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Dissertations / Theses on the topic 'Nonlinear optical signal processing'
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Maitra, Ayan. "Nonlinear resonators for all-optical signal processing." Karlsruhe Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/992791707/04.
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Atabaki, Amir Hossein. "Reconfigurable silicon photonic devices for optical signal processing." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41207.
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Processing of high-speed data using optical signals is a promising approach for tackling the bandwidth and speed challenges of today's electronics. Realization of complex optical signal processing functionalities seems more possible than any time before, thanks to the recent achievements in silicon photonics towards large-scale photonic integration. In this Ph.D. work, a novel thermal reconfiguration technology is proposed and experimentally demonstrated for silicon photonics that is compact, low-loss, low-power, fast, with a large tuning-range. These properties are all required for large-scale optical signal processing and had not been simultaneously achieved in a single device technology prior to this work. This device technology is applied to a new class of resonator-based devices for reconfigurable nonlinear optical signal processing. For the first time, we have demonstrated the possibility of resonance wavelength tuning of individual resonances and their coupling coefficients. Using this new device concept, we have demonstrated tunable wavelength-conversion through four-wave mixing in a resonator-based silicon device for the first time.
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Koos, Christian. "Nanophotonic devices for linear and nonlinear optical signal processing." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/987044451/34.
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Spasojevic, Mina. "Nonlinear optical signal processing and tunable optical delays in silicon-on-insulator waveguides." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119660.
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The continued trend of increasing demand for large communications bandwidths is placing great strain on today's communications technology. This underlines the need for improving capacities and scalability of the existing as well as the future transmission systems. Investigating the capabilities of different modulation formats presents one way of addressing the matter. This thesis explores the optical time-division (de)multiplexing (OTDM) modulation scheme and provides a platform for building an all-optical signal processing system in silicon-on-insulator (SOI) relying on OTDM. It demonstrates successful OTDM demultiplexing and tunable optical delays both implemented in silicon nanoscale optical devices. OTDM demultiplexing is carried out by exploiting the nonlinearities in silicon waveguides. It focuses on four wave mixing (FWM) phenomenon chosen for its great potential for very high data rates resulting from its instantaneous nature, in addition to the advantage of being transparent to modulation formats. The thesis demonstrates how all-optical OTDM demultiplexing can be achieved through a two step process, generation of continuously tunable delay line followed by demultiplexing process, with both steps implemented in the same silicon waveguide. It demonstrates successful 40 Gb/s-to-10 Gb/s demultiplexing resulting in four error free demultiplexed channels.For further integration of the demultiplexing process, this thesis explores achieving tunable optical delays in silicon waveguides. It shows two approaches for implementing sidewall grating structures, serial Bragg grating arrays and the step-chirped Bragg gratings. Both approaches were fabricated and characterized and demonstrate relatively large delays (up to 65 ps) in discrete steps (from 15 ps to 32 ps) over wide bandwidths (from 35 nm to 70 nm), however they require further optimization. All-optical signal processing and optical devices presented in this thesis provide building blocks and indicate future steps that can lead toward fully integrated OTDM demultiplexer in SOI.L'augmentation incessante de la demande pour de larges bandes passantes crée de grandes tensions sur les technologies de communications existantes. Cela met en évidence le besoin d'améliorer la capacité et l'extensibilité des systèmes de transmission existants et futurs. Cette question peut être résolue, entre autres, par l'exploration des capacités de formats de modulation différents. Cette thèse examine un schéma de (dé)multiplexage optique temporel (OTDM) et présente une plateforme pour la mise en place d'un système pour le traitement de signaux exclusivement optiques sur silicium sur isolant (SOI) qui s'appuie sur le démultiplexage OTDM. Le démultiplexage OTDM et les délais optiques réglables, tous deux implémentés sur des dispositifs en silicium à l'échelle nanométrique, sont démontrés avec succès. Le démultiplexage OTDM est effectuée par l'exploitation de la non-linéarité des guides d'onde sur silicium. Cette technique emploie le phénomène de mélange à quatre ondes (FWM) choisi pour son potentiel pour les très hautes fréquences de données grâce à sa nature instantanée en plus de posséder l'avantage d'être transparent aux formats de modulation. Cette thèse démontre que le démultiplexage OTDM exclusivement optique peut être effectué en deux étapes, la production de ligne à retard ajustable en continue suivit par un procédé de démultiplexage, tous deux implémentés dans le même guide d'onde sur silicium. Un démultiplexage de 40 Gb/s à 10 Gb/s résultant en quatre canaux démultiplexés sans erreur est démontré avec succès. Pour une intégration plus poussée du procédé de démultiplexage, cette thèse examine la possibilité de créer un délai optique ajustable dans les guides d'onde sur silicium. Deux approches pour la mise en œuvre de réseaux sur les parois d'un guide d'onde sont démontrées: une série de réseaux de Bragg et des réseaux de Bragg chirpés. Les deux approches ont été fabriquées et caractérisées et démontrent des délais relativement larges (jusqu'à 65 ps) par étapes discontinues (de 15 ps à 32 ps) sur une bande passante large (de 35 nm à 70 nm). Ces approches doivent cependant être davantage optimisées. Le traitement de signaux exclusivement optique et les dispositifs optiques présentés dans cette thèse fournissent les étapes et les informations nécessaires qui pourraient mener à un démultiplexeur OTDM sur silicium complètement intégré.
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Tseng, Shuo-Yen. "Development of linear and nonlinear components for integrated optical signal processing." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3650.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.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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Ettabib, Mohamed A. "All-optical signal processing in novel highly nonlinear fibres and waveguides." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/368583/.
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All-optical signal processing has recently become an attractive research field, a result of nonlinear optical systems making major advances in terms of cost, compactness, energy consumption, integrability and reliability. This technology has impacted several areas ranging from telecommunications and biomolecular sensing to military and quantum communications, and spanning a vast range of frequencies from the near to mid-infrared. This PhD research project was aimed at investigating the features and feasibility of two state-of-the-art all-optical signal processing technologies: highly nonlinear soft glass fibres and silicon-based waveguides. Of the various soft glasses available, lead silicate and tellurite are considered within this thesis. The optical properties of a highly nonlinear lead silicate W-type fibre are studied and the design process of such fibres is explained in detail. A number of telecommunications-based all-optical processing applications are also demonstrated in this fibre technology. Phase sensitive amplification is demonstrated in the W-type fibre and the process is used to regenerate the phase of 40 Gbit/s differential phase shift keying (DPSK) signals. The optical characteristics of a highly nonlinear tellurite fibre are also studied both at 1.55 and 2 µm. Efficient four wave mixing (FMW)-based wavelength conversion of 1.55 µm signals is demonstrated in the fibre and a detailed numerical study into the potential of the fibre in realizing phase-matched mid-infrared (MIR) to near-infrared (NIR) spectral translation is conducted. The second all-optical signal processing platform investigated in this project is silicon germanium (SiGe) waveguides. A detailed account of the linear and nonlinear optical properties of this newly emerging silicon-based technology is reported for the first time and the potential of this platform is highlighted by demonstrating wavelength conversion of 40 Gbaud DPSK and QPSK signals. Broadband spectral translation is also demonstrated in the SiGe waveguides with record FWM bandwidths.
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Twardowski, T. "Exact theory of surface-guided TM and coupled TE-TM nonlinear electromagnetic waves." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381757.
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Kuo, Ping-piu, and 郭炳彪. "Fiber-based nonlinear photonic processor: a versatile platform for optical communication signal processing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B4098817X.
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Kuo, Ping-piu. "Fiber-based nonlinear photonic processor a versatile platform for optical communication signal processing /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B4098817X.
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Koos, Christian [Verfasser]. "Nanophotonic devices for linear and nonlinear optical signal processing / von Christian Koos." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/987044451/34.
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Awad, Ehab S. "Ultra-fast optical signal processing for digital communications using all-optical nonlinear interactions in semiconductor optical waveguides." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/299.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2003.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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Slim, Joseph. "Optical signal processing for space division multiplexed systems." Thesis, Rennes 1, 2021. http://www.theses.fr/2021REN1S004.
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Bien que l’avantage principal des communications optiques est de permettre la transmission des capacités élevées en multiplexant les longueurs d’onde, le traitement des données, par exemple en vue de régénération ou de routage, doit être effectué dans le domaine électrique, nécessitant ainsi des conversions optique-électrique-optique. Cependant, certaines fonctions de traitement pourraient être effectuées plus efficacement directement dans le domaine optique, ce qui est connu par le traitement de signal tout-optique. Comme des nouvelles techniques exploitant la dimension spatiale dans les fibres multimodes ont été proposées afin d'augmenter la capacité de transmission, une meilleure compréhension des effets non linéaires associés aux interactions multimodes est donc souhaitable. Cette thèse visait à explorer le traitement du signal tout-optique dans le multiplexage modal. En particulier, l'objectif était de démontrer comment les effets non linéaires dans les fibres multimodes pouvaient être utilisés pour manipuler les propriétés des signaux, de manière indépendante ou dépendante du mode. Deux types de fibres ont été conçus. La première permet de réaliser certaines fonctions de traitement de signal tout-optique pour tous les modes de la fibre individuellement et simultanément, en utilisant l'effet non linéaire mélange à quatre ondes intramodal. La deuxième fibre a été conçue de manière à réaliser du traitement de signal tout-optique entre différents modes de la fibre, en utilisant le mélange à quatre ondes intermodalWhile the main advantage of optical communications is to enable transmission of ultra-high capacities by multiplexing dozens of wavelength channels operating at high bit rates, the processing of the data, for instance in view of its regeneration or routing, needs to be performed in the electrical domain, thus requiring optical-to-electrical-to-optical conversions. However, some processing functionalities could be performed more efficiently directly in the optical domain, which is known as all-optical signal processing. As new techniques exploiting the spatial dimension in multimode fibers have been proposed in order to further increase the transmitted capacity, a better understanding of nonlinear effects associated with multimode interactions is desirable. This thesis aimed to explore paths for all-optical signal processing in modedivision multiplexing. In particular, the target was to demonstrate how nonlinear effects in multimode fibers could be used to manipulate the properties of optical signals, either in a mode independent way, or mode dependent way. Two types of fibers were designed. The first one allows to perform some all-optical signal processing functionalities for all the modes of the fiber individually and simultaneously, by using the intramodal fourwave mixing nonlinear effect. The second fiber was designed in a way to perform all-optical signal processing between different modes of the fiber, using intermodal four-wave mixing
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Lee, Ju Han. "All-optical nonlinear signal processing devices and their applications within fibre-optic communication systems." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/42436/.
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This thesis is concerned with research into the development of a range of all-optical fibre based nonlinear devices for optical communication applications. The research can he divided into two main themes. The first concerns the use nf superstructured fibre Bragg grating technology together with fibre based nonlinear devices to improve the overall system performance in both OCDMA and OTDM systems. The second theme area concerns the use of highly nonlinear holey fibre within a range of nonlinear signal processing devices and an analysis of the perfomance of these devices from a system context. A range of nonlinear devices based on a holey fibre is demonstrated. Holey fibre has a nonlinearity around 10-100 times greater than conventional fibre. The use of a short (8.7 m), highly nonlinear holey fibre based optical switch is presented and shown to provide enhanced code recognition quality in a SSFBG based OCDMA system. The use of a short (75 m), highly nonlinear holey fibre to obtain strong L+-band Raman amplification and SRS based signal modulation is also demonstrated. The use of HF within Brillouin based devices is next considered. Both stimulated and spontaneous Brillouin scattering effects are investigated. The observed high SBS lasing threshold is found to be mainly due to reduction in the effective gain coefficient caused by structural non-uniformity along the HF length. A 5.8 m length of HF is then used to achieve tuneable WDM wavelength conversion based on XPM and it is experimentally demonstrated that HF with normal GVD should be used for this sort of device in order to eliminate the coherence degradation related intensity noise observed in experiments employing anomalously dispersive HF. Finally, a FWM based wavelength converter using a 15 m, highly nonlinear HF with a high SBS threshold is presented. The high SBS threshold is achieved by applying structural variation to the HF along its length during the fabrication process
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Matichak, Jonathan D. "The design, synthesis, and characterization of polymethine dyes for all-optical signal processing applications." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/41050.
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Material development is necessary before all-optical signal processing (AOSP) can be realized. Traditional AOSP will require materials with a large magnitude of the real part of the third-order polarizability, while having a small imaginary magnitude of third-order polarizability. The aim of this thesis is to investigate the potential for polymethine dyes to be used for AOSP applications. The basic structure of a polymethine dye was synthetically modified in a variety of positions to observe the effects upon the linear and nonlinear optical properties. The modifications included variation in the terminal group, substituents in the polymethine bridge, and exchange of the counterion. The dyes were generally synthesized using the Vilsmeyer-Haack reaction to form simple polymethine precursors, and then complexity was added by performing the Knoevenagel condensation with various acceptors and the polymethine precursor. Ion metathesis was often employed to exchange the initial counterion for a counterion that provided increased solubility in common organic solvents. The third-order nonlinear optical polarizabilities were characterized by Dr. Joel Hales who used the open- and closed-aperture Z-scan technique at 1300 nm and non-degenerate two-photon absorption experiments to identify the position of the two-photon absorption bands.
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Kim, Hyeongeu. "Investigation of optical properties of polymethines for potential application in all-optical signal processing." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53579.
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Demonstration of ultrafast all-optical signal processing (AOSP) using silicon as the active material has been limited by large two-photon absorption loss and long lifetimes of the resulting free carriers. For AOSP at speeds in the terahertz, an order of magnitude faster than that the fastest current electronic counterpart, a class of π-conjugated organic molecules called polymethines provides a promising alternative to silicon as they possess large third-order nonlinearities, and ultrafast polarization response to an incident field. The challenge in the application of polymethines as active nonlinear optical materials for AOSP is in translating their promising molecular properties into bulk material properties. The large linear polarizability and charged nature of the polymethines molecules strongly promote aggregation and phase-separation in solid blends, offsetting their advantageous molecular optical properties. In this work, polymethines’ resistance to deleterious spontaneous symmetry breaking and aggregation was enhanced by substitutions of metal- and chalcogen- containing terminal groups, and rigid steric groups above and below the π-conjugated plane of polymethine chain. The resulting polymethines/amorphous polycarbonate (APC) blend films demonstrated an unprecedentedly high two-photon figure-of-merit, |Re(χ(3))/Im(χ(3))| and low linear loss. The optical quality of the polymethines/APC films was also improved by replacing the commonly-used alkyl ammonium counterions with more polarizable aryl phosphonium counterions with moderate ground state dipole moment. The resulting dye-polymer blend films showed an enhanced near-infrared transparency while its magnitude of the third-order susceptibility, |χ(3)|, showed a good agreement with that extrapolated from the molecular third-order polarizability, γ. For facile integration of these promising organic materials into SOH, the substrate surface was functionalized using silane coupling chemistry for the reduction of surface energy mismatch between the polymer films and the waveguide containing substrates. The optical and SEM micrographs showed vastly improved coverage and infiltration of the microfeatures. Furthermore, to enable the precise engineering of waveguide cross-sectional dimensions for single-mode propagation in the organic cladding, the dispersion curves of the polymethines/polymer blends were generated using prism coupling and ellipsometry. The combined efforts in the development of molecules and materials discussed in the thesis have culminated into a successful identification and optimization of the polymethines dyes and their polymer blends for imminent demonstrations of on-chip AOSP at terahertz speed.
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KARAGULEFF, CHRIS. "DEGENERATE FOUR WAVE MIXING IN THIN FILM OPTICAL WAVEGUIDES (NONLINEAR OPTICS, INTEGRATED, PHASE CONJUGATION, SIGNAL PROCESSING)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187908.
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The incentive for conducting Degenerate Four Wave Mixing (DFWM) within guided wave devices is two-fold: (1) By coupling the optical beams into guided wave devices, the optical power densities can be increased orders of magnitude due to the tight confinement of the beams. Such an increase in power density means a concomitant increase in conversion efficiency of the signal beam. (2) The potential signal processing applications of DFWM (logic gates, switching, correlation/convolution), particularly for ultra-fast serial processing, would be better exploited, and adjoined to existing integrated circuit technology, by such an integrated optic/guided wave approach. In this dissertation we describe experiments and present data confirming the presence of DFWM within a planar glass thin film with carbon disulphide as the nonlinear cover medium. Optical pulses from a Q-switched, frequency doubled Nd:YAG laser are coupled into the glass film. The nonlinear polarization required to produce the desired conjugate signal is generated within the CS₂ by the evanescent tails of the guided input beams as they probe the nonlinear cover medium. The signals measured agree well with theory, but because they were so small in magnitude, signal-to noise ratios were small due to stray background radiation scattering from beamsplitters and other associated optics. Additionally, recent studies (Jain & Lind, 1983) indicate nonlinear responses in semiconductor (CdS/Se) doped glasses, commercially available as color glass filters, that are orders of magnitude higher than corresponding nonlinearities within CS₂, in addition to possessing subnanosecond response times. We have performed experiments upon such glasses in an effort to fabricate nonlinear optical waveguides within them via ion-exchange techniques. We have successfully fabricated single mode planar guides, but they are currently too lossy to allow demonstration of any guided wave nonlinearities. Also, we describe experiments in which we have measured (bulk) DFWM grating lifetimes with greater precision than previously reported. Results indicate a fast (20 to 50 pico-seconds, depending on the particular glass) electronic response, superimposed upon, but clearly distinguishable from, a slower (10's of nanoseconds) thermal response.
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Guiomar, Fernando Pedro Pereira. "Digital nonlinear equalization for optical transmission systems." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15977.
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Doutoramento em Engenharia EletrotécnicaThis thesis focuses on digital equalization of nonlinear fiber impairments for coherent optical transmission systems. Building from well-known physical models of signal propagation in single-mode optical fibers, novel nonlinear equalization techniques are proposed, numerically assessed and experimentally demonstrated. The structure of the proposed algorithms is strongly driven by the optimization of the performance versus complexity tradeoff, envisioning the near-future practical application in commercial real-time transceivers. The work is initially focused on the mitigation of intra-channel nonlinear impairments relying on the concept of digital backpropagation (DBP) associated with Volterra-based filtering. After a comprehensive analysis of the third-order Volterra kernel, a set of critical simplifications are identified, culminating in the development of reduced complexity nonlinear equalization algorithms formulated both in time and frequency domains. The implementation complexity of the proposed techniques is analytically described in terms of computational effort and processing latency, by determining the number of real multiplications per processed sample and the number of serial multiplications, respectively. The equalization performance is numerically and experimentally assessed through bit error rate (BER) measurements. Finally, the problem of inter-channel nonlinear compensation is addressed within the context of 400 Gb/s (400G) superchannels for long-haul and ultra-long-haul transmission. Different superchannel configurations and nonlinear equalization strategies are experimentally assessed, demonstrating that inter-subcarrier nonlinear equalization can provide an enhanced signal reach while requiring only marginal added complexity.
A presente tese foca-se no tema da equalização digital de distorções não lineares da fibra em sistemas coerentes de transmissão ótica. Tirando partido de modelos físicos bem conhecidos para a propagação de sinal em fibras óticas mono-modo, novas técnicas de equalização não linear são propostas, testadas numericamente e validadas por demonstração experimental. A estrutura dos algoritmos propostos é fortemente condicionada pela otimização do compromisso entre complexidade e desempenho, tendo em conta a sua futura implementação prática em transcetores comerciais operando em tempo-real. O trabalho desenvolvido foca-se inicialmente na mitigação das distorções não lineares intra-canal, aplicando o conceito de propagação digital inversa realizado através de filtros de Volterra. Após uma análise sistemática do núcleo de Volterra de terceira ordem, é identificado um conjunto de simplificações críticas, culminando no desenvolvimento de algoritmos de equalização não linear de baixa complexidade, formulados no domínio do tempo e frequência. A complexidade de implementação das técnicas propostas e analiticamente descrita em termos de esforço computacional e latência de processamento, através da determinação do número de multiplicações reais por amostra e do número de multiplicações realizadas em série, respetivamente. O desempenho da equalização e avaliado recorrendo a simulação numérica e validação experimental através da medição da taxa de erros. Por fim, a questão da compensação não linear inter-canal é abordada no contexto da propagação de supercanais 400G para sistemas de transmissão metro e longa distância. Nesse âmbito são experimentalmente testadas diferentes configurações de supercanal e estratégias de equalização não linear, demonstrando assim que a implementação de equalização inter-subportadora permite estender consideravelmente o alcance, requerendo apenas um esforço computacional ligeiramente superior.
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Gabel, Allan Harley. "Degenerate four wave mixing in semiconductor doped glass waveguides." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184367.
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This dissertation begins with a study of some of the linear and nonlinear optical properties of composite materials consisting of CdSₓSe₁₋ₓ microcrystallites embedded in a host glass matrix. These studies investigate changes in absorption, refractive index and nonlinear response time under a variety of experimental conditions. The data demonstrates that this class of materials exhibit: a strong saturation of absorption due to band filling; a large n₂ which also saturates; response times which range from <100ps to many nanoseconds; and a permanent darkening and change of n₂ induced by extended exposure to high energy pulses. These measurements were used to identify the optimum sample of the semiconductor doped glasses to demonstrate an efficient degenerate four-wave mixing process within a planar waveguide. High quality single mode waveguides were fabricated from the semiconductor doped glass by K⁺-ion exchange. Four wave mixing was performed in the waveguide that produced a peak reflectivity of ≅.003, which is 8 orders of magnitude larger than that achieved previously in a similar experiment where CS₂ was used as the nonlinear medium.
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Xie, Weilin. "Nonlinear properties of phase-sensitive fiber-optic parametric amplifiers for signal processing." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS108/document.
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La capacité et les performances des systèmes à fibres optiques et photoniques dépendent fortement du bruit et des non-linéarités des amplificateurs optiques. Dans ce contexte, les amplificateurs paramétriques à fibre optique (PS-FOPA), reposant sur le mélange à quatre ondes dans les fibres optiques, surpassent les amplificateurs conventionnels insensibles à la phase. En effet, leur sensibilité à la phase peut être exploitée pour l'amplification sans bruit et al compensation de la distortion non-linéaire. En conjonction avec leur large spectre de gain et d'autres fonctionnalités telles que la conversion de longueur d'onde, ils sont considérés comme des candidats prometteurs pour la prochaine génération d'amplificateurs optiques pour les communications et le traitement de signal tout optiques.Le PS-FOPA est classiquement décrit par les équations d'ondes couplées, dérivées de l'équation de Schrödinger non-linéaire qui ne contiennent que trois ou quatre ondes en interaction. Cependant, dans un cas plus général, l'apparition de fréquences supplementaires d’ordre plus élevé affectera inévitablement la sensibilité en phase.L’objectif de cette thèse est d'étudier de manière approfondie les propriétés non-linéaires, en termes de gain et de sensibilité en phase d'un PS-FOPA dégénéré à double pompe pour différentes configurations. Une analyse numérique plus précise est obtenue en utilisant le modèle à 7 ondes qui incorpore les ondes supplémentaires issues de processus de mélange à quatre ondes d’ordre élevé. Ce modèle permet de donner une interprétation physique plus précise des interactions multi-ondes en fonction des conditions d'accord de phase, révélant les relations sous-jacentes entre la dispersion et la sensibilité de phase. De plus, la capacité de régénération simultanée de phase et d'amplitude d'un PS-FOPA basique est évaluée pour l'optimisation globale. Il permet d'exploiter pleinement la capacité potentielle d'un PS-FOPA de base agissant comme un bloc de construction fondamental des futures fonctionnalités tout optiques. L’approche basée sur ce modèle permet une optimisation orientée vers l’application et revêt une importance particulière pour la conception et l'optimisation de tels PS-FOPAs dans divers scénariosThe capability and performance of the widely deployed fiber-optic and photonic systems strongly depend on the noise and nonlinearities of the optical amplifiers. In this context, phase-sensitive fiber-optic parametric amplifiers (PS-FOPAs), relying on four-wave mixing in optical fibers, outperforms conventional phase-insensitive amplifier thanks to the unique phase-sensitivity that can be exploited for noiseless amplification and mitigation of the nonlinear impairment. In conjunction with the vast gain spectrum and other functionality such as wavelength conversion, they have been regarded as a promising candidate for the next generation optical amplifiers towards all-optical communication and processing.The PS-FOPA is conventionally described by the fundamental coupled wave equations derived from the nonlinear Schrödinger equation that contains only three or four interacting waves. However, for a more general case, the emergence of high-order waves will inevitably affect the phase-sensitivity. The objective of this thesis aims at the thorough investigation of the nonlinear properties in terms of the gain properties and the phase sensitivities with respect to different configurations of a dual-pump signal-idler degenerate PS-FOPA. The more accurate numerical analysis is obtained by using the 7-wave model that incorporates the first order high-order waves stemming from the high-order four-wave mixing processing. This model permits to assess a more precise physical interpretation of the multi-wave interactions based on phase matching conditions, revealing the underlying relations between the dispersion and the phase-sensitivity. Moreover, the simultaneous phase and amplitude regenerative capability of a basic PS-FOPA is evaluated for the overall optimization. It allows fully exploiting the potential ability of a basic PS-FOPA acting as a fundamental building block of the future all-optical functionalities. The analysis approach based on this model permits application-oriented optimization and is of particular guiding significance for design and optimization of PS-FOPA in various scenarios
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Neumann, Niels. "Signal processing with optical delay line filters for high bit rate transmission systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-64036.
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In den letzten Jahrzehnten ist das globale Kommunikationssystem in einem immer größerem Maße ein integraler Bestandteil des täglichen Lebens geworden. Optische Kommunikationssysteme sind die technologische Basis für diese Entwicklung. Nur Fasern können die riesige benötigte Bandbreite bereitstellen. Während für die ersten optischen Übertragungssysteme die Faser als "flacher" Kanal betrachtet werden konnte, machen Wellenlängenmultiplex und steigende Übertragungsraten die Einbeziehung von immer mehr physikalischen Effekten notwendig. Bei einer Erhöhung der Kanaldatenrate auf 40 Gbit/s und mehr ist die statische Kompensation von chromatischer Dispersion nicht mehr ausreichend. Die intrinsische Toleranz der Modulationsformate gegenüber Dispersion nimmt quadratisch mit der Symbolrate ab. Daher können beispielsweise durch Umwelteinflüsse hervorgerufene Dispersionsschwankungen die Dispersionstoleranz der Modulationsformate überschreiten. Dies macht eine adaptive Dispersionskompensation notwendig, was gleichzeitig auch Dispersionsmonitoring erfordert, um den adaptiven Kompensator steuern zu können. Vorhandene Links können mit Restdispersionskompensatoren ausgestattet werden, um sie für Hochgeschwindigkeitsübertragungen zu ertüchtigen. Optische Kompensationstechniken sind unabhängig von der Kanaldatenrate. Daher wird eine Erhöhung der Datenrate problemlos unterstützt. Optische Kompensatoren können WDM-fähig gebaut werden, um mehrere Kanäle auf einmal zu entzerren. Das Buch beschäftigt sich mit optischen Delay-Line-Filtern als eine Klasse von optischen Kompensatoren. Die Filtersynthese von solchen Delay-Line-Filtern wird behandelt. Der Zusammenhang zwischen optischen Filtern und digitalen FIR-Filtern mit komplexen Koeffizienten im Zusammenhang mit kohärenter Detektion wird aufgezeigt. Iterative und analytische Methoden, die die Koeffizienten für dispersions- und dispersions-slope-kompensierende Filter produzieren, werden untersucht. Genauso wichtig wie die Kompensation von Dispersion ist die Schätzung der Dispersion eines Signals. Mit Delay-Line-Filtern können die Restseitenbänder eines Signals genutzt werden, um die Dispersion zu messen. Alternativ kann nichtlineare Detektion angewandt werden, um die Pulsverbreiterung, die hauptsächlich von der Dispersion herrührt, zu schätzen. Mit gemeinsamer Dispersionskompensation und Dispersionsmonitoring können Dispersionskompensatoren auf die Signalverzerrungen eingestellt werden. Spezielle Eigenschaften der Filter zusammen mit der analytischen Beschreibung können genutzt werden, um schnelle und zuverlässige Steueralgorithmen zur Filtereinstellung bereitzustellen. Schließlich wurden Prototypen derartiger faseroptischen Kompensatoren von chromatischer Dispersion und Dispersions-Slope hergestellt und charakterisiert. Die Einheiten und ihr Systemverhalten wird gezeigt und diskutiertOver the course of the past decades, the global communication system has become a central part of people's everyday lives. Optical communication systems are the technological basis for this development. Only fibers can provide the huge bandwidth that is required. Where the fiber could be regarded as a flat channel for the first optical transmission systems wavelength multiplexing and increasing line rates made it necessary to take more and more physical effects into account. When the line rates are increased to 40 Gbit/s and higher static chromatic dispersion compensation is not enough. The modulation format's intrinsic tolerance for dispersion decreases quadratically with the symbol rate. Thus, environmentally induced chromatic dispersion fluctuations may exceed the dispersion tolerance of the modulation formats. This makes an adaptive dispersion compensation necessary implying also the need for a monitoring scheme to steer the adaptive compensator. Legacy links that are CD-compensated by DCFs can be upgraded with residual dispersion compensators to make them ready for high speed transmission. Optical compensation is independent from the line rate. Hence, increasing the data rates is inherently supported. Optical compensators can be built WDM ready compensating multiple channels at once. The book deals with optical delay line filters as one class of optical compensators. The filter synthesis of such delay line filters is addressed. The connection between optical filters and digital FIR filters with complex coefficients that are used in conjunction with coherent detection could be shown. Iterative and analytical methods that produce the coefficients for dispersion (and also dispersion slope) compensating filters are researched. As important as the compensation of dispersion is the estimation of the dispersion of a signal. Using delay line filters, the vestigial sidebands of a signal can be used to measure the dispersion. Alternatively, nonlinear detection can be used to estimate the pulse broadening which is caused mainly by dispersion. With dispersion compensation and dispersion monitoring, dispersion compensators can be adapted to the signal's impairment. Special properties of the filter in conjunction with an analytical description can be used to provide a fast and reliable control algorithm for setting the filter to a given dispersion and centering it on a signal. Finally, prototypes of such fiber optic chromatic dispersion and dispersion slope compensation filters were manufactured and characterized. The device and system characterization of the prototypes is presented and discussed
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Asraf, Daniel. "Optimal Detectors for Transient Signal Families and Nonlinear Sensors : Derivations and Applications." Doctoral thesis, Uppsala : Signals and systems [Signaler och system], Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-506-1664-1/.
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Pessoa, Lucio Flavio Cavalcanti. "Nonlinear systems and neural networks with hybrid morphological/rank/linear nodes : optimal design and applications to image processing and pattern recognition." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/13519.
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Fernandez, de Jauregui Ruiz Ivan. "Advanced modulation formats and nonlinear mitigation for spectral efficient optical transmission systems." Thesis, Evry, Institut national des télécommunications, 2018. http://www.theses.fr/2018TELE0009/document.
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La majeure partie des communications mondiales est transportée par des systèmes transocéaniques à fibre optique. Il est estimé que d'ici 2020 le trafic de données atteindra 4.3 ZB par an. Afin de faire face à cette demande, différentes technologies sont actuellement étudiées pour augmenter la capacité des systèmes de transmission très longue distance. Avec l'avènement des circuits intégrés à haute vitesse, des formats de modulation avancés et des techniques de traitement de signal numérique (DSP) peuvent être utilisés pour maximiser l'efficacité spectrale de transmission. Par ailleurs, la capacité des systèmes modernes est fortement limitée par les effets non-linéaires de type Kerr dans la fibre. Ainsi, la première partie de ce travail est axée sur l’étude de la performance et des gains réalisables par des techniques DSP à faible complexité pour mitiger les effets non-linéaires monocanal. En outre, l’utilisation des formats de modulation multiniveaux à haute efficacité spectrale au-delà de 16QAM a pris de l'ampleur pour augmenter le débit de transmission des systèmes, notamment avec l’introduction des formats QAM avec mise en forme probabiliste (PCS-QAM), plus performants que les formats QAM classiques. La deuxième partie de ce travail présente donc une comparaison théorique ainsi qu’expérimentale du format PCS-64QAM avec d’autres formats à haute efficacité spectrale pour les distances transatlantiques. La mise en œuvre d’un format PCS-64QAM conçu pour les distances transpacifiques est également abordée. Enfin, la dernière partie de ce travail concrétise les résultats des travaux menés dans les deux sections précédentes en présentant plusieurs records de transmissionGlobal data traffic is expected to reach up to 4.3 ZB per year by 2020. With the majority of the global communications being transported on submarine point-to-point fiber-optic systems, different cutting-edge technologies have been under research to cope with this unprecedented traffic growth. Continuous advances in high-speed integrated circuits have allowed the use of advanced modulation formats and digital signal processing (DSP) techniques to maximize the transmission spectral efficiency. With mitigation of fiber linear effects efficiently carried out by DSP with relative low-complexity, the capacity of modern fiber optic systems rests limited by fiber nonlinearities. To this extent, in the first part of this work, the performance and achievable benefits of low-complexity DSP techniques aiming to mitigate fiber Kerr nonlinear effects are investigated. Besides nonlinear compensation techniques, the use of multi-level modulation formats beyond 16QAM and high symbol rate channels have gained momentum to increase the system spectral efficiency. One of the major breakthroughs in the recent years, has been the introduction of QAM-based probabilistic constellation shaping (PCS-QAM), which has proven to outperform regular QAM formats. In this sense, in the second part of this work, the practical achievable rate increase brought by PCS-QAM for transoceanic distances is investigated. A theoretical and experimental comparison with other high-capacity formats is performed, and the design of a PCS-QAM for trans-Pacific distances is addressed. Finally, in the last section, several transmission records using the two above techniques are reported
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Rankine, Luke. "Newborn EEG seizure detection using adaptive time-frequency signal processing." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16200/.
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Dysfunction in the central nervous system of the neonate is often first identified through seizures. The diffculty in detecting clinical seizures, which involves the observation of physical manifestations characteristic to newborn seizure, has placed greater emphasis on the detection of newborn electroencephalographic (EEG) seizure. The high incidence of newborn seizure has resulted in considerable mortality and morbidity rates in the neonate. Accurate and rapid diagnosis of neonatal seizure is essential for proper treatment and therapy. This has impelled researchers to investigate possible methods for the automatic detection of newborn EEG seizure. This thesis is focused on the development of algorithms for the automatic detection of newborn EEG seizure using adaptive time-frequency signal processing. The assessment of newborn EEG seizure detection algorithms requires large datasets of nonseizure and seizure EEG which are not always readily available and often hard to acquire. This has led to the proposition of realistic models of newborn EEG which can be used to create large datasets for the evaluation and comparison of newborn EEG seizure detection algorithms. In this thesis, we develop two simulation methods which produce synthetic newborn EEG background and seizure. The simulation methods use nonlinear and time-frequency signal processing techniques to allow for the demonstrated nonlinear and nonstationary characteristics of the newborn EEG. Atomic decomposition techniques incorporating redundant time-frequency dictionaries are exciting new signal processing methods which deliver adaptive signal representations or approximations. In this thesis we have investigated two prominent atomic decomposition techniques, matching pursuit and basis pursuit, for their possible use in an automatic seizure detection algorithm. In our investigation, it was shown that matching pursuit generally provided the sparsest (i.e. most compact) approximation for various real and synthetic signals over a wide range of signal approximation levels. For this reason, we chose MP as our preferred atomic decomposition technique for this thesis. A new measure, referred to as structural complexity, which quantifes the level or degree of correlation between signal structures and the decomposition dictionary was proposed. Using the change in structural complexity, a generic method of detecting changes in signal structure was proposed. This detection methodology was then applied to the newborn EEG for the detection of state transition (i.e. nonseizure to seizure state) in the EEG signal. To optimize the seizure detection process, we developed a time-frequency dictionary that is coherent with the newborn EEG seizure state based on the time-frequency analysis of the newborn EEG seizure. It was shown that using the new coherent time-frequency dictionary and the change in structural complexity, we can detect the transition from nonseizure to seizure states in synthetic and real newborn EEG. Repetitive spiking in the EEG is a classic feature of newborn EEG seizure. Therefore, the automatic detection of spikes can be fundamental in the detection of newborn EEG seizure. The capacity of two adaptive time-frequency signal processing techniques to detect spikes was investigated. It was shown that a relationship between the EEG epoch length and the number of repetitive spikes governs the ability of both matching pursuit and adaptive spectrogram in detecting repetitive spikes. However, it was demonstrated that the law was less restrictive forth eadaptive spectrogram and it was shown to outperform matching pursuit in detecting repetitive spikes. The method of adapting the window length associated with the adaptive spectrogram used in this thesis was the maximum correlation criterion. It was observed that for the time instants where signal spikes occurred, the optimal window lengths selected by the maximum correlation criterion were small. Therefore, spike detection directly from the adaptive window optimization method was demonstrated and also shown to outperform matching pursuit. An automatic newborn EEG seizure detection algorithm was proposed based on the detection of repetitive spikes using the adaptive window optimization method. The algorithm shows excellent performance with real EEG data. A comparison of the proposed algorithm with four well documented newborn EEG seizure detection algorithms is provided. The results of the comparison show that the proposed algorithm has significantly better performance than the existing algorithms (i.e. Our proposed algorithm achieved a good detection rate (GDR) of 94% and false detection rate (FDR) of 2.3% compared with the leading algorithm which only produced a GDR of 62% and FDR of 16%). In summary, the novel contribution of this thesis to the fields of time-frequency signal processing and biomedical engineering is the successful development and application of sophisticated algorithms based on adaptive time-frequency signal processing techniques to the solution of automatic newborn EEG seizure detection.
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Serna, Otálvaro Samuel Felipe. "Design and characterization of Silicon Photonic structures for third order nonlinear effects." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS409/document.
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Le présent travail a été consacré à l'étude des non linéarités de troisième ordre dans des structures intégrées à base de silicium exploitant des configurations de cavités à miroir de Bragg (nanobeam) et guides à cristaux photoniques à modes lents. Tout d'abord, nous avons développé une méthode non destructive à faisceau unique pour caractériser les effets de troisième ordre instantanés, c’est-à-dire la quantification de la susceptibilité complexe effective dans les guides d'ondes. La méthode a été dénommée "Top-hat D-Scan bi-directionnelle" et constitue un analogue temporel de la méthode Top-hat Z-Scan développée précédemment. Nous avons établi un modèle analytique et numérique et nous rendons compte de la première mesure d'un guide d'ondes en silicium utilisant une impulsion mis en forme dans un étireur et complétée par une procédure d’injection bi-directionnelle. L’ensemble instrumental développé constitue une expérience de métrologie des effets non-linéaires dans des guides d’ondes silicium au meilleur niveau de l’état de l’art. La méthode proposée a été validée dans des guides SiGe, chalcogénures et nitrure du silicium. Forts de cet outil métrologique, nos travaux d’exploration des interactions non linéaires lumière-matière ont été consacrés à deux grandes familles de nanostructures photoniques : des microcavités optiques et guides d'ondes en régime de lumière lente. Dans la première des deux situations, les variations d'indice provoquées par les non linéarités sont responsables d’un décalage des fréquences de résonance excluant sa coïncidence avec la fréquence du signal d'excitation et diminuant ainsi l'efficacité de l'injection optique de manière drastique. Afin de maintenir le bénéfice de localisation de la lumière tout au long de l'excitation pulsée, nous avons expérimentalement et numériquement étudié le comportement d'une cavité en silicium conçue, fabriquée, et enfin excitée par une impulsion présentant une puissance crête élevée. En contrôlant temporellement la phase des composantes spectrales injectée, la relation de phase spectrale compensant la dérive de fréquence non linéaire de la résonance de la cavité, nous avons effectué la première démonstration expérimentale de l'excitation cohérente d'une micro-cavité silicium non linéaire. Enfin, nous avons consacré des efforts importants pour concevoir, fabriquer et caractériser des guides d'ondes à cristaux photoniques (SPhCW) en silicium à fente, matrice d’une intégration hybride de matériaux optiques non-linéaires sur silicium. Les résultats rapportés fournissent la première preuve expérimentale d’un contrôle précis des propriétés de dispersion de guides à cristaux photoniques à fente propres à être remplis par des matériaux souples comme des polymères ou des couches minces dopées. La dispersion de groupe des modes lents guidés est contrôlable en signe et en amplitude et correspond à des bandes passantes optiques exploitables (~10nm). Ces résultats démontrent l’intérêt direct pour le traitement des données tout-optique sur puce des guides à modes lents à cœur creux utilisant des effets optiques non linéaires d’ordre trois pour le traitement tout-optique des données sur puceAll-optical signal processing implemented in silicon photonics is considered as a promising route to solve several bottlenecks for the realization of future dense and mixed integrated electronic and photonic chips including ultrahigh data bit rate issues and power consumption constraints. In the context of the planar silicon photonics technology, a dramatic reduction of the needed power to reach optical nonlinear effects is obtained due to the sub-micrometer size of silicon wires (~450nmX260nm) in the telecommunication wavelength window, although silicon does not exhibit second-order response (χ^((2))) due to the centrosymmetry of its lattice. Moreover, third-order effects (χ^((3))) are partially spoiled in this material due to the strength of the two-photon-absorption (TPA) effect, which in turn generates free-carriers inducing additional absorption and refractive index changes. One way to overcome this limitation is the hybrid integration on silicon of low index soft materials with luminescence or nonlinear optical properties lacking to silicon. In this context, the present work is devoted to the study of third order nonlinearities in silicon-based integrated structures exploiting enhanced electromagnetic field effects (e.g. in Si resonators and slow light waveguides). First, we have developed a dedicated single beam non-destructive method to characterize the instantaneous third order effects though the quantification of complex effective waveguide susceptibility. The method is named “Bi-directional top-hat D-Scan” and consists on a temporal analogous of the top-hat Z-Scan. We have established an analytical and numerical model and we report the first measurement of a silicon waveguide by using a pulse shaping set-up and a bi-directional procedure. The originality of our methods stands in the capability to measure in two steps : the 3rd order nonlinear Figure-Of-Merit (FOM) independently of the injection losses, and the effective nonlinear waveguide parameters (Kerr and TPA) taking into account measured coupling losses at each facet. Furthermore, we apply the method to other integrated novel materials including Ge-rich GeSi alloys, carbon nanotube doped thin films, and chalcogenide waveguides. Additionally, two further enhancements of light-matter nonlinear interactions have been explored within this work: optical microcavities and slow light waveguides. In the first picture, index variations caused by non-linearities shift the resonance frequencies precluding the coincidence with the excitation signal frequency, thereby decreasing the injection efficiency. In order to maintain the benefit of light localization throughout the pulsed excitation, we have experimentally and numerically studied the behavior of a designed and fabricated silicon nanobeam cavity excited by a high power tailored chirped pulse whose spectral phase relation compensates for the nonlinear frequency drift of the cavity resonance. We report a numerical study of this first experimental demonstration of the coherent excitation of a nonlinear micro-cavity, leading to an enhanced intra-cavity nonlinear interaction. Finally, we have dedicated efforts to engineer, fabricate and characterize silicon slot photonic crystal waveguides (SPhCW) in order to compensate their strong dispersion present in the slow light regime while taking benefit from large group index light propagation. We showed that their frequency dispersion properties can be engineered from anomalous to normal dispersion, along with zero group velocity dispersion (ZGVD) crossing points exhibiting a Normalized Delay Bandwidth Product (NDBP) as high as 0.156. The reported results provide the first experimental evidence for an accurate control of the dispersion properties of fillable periodical slotted structures in silicon photonics, which is of direct interest for on-chip all-optical data treatment using nonlinear optical effects in hybrid-on-silicon technologies
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Baillot, Maxime. "Mélange à quatre ondes multiple pour le traitement tout-optique du signal dans les fibres optiques non linéaires." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S068/document.
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Le mélange à quatre ondes est un effet non linéaire sensible à la phase qui suscite de nombreux intérêts dans le domaine de la génération de peignes de fréquences et du traitement tout optique du signal par exemple. Un peigne de fréquences peut en effet s'obtenir par effet de mélange à quatre ondes 1en cascade. Dans ce cas, un nombre N d'ondes interagissent entre elles via l'effet Kerr et la modélisation d'un tel processus doit tenir compte de tous les couplages possibles entre les ondes. Au cours de mes travaux de thèse, je me suis intéressé, dans un premier temps, à la modélisation du mélange à quatre ondes dit multiple pour lequel un nombre quelconque N d'ondes interagissent entre elles. J'ai proposé une formulation générale permettant d'identifier simplement tous les termes de mélange à quatre ondes issus de toutes les combinaisons possibles de couplage entre les ondes et leur désaccord de phase associé. J'ai validé cette approche en proposant une étude théorique et expérimentale d'un processus de mélange à quatre ondes multiple dans une fibre optique non linéaire. Dans une deuxième partie, j'ai proposé, grâce au modèle élaboré précédemment, une étude théorique du phénomène de conversion de fréquence sensible à la phase, permettant la décomposition des composantes en quadrature d'un signal optique. Dans la littérature, cette expérience fut démontrée initialement avec quatre ondes pompes et dans plusieurs types de composants non linéaires. J'ai pu démontrer, au cours de mes travaux, que trois pompes étaient suffisantes pour réaliser l'expérience et j'ai déterminé des relations analytiques simples permettant de choisir les paramètres expérimentaux (notamment l'amplitude et la phase des pompes) rendant possible la décomposition des composantes en quadrature d'un signal. J'ai validé cette étude par la démonstration expérimentale d'un convertisseur de fréquence sensible à la phase avec uniquement trois pompes et j'ai étudié théoriquement les effets de la dispersion chromatique sur les performances du convertisseur de fréquence. Enfin, dans une dernière partie, j'ai caractérisé des fibres optiques microstructurées en verre de chalcogénure fabriquées dans le cadre d'une collaboration avec Perfos, l'Institut des Sciences Chimiques de Rennes et SelenOptics. Dans ce cadre, j'ai mis en place un banc de mesure de la dispersion chromatique et du coefficient non linéaire des fibres optiques basé sur le mélange à quatre ondesFour-wave mixing is a phase-sensitive nonlinear effect that arouses interest, particularly in the fields of frequency comb generation and all-optical signal processing. As an example, frequency combs can be produced thanks to a cascaded four-wave mixing process. In this case, N waves can interact with each other through the optical Kerr effect, and one has to take into account all the possible interactions to be able to adequately model the process. During my PhD thesis, I was interested in modeling the so-called multiple four-wave mixing process, in which any number N of waves can interact with each other. I proposed a general formulation that allows to easily identify all the four-wave mixing terms originating from all the possible combinations of wave coupling and their associated phase-mismatch terms. I validated this approach through the theoretical and experimental study of a multiple four-wave mixing process in a nonlinear optical fiber. Thanks to the developed model, I then proposed a theoretical study of the phase-sensitive frequency conversion process, which permits to demultiplex the quadrature components of an optical signal. In the literature, this process was first experimentally demonstrated in several nonlinear devices using four pump waves. I demonstrated that only three pump waves were required to successfully perform the experiment, and I determined the simple analytical relations from which the adequate experimental parameters (namely, the amplitudes and phases of the pump waves) could be deduced. I finally validated this study by experimentally demonstrating a phase-sensitive frequency conversion process with only three pump waves, and I theoretically studied the influence of chromatic dispersion on the performance of this frequency converter. Finally, I characterized some chalcogenide microstructured optical fibers that were fabricated in the framework of a collaboration with Perfos, the Institut des Sciences Chimiques de Rennes, and SelenOptics. I set up a test bench based on the four-wave mixing process in order to measure the chromatic dispersion and nonlinear coefficient of some optical fibers
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Amari, Abdelkerim. "Compensation des effets nonlinéaires pour les transmissions WDM longue distance à 400Gbps et au-delà." Thesis, Paris, ENST, 2016. http://www.theses.fr/2016ENST0031/document.
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Les systèmes de communications optiques jouent un role important pour satisfaire la demande incessante de trafics de données. Cette demande, induite par des applications gourmandes en termes de bande passante et débit, necéssite une augmentation de la capacité des réseaux optiques d’accès et par conséquent une augmentation des capacités de réseaux de transports métropolitains et longues distances. La prochaine génération de systèmes WDM longue distance devrait opérée à des débits de 400Gbps ou 1Tbps. Cette montée en débit s’appuiera sur des nouvelles formes d’ondes avancées de type mono-porteuse (Nyquist-WDM) ou multi-porteuse (OFDM multi-bande). Ces approches sont basées sur le multipléxage de plusieurs porteuses espacées par des intervalles de garde réduits. D’autre part, pour générer ces très haut débits, des modulations multi-états sont utilisées pour chaque porteuse grâce à leur efficacité spectrale élevée. Ces types de systèmes, qui combinent à la fois les approches multi-bande et les modulations multi-états, sont extrêmement vulnérables aux effets nonlinéaires de la fibre optique. En fait, les effets nonlinéaires sont dépendants de la puissance de transmission et inversement proportionels à l’intervalle de garde. Cela rend leur compensation indispensable pour maintenir des bonnes performances des systèmes en terme de distance de transmission. Grâce à l’emploi de récepteurs à détection cohérente, des techniques de traitement du signal numérique sont utlisées pour combattre les effets nonlinéaires. Dans cette thèse, nous avons proposé des nouvelles techniques basées sur les séries de Volterra et les égaliseurs à retour de decision pour compenser respectivement les effets nonlinéaires intrabande et les interférences nonlinéaires inter-bandeOptical communication systems have evolved since their deployment to meet the growing demand for high-speed communications. Over the past decades, the global demand for communication capacity has increased exponentially and the most of the growth has occurred in the last few years when data started dominating network traffic. In order to meet the increase of traffic demands fueled by the growth of internet services, an increase of access network capacity and consequently metro and long-haul network capacities is required. Next generation of long-haul WDM transmission systems is expected to operate at 400Gbps or 1Tbps bit rate. Superchannel approaches, such as Nyquist WDM and multi-band OFDM, allow both high spectral efficiency and small guardband which makes them promising candidates to generate these high bit rates in combination with multi-level modulations formats. Such transmission systems are strongly disturbed by fiber nonlinear effects which increase with the data rate and the small guard band. Therefore, fiber nonlinearities compensation is required to get the desired performance in terms of transmission reach. DSP based approaches such as digital back propagation and third-order Volterra based nonlinear equalizer have been already proposed to deal with intra-channel or intra-band nonlinear effects. In the context of superchannel systems, we have proposed two new compensation techniques to deal with fiber nonlinear effects. The first one, called fifth-order inverse Volterra based nonlinear equalizer, compensate for intra-band nonlinear effects. The second approach, which is the interband/ subcarrier nonlinear interference canceler, is proposed to combat the nonlinear interference insuperchannel systems
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Ahlström, Christer. "Nonlinear phonocardiographic Signal Processing." Doctoral thesis, Linköpings universitet, Fysiologisk mätteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11302.
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The aim of this thesis work has been to develop signal analysis methods for a computerized cardiac auscultation system, the intelligent stethoscope. In particular, the work focuses on classification and interpretation of features derived from the phonocardiographic (PCG) signal by using advanced signal processing techniques. The PCG signal is traditionally analyzed and characterized by morphological properties in the time domain, by spectral properties in the frequency domain or by nonstationary properties in a joint time-frequency domain. The main contribution of this thesis has been to introduce nonlinear analysis techniques based on dynamical systems theory to extract more information from the PCG signal. Especially, Takens' delay embedding theorem has been used to reconstruct the underlying system's state space based on the measured PCG signal. This processing step provides a geometrical interpretation of the dynamics of the signal, whose structure can be utilized for both system characterization and classification as well as for signal processing tasks such as detection and prediction. In this thesis, the PCG signal's structure in state space has been exploited in several applications. Change detection based on recurrence time statistics was used in combination with nonlinear prediction to remove obscuring heart sounds from lung sound recordings in healthy test subjects. Sample entropy and mutual information were used to assess the severity of aortic stenosis (AS) as well as mitral insufficiency (MI) in dogs. A large number of, partly nonlinear, features was extracted and used for distinguishing innocent murmurs from murmurs caused by AS or MI in patients with probable valve disease. Finally, novel work related to very accurate localization of the first heart sound by means of ECG-gated ensemble averaging was conducted. In general, the presented nonlinear processing techniques have shown considerably improved results in comparison with other PCG based techniques. In modern health care, auscultation has found its main role in primary or in home health care, when deciding if special care and more extensive examinations are required. Making a decision based on auscultation is however difficult, why a simple tool able to screen and assess murmurs would be both time- and cost-saving while relieving many patients from needless anxiety. In the emerging field of telemedicine and home care, an intelligent stethoscope with decision support abilities would be of great value.
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Wallace, Angus Keith, and wallace angus@gmail com. "Epilepsy research using nonlinear signal processing." Flinders University. Computer Science, Engineering and Mathematics, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081124.210552.
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This thesis applies several standard nonlinear quantifiers to EEG analysis to examine both human primary generalised epilepsy (PGE) and rat models of human epilepsy.
We analysed rat EEG, and then used the analysed data, in parallel with an impedance recording, to better understand the events during experiments.
Next, the nonlinear analysis of EEG was used to attempt to model the behaviour of the impedance data. This modeling did not yield a useful predictive tool, so we recommend the continued recording of impedance data as a means of augmenting EEG recordings.
The analyses were also applied to human data, and showed differences between the PGE and control groups in apparently normal EEG. We then attempted to use these differences to detect the presence of PGE in an unclassified subject a diagnostic tool. This was done using a feed-forward neural network. We found that the inter-group differences were exploitable and facilitated the diagnosis of PGE in previously unknown subjects. The extent to which this is useful as a diagnostic tool should be assessed by further trials.
Finally, the analyses were used to examine data from a paralysed human subject, in an attempt to identify the mental task being performed by that
subject. This was not successful, suggesting that the same analyses that were useful in discriminating between PGE and control were not useful in detecting the mental state of the subject. It was also apparent that the presence of EMG (in an unparalysed state) assisted task-classification.
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Little, M. A. "Biomechanically informed nonlinear speech signal processing." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:6f5b84fb-ab0b-42e1-9ac2-5f6acc9c5b80.
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Linear digital signal processing based around linear, time-invariant systems theory finds substantial application in speech processing. The linear acoustic source-filter theory of speech production provides ready biomechanical justification for using linear techniques. Nonetheless, biomechanical studies surveyed in this thesis display significant nonlinearity and non-Gaussinity, casting doubt on the linear model of speech production. In order therefore to test the appropriateness of linear systems assumptions for speech production, surrogate data techniques can be used. This study uncovers systematic flaws in the design and use of exiting surrogate data techniques, and, by making novel improvements, develops a more reliable technique. Collating the largest set of speech signals to-date compatible with this new technique, this study next demonstrates that the linear assumptions are not appropriate for all speech signals. Detailed analysis shows that while vowel production from healthy subjects cannot be explained within the linear assumptions, consonants can. Linear assumptions also fail for most vowel production by pathological subjects with voice disorders. Combining this new empirical evidence with information from biomechanical studies concludes that the most parsimonious model for speech production, explaining all these findings in one unified set of mathematical assumptions, is a stochastic nonlinear, non-Gaussian model, which subsumes both Gaussian linear and deterministic nonlinear models. As a case study, to demonstrate the engineering value of nonlinear signal processing techniques based upon the proposed biomechanically-informed, unified model, the study investigates the biomedical engineering application of disordered voice measurement. A new state space recurrence measure is devised and combined with an existing measure of the fractal scaling properties of stochastic signals. Using a simple pattern classifier these two measures outperform all combinations of linear methods for the detection of voice disorders on a large database of pathological and healthy vowels, making explicit the effectiveness of such biomechanically-informed, nonlinear signal processing techniques.
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Han, Yichen. "All-optical Microwave Signal Processing." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20234.
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Microwave signal processing in the optical domain is investigated in this thesis. Two signal processors including an all-optical fractional Hilbert transformer and an all-optical microwave differentiator are investigated and experimentally demonstrated.
Specifically, the photonic-assisted fractional Hilbert transformer with tunable fractional order is implemented based on a temporal pulse shaping system incorporating a phase modulator. By applying a step function to the phase modulator to introduce a phase jump, a real-time fractional Hilbert transformer with a tunable fractional order is achieved.
The microwave bandpass differentiator is implemented based on a finite impulse response (FIR) photonic microwave delay-line filter with nonuniformly-spaced taps. A microwave bandpass differentiator based on a six-tap nonuniformly-spaced photonic microwave delay-line filter with all- positive coefficients is designed, simulated, and experimentally demonstrated. The reconfigurability of the microwave bandpass differentiator is experimentally investigated. The employment of the differentiator to perform differentiation of a bandpass microwave signal is also experimentally demonstrated.
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Davison, Alan Stephen. "All-optical signal processing devices." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316729.
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Albuquerque, André Antunes de Carvalho. "All-optical signal processing for optical communication systems." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23624.
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Doutoramento em Engenharia FísicaO processamento ótico de sinal é uma alternativa possível para melhorar o desempenho e eficiência de sistemas de comunicações óticas, mas o seu estágio atual de desenvolvimento é ainda insuficiente para aplicações em sistemas reais. De forma a inverter esta situação, novas estratégias e pos-sibilidades para processamento ótico de sinal são aqui investigadas, com ênfase em conversão de comprimento de onda, regeneração de fase e amplificação sensível à fase em dispositivos de niobato de lítio com inversão periódica dos domínios ferroelétricos e fibras fortemente não-lineares. Um novo método para o desenho do perfil de inversão dos domínios fer¬roelétricos nos dispositivos de niobato de lítio de acordo com um espetro de conversão alvo é investigado nesta tese. O método proposto é validado numericamente e através da produção de um dispositivo real com largura de banda de conversão de 400 GHz. O dispositivo produzido é utilizado para conversão de onda multicanal de oito sinais modulados em fase, com a possibilidade adicional de sintonizar o comprimento de onda dos sinais con¬vertidos. Observa-se a existência de um compromisso entre elevada largura de banda de conversão e eficiência do dispositivo. São também investigadas nesta tese conversão e permuta de comprimento de onda tolerantes ao ruído de fase adicionado por fontes de bombeamento. Demonstra-se neste trabalho que a utilização de fontes de bombeamento coerentes permite evitar a adição de ruído de fase aos sinais convertidos. Nesta tese é também analisada analítica e numericamente amplificação sensível a fase baseada em dispositivos de niobato de lítio com inversão periódica dos domínios ferroelétricos para configurações de amplificadores de um, dois ou quatro modos. É ainda avaliada a possibilidade de ge¬rar ondas correlacionadas e de realizar amplificação sensível a fase num único dispositivo com propagação bidirecional. Com base neste esquema, demonstra-se regeneração de fase de sinais modulados em fase, porém com ganho limitado devido à baixa eficiência de conversão dos dispositivos e com desempenho afetado por instabilidades térmicas e foto refrativas. Mo¬tivado por estas limitações, demonstra-se amplificação de elevado ganho num amplificador sensível à fase de quatro modos, construído com uma fibra fortemente não-linear em vez de um dispositivo de niobato de lítio. Por fim, é efetuada uma análise numérica do impacto de utilizar amplifica¬dores sensíveis à fase em vez de amplificadores de fibra dopada com érbio no alcance em transmissão ponto a ponto de sinais e na amplificação e regeneração em redes óticas. Demonstra-se que amplificadores sensíveis à fase são mais vantajosos para formatos de modulação avançados e siste¬mas compostos por ligações óticas longas. As simulações assumem mode¬los simplificados para o ganho e ruído dos amplificadores, bem como uma versão modificada do modelo de ruído Gaussiano para estimar a potência das distorções não-lineares em sistemas com compensação total da dispersão cromática no final de cada segmento de fibra entre amplificadores.
All-optical signal processing techniques are a possible way to improve the performance and efficiency of optical communication systems, but the cur¬rent stage of development of such techniques is still unsatisfactory for real- world implementation. In order to invert this situation, new strategies and possibilities for all-optical signal processing are investigated here, with a particular focus on wavelength conversion, phase regeneration and phase- sensitive amplification in periodically poled lithium niobate waveguides and highly nonlinear fibers. A new and flexible method to design the poling pattern of periodically poled lithium niobate devices according to a target conversion spectrum is inves¬tigated in this work. The proposed method is validated through numerical simulations and by producing a real device with broad conversion bandwidth of 400 GHz. The device is then used for multichannel wavelength conversion of eight phase-modulated signals, with the additional possibility to tune the wavelength of the converted signals. A trade-off between high conversion bandwidth and conversion efficiency is observed. Advanced wavelength conversion and wavelength exchange tolerant to the phase noise added by the pump lasers are also investigated. It is shown that the additional phase noise transferred to the converted signals is eliminated by using coherent pumps, generated from the same light source. Phase-sensitive amplification based on periodically poled lithium niobate devices is also investigated in this thesis by numerically comparing the gain properties for one-, two- and four-mode configurations. The possibility to si¬multaneously generate correlated waves and observe phase-sensitive amplifi¬cation in a single device with bidirectional propagation is also demonstrated. Using such scheme,"black-box" phase regeneration of phase-encoded sig¬nals is experimentally demonstrated, albeit with limited net gain due to the low conversion efficiency of the device, and the limited reliability due to thermal and photorefractive instabilities. Motivated by such limitations, high-gain amplification in a four-mode phase-sensitive amplifier built with a highly nonlinear fiber instead of a periodically poled lithium niobate is demonstrated. Finally, the impact of using phase-sensitive amplifiers instead of common erbium-doped fiber amplifiers on the reach in point-to-point transmission and on the amplification and regeneration requirements in optical transport networks is numerically investigated. The calculations show that phase- sensitive amplifiers are particularly advantageous when considering high- order modulation formats and for transport networks comprised by long links. The numerical simulations are performed using simplified models for the gain and noise properties of the amplifiers, and a modified enhanced Gaussian noise model to estimate the power of the nonlinear distortions in systems with full dispersion compensation at the end of each span of fiber.
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Voronenko, Sergej Olegovic. "Nonlinear signal processing by noisy spiking neurons." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/18793.
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Neurone sind anregbare Zellen, die mit Hilfe von elektrischen Signalen miteinander kommunizieren. Im allgemeinen werden eingehende Signale von den Nervenzellen in einer nichtlinearen Art und Weise verarbeitet. Wie diese Verarbeitung in einer umfassenden und exakten Art und Weise mathematisch beschrieben werden kann, ist bis heute nicht geklärt und ist Gegenstand aktueller Forschung. In dieser Arbeit untersuchen wir die nichtlineare Übertragung und Verarbeitung von Signalen durch stochastische Nervenzellen und wenden dabei zwei unterschiedliche Herangehensweisen an. Im ersten Teil der Arbeit befassen wir uns mit der Frage, auf welche Art und Weise ein Signal mit einer bekannten Zeitabhängigkeit die Rate der neuronalen Aktivität beeinflusst. Im zweiten Teil der Arbeit widmen wir uns der Rekonstruktion eingehender Signale aus der durch sie hervorgerufenen neuronalen Aktivität
und beschäftigen uns mit der Abschätzung der übertragenen Informationsmenge.
Die Ergebnisse dieser Arbeit demonstrieren, wie die etablierten linearen Theorien, die die Modellierung der neuronalen Aktivitätsrate bzw. die Rekonstruktion von Signalen beschreiben, um Beiträge höherer Ordnung erweitert werden können. Einen wichtigen Beitrag dieser Arbeit stellt allerdings auch die Darstellung der Signifikanz der nichtlinearen Theorien dar. Die nichtlinearen Beiträge erweisen sich nicht nur als schwache Korrekturen zu den etablierten linearen Theorien, sondern beschreiben neuartige Effekte, die durch die linearen Theorien nicht erfasst werden können. Zu diesen Effekten gehört zum Beispiel die Anregung von harmonischen Oszillationen der neuronalen Aktivitätsrate und die Kodierung von Signalen in der signalabhängigen Varianz einer Antwortvariablen.Neurons are excitable cells which communicate with each other via electrical signals. In general, these signals are processed by the Neurons in a nonlinear fashion, the exact mathematical description of which is still an open problem in neuroscience. In this thesis, the broad topic of nonlinear signal processing is approached from two directions. The first part of the thesis is devoted to the question how input signals modulate the neural response. The second part of the thesis is concerned with the nonlinear reconstruction of input signals from the neural output and with the estimation of the amount of the transmitted information. The results of this thesis demonstrate how existing linear theories can be extended to capture nonlinear contributions of the signal to the neural response or to incorporate nonlinear correlations into the estimation of the transmitted information. More importantly, however, our analysis demonstrates that these extensions do not merely provide small corrections to the existing linear theories but can account for qualitatively novel effects which are completely missed by the linear theories. These effects include, for example, the excitation of harmonic oscillations in the neural firing rate or the estimation of information for systems with a signal-dependent output variance.
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Hussein, Ghazanfar. "Optical signal processing using photorefractive crystals." Thesis, University of Southampton, 1992. https://eprints.soton.ac.uk/396383/.
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I describe in this thesis various techniques of optical signal processing using photorefractive BSO and BaTiO3 crystals. Operations of contrast manipulation, motion detection and parallel optical logic operations are demonstrated. Dynamic instabilities have also been investigated in photorefractive BaTiO3, in the mutually pumped geometry. Contrast manipulation of optical images has been performed via degenerate four wave mixing in BSO and BaTiO3 crystals. In BSO the technique adopted has the apparent drawback of intensity reduction, due to low reflectivities achieved, while using BaTiO3, selective enhancement is achieved for specific Fourier components. An improved versatile technique of polarization encoding of the object Fourier transform has also been implemented with, and without the inclusion of photorefractive crystals. Applications of this technique for phase contrast imaging, and observation in the field of aerodynamics, and Fourier transform synthesis, has been proposed and demonstrated. Optical motion detection using the differential response time of multiplexed gratings in photorefractive BSO has been demonstrated. The operation of velocity filtering has also been demonstrated using complementary gratings in a BSO crystal, in which specific features are only detected at particular speeds. All sixteen basic parallel optical logic operations have been demonstrated using polarization encoding in a phase conjugate Michelson interferometer with a crystal of BSO as a phase conjugate mirror. Finally dynamic instabilities in BaTiO3 in the 'Bird-wing' mutually-pumped configuration have also been investigated, and a phenomenological model is developed. Additionally various improvements and refinements have been proposed which will make these techniques more flexible and versatile.
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Dawber, W. N. "Radiofrequency analysis using optical signal processing." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/15035.
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The basic form of conventional electronic and acoustooptic radiofrequency spectrum analysers is described. The advantages and disadvantages of the various systems are discussed with particular reference to radar signal processing in a hostile environment. Acoustooptic interaction is described using electromagnetic wave theory and also in terms of particle dynamics. A discussion of the various factors which effect Bragg-cell performance is presented, together with experimental results from the characterisation of acoustooptic cells. Coherent light detection is described when used in conjunction with a Bragg-cell spectrum analyser. Using this approach the dynamic range of the device may be dramatically increased. A novel approach is described which uses optical fibres in the Fourier transform plane and fusion spliced couplers to combine the signal and local oscillator beams. Experimental results are presented using single-mode fibres. Improvements in diffraction efficiency, reduced material intermodulation and increased frequency resolution are possible in an acoustooptic spectrum analyser if a Bragg-cell with a long transducer is used. However this leads to reduced instantaneous bandwidth in a conventional configuration. Two new approaches are described which allow a long transducer to be used without loss of bandwidth. An analysis of Bragg-cell diffraction within active and passive resonant optical cavities shows the diffraction efficiency per watt of a Bragg-cell may be increased by orders of magnitude by placing it within a passive cavity. Various cavity configurations are analysed and experimental results are given. A temporal analysis of light diffracted from radiofrequency pulses within an acoustooptic Bragg-cell is presented. Experimental evidence backs up the theory, which shows a possible means of eliminating the "Rabbit's Ears" phenomenon. Conventional acoustooptic Bragg cells have bandwidths limited by the acoustic losses in the crystals used for the cells and impedance matching of the transducer to the driver and crystal. Commercial cells are available with bandwidths of several gigahertz. Many applications require significantly larger bandwidths than are offered by conventional Bragg cells. We describe a new kind of diffraction cell with a potential bandwidth in excess of fifty gigahertz. The theory of operation and an example design are presented. A novel ultra-high data rate optical communication link is described. This makes use of the temporal distribution produced by light diffracted from radiofrequency pulses within a Bragg-cell. Also a covert, free-space link is described. A two channel system is demonstrated using acoustooptic cells.
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Kissinger, Thomas. "Range-resolved optical interferometric signal processing." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9598.
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The ability to identify the range of an interferometric signal is very useful in interferometry, allowing the suppression of parasitic signal components or permitting several signal sources to be multiplexed. Two novel range-resolved optical interferometric signal processing techniques, employing very different working principles, are theoretically described and experimentally demonstrated in this thesis. The first technique is based on code-division multiplexing (CDM), which is combined with single-sideband signal processing, resulting in a technique that, unlike prior work, only uses a single, regular electro-optic phase modulator to perform both range-based signal identification and interferometric phase evaluation. The second approach uses sinusoidal optical frequency modulation (SFM), induced by injection current modulation of a diode laser, to introduce range-dependent carriers to determine phase signals in interferometers of non-zero optical path difference. Here, a key innovation is the application of a smooth window function, which, when used together with a time-variant demodulation approach, allows optical path lengths of constituent interferometers to be continuously and independently variable, subject to a minimum separation, greatly increasing the practicality of the approach. Both techniques are applied to fibre segment interferometry, where fibre segments that act as long-gauge length interferometric sensors are formed between pairs of partial in-fibre reflectors. Using a regular single-mode laser diode, six fibre segments of length 12.5 cm are multiplexed with a quadrature bandwidth of 43 kHz and a phase noise floor of 0.19 mrad · Hz -0.5 using the SFM technique. In contrast, the 16.5 m spatial resolution achieved with the CDM technique points towards its applicability in medium-to-long range sensing. The SFM technique also allows high linearity, with cyclic errors as low as 1 mrad demonstrated, and with modelling indicating further room for improvement. Additionally, in an industrial measurement, the SFM technique is applied to single-beam, multi-surface vibrometry, allowing simultaneous differential measurements between two vibrating surfaces.
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Ghauri, Farzan Naseer. "Hybrid Photonic Signal Processing." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3233.
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This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an analog-digital hybrid MEMS beam profiler that allows high-power watt-level laser beam profiling and also provides both submicron-level high resolution and wide area profiling coverage; and all optical transversal RF filters that operate on the principle of broadband optical spectral control using MEMS and/or Acousto-Optic tunable Filters (AOTF) devices which can provide continuous, digital or hybrid signal time delay and weight selection. The hybrid optical sensors presented in the thesis are extreme environment pressure sensors and dual temperature-pressure sensors. The sensors employ hybrid free-space and fiber-coupled techniques for remotely monitoring a system under simultaneous extremely high temperatures and pressures.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Vaughn, Mark Douglas. "Optical subcarrier multiplexed signal processing using semiconductor optical amplifiers." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13327.
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Lai, Ming-fai, and 黎明輝. "All-optical signal processing based on optical parametric amplification." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41508877.
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Lai, Ming-fai. "All-optical signal processing based on optical parametric amplification." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41508877.
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EASTON, ROGER LEE JR. "TWO-DIMENSIONAL SIGNAL PROCESSING IN RADON SPACE (OPTICAL SIGNAL, IMAGE PROCESSING, FOURIER TRANSFORMS)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183978.
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This dissertation considers a method for processing two-dimensional (2-D) signals (e.g. imagery) by transformation to a coordinate space where the 2-D operation separates into orthogonal 1-D operations. After processing, the 2-D output is reconstructed by a second coordinate transformation. This approach is based on the Radon transform, which maps a two-dimensional Cartesian representation of a signal into a series of one-dimensional signals by line-integral projection. The mathematical principles of this transformation are well-known as the basis for medical computed tomography. This approach can process signals more rapidly than conventional digital processing and more flexibly and precisely than optical techniques. A new formulation of the Radon transform is introduced that employs a new transformation--the central-slice transform--to symmetrize the operations between the Cartesian and Radon representations of the signal and to aid in analyzing operations that may be susceptible to solution in this manner. It is well-known that 2-D Fourier transforms and convolutions can be performed by 1-D operations after Radon transformation, as proven by the central-slice and filter theorems. Demonstrations of these operations via Radon transforms are described. An optical system has been constructed to derive the line-integral projections of 2-D transmissive or reflective input data. Fourier transforms of the projections are derived by a surface-acoustic-wave chirp Fourier transformer, and filtering is performed in a surface-acoustic-wave convolver. Reconstruction of the processed 2-D signal is performed optically. The system can process 2-D imagery at approximately 5 frames/second, though rates to 30 frames/second are achievable if a faster image rotator is added. Other signal processing operations in Radon space are demonstrated, including Labeyrie stellar speckle interferometry, the Hartley transform, and the joint coordinate-frequency representations such as the Wigner distribution function. Other operations worthy of further study include derivation of the 2-D cepstrum, and several spectrum estimation algorithms.
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Salem, Reza. "Polarization-insensitive techniques for optical signal processing." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3947.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.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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Weverka, Robert T. "Optical signal processing of phased array radar." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207762.
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Webb, M. R. "Millimetre wave quasi-optical signal processing systems." Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/2827.
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The development of spatial signal processing techniques at millimetre wavelengths represents an area of science and technology that is new. At optical wavelengths, spatial signal processing techniques are well developed and are being applied to a variety of situations. In particular they are being used in pattern recognition systems with a great deal of success. At millimetre wavelengths, the kind of technology used for signal transport and processing is typically either waveguide based or quasi-optically based, or some hybrid of the two. It is the use of quasi-optical methods that opens up the possibility of applying some of the spatial signal processing techiques that up to the present time have almost exclusively been used at optical wavelengths. A generic device that opens up this dimension of spatial signal processing to millimetre wave quasi-optical systems is at the heart of the work described within this thesis. The device could be suitably called a millimetre wave quasi-optical spatial light modulator (8LM), and is identical in operation to the spatial light modulators used in many optical signal processing systems. Within this thesis both a theoretical and an experimental analysis of a specific millimetre wave quasi-optical spatial light modulator is undertaken. This thesis thus represents an attempt to open up this new area of research and development, and to establish for it, a helpful theoretical and experimental foundation. It is an area that involves a heterogeneous mix of various technologies, and it is an area that is full of potential. The development of the experimental method for measuring the beam patterns produced by millimetre wave quasi-optical spatial light modulators involved the separate development of two other components. Firstly, a sensitive, low-cost millimetre wave pyroelectric detector has been developed and characterised. And secondly, a high performance quasi-optical Faraday rotator (a polarisation rotator) has been developed and characterised. The polarisation state of a quasi-optical beam is the parameter most often exploited for signal processing applications in millimetre wave quasi-optical systems, and thus a high performance polarisation rotator has readily found many opportunities for use.
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Naulleau, Patrick. "Optical signal processing and real world applications /." Online version of thesis, 1993. http://hdl.handle.net/1850/12136.
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Flinn, A. R. "Optical fibres in pre-detector signal processing." Thesis, University of St Andrews, 1989. http://hdl.handle.net/10023/13599.
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The basic form of conventional electro-optic sensors is described. The main drawback of these sensors is their inability to deal with the background radiation which usually accompanies the signal. This 'clutter' limits the sensors performance long before other noise such as 'shot' noise. Pre-detector signal processing using the complex amplitude of the light is introduced as a means to discriminate between the signal and 'clutter'. Further improvements to predetector signal processors can be made by the inclusion of optical fibres allowing radiation to be used with greater efficiency and enabling certain signal processing tasks to be carried out with an ease unequalled by any other method. The theory of optical waveguides and their application in sensors, interferometers, and signal processors is reviewed. Geometrical aspects of the formation of linear and circular interference fringes are described along with temporal and spatial coherence theory and their relationship to Michelson's visibility function. The requirements for efficient coupling of a source into singlemode and multimode fibres are given. We describe interference experiments between beams of light emitted from a few metres of two or more, singlemode or multimode, optical fibres. Fresnel's equation is used to obtain expressions for Fresnel and Fraunhofer diffraction patterns which enable electro-optic (E-0) sensors to be analysed by Fourier optics. Image formation is considered when the aperture plane of an E-0 sensor is illuminated with partially coherent light. This allows sensors to be designed using optical transfer functions which are sensitive to the spatial coherence of the illuminating light. Spatial coherence sensors which use gratings as aperture plane reticles are discussed. By using fibre arrays, spatial coherence processing enables E-0 sensors to discriminate between a spatially coherent source and an incoherent background. The sensors enable the position and wavelength of the source to be determined. Experiments are described which use optical fibre arrays as masks for correlation with spatial distributions of light in image planes of E-0 sensors. Correlations between laser light from different points in a scene is investigated by interfering the light emitted from an array of fibres, placed in the image plane of a sensor, with each other. Temporal signal processing experiments show that the visibility of interference fringes gives information about path differences in a scene or through an optical system. Most E-0 sensors employ wavelength filtering of the detected radiation to improve their discrimination and this is shown to be less selective than temporal coherence filtering which is sensitive to spectral bandwidth. Experiments using fibre interferometers to discriminate between red and blue laser light by their bandwidths are described. In most cases the path difference need only be a few tens of centimetres. We consider spatial and temporal coherence in fibres. We show that high visibility interference fringes can be produced by red and blue laser light transmitted through over 100 metres of singlemode or multimode fibre. The effect of detector size, relative to speckle size, is considered for fringes produced by multimode fibres. The effect of dispersion on the coherence of the light emitted from fibres is considered in terms of correlation and interference between modes. We describe experiments using a spatial light modulator called SIGHT-MOD. The device is used in various systems as a fibre optic switch and as a programmable aperture plane reticle. The contrast of the device is measured using red and green, HeNe, sources. Fourier transform images of patterns on the SIGHT-MOD are obtained and used to demonstrate the geometrical manipulation of images using 2D fibre arrays. Correlation of Fourier transform images of the SIGHT-MOD with 2D fibre arrays is demonstrated.
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Park, William Heuywon. "Fluorescence lifetime sensor using optical fiber and optical signal processing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0009/MQ34107.pdf.
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Dai, Bo. "Optical code-division multiple access system and optical signal processing." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2663.
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This thesis presents our recent researches on the development of coding devices, the investigation of security and the design of systems in the optical cod-division multiple access (OCDMA) systems. Besides, the techniques of nonlinear signal processing used in the OCDMA systems fire our imagination, thus some researches on all-optical signal processing are carried out and also summarized in this thesis. Two fiber Bragg grating (FBG) based coding devices are proposed. The first coding device is a superstructured FBG (SSFBG) using ±π/2-phase shifts instead of conventional 0/π-phase shifts. The ±π/2-phase-shifted SSFBG en/decoders can not only conceal optical codes well in the encoded signals but also realize the reutilization of available codes by hybrid use with conventional 0/π-phase-shifted SSFBG en/decoders. The second FBG based coding device is synthesized by layer-peeling method, which can be used for simultaneous optical code recognition and chromatic dispersion compensation. Then, two eavesdropping schemes, one-bit delay interference detection and differential detection, are demonstrated to reveal the security vulnerability of differential phase-shift keying (DPSK) and code-shift keying (CSK) OCDMA systems. To address the security issue as well as increase the transmission capacity, an orthogonal modulation format based on DPSK and CSK is introduced into the OCDMA systems. A 2 bit/symbol 10 Gsymbol/s transmission system using the orthogonal modulation format is achieved. The security of the system can be partially guaranteed. Furthermore, a fully-asynchronous gigabit-symmetric OCDMA passive optical network (PON) is proposed, in which a self-clocked time gate is employed for signal regeneration. A remodulation scheme is used in the PON, which let downstream and upstream share the same optical carrier, allowing optical network units source-free. An error-free 4-user 10 Gbit/s/user duplex transmission over 50 km distance is reazlied. A versatile waveform generation scheme is then studied. A theoretical model is established and a waveform prediction algorithm is summarized. In the demonstration, various waveforms are generated including short pulse, trapezoidal, triangular and sawtooth waveforms and doublet pulse. ii In addition, an all-optical simultaneous half-addition and half-subtraction scheme is achieved at an operating rate of 10 GHz by using only two semiconductor optical amplifiers (SOA) without any assist light. Lastly, two modulation format conversion schemes are demonstrated. The first conversion is from NRZ-OOK to PSK-Manchester coding format using a SOA based Mach-Zehnder interferometer. The second conversion is from RZ-DQPSK to RZ-OOK by employing a supercontinuum based optical thresholder.
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Mueller, Thorsten Oliver. "Nonlinear Ultrasonics: Signal Processing Considerations and a Nonlinear Parameter for Rayleigh Waves." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-09282005-114142/.
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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.Kim, Jin-Yeon, Committee Member ; Qu, Jianmin, Committee Member ; Jacobs, Laurence, Committee Chair. Includes bibliographical references.