Diploma thesis focuses on a problematics of an optical networks in terms of an optical cables laying and a work with individual fibers. Thesis contains an basic physical properties which are used in a fiber optics. Methodology of correct working procedures used in fiber optics is discussed at the same time. Thesis also contains detailed documentation of realized optical connections including scheme of realized outdoor connection. 3D design of an rack case is also part of the thesis. Rack case provides an option to simulate plenty of different lengths of optical routes. Rack case is designed in 6U variant.

This diploma thesis deals with optic fiber connectors and their influence on transmissions realized via fiber optics. Optical fibers and lightguides play the key role in telecommunications because of constant demands of higher bandwidth and data rates. Original metalic wires do not meet market requirements and so the fiber optics are more and more being used. There are various types of fibers and there are also many ways of connections. This work deals with demountable way of connection – optical connectors, which have the biggest influence on a total attenuation and route length. Connector has to meet various requirements such as cleannes, quality, mechanical construction and ferrule polishing.

This diploma thesis is focused on use of polarization mode dispersion for measurement of temperature. It also deals with representation of polarization mode dispersion in Poincaré sphere and a mathematical description of polarization mode dispersion by using Stokes and Jones vectors. Here are described basic alternatives of settings, selected temperature relationships and dependence and relationship between coherency and polarization. The practical portion of the diploma thesis examines behavior of the temperature sensor at different temperatures for wavelength 1550 nm and 633 nm.

In dieser Arbeit werden verschiedene Methoden zur Erhöhung der Systemtoleranz optischer Übertragungssysteme theoretisch analysiert, durch numerische Simulationen untersucht und in Experimenten und Feldversuchen praktisch überprüft. Der Schwerpunkt lag dabei auf empfängerseitigen elektronischen sowie optischen Entzerrern. Diese Entzerrer verbessern die Signalübertragung, in dem sie die Augenöffnung des Signals am Empfänger vergrößern oder in dem sie durch digitale Logikschaltungen das gesendete Signal aus einem gestörten Signal rekonstruieren. Der Schwerpunkt dieser Arbeit liegt jedoch auf der Untersuchung der Entzerrer auf Systemebene, d.h. es wird das Verhalten in einem kompletten optischen Übertragungssystem bestehend aus Sender, Glasfaserstrecke und Empfänger bewertet. Zur Untersuchung wurde eine Simulationsumgebung in der Programmiersprache FORTRAN erstellt, in der die unterschiedlichen Entzerrer in verschiedenen Netz-Szenarien untersucht wurden. Zur praktischen Untersuchung wurde außerdem eine Testumgebung im verlegten Glasfasernetz aufgebaut und eine Realisierung eines Entzerrers experimentell untersucht.:Inhaltsverzeichnis 1 Einleitung 1 2 Grundaufbau und Komponenten optischer Übertragungssysteme 3 2.1 Optische Sender 4 2.2 Das Übertragungsmedium Glasfaser 9 2.3 Optische Faserverstärker 22 2.4 Optische Empfänger und Signalauswertung 24 3 Filterstrukturen und Polynomsysteme 29 3.1 Digitalfilter 29 3.2 Optische Filter 30 3.3 Volterra-Systeme 33 4 Elektronische Entzerrung zur Erhöhung der Systemtoleranz 35 4.1 Klassische Entzerrer 35 4.2 Nichtlineare Entzerrer basierend auf Volterra-Systemen 41 4.3 Maximum Likelihood Sequence Estimation 45 5 Optische Entzerrung und Kompensation 49 5.1 Dispersionskompensationsfasern 49 5.2 Optische FIR-Filter 50 6 Entzerrung in unkompensierten Übertragungssystemen 61 6.1 Prinzipieller Vergleich der Entzerrer bei linearer Übertragung 61 6.2 Entzerrung unter Berücksichtigung nichtlinearer Fasereffekte 78 7 Entzerrung in dispersionskompensierten Übertragungssystemen 87 7.1 Ausgleich einer DCF-Fehlanpassung 87 7.2 Entzerrung von Restdispersion 93 8 Gleichzeitige Entzerrung mehrerer Fasereffekte 97 8.1 Simulation der Entzerrung durch MLSE-Entzerrer 97 8.2 Experimentelle Untersuchung von MLSE-Entzerrern im Feldversuch 99 9 Alternative Verfahren zur Erhöhung der Systemtoleranz 113 9.1 Optisches Subcarrier-Multiplexing 113 9.2 Gezielter Austausch von Glasfasern mit hoher PMD 117 10 Zusammenfassung und Schlussfolgerung 121 Literaturverzeichnis 123 Verzeichnis der im Rahmen dieser Arbeit entstandenen Veröffentlichungen 133 Anhang A 137 Anhang B 138 / In this thesis, several methods for the enhancement of the tolerance of optical transmission systems are analyzed theoretically, investigated in numerical simulations and evaluated in experiments and field trials. The investigations were thereby focused on receiver sided electronic and optical equalizers. Those devices improve the signal transmission by increasing the eye-opening at the receiver or by reconstructing the original signal from the distorted received signal by the use of digital signal processing. However, this thesis is focused on the investigation of different equalizers on a system level where the performance of a complete transmission system consisting of a transmitter, transmission fiber and receiver is evaluated. For those studies a simulation environment was created using the programming language FORTRAN where the different equalizers were evaluated in different network scenarios. For practical investigations, a test environment was created using the deployed fiber infrastructure and specific equalizer realization were evaluated experimentally.:Inhaltsverzeichnis 1 Einleitung 1 2 Grundaufbau und Komponenten optischer Übertragungssysteme 3 2.1 Optische Sender 4 2.2 Das Übertragungsmedium Glasfaser 9 2.3 Optische Faserverstärker 22 2.4 Optische Empfänger und Signalauswertung 24 3 Filterstrukturen und Polynomsysteme 29 3.1 Digitalfilter 29 3.2 Optische Filter 30 3.3 Volterra-Systeme 33 4 Elektronische Entzerrung zur Erhöhung der Systemtoleranz 35 4.1 Klassische Entzerrer 35 4.2 Nichtlineare Entzerrer basierend auf Volterra-Systemen 41 4.3 Maximum Likelihood Sequence Estimation 45 5 Optische Entzerrung und Kompensation 49 5.1 Dispersionskompensationsfasern 49 5.2 Optische FIR-Filter 50 6 Entzerrung in unkompensierten Übertragungssystemen 61 6.1 Prinzipieller Vergleich der Entzerrer bei linearer Übertragung 61 6.2 Entzerrung unter Berücksichtigung nichtlinearer Fasereffekte 78 7 Entzerrung in dispersionskompensierten Übertragungssystemen 87 7.1 Ausgleich einer DCF-Fehlanpassung 87 7.2 Entzerrung von Restdispersion 93 8 Gleichzeitige Entzerrung mehrerer Fasereffekte 97 8.1 Simulation der Entzerrung durch MLSE-Entzerrer 97 8.2 Experimentelle Untersuchung von MLSE-Entzerrern im Feldversuch 99 9 Alternative Verfahren zur Erhöhung der Systemtoleranz 113 9.1 Optisches Subcarrier-Multiplexing 113 9.2 Gezielter Austausch von Glasfasern mit hoher PMD 117 10 Zusammenfassung und Schlussfolgerung 121 Literaturverzeichnis 123 Verzeichnis der im Rahmen dieser Arbeit entstandenen Veröffentlichungen 133 Anhang A 137 Anhang B 138

Les réseaux optiques à très haut-débit sont à la base des technologies de l’information d’aujourd’hui et le sujet d’intenses recherches. Alors que l’innovation permet de rendre les transpondeurs flexibles et versatiles, les réseaux de transmission par fibres optiques sont encore configurés manuellement et surtout rarement modifiés au cours de la vie du réseau. Un des points bloquants pour aller vers la reconfiguration et l’automatisation des réseaux optiques est le besoin de prédiction de la performance de tous les liens du réseau de façon précise et rapide. Cependant, la prédiction est rendue plus complexe par la diversité du type de fibres optiques déployées et les régimes de propagation utilisés.Au cours de mes travaux, j’ai étudié expérimentalement les distorsions du signal provenant des effets non-linéaires de type Kerr, accumulées sur des centaines de kilomètres de fibres optiques. Au travers d’expériences spécifiques et contrôlées, j’ai mesuré et mis en évidence les propriétés fondamentales des distorsions non-linéaires. Ces analyses m’ont permis de concevoir l’estimateur d’un modèle de performance destiné à des liens optiques hétérogènes, qui s’applique pour différents types de fibre et différents régimes de propagation.La flexibilité des transpondeurs associés à un estimateur de performance permettront de concevoir, d’optimiser et d’adapter de façon dynamique les canaux en fonction de la demande et de la topologie du réseau, ainsi que de calculer la protection et la restauration des chemins. / Nowadays, high-speed fiber-optic communication networks are the basis of information technology and the subject of intense research. Innovation enables transponders to be flexible and versatile, but fiber optical networks are still configured manually and especially almost never tuned during the life of the network. One of the blocking points toward reconfigurable and automated optical networks is the need of performance prediction for any link of the network in an accurate and fast way. However, the prediction is made even more complex by the diversity of deployed optical fiber types and propagation regimes.During my work, I addressed experimentally the signal distortions coming from nonlinear Kerr effects accumulated on hundreds of kilometers of optical fibers. Based on specific and controlled experiments, I have measured and highlighted the properties of the nonlinear distortions. These analyses allowed me to design a performance model estimator that can be applied to heterogeneous optical links with various optical fiber types and propagation regimes.The flexibility of transponders associated with a performance estimator will optimize and tune the channels dynamically depending on the load and the topology of the network, as well as compute the protection and restoration links.

Tesis por compendio / [ES] El desarrollo científico y tecnológico de las últimas décadas ha dado lugar a sistemas sensores capaces de obtener, procesar y transmitir información sobre multitud de aspectos físicos y químicos, y utilizarla para mejorar aspectos clave de multitud de áreas de nuestra sociedad. Los sensores químicos son dispositivos compactos y miniaturizados capaces de ofrecer soluciones alternativas a las técnicas de análisis instrumental convencionales. En especial, los biosensores han adquirido gran relevancia por los avances que han supuesto para sectores estratégicos como el diagnóstico clínico, la industria alimentaria y el medio ambiente. Los biosensores ópticos se basan en interacciones entre la luz y la materia para transducir eventos de bioreconocimiento y presentan prestaciones importantes como la estabilidad, inmunidad a estímulos externos y versatilidad en el desarrollo de aproximaciones sin marcaje (label-free). Este último aspecto suele aprovechar fenómenos nanoscópicos y su desarrollo se encuentra muy ligado al progreso de la nanociencia y nanotecnología. Un aspecto clave en el biosensado sin marcaje consiste en descubrir y desarrollar nuevas estrategias de transducción. En este sentido, aunque se encuentren aun en una etapa temprana de desarrollo, los biosensores difractivos presentan un gran potencial en términos de simplicidad, miniaturización, y capacidad para minimizar señales no deseadas fruto de interacciones no específicas, entre otros aspectos. / [CA] El desenvolupament científic i tecnològic de les últimes dècades ha donat lloc a sistemes sensors capaços d'obtindre, processar i transmetre informació sobre multitud d'aspectes físics i químics, i utilizar-la per a millorar aspectes clau de multitud d'arees de la nostra societat. Els sensors químics són dispositius compactes i miniaturitzats capaços d'oferir solucions alternatives a les tècniques d'analisi instrumental convencionals. Especialment, els biosensors han adquirit gran rellevància pels avanços que han suposat per als sectors estratègics com el diagnòstic clínic, la industria alimentària i el medi ambient. Els biosensors òptics es basen en interaccions entre la llum i la matèria per a transduir esdeveniments de bioreconèixement i presenten prestacions importants com estabilitat, immunitat a estímuls externs i versatilitat en el desenvolupament d'aproximacions sense marcatge (label-free). Aquest últim aspecte sol aprofitat fenòmens nanoscòpics i el seu desenvolupament es troba molt lligat al progrés de la nanociència i nanotecnologia. Un aspecte clau en el biosensat sense marcatge consisteix a descobrir i desenvolupar noves estratègies de transducció. En aquest sentit, encara que es troben fins i tot en una etapa primerenca de desenvolupament, els biosensors difractius presenten un gran potencial en termes de simplicitat, miniaturització, i capacitat per a minimitzar senyals no desitjats fruit d'interaccions no específiques, entre altres aspectes. / [EN] The scientific and technological progress in recent decades has given rise to sensor systems capable of obtaining, processing, and transmitting information on a multitude of physical and chemical aspects and using it to improve key aspects of many areas of our society. Chemical sensors are compact, miniaturized devices capable of offering alternative solutions to conventional instrumental analysis techniques. In particular, biosensors have become highly relevant due to the progress they have brought to strategic sectors such as clinical diagnostics, the food industry, and the environment. Optical biosensors rely on interactions between light and matter to transduce biosensing events and provide important features such as stability, immunity to external stimuli, and versatility in the development of label-free approaches. This last aspect usually exploits nanoscopic phenomena and its development in closely linked to the progress in nanoscience and nanotechnology. A key aspect of label-free biosensing is the discovery and development of new transduction strategies. In this regard, although they are at an early stage of development, diffractive biosensors offer great potential in terms of simplicity, miniaturization, and the ability to minimize unwanted signals from non-specific interactions, among other aspects. / This work was financially supported by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033) co-funded by the European Union “ERDF A way of making Europe” (PID2019-110713RB-I00, TED2021-132584B-C21, PID2019-110877GB-I00), Ministerio de Economía y Competitividad (TEC2016-80385-P), Generalitat Valenciana (PROMETEO/2019/048 PROMETEO/2020/094, PROMETEO/2021/015, IDIFEDER/2021/046). A.J.D. ackowledges the FPI-UPV 2017 grant program. The authors acknowledge Instituto de Microelectrónica de Barcelona CNM-CSIC for the support in the fabrication of the measured chip samples on the Multiproject CNM-VLC silicon nitride technology platform. / Juste Dolz, AM. (2023). Biogratings: Diffractive Transducers for Biosensing in Photonic Platforms [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/194251 / Compendio

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In this thesis, we explore the four aspects of fiber Bragg grating sensors: mathematical modeling of Fiber Bragg Grating response/spectral characteristics, fabrication using phase mask, application and interrogation. Applications of fiber Bragg gratings, also known as in-fiber gratings, with emphasis on their sensing capabilities, interrogation of an array of sensors and their performance in structural health monitoring scenario are documented. First, we study the process of photosensitivity phenomenon in glasses, in particular GeO2:SiO2 glasses. For mathematical modeling we consider the 1-D refractive index profile along the propagation axis of an optical fiber drawn from the preform of such glasses. These 1-D index structures exhibit a bandgap for propagation along the fiber axis. We show how the bandgap is dependent on the two structural parameters: index periodicity and effective refractive index. The mathematical model provides the characteristics of three sensor parameters -resonance wavelength also known as the Bragg wavelength (λB ), filter bandwidth (ΔλB ), and reflectivity (R). We show that the evolution of the index structure in germanosilicate glasses is dependent on the inscription parameters such as exposure time, intensity of the laser used for inscribing, the interference pattern, and coherence of the laser system. In particular, a phase mask is used as the diffffacting element to generate the required interference pattern, that is exposed on the photosensitive fiber. We present a mathematical model of the electromagnetic diffraction pattern behind the phase mask and study the effect of the limited coherence of the writing laser on the interference pattern produced by the diffracting beams from the mask. Next, we demostrate the sensing capabilities of the fiber Bragg gratings for measuring strain, temperature and magnetic fields. We report linearity of 99.7% and sensitivity of 10.35pm/◦C for the grating temperature sensor. An array of gratings assigned with non-overlapping spectral windows is inscribed in a single fiber and applied for distributed sensing of structural health monitoring of an aircraft’s composite air-brake panel. The performance of these sensors is compared with the industry standard resistance foil gauges. We report good agreement between the two gauges (FBG and RSG). In some applications it is more desirable to know the spectral content, rather than the magnitude of perturbation. Fiber Bragg gratings sensors can be used to track events that occur in a very small span of time and contain high frequencies. Such applications demand very high speed wavelength demodulation methods. We present two interrogation techniques: wavelength-shift time-stamping (WSTS) and reflectivity division multiplexing (RDM). WSTS interrogation method employs the multiple threshold-crossing technique to quantize the sensor grating fluctuations and in the process produces the time stamps at every level-cross. The time-stamps are assembled and with the a priori knowledge of the threshold levels, the strain signal is reconstructed. The RDM methodology is an extension of the WSTS model to address multiple sensors. We show that by assigning unique reflectivities to each of the sensors in an array, the time-stamps from each of the sensors can be tagged. The time-stamps are collected by virtue of their corresponding pulse heights, and assembled to reconstruct the strain signal of each of the array sensor. We demonstrate that the two interrogation techniques are self-referencing systems, i.e., the speed at which the signals are reconstructed is instantaneous or as fast as the signal itself.

Modulation instability (MI) is a general characteristic of wave propagation in nonlinear dispersive media and it has been intensively investigated in several branches of physics due to its fundamental nature as well as technological applications. This phenomenon corresponds to the exponential growth of weak harmonic perturbations in virtue of the interplay between dispersive and nonlinear effects. Hence, despite its important features, MI is also a main source of channel depletion and degradation in optical fiber communications. In this thesis, we investigate the modulational instability (MI) induced by cross-phase-modulation (XPM) of two incoherently coupled optical pulses co-propagating in a lossless fiber with a finite nonlinear response time. The non-instantaneous character of the nonlinear response is introduced through a Debye relaxation process. We analytically obtain the exact dispersion relation for weak harmonic perturbations over the stationary solution. We show that the instability spectrum, present in both normal and anomalous dispersive regimes in instantaneously responding Kerr media, develops a double peak structure whose relative strength and typical frequency range depend on the response time. Further, we reveal that there are two unstable modes in the entire frequency spectrum. We report the dependence of the maximum gain and central frequency within each unstable mode as a function of the group velocity mismatch and response time, showing the crossover between the regimes of fast and slow non-linear responses. / Fundação de Amparo a Pesquisa do Estado de Alagoas / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Instabilidade Modulacional (IM) é um fenômeno característico da propagação de ondas em meios dispersivos não-lineares e tem sido estudado em diversas áreas da Física devido a sua natureza fundamental bem como suas importantes plicações tecnológicas. Esse fenômeno corresponde ao enriquecimento exponencial de pequenas perturbações harmônicas devido a cooperação dos efeitos não-lineares e dispersivos. Portanto, não obstante sua aplicabilidade, IM é, de igual modo, uma fonte importante de degradação em sistemas de comunicação por fibras ópticas. Nesta tese investigamos a instabilidade modulacional (IM) induzida por Modulação de Fase Cruzada (MFC) de dois pulsos ópticos acoplados incoerentemente que se propagam em uma fibra sem perda com tempo de resposta não-linear finito. O caráter não-instantâneo da resposta não-linear é introduzido através de um processo de relaxação de Debye. Obtemos analiticamente, de modo exato, a relação de dispersão para fracas perturbações harmônicas da solução estacionária. Mostramos que o espectro de instabilidade, presente tanto no regime de dispersão normal quanto no anômalo em meios Kerr com resposta instantânea, desenvolve uma estrutura de pico duplo cuja a intensidade relativa e a frequência típica dependem do tempo de resposta considerado. Além do mais, revelamos que existem dois modos instáveis ao longo de todo o espectro de frequência. Apresentamos a dependência do ganho máximo e da frequência correspondente dentro de cada modo instável como função da diferença da velocidade de grupo e do tempo de resposta, mostrando o cruzamento entre os regimes de resposta não-linear rápida e lenta.

Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished