches have been fabricated with over 1,000 ports which meet the port count requirements in data centre networks. However, the reconfiguration speed of the MEMS switches is limited to the millisecond to microsecond timescale, which is not sufficient for packet switching in datacentres. Opto-electronic devices, such as Mach-Zehnder Interferometers (MZIs) and semiconductor optical amplifiers (SOAs) with nanosecond response time show the potential to fulfil the requirements of packet switching. However, the scalability of MZI switches is inherently limited by insertion loss and accumulated crosstalk, while the scalability of SOA switches is restricted by accumulated noise and distortion. We, therefore, have proposed a dilated Beneš hybrid MZI-SOA design, where MZIs are implemented as 1×2 or 2×1 low-loss switching elements, minimising crosstalk by using a single input, and where short SOAs are included as gain or absorption units, offering either loss compensation or crosstalk suppression though adding only minimal noise and distortion. A 4×4 device has been fabricated and exhibits a mere 1.3dB loss, an extinction ratio of 47dB, and more than 13dB IPDR for a 0.5dB power penalty. When operating with 10 Gb/s per port, 6pJ/bit energy consumption is demonstrated, delivering 20% reduced energy consumption compared with SOA-based switches. The tolerance of the current control accuracy of this switch is very broad. Within a 5 mA bias current range, the power penalty can be maintained below 0.2 dB for 8 dB IPDR and 12 mA for 10 dB IPDR with a penalty less 0.5 dB. The excellent crosstalk and power penalty performance demonstrated by this chip enable the scalability of this hybrid approach. The performance of 16×16 port dilated Beneš hybrid switch is experimentally assessed by cascading 4×4 switch chips, demonstrating an IPDR of 15 dB at a 1 dB penalty with a 0.6 dB power penalty floor. In terms of switches with port count larger than 16×16, the power penalty performance has been analysed with physical layer simulations fitted with state-of-the-art data. We assess the feasibility of three potential topologies, with different architectural optimisations: dilated Beneš, Beneš and Clos-Beneš. Quantitative analysis for switches with up to 2048 ports is presented, achieving a 1.15dB penalty for a BER of 10-3, compatible with soft-decision forward error correction.
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Ng, Han-Yong. "Thermally Controllable Microring Resonator-based Silicon Photonic Switch." Scholarly Repository, 2007. http://scholarlyrepository.miami.edu/oa_theses/82.
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A 4 × 4 photonic switch matrix was designed, fabricated and characterized. The photonic switch matrix was based on microring resonator (MR) and was fabricated on relatively low-cost silicon-on-insulator (SOI). Independent wavelength channel switching was accomplished by thermo-optic tuning of the MRs through highly localized resistive micro-heaters. The device was fabricated using the relatively mature silicon fabrication technology. Waveguide patterns were defined with high definition eBeam lithography, etching was done in a reactive-ion etching chamber, and the top cladding SiO2 layer was deposited through plasma-enhanced chemical vapor deposition. Finally, resistive Nichrome micro-heaters were deposited locally directly above each MR to offer the dynamic tuning capability. The strong optical confinement offered by the high index contrast between silicon and SiO2 makes it possible to fabricate micrometer-sized MRs with acceptable optical power loss caused by the small bending radii. The MRs were designed with a uniform diameter of 10 µm to support a wide free spectral range. All waveguides have a design dimension of 450 nm × 250 nm to allow operation exclusively in the fundamental mode at the 1.55 µm wavelength. A FSR of 18 nm with a spectral linewidth of 0.1 nm were observed for the fabricated MRs offering high wavelength selectivity. The device exhibits virtually no thermal crosstalk between adjacent channels, showing no output peak wavelength shift at 0.01 nm wavelength measurement precision by thermally tuning an adjacent MR with electric current as high as 7 mA, which is equivalent to about 2.5 nm in resonance wavelength tuning. The device showed a tuning delay time of about 1 ms. The overall bare chip size of the device is 20 mm × 4 mm. We demonstrated through this work a wavelength selective photonic switch device using low-cost SOI technology that is compact and easy to fabricate. It shows high potential for further development into high port-count photonic switch matrix.
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Wang, Kai. "Design and experiment implementation on low energy and power controlled SOA based optical switches for large scale switch applications." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648882.
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Brown, G. J. "Optical switch systems." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419354.
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Ma, Yuan. "Optimal mems plate design and control for large channel count optical switches." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2071.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Chu, Hsiao-Hua. "Optical beam-steering switches." Thesis, King's College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271112.
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Vilar, Mateo Ruth. "Optical performance monitoring in optical packet-switched networks." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8926.
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Para poder satisfacer la demanda de mayores anchos de banda y los requisitos de los nuevos servicios, se espera que se produzca una evolución de las redes ópticas hacia arquitecturas reconfigurables dinámicamente. Esta evolución subraya la importancia de ofrecer soluciones en la que la escalabilidad y la flexibilidad sean las principales directrices. De acuerdo a estas características, las redes ópticas de conmutación de paquetes (OPS) proporcionan altas capacidades de transmisión, eficiencia en ancho de banda y excelente flexibilidad, además de permitir el procesado de los paquetes directamente en la capa óptica. En este escenario, la solución all-optical label switching (AOLS) resuelve el cuello de botella impuesto por los nodos que realizan el procesado en el dominio eléctrico. A pesar de los progresos en el campo del networking óptico, las redes totalmente ópticas todavía se consideran una solución lejana . Por tanto, es importante desarrollar un escenario de migración factible y gradual desde las actuales redes ópticas basadas en la conmutación de circuitos (OCS). Uno de los objetivos de esta tesis se centra en la propuesta de escenarios de migración basados en redes híbridas que combinan diferentes tecnologías de conmutación. Además, se analiza la arquitectura de una red OPS compuesta de nodos que incorporan nuevas funcionalidades relacionadas con labores de monitorización y esquemas de recuperación.
Las redes ópticas permiten mejorar la transparencia de la red, pero a costa de aumentar la complejidad de las tareas de gesión. En este escenario, la monitorización óptica de prestaciones (OPM) surge como una tecnología capaz de facilitar la administración de las redes OPS, en las que cada paquete sigue su propia ruta en la red y sufre un diferente nivel de degradación al llegar a su destino. Aquí reside la importancia de OPM para garantizar los requisitos de calidad de cada paquete.Vilar Mateo, R. (2010). Optical performance monitoring in optical packet-switched networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8926
Palancia
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Gunning, Paul. "Distributed optical TDMA photonic switch fabric based on gain-switched distributed feedback semiconductor laser diodes and electroabsorption modulators." Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247025.
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Chowdhury, Arshad M. "Optical Label Switching Technologies for Optical Packet Switched Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14047.
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Optical packet switching (OPS) is the most prominent candidate transport solution that can seamlessly integrate electrical and optical layers by transferring certain switching functionality from electronics to optics, thus alleviating unnecessarily slow and expensive optical-electrical-optical conversions and signal processing at the switching node. Optical Label Switching (OLS) is an important aspect of the optical packet switched network that enables very low-latency forwarding of ultra-high bit-rate, protocol-independent packets entirely in the optical domain.
The objective of the proposed research is to develop novel, efficient techniques to realize several key enabling technologies such as optical label generation and encoding, optical label swapping, all-optical buffering, and spectral efficient transmission system for optical label switched based OPS networks. A novel scheme of generating optical label at the ingress node using optical carrier suppression and separation (OCSS) technique is proposed. This scheme does not suffer from any unavoidable interference, limited extinction ratio or strict synchronization requirements between payload and label as observed by the currently available other label generation methods. One of the primary challenges to realize optical label swapping at the core node of scalable OLS network is the insertion of new optical labels without any wavelength conversion for same wavelength packet routing. A novel mechanism to realize same wavelength packet switching without using any conventional wavelength converter in the OLS network carrying differential phase-shift keying (DPSK) modulated payload and on-off keying (OOK) modulated optical label is demonstrated. Also a new dense wavelength division multiplexing (DWDM) optical buffer architecture using optical fiber delay lines that can provide wavelength selective reconfigurable variable delays is proposed. Optical packet switching provides automated, reconfigurable, and faster provision of both wavelength and bandwidth with finer granularity in the optical layer. However, a newer, cost-effective, and spectrally efficient optical transmission technology is essential to support the explosive bandwidth demand expected by the future optical packet switched networks. To meet this challenge, a spectrally efficient solution for transporting 40 Gbps per channel data over 50 GHz spaced DWDM system is developed by exploiting optical carrier suppression and separation technique and optical duobinary modulation.
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Fischer, Stefan. "Versatile all-optical interferometric switch for optical telecommunication systems /." Zürich, 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13836.
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Ménard, Michaël. "Integrated Fabry-Perot optical space switches." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66761.
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As information technologies are adopted by more people to accomplish a greater variety of tasks, the need for optical telecommunication networks with higher capacity and flexibility grows. In addition to improving throughput by increasing transmission rates and the number of wavelength channels, novel network architectures using optical burst or packet based switching are investigated because they allow a more efficient use of transmission capacity and they enable the reorganisation of wavelength connections according to traffic demands. The implementation of such networks requires fast, broadband, transparent, and scalable optical space switches. Although research on optical space switches has been on going for decades, no solution that meets all of the above requirements has been reported yet. The work presented in this thesis introduces a novel optical space switch configuration based on tuneable integrated Fabry-Perot filters working at oblique incidence and investigates their performance. A design method to implement this new switch concept is described and demonstrated with the fabrication and characterisation of optical prototypes. The prototypes are implemented in GaAs/AlGaAs planar waveguides and they are designed to be operated using the electro-optic effect. Deep etching is used to create the switch features and a comprehensive optimization of the waveguide structure is conducted to minimize radiation losses. To maximize the number of wavelength channels that can be controlled with a small refractive index modulation, the switches have a 200 GHz comb frequency response that transmits/reflects one out of every two channels on the ITU 100 GHz grid. Thus, shifting their frequency response by one channel spacing is sufficient to change the state of every channel. Furthermore, four Fabry-Perot cavities are coupled to obtain a flat and wide theoretical passband of more than 50 GHz. A Gaussian beam pAlors que de plus en plus de gens utilisent les technologies de l'information pour accomplir une variété croissante de tâches, le besoin pour des réseaux de télécommunication optique plus flexibles et de plus grande capacité est grandissant. En plus d'augmenter la vitesse de transmission et le nombre de canaux disponibles, de nouvelles architectures utilisant la commutation optique par rafale ou par paquet sont en développement puisqu'elles permettent une utilisation plus efficace de la capacité de transmission et qu'elles rendent possible la réorganisation du réseau en fonction des variations des demandes de service. L'implémentation de tels réseaux nécessite des commutateurs optiques rapides, transparents, à large bande et extensibles. Bien que la recherche sur les commutateurs optiques est cours depuis des décennies, aucune des solutions proposées jusqu'à maintenant ne possède toutes ces qualités. Le travail présenté dans cette thèse décrit une nouvelle configuration de commutateurs optiques utilisant des filtres Fabry-Perot intégrés et accordables qui fonctionnent à incidence oblique et explore leur performance.L'approche utilisée pour concevoir ce nouveau commutateur est expliquée et démontrée par la fabrication et la caractérisation de prototypes optiques. Ces prototypes sont construits dans un guide d'onde planaire en arsenic de gallium et ils sont conçus pour être opérés à l'aide des effets électro-optiques. De profondes gravures sont utilisées pour créer les composantes du commutateur et une étude sur l'optimisation de la structure du guide d'onde est faite dans le but de minimiser les pertes par radiation. Afin de maximiser le nombre de canaux opérables avec une faible modulation de l'indice de réfraction, les commutateurs possèdent une réponse en peigne espacée de 200 GHz qui transmet/réfléchit un canal sur deux de la grille de 100 GHz de l'ITU.$
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Bryant, Reginald (Reginald Eugene) 1978. "High-index-contrast electromechanical optical switches." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65998.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2011."June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 278-288).
System developers are looking to replace protocol-dependent, bandwidth-limited optical networks with intelligent optically-transparent integrated photonic networks. Several electromechanical optical switches are explored with the intent of being utilized as optical switching elements in transparent, integrated photonic networks. The electromechanical optical switches are based on high-index-contrast waveguide optics that is integrated with electrostatic parallel plate actuators on submicron scales. High-index-contrast waveguides are attractive due to their reduced bending radius and low in-plane scattering and optical loss. These qualities of high-index-contrast waveguides make them uniquely suited for low-cost, large-scale integration. The parallel plate actuators are used to control the waveguide light switching by mechanically establishing and terminating light pathways on time scales well below 100s of microseconds. Investigations of light pathway coupling schemes and parallel plate actuator configurations led to the development of several device structures that are categorized in three distinct device generations. Design premiums were placed upon device footprint minimization, polarization independence, high extinction ratios, and operational robustness.
by Reginald Eugene Bryant.
Ph.D.
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Owen, Mark. "Monolithic integration of optical space switches." Thesis, University of Bristol, 1998. http://hdl.handle.net/1983/24cce4d9-04e1-4363-843b-c0e24f547dea.
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Aw, Eng Tin. "Architectures for large scale optical switches in optical interconnection networks." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611407.
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Wang, Haibo. "Semiconductor optical amplifier based optical switches for large scale integration." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609412.
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SATO, Ken-ichi, Hiroshi HASEGAWA, and Shoji KAKEHASHI. "Optical Cross-Connect Switch Architectures for Hierarchical Optical Path Networks." Institute of Electronics, Information and Communication Engineers, 2008. http://hdl.handle.net/2237/14993.
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Huxley, Allen John McAllister. "Switches based on molecular recognition processes." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322948.
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Li, Xin. "Scheduling optical packet switches with reconfiguration delay /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?COMP%202005%20LI.
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Lu, Zeqin. "Silicon photonic switches for optical communication applications." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63132.
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Optical switches are used for signal switching in optical communication networks. Silicon photonics is a low-cost and mature technology to develop high-performance optical switches. This thesis is a theoretical and experimental study on silicon photonic switches, featuring broadband, low-power, high-speed, and low-crosstalk performance.
Broadband 3-dB couplers are fundamental building blocks for broadband switches based on Mach-Zehnder interferometer (MZI) structures. A broadband 3-dB coupler, which has a 100 nm operation bandwidth with coupling imbalance being much less than its competitors, i.e., adiabatic couplers and multimode interference couplers, has been theoretically designed and experimentally demonstrated.
Switches using thermo-optic phase tuning typically have high power consumption. In this thesis, two methods to improve the tuning efficiency of thermo-optic phase shifters have been investigated and employed: 1) using thermal isolation structures and 2) using folded waveguides structures. Accordingly, thermo-optic switches with state-of-the-art, ultra-low power consumption of down to 50μW/π have been demonstrated.
MZI switches using carrier injection phase tuning have high-speed performance but with a large switching crosstalk, due to the imbalanced tuning loss in the MZI structure. A novel carrier injection switch based on a balanced nested Mach-Zehnder interferometer (BNMZI) structure has been theoretically proposed. The BNMZI switch has balanced tuning schemes and therefore can be both high-speed and crosstalk-free. Besides, the switch has three switching states: cross, bar, and blocking.
Polarization control is necessary for single-mode switches. A high-performance polarization beamsplitter (PBS), which has a 120 nm operation bandwidth with modal isolations of more than 20 dB, has been designed and demonstrated, and it can be used for polarization control for single-mode switches.
Characterizing fabrication variability and performing yield prediction for photonic integrated circuits (PICs) are both challenging for photonics designers. We have developed an accurate and cost-efficient characterization method for fabrication variations, which extracts waveguide dimension variations from the spectral response of a single racetrack resonator. In addition, we have proposed a novel yield prediction method for PICs, which, for the first time in silicon photonics, is able to model the impacts of layout-dependent correlated manufacturing variations and take them into account in circuit simulations.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Roberts, Guy Frank. "Wavelength coding for SOA switched optical interconnects." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613348.
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Zhao, Yun. "Low Noise All Optical Switch and GeSn Laser for Silicon Photonics." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1460648525.
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Yow, Chee Kim. "Ultrafast semiconductor-based interferometer all-optical switch for future optical networks." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614232.
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Thomson, David. "Silicon based total internal reflection optical switch." Thesis, University of Surrey, 2009. http://epubs.surrey.ac.uk/844092/.
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Total internal reflection (TIR) based optical switches offer wavelength insensitivity, thermal stability, a short device length, the ability for over-driving without pre-emphasis and polarisation independence. When implemented in silicon the plasma dispersion effect is normally employed, using a PIN diode to inject carriers into the active region of the device, and allowing electrical control of the switching operation. The free diffusion of these injected carriers inhibits the formation of a large and abrupt spatial variation in free carrier concentration (and therefore refractive index) as required for an efficient switching operation. In this work the use of two types of carrier restrictive barrier have been investigated as feasible methods of improving the injected free carrier profile. The first barrier consists of an insulating silicon dioxide layer which completely isolates the PIN diode from the surrounding silicon. A 2mm thick layer has been shown to be thin enough such that the propagating light is not significantly perturbed, whilst being effective at blocking free carrier diffusion. Full device modelling has demonstrated an improved performance over the only other carrier injection based TIR switch in silicon-on-insulator (SOI) from the literature. The second barrier consists of a region of ion implantation induced defective silicon which is positioned along the opposite half of the switching region to the PIN diode. Defective silicon has a decreased free carrier lifetime and therefore any free carriers which diffuse into such material experience an enhanced recombination rate, resulting in reduced diffusion lengths. Experimentally it has been shown that the required electrical and optical properties can be produced by fully amorphising the SOI overlayer and then thermally regrowing it into polycrystalline silicon. Results obtained from fabricated devices with defective silicon barriers have shown an improvement in switching performance over those without barriers, hence successfully demonstrating the principle of barrier enhanced switching.
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Muhyaldin, Siham. "Investigation of EDFA power transients in circuit-switched and packet-switched optical networks." Thesis, Aston University, 2009. http://publications.aston.ac.uk/18275/.
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Erbium-doped fibre amplifiers (EDFA’s) are a key technology for the design of all optical communication systems and networks. The superiority of EDFAs lies in their negligible intermodulation distortion across high speed multichannel signals, low intrinsic losses, slow gain dynamics, and gain in a wide range of optical wavelengths. Due to long lifetime in excited states, EDFAs do not oppose the effect of cross-gain saturation. The time characteristics of the gain saturation and recovery effects are between a few hundred microseconds and 10 milliseconds. However, in wavelength division multiplexed (WDM) optical networks with EDFAs, the number of channels traversing an EDFA can change due to the faulty link of the network or the system reconfiguration. It has been found that, due to the variation in channel number in the EDFAs chain, the output system powers of surviving channels can change in a very short time. Thus, the power transient is one of the problems deteriorating system performance. In this thesis, the transient phenomenon in wavelength routed WDM optical networks with EDFA chains was investigated. The task was performed using different input signal powers for circuit switched networks. A simulator for the EDFA gain dynamicmodel was developed to compute the magnitude and speed of the power transients in the non-self-saturated EDFA both single and chained. The dynamic model of the self-saturated EDFAs chain and its simulator were also developed to compute the magnitude and speed of the power transients and the Optical signal-to-noise ratio (OSNR). We found that the OSNR transient magnitude and speed are a function of both the output power transient and the number of EDFAs in the chain. The OSNR value predicts the level of the quality of service in the related network. It was found that the power transients for both self-saturated and non-self-saturated EDFAs are close in magnitude in the case of gain saturated EDFAs networks. Moreover, the cross-gain saturation also degrades the performance of the packet switching networks due to varying traffic characteristics. The magnitude and the speed of output power transients increase along the EDFAs chain. An investigation was done on the asynchronous transfer mode (ATM) or the WDM Internet protocol (WDM-IP) traffic networks using different traffic patterns based on the Pareto and Poisson distribution. The simulator is used to examine the amount and speed of the power transients in Pareto and Poisson distributed traffic at different bit rates, with specific focus on 2.5 Gb/s. It was found from numerical and statistical analysis that the power swing increases if the time interval of theburst-ON/burst-OFF is long in the packet bursts. This is because the gain dynamics is fast during strong signal pulse or with long duration pulses, which is due to the stimulatedemission avalanche depletion of the excited ions. Thus, an increase in output power levelcould lead to error burst which affects the system performance.
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Li, Jie. "Design and synthesis of organic chiroptical switches." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/27385.
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Rinehart, Michael David. "Optimal control of controllable switched systems." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33201.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 83-85).
Many of the existing techniques for controlling switched systems either require the solution to a complex optimization problem or significant sacrifices to either stability or performance to offer practical controllers. In [13], it is shown that stabilizing, practical controllers with meaningful performance guarantees can be constructed for a specific class of hybrid systems by parameterizing the controller actions by a finite set. We extend this approach to the control of controllable switched systems by constraining the switching portion of the control input and fixing the feedback controller for each subsystem. We show that, under reasonable assumptions, the resulting system is guaranteed to converge to the target while providing meaningful performance. We apply our approach to the direct-injection stratified charge (DISC) engine and compare the results to that of a model predictive controller designed for the same application.
by Michael David Rinehart.
S.M.
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Salas, Emilio Hugues. "Design and implementation of optical buffer architectures for optical packet-switched networks." Thesis, University of Essex, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495571.
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This thesis focuses on the design, modelling and demonstration of a synchronous optical buffer for an optical packet switch, placed in the core of an optical transport network. The features of the optical buffer are the ability to store and route fixed and variable length packets at fast bit rates. First, an overview of the future optical networks is addressed, presenting the incentives to achieve the next generation optical packet-switched networks. Emerging technologies for signal processing in optical switches are introduced as an alternative to provide better features to the packet switch architecture. Next, the main subsystems of an optical packet switch are provided. Optical packet switching issues are discussed addressing the main needs. The key subsystem considered is the contention resolution technique. Subsequently, the description of the network traffic is provided. From this overview, the requirements of a synchronous optical packet buffer will be described, addressing design rules for an optical buffer in a packet switch node. A novel and simple technique for optical buffering is chosen as part of the contention resolution method within the packet switch. This scheme is examined through modelling and experimentally, and is compared to other contention resolution techniques. The Mach-Zehnder Interferometer is chosen as the main component of the packet buffer method. Through this device, wavelength conversion and regeneration can be achieved, supporting fast transmission speeds. The characteristics ofthenon-linear Mach-Zehnder Interferometer are examined as well. Subsequently, the technique is proved experimentally in order to confirm its feasibility as an optical buffer. Architectural issues concerning the structure of the optical buffer are discussed and the various subsystems of the final model are presented. The buffer limitations are examined and design rules are discussed. Finally, the simulation of a packet switch using this type of optical buffer is presented, proving its feasibility and functionality.
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Jong, Jacob Jan Dirk de. "Dithienylcyclopentene optical switches addressing dynamic chirality and aggregation /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/292375689.
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Redic, Richard Charles. "Design and synthesis of potential organic optical switches." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30865.
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Yuan, Xiaochun, and 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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Lam, Candies T. Y. "Photonic edge router for optical packet switched networks." Thesis, University of Essex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402834.
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Weichenberg, Guy E. (Guy Elli) 1978. "Design and analysis of optical flow switched networks." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/47743.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 253-279).
In the four decades since optical fiber was introduced as a communications medium, optical networking has revolutionized the telecommunications landscape. It has enabled the Internet as we know it today, and is central to the realization of Network-Centric Warfare in the defense world. Sustained exponential growth in communications bandwidth demand, however, is requiring that the nexus of innovation in optical networking continue, in order to ensure cost-effective communications in the future. In this thesis, we present Optical Flow Switching (OFS) as a key enabler of scalable future optical networks. The general idea behind OFS-agile, end-to-end, all-optical connections-is decades old, if not as old as the field of optical networking itself. However, owing to the absence of an application for it, OFS remained an underdeveloped idea-bereft of how it could be implemented, how well it would perform, and how much it would cost relative to other architectures. The contributions of this thesis are in providing partial answers to these three broad questions. With respect to implementation, we address the physical layer design of OFS in the metro-area and access, and develop sensible scheduling algorithms for OFS communication. Our performance study comprises a comparative capacity analysis for the wide-area, as well as an analytical approximation of the throughput-delay tradeoff offered by OFS for inter-MAN communication. Lastly, with regard to the economics of OFS, we employ an approximate capital expenditure model, which enables a throughput-cost comparison of OFS with other prominent candidate architectures. Our conclusions point to the fact that OFS offers significant advantage over other architectures in economic scalability.
(cont.) In particular, for sufficiently heavy traffic, OFS handles large transactions at far lower cost than other optical network architectures. In light of the increasing importance of large transactions in both commercial and defense networks, we conclude that OFS may be crucial to the future viability of optical networking.
by Guy E. Weichenberg.
Ph.D.
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Molter, Lynne Ann. "Integrated optical multiple waveguide coupler switches and lenses." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/68228.
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Lin, Tao. "Switched optical interconnect in short reach data networks." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613162.
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Grimsley, Jonathan Scot. "Light Loss In Single Mode Fiber Optical Switches." Master's thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/37142.
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Light loss in single mode fiber optical switches is investigated. Loss due to reflection, aberration and fiber misalignment are evaluated. A simple model of image to fiber end face overlap for the fiber/lens system is developed. The intensity distribution of light in the fiber and imaging system is assumed to be gaussian. It was found that aberration is a major cause of loss and that fiber misalignment did not cause as much loss as expected. Loss due to reflection is assumed to be minimal due to the presence of anti-reflection coatings on the optical components.Master of Science
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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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Sabesan, L. "Modelling of a twin-ridge optical amplifier switch." Thesis, London South Bank University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618639.
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Millett, Ronald. "Design of an SOA-based integrated optical switch." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26984.
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This thesis describes and validates the design of an optical switch that uses a vertically-integrated active/passive waveguide in an InP-based heterostructure. The goal was to design a monolithically integrated proof-of-concept 2x2 switch for use in a reconfigurable optical add-drop module (ROADM). The 1x2 building-block used for this switch consists of a passive 3dB power splitter with two semiconductor optical amplifiers (SOAs) incorporated into each of the output arms. The major contributions are an integrated 3dB power splitter design derived from a validated general design procedure based on a reductionist approach, active waveguide modeling based on evanescent coupling to a weakly-confined SOA region for the switch function, and preliminary layout designs of 2x2 and 4x4 switch fabrics. The performance of the switch was determined through finite-element analysis using FEMLAB, based on material simulations performed using OptiHS, employing post-processing in MATLAB, and validated with beam-propagation analysis using OptiBPM.
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Burnham, Kikue Sugiyama. "Phototriggers for a liquid crystal-based optical switch." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/27900.
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Tang, Xinke. "Optically switched quantum key distribution network." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289444.
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Encrypted data transmission is becoming increasingly more important as information security is vital to modern communication networks. Quantum Key Distribution (QKD) is a promising method based on the quantum properties of light to generate and distribute unconditionally secure keys for use in classical data encryption. Significant progress has been achieved in the performance of QKD point-to-point transmission over a fibre link between two users. The transmission distance has exceeded several hundred kilometres of optical fibre in recent years, and the secure bit rate achievable has reached megabits per second, making QKD applicable for metro networks. To realize quantum encrypted data transmission over metro networks, quantum keys need to be regularly distributed and shared between multiple end users. Optical switching has been shown to be a promising technique for cost-effective QKD networking, enabling the dynamic reconfiguration of transmission paths with low insertion loss. In this thesis, the performance of optically switched multi-user QKD systems are studied using a mathematical model in terms of transmission distance and secure key rates. The crosstalk and loss limitations are first investigated theoretically and then experimentally. The experiment and simulation both show that negligible system penalties are observed with crosstalk of -20 dB or below. A practical quantum-safe metro network solution is then reported, integrating optically-switched QKD systems with high speed reconfigurability to protect classical network traffic. Quantum signals are routed by rapid optical switches between any two endpoints or network nodes via reconfigurable connections. Proof-of-concept experiments with commercial QKD systems are conducted. Secure keys are continuously shared between virtualised Alice-Bob pairs over effective transmission distances of 30 km, 31.7 km, 33.1 km and 44.6 km. The quantum bit error rates (QBER) for the four paths are proportional to the channel losses with values between 2.6% and 4.1%. Optimising the reconciliation and clock distribution architecture is predicted to result in an estimated maximum system reconfiguration time of 20 s, far shorter than previously demonstrated. In addition, Continuous Variable (CV) QKD has attracted much research interest in recent years, due to its compatibility with standard telecommunication techniques and relatively low cost in practical implementation. A wide band balanced homodyne detection system built from modified off-the-shelf components is experimentally demonstrated. Practical limits and benefits for high speed CVQKD key transmission are demonstrated based on an analysis of noise performance. The feasibility of an optically switched CV-QKD is also experimentally demonstrated using two virtualised Alice-Bob pairs for the first time. This work represents significant advances towards the deployment of CVQKD in a practical quantum-safe metro network. A method of using the classical equalization technique for Inter-symbol-interference mitigation in CVQKD detection is also presented and investigated. This will encourage further research to explore the applications of classical communication tools in quantum communications.
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Johnston, Wesley James. "Nonlinear optics in Bragg-spaced quantum wells." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/826.
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Bragg spaced quantum wells represent a unique class of resonant photonic materials, wherein a photonic bandgap is created by the periodic spacing of quantum wells and the associated variation in the complex susceptibility (index and absorption) of the material. Interest in BSQWs has grown in the past decade due to their large ultrafast nonlinearities and the corresponding large ultrafast reflectivity changes and transmissivity. These nonlinearities are of particular interest in areas of communication technology, where ultrafast all-optical logic components have become increasingly in demand. This research will further investigate BSQWs and the for the first time effects of spin-dependent nonlinear excitation on their photonic band structures. It will also investigate how these effects can be used in all-optical polarization switching and tunable optical buffer (slow light) applications.
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Yeo, Yong-Kee. "Dynamically Reconfigurable Optical Buffer and Multicast-Enabled Switch Fabric for Optical Packet Switching." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14615.
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Optical packet switching (OPS) is one of the more promising solutions for meeting the diverse needs of broadband networking applications of the future. By virtue of its small data traffic granularity as well as its nanoseconds switching speed, OPS can be used to provide connection-oriented or connectionless services for different groups of users with very different networking requirements. The optical buffer and the switch fabric are two of the most important components in an OPS router. In this research, novel designs for the optical buffer and switch fabric are proposed and experimentally demonstrated. In particular, an optical buffer that is based on a folded-path delay-line tree architecture will be discussed. This buffer is the most compact non-recirculating optical delay line buffer to date, and it uses an array of high-speed ON-OFF optical reflectors to dynamically reconfigure its delay within several nanoseconds. A major part of this research is devoted to the design and performance optimization of these high-speed reflectors. Simulations and measurements are used to compare different reflector designs as well as to determine their optimal operating conditions. Another important component in the OPS router is the switch fabric, and it is used to perform space switching for the optical packets. Optical switch fabrics are used to overcome the limitations imposed by conventional electronic switch fabrics: high power consumption and dependency on the modulation format and bit-rate of the signals. Currently, only those fabrics that are based on the broadcast-and-select architecture can provide truly non-blocking multicast services to all input ports. However, a major drawback of these fabrics is that they are implemented using a large number of optical gates based on semiconductor optical amplifiers (SOA). This results in large component count and high energy consumption. In this research, a new multicast-capable switch fabric which does not require any SOA gates is proposed. This fabric relies on a passive all-optical gate that is based on the Four-wave mixing (FWM) wavelength conversion process in a highly-nonlinear fiber. By using this new switch architecture, a significant reduction in component count can be expected.
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Minakhmetov, Artur. "Cross-layer hybrid and optical packet switching." Electronic Thesis or Diss., Institut polytechnique de Paris, 2019. http://www.theses.fr/2019IPPAT006.
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Les réseaux de télécommunication transparents constituent une étape de développement des réseaux entièrement électroniques. Les technologies de réseau de données actuelles utilisent déjà activement les fibres optiques et les réseaux transparents dans les réseaux centraux, métropolitains et résidentiels. Toutefois, ces réseaux reposent toujours sur la commutation électronique de paquets (EPS) pour le routage des paquets, qui rend obligatoire pour chaque paquet d'avoir une conversion de signal optique à électronique à optique (OEO). D'autre part, la commutation optique de paquets (OPS), qui semblait remplacer le système EPS, promet depuis longtemps des améliorations en termes de performances et de consommation d'énergie en s'éloignant des conversions OEO; cependant, l'absence de buffers optiques pratiques rendait OPS extrêmement vulnérable aux contentions, entraînant une réduction des performances et empêchant de tirer profit des gains de l'OPS. L'objectif de cette recherche est d'étudier la performance des réseaux avec des commutateurs tout optiques et hybrides, tandis que les activités de transmission côté serveur sont régies par des protocoles de contrôle de transport basés sur des algorithmes de contrôle de congestion (TCP CCA). Nous considérons que l'opération OPS pourrait être activée en utilisant un commutateur hybride, c.a.d. une solution au niveau de l'appareil, ainsi que des TCP CCA spécialement conçus, c.a.d. une solution au niveau du réseau, donnant naissance à des réseaux hybrides à commutation de paquets optique (HOPS). Nous étudions les réseaux de centres de données (DCN) de type OPS, HOPS et EPS associés à différentes TCP CCAs en suivant les trois axes de la performance: débit, consommation d'énergie et latence. En ce qui concerne les TCP CCA, nous considérons non seulement les solutions existantes, mais également celles développées. Si Stop-And-Wait (SAW), Selective Acknowledgment (SACK), SACK modifié (mSACK) et Data Center TCP (DCTCP) sont déjà connus, Stop-And-Wait- Longer (SAWL) est présenté ici et conçu pour tirer le meilleur du HOPS DCN. Il est démontré que les solutions de commutateurs hybrides surpassent de manière significative les commutateurs tout optiques sans buffer et atteignent le niveau de commutateurs tout électroniques en termes de débit du réseau. En termes de consommation d'énergie, les solutions hybrides peuvent économiser jusqu'à 4 fois plus d'énergie de la commutation par rapport aux solutions tout électroniques. De plus, les DCN HOPS peuvent atteindre des latences moyennes à l'échelle des microsecondes, dépassant ainsi les EPS et se situant au même niveau que les OPS. La question de l'introduction de classes de service dans HOPS DCN est examinée: on constate que les règles de commutation spécifiques en commutation hybride peuvent améliorer la performance de certaines classes sans pertes significatives d'autresTransparent optical telecommunication networks constitute a development step from all-electronic networks. Current data network technologies already actively employ optical fibers and transparent networks in the core, metro, and residential area networks. However, these networks still rely on Electronic Packet Switching (EPS) for packets routing, constituting obligatory for each packet optical-to-electronic-to-optical (OEO) signal conversion. On the other hand, Optical Packet Switching (OPS), seemed to be as replacement of EPS, has long promised performance and energy consumption improvements by going away from OEO conversions; however, the absence of practical optical buffers made OPS highly vulnerable to contention, incurring performance reduction, and getting in the way of profiting from OPS gains. The subject of this research lies in the investigation of the performance of OPS networks under all-optical and hybrid switches, while server-side transmission activities are regulated by Transport Control Protocols based on Congestion Control Algorithms (TCP CCAs). We consider that OPS could be enabled by use hybrid switch, i.e. device-level solution, as well by use of specially designed TCP CCAs, i.e. networklevel solution, giving birth to Hybrid Optical Packet Switching (HOPS) networks. We extensively study OPS, HOPS and EPS types of Data Center Networks (DCN) coupled with different TCP CCAs use by following the next three axes of DCN performance: Throughput, Energy Consumption, and Latency. As for TCP CCAs we consider not only existing but also newly developed solutions. If Stop-And-Wait (SAW), Selective Acknowledgment (SACK), modified SACK (mSACK) and Data Center TCP (DCTCP) are already known to the world, StopAnd-Wait-Longer (SAWL) is newly presented and is designed to bring the best out of the HOPS DCN. As a result, it is shown that hybrid switch solutions significantly outperform bufferless all-optical switches and reach the level of all-electronic switches in DCNs in terms of throughput. In terms of energy consumption, hybrid solutions can save up to 4 times on energy on switching compared to all-electronic solutions. As well HOPS DCNs can exhibit microseconds-scale average latencies, surpassing EPS and performing on the level with OPS. The question of the introduction of Classes of Service to HOPS DCN is also investigated: it was found that class-specific switching rules to hybrid switch can ameliorate the performance of certain classes without almost performance loss in others
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Bachmann, Maurus. "Polarization intensive integrated optical waveguide switches using InGaAsP / InP /." Zürich, 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11072.
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Manolis, Ilias G. "Electrically addressed liquid crystal phase gratings for optical switches." Thesis, University of Cambridge, 2002. https://www.repository.cam.ac.uk/handle/1810/251845.
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AlTaha, Mohammed Wadah. "Automatic tuning circuits for Mach-Zehnder interferometer optical switches." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63660.
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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
Electrical and Computer Engineering, Department of
Graduate
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Said, Salim Youssef. "Control and survivability issues for optical burst switched networks." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/27029.
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Optical burst switching (OBS) is the most promising all-optical architectures for the next generation Internet. OBS is still being developed and several issues still need to be addressed. Several studies have stressed the importance of the choice of the offset time and its criticality in influencing the burst loss phenomenon in OBS networks. The main problem arises in estimating the initial delay that is compatible with the optical burst switching architecture implemented.
This thesis aims to provide a mechanism to calculate the offset time and to study its effect on the network performance and refining QoS levels. The study is extended to networks under failure to investigate the influence of the delay factor on the restoration process especially in compensating failed-network performance degradations. The simulation studies validated the proposed mechanism and formed an annex that can be integrated on any OBS restoration mechanism. A new QoS parameter is defined to meet service differentiation with respect to the data losses and delays.
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Granger, Timothy John. "Reconfigurable wavelength-switched optical networks for the internet core." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615682.
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