Le stockage de données par holographie suscite un intérêt renouvelé. Il semble bien placé pour conduire à une nouvelle génération de mémoires optiques aux capacités et débits de lecture bien supérieurs à ceux des disques optiques actuels basés sur l’enregistrement dit surfacique. Dans ce travail de thèse, nous proposons une nouvelle architecture de stockage optique de données qui s’inspire du principe de la photographie interférentielle de Lippmann. Les informations y sont inscrites dans le volume du matériau d’enregistrement sous la forme de pages de données par multiplexage en longueur d’onde en exploitant la sélectivité de Bragg. Cette technique, bien que très voisine de l’holographie, n’avait jamais été envisagée pour le stockage à hautes capacités. L’objectif de la thèse a été d’analyser cette nouvelle architecture afin de déterminer les conditions pouvant conduire à de très hautes capacités. Cette analyse s’est appuyée sur un outil de simulation numérique des processus de diffraction en jeu dans cette mémoire interférentielle. Elle nous a permis de définir deux conditions sous lesquelles ces hautes capacités sont atteignables. En respectant ces conditions, nous avons conçu un démonstrateur de mémoire dit de « Lippmann » et avons ainsi démontré expérimentalement que la capacité est bien proportionnelle à l’épaisseur du matériau d’enregistrement. Avec une telle architecture, des capacités de l’ordre du Téraoctet sont attendues pour des disques de 12 cm de diamètre. / Nowadays, the holographic data storage presents a renewed interest. It seems well placed to lead a new generation of optical storage capacity and playback speeds much higher than current optical discs based on the recording onto a surface. In this thesis, we propose a new architecture for optical data storage that is based on the principle of Lippmann photography interferential. Information are included in the volume of the recording material in the form of pages of data multiplexing in wavelength by exploiting the Bragg selectivity. This technique, although very similar to holography, had never been considered for high storage capacities. The aim of the thesis was to analyze this new architecture to determine the conditions that can lead to very high capacities. This analysis was based on a numerical simulation tool of diffraction process involved in this memory interferential. It allowed us to define two conditions under which these high capacities are achievable. In accordance with these conditions, we developed a demonstrator called "Lippmann’s memory" and have thus demonstrated experimentally that the capacity is proportional to the thickness of the recording material. With such an architecture, Terabyte disks of 12 cm in diameter are expected.

Moduladores espaciais de luz são elementos que fazem a modulação de uma frente de onda de modo a resultar em uma distribuição de luz desejada. Eles operam por difração, de acordo com o princípio de Huygens-Fresnel, e por este motivo são chamados Elementos Ópticos Difrativos (EODs). O foco deste trabalho é o estudo da modulação de frentes de onda, através da Teoria Escalar da Difração. O objetivo inicial foi o domínio do cálculo dos moduladores espaciais de luz, através da implementação do Algoritmo Iterativo da Transformada de Fourier. São calculados três EODs de fase: fase contínua, 4 níveis de fase e fase binária. Os resultados são avaliados através do cálculo da eficiência difrativa e da relação sinal-ruído. Para verificação do cálculo, hologramas binários foram fabricados usando filme fotográfico, de maneira simples e baixo custo. Algumas reconstruções simuladas e ópticas são apresentadas, demonstrando a viabilidade do uso do algoritmo na codificação de EODs. Em seguida, é feita a análise das frequências de ressonância de moduladores de ferroeletretos com canaleta, através de uma montagem experimental baseada no interferômetro de Michelson. Os ferroeletretos apresentam o efeito piezoelétrico e vêm sendo produzidos através de novas técnicas de fabricação. No campo da óptica tem-se o interesse em caracterizar ferroeletretos de modo a utilizá-los como possíveis moduladores de luz. São apresentados a montagem interferométrica em detalhes e o procedimento usado para medir as frequências de ressonância. Os resultados obtidos e as discussões demonstram a viabilidade do uso da montagem interferométrica proposta na caracterização de ferroeletretos. / Spatial light modulators perform the modulation of wavefront so that the desired light distribution is acquired. They work by diffraction, according to the Huygens-Fresnel principie, and for that they are called Diffractive Optical Elements (DOEs). The focus of this work is the study of light modulators through Scalar Diffraction Theory. The initial objective was to execute the calculation of spatial light modulators through the implementation of the so-called Iterative Fourier Transform AIgorithm. The calculation of three phase holograms is made: analog phase, 4 leveI phase and binary phase. The results are evaluated by calculating the diffraction efficiency and by signal to noise ratio. To verify the calculation, binary holograms were fabricated using photographic film in a simple and low cost way. Simulated and optical reconstructions are presented, showing the viability for the use of the algorithm in the coding of DOEs. Next, the resonance frequencies analysis in open tubular channels ferroelectrets is made through an experimental setup based in the Michelson interferometer. The ferroelectrets present the piezoelectric effect and are continuously produced through new techniques. In optics there is in interest in feroelectrets characterization in order to use them as spatial light modulators. The interferometric setup and the procedure used to measure the resonance frequencies are shown. The obtained results and discussion demonstrate the viability of the use of optical measurements in the characterization of ferroelectrets.

Orientador: Prof. Dr. Marcos Roberto de Rocha Gesualdi / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, 2014. / Neste trabalho, realizando uma revisão teórica e experimental da geração de feixes não difrativos a partir dos fundamentos de teoria de difração, Hologramas Gerados por Computador (CGH) e Holograa, utilizando Moduladores Espaciais de Luz (SLM). Mostramos a possibilidade de geração de múltiplos feixes não difrativos de iguais ou diferentes simetrias utilizando a reconstrução holográca em SLM. Apresentamos de forma inédita a obtenção experimental de um novo conceito de feixe não difrativo que utiliza a superposição de feixes de Bessel cujo padrão longitudinal de intensidade pode ser escolhido a priori, a chamada Frozen Wave. Finalmente realizamos uma revisão teórica das propriedades de ondas em meios não lineares Fotorrefrativos, e a partir desse estudo desenvolvemos e montamos um arranjo de Holograa Fotorrefrativa e demonstramos experimentalmente a possibilidade de gerar feixes não difrativos utilizando essa técnica. Evidenciamos através dessa técnica uma nova possibilidade de geração de feixes não difrativos e em especial para geração de Frozen Waves. / In this work, we perform a theoretical and experimental review of genration non diractive beams since difraction theory, Computing Generation Hologram (CGH) and Holography using Spatial Light Modulator (SLM). We show the possibility to generate multiple non diractive beams with the igual or dierent symetry using a holographic reconstruction in SLM. We show for the rst time the experimental observation of a new nondifractive beam concepte that use Bessel beam superpositions whose intensite longitudinal shape can be chosen a priori, known as Frozen Wave. Finally, we made a theoretical review of the nonlinear Photorefractive properties, and of from this study we developed and mont a Photorefractive holography setup to show the nondiractive beam generation through this technique. Evidencing through this technique a new possibility to generate a non diractive beams and on special case to generate Frozen Waves.

<p>Laser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. Physical constraints set limitations to the SLM and an ideal phase distribution can usually not be realised. In order to understand how such components can be used for non-mechanical beam control three nematic liquid crystal (NLC) SLMs have been thoroughly characterised and modelled.</p><p>The pixel structure and phase quantisation give a discrepancy between ideal and realised phase distributions. The impact on beam steering capability was examined by measurements and simulations of the intensity distribution in the far-field.</p><p>In two of the studied SLMs the pixel period was shorter than the thickness of the LC layer giving the optical phase shift. This results in a so-called “fringing field”, which was shown to degrade the phase modulation and couple light between polarisation modes. The deformation of the LC was simulated and a finite-difference time-domain (FDTD) algorithm was used to calculate how polarised light propagates through the optically anisotropic SLM.</p><p>Non-mechanical beam steering and tracking in an optical free-space communication link were demonstrated. Continual optimisation of the steering angle was achieved by feedback from a video camera.</p><p>The optical properties of the SLM in the time period right after a voltage update were studied. It was shown how light is redistributed between orders during the switching from one blazed grating to another. By appropriate choice of the blazed gratings the effects on the diffraction efficiency can be minimised.</p><p>The detailed knowledge of the SLM structure and its response to electronic control makes it possible to predict and optimise the device performance in future systems.</p>

Laser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. Physical constraints set limitations to the SLM and an ideal phase distribution can usually not be realised. In order to understand how such components can be used for non-mechanical beam control three nematic liquid crystal (NLC) SLMs have been thoroughly characterised and modelled. The pixel structure and phase quantisation give a discrepancy between ideal and realised phase distributions. The impact on beam steering capability was examined by measurements and simulations of the intensity distribution in the far-field. In two of the studied SLMs the pixel period was shorter than the thickness of the LC layer giving the optical phase shift. This results in a so-called “fringing field”, which was shown to degrade the phase modulation and couple light between polarisation modes. The deformation of the LC was simulated and a finite-difference time-domain (FDTD) algorithm was used to calculate how polarised light propagates through the optically anisotropic SLM. Non-mechanical beam steering and tracking in an optical free-space communication link were demonstrated. Continual optimisation of the steering angle was achieved by feedback from a video camera. The optical properties of the SLM in the time period right after a voltage update were studied. It was shown how light is redistributed between orders during the switching from one blazed grating to another. By appropriate choice of the blazed gratings the effects on the diffraction efficiency can be minimised. The detailed knowledge of the SLM structure and its response to electronic control makes it possible to predict and optimise the device performance in future systems.

Le but initial de ce travail de thèse est de proposer une technique (basée sur la Fluorescence Correlation Spectroscopy, FCS) pour améliorer la sensibilité dans la discrimination de deux molécules ayant des constantes de diffusion proches. C'est dans ce contexte que nous avons étudié la FCCS (Fluorescence Cross-Correlation Spectroscopy). A défaut d'améliorer la sensibilité de la Spectroscopie à Correlation de Fluorescence nous avons proposé trois géométries de FCCS pour élargir le champ d'application de la corrélation de fluorescence.

Šioje disertacijoje teoriškai ir eksperimentiškai tiriamas erdvinių šviesos darinių formavimasis didelės apertūros monolitiniuose parametriniuose šviesos generatoriuose (PŠG), nagrinėjamos fotoninių kristalų (FK) rezonatorių erdvinės dispersijos savybės. Darbas susideda iš įvado, literatūros apžvalgos ir dviejų pagrindinių dalių. Pirmoje dalyje aprašomas PŠG tyrimas didelės apertūros (5x5x1,5 mm) BBO I fazinio sinchronizmo tipo kristalo monolitiniame mini rezonatoriuje. Generatoriui kaupinti naudojami antros Nd:IAG lazerio harmonikos (532 nm) 13 ns trukmės ir 7-15 mJ energijos impulsai. Erdviniai šviesos dariniai registruojami artimajame ir tolimajame laukuose. Eksperimentiškai parodoma ir teoriškai interpretuojama, kad tokio rezonatoriaus emisija gali būti kūginė ir daugiakūgė, o signalinės ir skirtuminės bangų kryptys gali būti valdomos keičiant kampą tarp rezonatoriaus optinės ašies ir kaupinimo pluošto. Taip pat parodoma, kad dryžių erdvinio šviesos darinio formavimasis gali būti pasiekiamas injektuojant pagrindinio dažnio užkrato signalą. Antrojoje disertacijos dalyje pristatomi ir tiriami plokščiųjų veidrodžių Fabri ir Pero tipo rezonatoriai su vidine lūžio rodiklio moduliacija, atitinkančia vieną fotoninio kristalo (FK) išilginį periodą. FK rezonatoriai sukurti veidrodžių paviršiuje suformuojant 2 µm, 4 µm ir 15 µm periodinę lūžio rodiklio moduliaciją (t.y. suformuojant vienmatę arba dvimatę fazinę difrakcinę gardelę). FK rezonatorių kampinis pralaidumas matuotas... [toliau žr. visą tekstą] / This Ph.D. thesis contains experimental and theoretical analysis of nonlinear optical pattern formation in monolithic mini-cavity optical parametrical oscillators and spatial properties of linear photonic crystal resonators. The thesis consists of introduction, literature review and two chapters. In the first chapter experimental investigation of optical parametrical oscillation (OPO) in broad aperture monolithic (5x5x1.5 mm) BBO type I crystal mini-cavity is described. OPO was pumped by second harmonic (532 nm) 13 ns duration, 7 15 mJ energy pulses, of Nd:YAG laser. Optical patterns were registered in a near and far field of OPO emission. Experiments and theoretical interpretation revealed that emission of such resonator can be conical and multiconical and direction of signal and idler waves can be controlled by changing the mini-cavity orientation with respect to pump beam. It was also showed, that the stabilization of stripes (or roll) pattern can be achieved by a weak seed injection at subharmonic frequency and temporal spectrum of the stripe pattern degenerate OPO emission is 1/f – like noise spectrum . In the second chapter plane-mirror Fabry-Pérot resonators filled with a single period of photonic crystal (PhC) are introduced and analyzed. PhC resonators are realized by adding periodical 2 µm, 4 µm and 15 µm refraction index modulation on a resonator mirror surfaces (i.e. fabricating 1D or 2D phase diffraction grating). PhC resonator angular transmission measured by... [to full text]

This Ph.D. thesis contains experimental and theoretical analysis of nonlinear optical pattern formation in monolithic mini-cavity optical parametrical oscillators and spatial properties of linear photonic crystal resonators. The thesis consists of introduction, literature review and two chapters. In the first chapter experimental investigation of optical parametrical oscillation (OPO) in broad aperture monolithic (5x5x1.5 mm) BBO type I crystal mini-cavity is described. OPO was pumped by second harmonic (532 nm) 13 ns duration, 7 15 mJ energy pulses, of Nd:YAG laser. Optical patterns were registered in a near and far field of OPO emission. Experiments and theoretical interpretation revealed that emission of such resonator can be conical and multiconical and direction of signal and idler waves can be controlled by changing the mini-cavity orientation with respect to pump beam. It was also showed, that the stabilization of stripes (or roll) pattern can be achieved by a weak seed injection at subharmonic frequency and temporal spectrum of the stripe pattern degenerate OPO emission is 1/f – like noise spectrum . In the second chapter plane-mirror Fabry-Pérot resonators filled with a single period of photonic crystal (PhC) are introduced and analyzed. PhC resonators are realized by adding periodical 2 µm, 4 µm and 15 µm refraction index modulation on a resonator mirror surfaces (i.e. fabricating 1D or 2D phase diffraction grating). PhC resonator angular transmission measured by... [to full text] / Šioje disertacijoje teoriškai ir eksperimentiškai tiriamas erdvinių šviesos darinių formavimasis didelės apertūros monolitiniuose parametriniuose šviesos generatoriuose (PŠG), nagrinėjamos fotoninių kristalų (FK) rezonatorių erdvinės dispersijos savybės. Darbas susideda iš įvado, literatūros apžvalgos ir dviejų pagrindinių dalių. Pirmoje dalyje aprašomas PŠG tyrimas didelės apertūros (5x5x1,5 mm) BBO I fazinio sinchronizmo tipo kristalo monolitiniame mini rezonatoriuje. Generatoriui kaupinti naudojami antros Nd:IAG lazerio harmonikos (532 nm) 13 ns trukmės ir 7-15 mJ energijos impulsai. Erdviniai šviesos dariniai registruojami artimajame ir tolimajame laukuose. Eksperimentiškai parodoma ir teoriškai interpretuojama, kad tokio rezonatoriaus emisija gali būti kūginė ir daugiakūgė, o signalinės ir skirtuminės bangų kryptys gali būti valdomos keičiant kampą tarp rezonatoriaus optinės ašies ir kaupinimo pluošto. Taip pat parodoma, kad dryžių erdvinio šviesos darinio formavimasis gali būti pasiekiamas injektuojant pagrindinio dažnio užkrato signalą. Antrojoje disertacijos dalyje pristatomi ir tiriami plokščiųjų veidrodžių Fabri ir Pero tipo rezonatoriai su vidine lūžio rodiklio moduliacija, atitinkančia vieną fotoninio kristalo (FK) išilginį periodą. FK rezonatoriai sukurti veidrodžių paviršiuje suformuojant 2 µm, 4 µm ir 15 µm periodinę lūžio rodiklio moduliaciją (t.y. suformuojant vienmatę arba dvimatę fazinę difrakcinę gardelę). FK rezonatorių kampinis pralaidumas matuotas... [toliau žr. visą tekstą]

Traffic from wireless and mobile devices is predicted to increase 10-fold between 2014 and 2019, surpassing wired data traffic by 2016. Given the expected radio frequency (RF) capacity crunch, this growing wireless demand will have to be met using a variety of new technologies exploiting other parts of the electromagnetic spectrum. Promising research areas include the Millimetre Band as well as Optical Wireless Communications (OWC). Millimetre Band demonstrations have accomplished ultrafast multi-Gigabit links, making use of state-of-the-art fibre transmission systems. However, complex opto-electronic (OE) interfaces are required to convert the optical carrier into Millimetre wireless signals. To avoid these interfaces, an all-optical transparent network is proposed here, spanning over both the fibre and OWC domains, in order to deliver ultrahigh data rates to mobile end-users in indoor environments. This is supported by the recent deployment of fibre-to-the-home (FTTH) networks creating the potential for Terabit aggregate connections at the user's doorstep. Therefore, infrared fibre-wireless-fibre (FWF) links are studied to support data rates over 100 Gb/s in nomadic applications. The link coverage is achieved via narrow beam beamsteering over a wide field-of-view (FOV) using suitable localization and tracking techniques. The proposed model is inherently bidirectional and transparent, i.e. independent of the data rate and modulation format. In this thesis, the potential for ultrafast wide coverage OWCs using SMF-based transceivers and coherent transmission is demonstrated. A record data rate of 418 Gb/s and 209 Gb/s with a wide FOV of &theta;_FOV=±30° and &theta;_FOV=±20°, respectively, is shown at a free space range of 3 m. To the best of our knowledge, this is the fastest demonstration of an indoor wireless link that offers practical room-scale coverage. The automated alignment of this FWF link is also demonstrated with the design and implementation a mm-accurate localization and tracking system. Finally, architectures for point-to-multipoint communications are explored in order to adapt the system to multiple users.

Moduladores espaciais de luz são elementos que fazem a modulação de uma frente de onda de modo a resultar em uma distribuição de luz desejada. Eles operam por difração, de acordo com o princípio de Huygens-Fresnel, e por este motivo são chamados Elementos Ópticos Difrativos (EODs). O foco deste trabalho é o estudo da modulação de frentes de onda, através da Teoria Escalar da Difração. O objetivo inicial foi o domínio do cálculo dos moduladores espaciais de luz, através da implementação do Algoritmo Iterativo da Transformada de Fourier. São calculados três EODs de fase: fase contínua, 4 níveis de fase e fase binária. Os resultados são avaliados através do cálculo da eficiência difrativa e da relação sinal-ruído. Para verificação do cálculo, hologramas binários foram fabricados usando filme fotográfico, de maneira simples e baixo custo. Algumas reconstruções simuladas e ópticas são apresentadas, demonstrando a viabilidade do uso do algoritmo na codificação de EODs. Em seguida, é feita a análise das frequências de ressonância de moduladores de ferroeletretos com canaleta, através de uma montagem experimental baseada no interferômetro de Michelson. Os ferroeletretos apresentam o efeito piezoelétrico e vêm sendo produzidos através de novas técnicas de fabricação. No campo da óptica tem-se o interesse em caracterizar ferroeletretos de modo a utilizá-los como possíveis moduladores de luz. São apresentados a montagem interferométrica em detalhes e o procedimento usado para medir as frequências de ressonância. Os resultados obtidos e as discussões demonstram a viabilidade do uso da montagem interferométrica proposta na caracterização de ferroeletretos. / Spatial light modulators perform the modulation of wavefront so that the desired light distribution is acquired. They work by diffraction, according to the Huygens-Fresnel principie, and for that they are called Diffractive Optical Elements (DOEs). The focus of this work is the study of light modulators through Scalar Diffraction Theory. The initial objective was to execute the calculation of spatial light modulators through the implementation of the so-called Iterative Fourier Transform AIgorithm. The calculation of three phase holograms is made: analog phase, 4 leveI phase and binary phase. The results are evaluated by calculating the diffraction efficiency and by signal to noise ratio. To verify the calculation, binary holograms were fabricated using photographic film in a simple and low cost way. Simulated and optical reconstructions are presented, showing the viability for the use of the algorithm in the coding of DOEs. Next, the resonance frequencies analysis in open tubular channels ferroelectrets is made through an experimental setup based in the Michelson interferometer. The ferroelectrets present the piezoelectric effect and are continuously produced through new techniques. In optics there is in interest in feroelectrets characterization in order to use them as spatial light modulators. The interferometric setup and the procedure used to measure the resonance frequencies are shown. The obtained results and discussion demonstrate the viability of the use of optical measurements in the characterization of ferroelectrets.