Les pointes épileptiques intercritiques (IES) représentent une signature neuronale de l'activation transitoire hypersynchrone et excessive d'un grand ensemble de neurones corticaux hétérogènes. Elles sont considérées comme la signature de l’épileptogénicité du réseau neuronal sous-jacent. Dans cette étude, des changements sur la configuration neurale ont été observés chez des modèles animaux et humains au cours de l'IES. Pour la première fois, ces changements ont été détectés à l'aide de la spectroscopie optique rapide (FOS), qui correspond aux variations de la lumière diffusée par le tissu neural pendant l'activation. Ces chages [i.e. changements] sont associés à des mécanismes cellulaires plutôt qu'à des réponses hémodynamiques à haute résolution spatiale et temporelle. Pour étudier le mécanisme IES, une analyse simultanée multimodale des changements optiques rapides (FOS) et électriques (EEG/ECoG: temps et fréquence) a été développée chez des modèles animaux (15 rats) et humains (IES frontales,3 enfants). Pour évaluer de manière indépendante nos méthodes, un potentiel évoquant somatosensoriel et une réponse optique ont été conçus dans des modèles animaux et humains (5 volontaires sains).Les résultats suggèrent une relation entre la (dé)synchronisation et les changements optiques quel que soit le modèle épileptique. Nous avons démontré que cette approche multimodale non invasive multi-échelles (FOS, ECoG / EEG) permet d'étudier la physiopathologie de l'IES chez les patients et de mieux comprendre les mécanismes qui propulsent les neurones vers l'hypersynchronisation chez les modèles épileptiques humains et animaux / Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons and are widely accepted diagnostically as a signature of an epileptic underlying network. In this study, changes on neural configuration were observed in an animal and human models during the IES. For the first time, these changes were detected using Fast Optical Spectroscopy (FOS), which correspond to variations of scattered light from neural tissue during activation. These chages [i.e. changes] are associated with cellular mechanisms rather than hemodynamic responses with high spatial and temporal resolution. To investigate IES mechanism, a multimodal simultaneous analysis of the fast optical (FOS) and electrical (EEG/ECoG: time and frequency domain) changes was developed in both animal (15 rats) and human models (frontal IES, 3 children). To independently evaluate our methods, a control somatosensory evoked potential and optical response was designed in both animal and human models (5 healthy volunteers). The results suggest a relationship between (de)synchronization and optical changes whatever the epileptic model. This also proposed that changes in the fast optical signal which reflect changes in membrane configuration, are associated with the complex perturbations of the neuronal activation of the epileptic networks. We demonstrated that this non-invasive multiscale multimodal approach (FOS, ECoG/EEG) is suitable to study the pathophysiology of the IES in patients and shed new light on the mechanisms that propel neurons to the hypersynchronization in both animal and human epileptic models

O Estudo de Materiais Fotorrefrativos e suas Aplicações no Processamento Óptico Holográfico de Informação vêm sendo feitos por diversos Grupos de Pesquisas em vários laboratórios devido aos bons resultados obtidos com esses meios em diversas áreas. Entre outros efeitos foto-induzidos o processo que possibilita essas aplicações é o efeito fotorrefrativo, um fenômeno onde o registro holográfico no meio fotorrefrativo ocorre pela modulação do índice de refração de acordo com a distribuição espacial da intensidade da luz incidente, devido a uma redistribuição foto-induzida de cargas espaciais, e conseqüente, geração de um campo espaço-carga no meio. Neste trabalho, estuda-se a propagação e acoplamento de ondas eletromagnéticas em monocristais elétro-ópticos paraelétricos da Família das Silenitas \'BI IND. 12\'\'SI\'\'O IND. 20\' (BSO) e \'BI IND. 12\'\'TI\'\'O IND. 20\' (BTO) e nos ferroelétricos \'LI\'\'NB\'\'O IND. 3\' puros e dopados. O propósito de estudar esses materiais é caracterizá-los e, principalmente, otimizá-los para aplicação no processamento óptico e holográfico de informação. Utiliza-se técnicas de caracterização de redes holográficas fotorrefrativas e de lentes foto-induzidas para determinação de figuras de mérito e parâmetros fotorrefrativos e termo-ópticos nestes meios fotorrefrativos. Propõe-se também algumas aplicações no processamento óptico e holográfico de informação, nas áreas de pesquisa básica, tecnológicas e biomédicas, que vêm despertando grande interesse nos últimos anos, como holografia em tempo real com mapeamento de fase, interterometria speckle em tempo real e registro não-holográfico no processo de conversão incoerente-incoerente; entre outras no processamento óptico e holográfico de dados. / The Study of Photorefractive Materials and their Applications in Optical and Holographical Information Processing come being made for diverse Groups of Research in some laboratories due to the good results in many areas. Among other photo-induced effects, the process that allows these applications is the photorefractive effect, a phenomenon where the holographic recording in photorefractive medium occurs by means of the refractive index modulation due to the space distribution of the light intensity, producing a space-charge photo-induced redistribution, and consequently, the generation of a space-charge field governed by an electro-optic medium. In this work, we study the propagation and coupling of electromagnetic waves in electro-optic monocrystals of the sillemite family Bi12SiO20 (BSO) and Bi12TiO20 (BTO) and in the pure and dop-ed LiNbO3 crystals. The purpose to study these materials is to characterize them and, mainly, to optimize the conditions of their application in the optical and holographical information processing. We use photorefractive holographic gratings and photo-induced lens techniques for determination of figures of merit and photorefractive and thermo-optic parameters in these photorefractive materials. We also consider some applications in the optical and holographical information processing in the research basic, technological and biomedical areas, that come waken great interest in the last years, as phase- shifting real-time holography, real-time speckle interferometry and non-holographic recording with incoherent-incoherent conversion process; among others in the optic and holographic data processing.

In this dissertation I investigated a multi-channel and multi-bit rate all-optical clock recovery device. This device, a birefringent Fabry-Perot resonator, had previously been demonstrated to simultaneously recover the clock signal from 10 wavelength channels operating at 10 Gb/s and one channel at 40 Gb/s. Similar to clock signals recovered from a conventional Fabry-Perot resonator, the clock signal from the birefringent resonator suffers from a bit pattern effect. I investigated this bit pattern effect for birefringent resonators numerically and experimentally and found that the bit pattern effect is less prominent than for clock signals from a conventional Fabry-Perot resonator.I also demonstrated photonic balancing which is an all-optical alternative to electrical balanced detection for phase shift keyed signals. An RZ-DPSK data signal was demodulated using a delay interferometer. The two logically opposite outputs from the delay interferometer then counter-propagated in a saturated SOA. This process created a differential signal which used all the signal power present in two consecutive symbols. I showed that this scheme could provide an optical alternative to electrical balanced detection by reducing the required OSNR by 3 dB.I also show how this method can provide amplitude regeneration to a signal after modulation format conversion. In this case an RZ-DPSK signal was converted to an amplitude modulation signal by the delay interferometer. The resulting amplitude modulated signal is degraded by both the amplitude noise and the phase noise of the original signal. The two logically opposite outputs from the delay interferometer again counter-propagated in a saturated SOA. Through limiting amplification and noise modulation this scheme provided amplitude regeneration and improved the Q-factor of the demodulated signal by 3.5 dB.Finally I investigated how SPM provided by the SOA can provide a method to reduce the in-band noise of a communication signal. The marks, which represented data, experienced a spectral shift due to SPM while the spaces, which consisted of noise, did not. A bandpass filter placed after the SOA then selected the signal and filtered out what was originally in-band noise. The receiver sensitivity was improved by 3 dB.

The main objective of this thesis is to investigate the intrinsic optical signals (IOSs) with an ultra-high resolution optical coherence tomography system (UHROCT). In order to study the retinal IOSs evoked by visible light, an UHROCT and an Electroretinogram (ERG) system was combined. An animal model (chicken retina) based on its retinal avascularity and cone dominance, was selected. Imaging the chicken retina with OCT resulted in high contrast, high resolution (~3μm axial and ~5 μm lateral resolution) 2D and 3D volumetric tomograms, in which all retina layers were clearly distinguishable. Using the combined UHROCT and ERG system to image IOSs from the chicken retina exposed to visible light (7ms green flash) resulted in highly reproducible IOS recordings from all retinal layers for the first time. All inner retinal layers showed an initial increase and subsequently a decrease in the intensity of the backreflected imaging light within the first 100 ms after the onset of the stimulus. Outer segments of the photoreceptors also showed a decrease in the backreflected imaging light within 100 ms after the onset of the flash. All retinal layers showed a strong decrease in the backreflected light within 150 to 175 ms after the onset of the flash. Imaging the pupil dynamics of the chicken with a modified combined UHROCT and ERG system showed that part of the strong negative IOSs observed in all retinal layers resulted from the vignetting of the imaging beam due to the light induced pupil constriction. Thorough analysis of the pupil dynamics acquired with UHROCT showed a time dependent effect of the anesthesia agent on pupil constriction. Further experiments to investigate an anesthesia effects on retinal function showed significant changes in ERG components. Statistical analysis showed that Isoflurane anesthesia severely affects the inner retinal response. In conclusion, it was hypothesized that the fast IOSs within ~50-100 ms after the onset of the visual stimulus originated from the neuronal tissue in the retina and are related to tissue optical property changes as a result of the electrical signal propagation in the light activated retina. Longer term decreases in backreflected light are likely due to pupil changes.

The main objective of this thesis is to investigate the intrinsic optical signals (IOSs) with an ultra-high resolution optical coherence tomography system (UHROCT). In order to study the retinal IOSs evoked by visible light, an UHROCT and an Electroretinogram (ERG) system was combined. An animal model (chicken retina) based on its retinal avascularity and cone dominance, was selected. Imaging the chicken retina with OCT resulted in high contrast, high resolution (~3μm axial and ~5 μm lateral resolution) 2D and 3D volumetric tomograms, in which all retina layers were clearly distinguishable. Using the combined UHROCT and ERG system to image IOSs from the chicken retina exposed to visible light (7ms green flash) resulted in highly reproducible IOS recordings from all retinal layers for the first time. All inner retinal layers showed an initial increase and subsequently a decrease in the intensity of the backreflected imaging light within the first 100 ms after the onset of the stimulus. Outer segments of the photoreceptors also showed a decrease in the backreflected imaging light within 100 ms after the onset of the flash. All retinal layers showed a strong decrease in the backreflected light within 150 to 175 ms after the onset of the flash. Imaging the pupil dynamics of the chicken with a modified combined UHROCT and ERG system showed that part of the strong negative IOSs observed in all retinal layers resulted from the vignetting of the imaging beam due to the light induced pupil constriction. Thorough analysis of the pupil dynamics acquired with UHROCT showed a time dependent effect of the anesthesia agent on pupil constriction. Further experiments to investigate an anesthesia effects on retinal function showed significant changes in ERG components. Statistical analysis showed that Isoflurane anesthesia severely affects the inner retinal response. In conclusion, it was hypothesized that the fast IOSs within ~50-100 ms after the onset of the visual stimulus originated from the neuronal tissue in the retina and are related to tissue optical property changes as a result of the electrical signal propagation in the light activated retina. Longer term decreases in backreflected light are likely due to pupil changes.

O Estudo de Materiais Fotorrefrativos e suas Aplicações no Processamento Óptico Holográfico de Informação vêm sendo feitos por diversos Grupos de Pesquisas em vários laboratórios devido aos bons resultados obtidos com esses meios em diversas áreas. Entre outros efeitos foto-induzidos o processo que possibilita essas aplicações é o efeito fotorrefrativo, um fenômeno onde o registro holográfico no meio fotorrefrativo ocorre pela modulação do índice de refração de acordo com a distribuição espacial da intensidade da luz incidente, devido a uma redistribuição foto-induzida de cargas espaciais, e conseqüente, geração de um campo espaço-carga no meio. Neste trabalho, estuda-se a propagação e acoplamento de ondas eletromagnéticas em monocristais elétro-ópticos paraelétricos da Família das Silenitas \'BI IND. 12\'\'SI\'\'O IND. 20\' (BSO) e \'BI IND. 12\'\'TI\'\'O IND. 20\' (BTO) e nos ferroelétricos \'LI\'\'NB\'\'O IND. 3\' puros e dopados. O propósito de estudar esses materiais é caracterizá-los e, principalmente, otimizá-los para aplicação no processamento óptico e holográfico de informação. Utiliza-se técnicas de caracterização de redes holográficas fotorrefrativas e de lentes foto-induzidas para determinação de figuras de mérito e parâmetros fotorrefrativos e termo-ópticos nestes meios fotorrefrativos. Propõe-se também algumas aplicações no processamento óptico e holográfico de informação, nas áreas de pesquisa básica, tecnológicas e biomédicas, que vêm despertando grande interesse nos últimos anos, como holografia em tempo real com mapeamento de fase, interterometria speckle em tempo real e registro não-holográfico no processo de conversão incoerente-incoerente; entre outras no processamento óptico e holográfico de dados. / The Study of Photorefractive Materials and their Applications in Optical and Holographical Information Processing come being made for diverse Groups of Research in some laboratories due to the good results in many areas. Among other photo-induced effects, the process that allows these applications is the photorefractive effect, a phenomenon where the holographic recording in photorefractive medium occurs by means of the refractive index modulation due to the space distribution of the light intensity, producing a space-charge photo-induced redistribution, and consequently, the generation of a space-charge field governed by an electro-optic medium. In this work, we study the propagation and coupling of electromagnetic waves in electro-optic monocrystals of the sillemite family Bi12SiO20 (BSO) and Bi12TiO20 (BTO) and in the pure and dop-ed LiNbO3 crystals. The purpose to study these materials is to characterize them and, mainly, to optimize the conditions of their application in the optical and holographical information processing. We use photorefractive holographic gratings and photo-induced lens techniques for determination of figures of merit and photorefractive and thermo-optic parameters in these photorefractive materials. We also consider some applications in the optical and holographical information processing in the research basic, technological and biomedical areas, that come waken great interest in the last years, as phase- shifting real-time holography, real-time speckle interferometry and non-holographic recording with incoherent-incoherent conversion process; among others in the optic and holographic data processing.

The dissertation is concerned with the description and utilization of interference of two coherent optical rays. In addition, the conditions of coherence and its connections with the occurance of interference are discussed. Michelson's interferometer is used for the practical utilization of the interference effect. The possibility of measuring relatively small changes is demonstrated - deviation of piezocrystal, measurement of the coherent length of optical source and measurement of the index of refraction of tramsparent materials. The manner of optical coherent detention and its utilization in optical communication systems is indicated. After demonstration of the principle was carried out the measuring of detection of optical signal modified by the external modulator.

No description available.

No description available.

[ES] A día de hoy, las redes de comunicaciones de fibra óptica están alcanzando su capacidad límite debido al rápido crecimiento de la demanda de datos en la última década, generado por el auge de los teléfonos inteligentes, las tabletas, las redes sociales, la provisión de servicios en la nube, las transmisiones en streaming y las comunicaciones máquina-a-máquina. Con el fin de solventar dicho problema, se ha propuesto incrementar la capacidad límite de las redes ópticas mediante el reemplazo de la fibra óptica clásica por la fibra óptica multinúcleo (MCF, acrónimo en inglés de multi-core fiber), la cual es capaz de integrar la capacidad de varias fibras ópticas clásicas en su estructura ocupando prácticamente la misma sección transversal que éstas. Sin embargo, explotar todo el potencial de una fibra MCF requiere entender en profundidad los fenómenos electromagnéticos que aparecen en este tipo de fibras cuando guiamos luz a travésde ellas. Así pues, en la primera parte de la tesis se analizan teóricamente estos fenómenos electromagnéticos y, posteriormente, se estudia la viabilidad de la tecnología MCF en distintos tipos de redes ópticas de transporte, específicamente, en aquellas que hacen uso de transmisiones radio-sobre-fibra. Estos resultados pueden ser de gran utilidad para las futuras generaciones móviles 5G y Beyond-5G en las próximas décadas. Adicionalmente, con el fin de expandir las funcionalidades básicas de las fibras MCF, esta tesis explora nuevas estrategias de diseño de las mismas utilizando la analogía existente entre las ecuaciones que rigen la mecánica cuántica y el electromagnetismo. Con esta idea en mente, en la segunda parte de la tesis se propone diseñar una nueva clase de fibras MCF usando las matemáticas de la supersimetría, surgida en el seno de la teoría de cuerdas y de la teoría cuántica de campos como un marco teórico de trabajo que permite unificar las interacciones fundamentales de la naturaleza (la nuclear fuerte, la nuclear débil, el electromagnetismo y la gravedad). Girando en torno a esta idea surgen las fibras MCF supersimétricas, las cuales nos permiten procesar la información de los usuarios durante la propia propagación de la luz a través de ellas, reduciendo así la complejidad del procesado de datos del usuario en recepción. Finalmente, esta tesis se completa introduciendo un cambio de paradigma que permite diseñar dispositivos fotónicos disruptivos. Demostramos que la supersimetría de mecánica cuántica no relativista, propuesta como una serie de transformaciones matemáticas restringidas al dominio espacial, se puede extender también al dominio del tiempo, al menos dentro del marco de trabajo de la fotónica. Como resultado de nuestras investigaciones, demostramos que la supersimetría temporal puede convertirse en una plataforma prometedora para la fotónica integrada ya que nos permite diseñar nuevos dispositivos ópticos versátiles y ultra-compactos que pueden jugar un papel clave en los procesadores del futuro. Asimismo, con el fin de hacer los resultados principales de esta tesis doctoral lo más generales posibles, se detalla cómo poder extrapolarlos a otros campos de la física como acústica y mecánica cuántica. / [CA] Avui en dia, les xarxes de comunicacions de fibra òptica estan aconseguint la seua capacitat límit a causa del ràpid creixement de la demanda de dades duante l'última dècada, generat per l'auge dels telèfons intel·ligents, les tablets, les xarxes socials, la provisió de servicis en la núvol, les transmissions en streaming i les comunicacions màquina-a-màquina. Per a resoldre el dit problema, s'ha proposat incrementar la capacitat límit de les xarxes òptiques per mitjà del reemplaçament de la fibra òptica clàssica per la fibra òptica multinúcleo (MCF, acrònim en anglés de multi-core fiber), la qual és capaç d'integrar la capacitat de diverses fibres òptiques clàssiques en la seua estructura ocupant pràcticament la mateixa secció transversal que estes. Tanmateix, explotar tot el potencial d'una fibra MCF requereix entendre en profunditat els fenòmens electromagnètics que apareixen en aquestes fibres quan guiem llum a través d'elles. Així, doncs, en la primera part de la tesi analitzem teòricament aquests fenòmens electromagnètics i, posteriorment, estudiem la viabilitat de la tecnologia MCF en distints tipus de xarxes òptiques de transport, específicament, en aquelles que fan ús de transmissions ràdio-sobre-fibra. Estos resultats poden ser de gran utilitat per a les futures generacions mòbils 5G i Beyond-5G en les pròximes dècades. Addicionalment, a fi d'expandir les funcionalitats bàsiques de les fibres MCF, esta tesi explora noves estratègies de disseny de les mateixes utilitzant l'analogia existent entre les equacions que regixen la mecànica quàntica i l'electromagnetisme. Amb aquesta idea en ment, en la segona part de la tesi proposem dissenyar una nova classe de fibres MCF usant les matemàtiques de la supersimetria, sorgida en el si de la teoria de cordes i de la teoria quàntica de camps com un marc teòric de treball que permet unificar les interaccions fonamentals de la natura (la nuclear forta, la nuclear feble, l'electromagnetisme i la gravetat). Al voltant d'aquesta idea sorgeixen les fibres MCF supersimètriques, les quals ens permeten processar la informació dels usuaris durant la pròpia propagació de la llum a través d'elles, reduint així la complexitat del processament de dades de l'usuari a recepció. Finalment, esta tesi es completa introduint un canvi de paradigma que permet dissenyar dispositius fotónicos disruptius. Demostrem que la supersimetria de mecànica quàntica no relativista, proposta com una sèrie de transformacions matemàtiques restringides al domini espacial, es pot estendre també al domini del temps, almenys dins del marc de treball de la fotónica. Com resultat de les nostres investigacions, demostrem que la supersimetria temporal pot convertir-se en una plataforma prometedora per a la fotònica integrada ja que ens permet dissenyar nous dispositius òptics versàtils i ultracompactes que poden jugar un paper clau en els processadors del futur. Per tal de fer els resultats principals d'aquesta tesi doctoral el més generals possibles, es detalla com poder extrapolar-los a altres camps de la física com ara la acústica i la mecànica quàntica. / [EN] To date, communication networks based on optical fibers are rapidly approaching their capacity limit as a direct consequence of the increment of the data traffic demand in the last decade due to the ubiquity of smartphones, tablets, social networks, cloud computing applications, streaming services including video and gaming, and machine-to-machine communications. In such a scenario, a new class of optical fiber which is able to integrate the capacity of several classical optical fibers approximately in the same transverse section as that of the original one, the multi-core fiber (MCF), has been recently proposed to overcome the capacity limits of current optical networks. However, the possibility of exploiting the full potential of an MCF requires to deeply understand the electromagnetic phenomena that can be observed when guiding light in this optical medium. In this vein, in the first part of this thesis, we analyze theoretically these phenomena and, next, we study the suitability of the MCF technology in optical transport networks using radio-over-fiber transmissions. These findings could be of great utility for 5G and Beyond-5G cellular technology in the next decades. In addition, the close connection between the mathematical framework of quantum mechanics and electromagnetism becomes a great opportunity to explore ground-breaking design strategies of these new fibers that allow us to expand their basic functionalities. Revolving around this idea, in the second part of this thesis we propose to design a new class of MCFs using the mathematics of supersymmetry (SUSY), emerged within the context of string and quantum field theory as a means to unify the basic interactions of nature (strong, electroweak, and gravitational interactions). Interestingly, a supersymmetric MCF will allow us, not only to propagate the light, but also to process the information of users during propagation. Finally, we conclude this thesis by introducing a paradigm shift that allows us to design disruptive optical devices. We demonstrate that the basic ideas of SUSY in non-relativistic quantum mechanics, restricted to the space domain to clarify unsolved questions about SUSY in string and quantum field theory, can also be extended to the time domain, at least within the framework of photonics. In this way, it is shown that temporal supersymmetry may serve as a key tool to judiciously design versatile and ultra-compact optical devices enabling a promising new platform for integrated photonics. For the sake of completeness, we indicate how to extrapolate the main results of this thesis to other fields of physics, such as acoustics and quantum mechanics. / Macho Ortiz, A. (2019). Multi-Core Fiber and Optical Supersymmetry: Theory and Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124964