Este trabalho relata a produção, implementação e avaliação de um curso sobre física quântica destinado a alunos do Ensino Médio. A unidade didática foi inspirada nas propostas de Ostermann et al. (2009) e Pessoa Jr. (1997, 2003). Ela introduz a física quântica considerando a óptica ondulatória como um contexto para introduzir algumas analogias conceituais básicas para conceitos fundamentais da física quântica. O conceito central desta abordagem é a dualidade onda-partícula e o Interferômetro Virtual de Mach-Zehnder (IVMZ) é utilizado como sua ferramenta didática principal ou, em termos vygotskyanos, ferramenta de mediação. A proposta foi aplicada no formato de uma oficina extracurricular em uma escola privada de Porto Alegre no Brasil. Um dos professores de Física da escola se engajou e colaborou com este projeto. As aulas ocorreram entre os meses de Outubro e Novembro de 2013, em encontros semanais de uma hora. A perspectiva sociocultural de Vygotsky foi utilizada para embasar as aulas do curso. A translinguística de Bakhtin e os conceitos vygotskyanos foram utilizados para a análise das falas dos estudantes durante as atividades do curso. Nesta perspectiva analítica buscamos compreender como os estudantes elaboram estratégias discursivas para entender o conceito de dualidade onda-partícula, analisando a importância das interações com parceiros mais capazes (como professores), textos, simulações e outras ferramentas didáticas. Os resultados indicam que os estudantes desenvolveram algum domínio das ferramentas mediacionais necessárias para compreender a dualidade onda-partícula em um nível satisfatório. O Interferômetro Virtual de Mach-Zehnder, os roteiros exploratórios e os professores mostraram-se importantes para tornar mais efetivas as experiências de aprendizagem dos estudantes. / This dissertation reports the development, implementation and evaluation of a quantum physics course directed to high school students. The course was conceived inspired in proposals of Ostermann et al. (2009) and Pessoa Jr. (1997, 2003). It introduces quantum physics considering wave optics as a context to introduce some basic conceptual analogies to quantum fundamental concepts. The core concept of this approach is the wave-particle duality and the Virtual Mach-Zehnder Interferometer (VMZI) is used as its main didactical tool or, in vygotskyan terms, a mediational tool. The course was applied as an extracurricular workshop in a private school from Porto Alegre, Brazil. One of the school´s Physics teacher collaborated and engaged in this project. The classes took place between October and November 2013, in a set of one-hour weekly meetings. Vygotsky´s sociocultural perspective is adopted to ground the practices of the course. Both Bakhtin´s translinguistics and Vygotsky’s concepts were used to perform the analysis of students’ utterances along didactical activities at the classes. In this analytical framework, we try to understand how students elaborate discursive strategies to understand the concept of wave-particle duality, analyzing the importance of interaction with more experienced peers (like teachers), texts, simulation and other teaching tools. The results indicate that the students developed some mastery of mediational means needed to understand the wave-particle duality at a satisfactory level. The Virtual Mach-Zehnder Interferometer, the exploratory guides and the teachers were important to enhance the students’ learning experiences.

Les travaux de cette thèse s’inscrivent dans un projet de développement d’un Lab-On-Chip destiné à la biodétection. Les plateformes conçues sont basées sur des circuits optiques intégrés sur niobate de lithium. La particularité de ces circuits est qu’ils intègrent le phénomène d’interférence à la fonction de guidage des ondes lumineuses.La fonction d’interférométrie est assurée grâce à une cavité Fabry-Pérot intégrée à un guide d’onde rectiligne et à une structure Mach-Zehnder. Lorsque la surface des supports de ces circuits est bio-fonctionnalisée, ces microsystèmes deviennent sensibles à des molécules cibles. Cette sensibilité se traduit par une variation de l’indice effectifde l’onde en propagation par couplage évanescent modifiant ainsi les conditions de résonance du résonateur Fabry-Pérot. Le vrai challenge de ce travail réside essentiellement dans la bio-fonctionnalisation du niobate de lithium.A notre connaissance, ce matériau favori en optique guidée grâce à ses propriétés physiques exceptionnelles n’a été que rarement sujet à des modifications chimiques de surface. L’implantation réussie de groupements fonctionnels amines à la surface de ce matériau a permis de générer un lien covalent entre ce support et les groupements fonctionnels des molécules sondes. En raison de la grande affinité entre l’avidine et la biotine, ce couple a servi de modèle pour la mise au point de ces bio-capteurs. Un suivi en temps réel des interactions à la surface était rendu possible par une expérimentation sur l’un des bio-capteurs. / The work of this thesis is part of a project of a Lab-On-Chip development intended for biosensing. The de-signed platforms are based on integrated optical circuits on lithium niobate. The peculiarity of these circuits isthat they incorporate the phenomenon of interference with the function of guiding light waves. The interferometricfunction is provided by a Fabry-Perot cavity embedded in a straight waveguide and a Mach-Zehnder structure.When the surface of these circuits substrates is biofunctionalized, these microsystems become sensitive to targetmolecules. This sensitivity results in a variation of the effective index of the propagation wave by evanescent cou-pling and modifying the resonance conditions of the Fabry-Perot resonator. The real challenge of this work liesin the biofunctionalization of lithium niobate. To our knowledge, this guided optics favorite material thanks toits exceptional physical properties has been hitherto rarely subject to chemical surface modifications. Successfulimplementation of amino functions on the surface of this material has generating a covalent bond between thissubstrate and the functional groups of the probe molecules. Due to the high affinity between avidin and biotin, thiscouple served as a model for the development of biosensors. A real-time monitoring of surface interactions wasmade possible by experimentation on one of biosensors.

Le développement permanent des applications informatiques telles que le stockage de masse, le calcul intensif et les communications large bande, encourage l’émergence de nouvelles technologies de communication. D’une part, les communications à travers des interconnexions métalliques approchent de leurs limites intrinsèques en termes d’énergie, surface et coût par bit. D’autre part, la photonique hybride conventionnelle, basée sur des assemblages 2D/3D de composants photoniques en technologies III-V, ne peut pas être complètement intégrée. Le développement de nouvelle architecture photonique sur silicium est une bonne alternative afin de proposer des systèmes intégrés de communication haut débit. La conception d’un modulateur électro-optique à très haut débit sur silicium fait l’objet de cette thèse. Dans un premier temps, un état de l’art des différents systèmes optiques est dressé, afin d’identifier les principaux verrous technologiques limitant leurs performances. Suite à l’analyse des différents types de modulateur optique implémentés sur silicium, une proposition d’architecture a été faite pour un modulateur Mach Zehnder 100 Gbits/s. Ce premier circuit a été développé avec la technologie PIC25G du fondeur STMicroelectronics. Le driver de ce modulateur a, quant à lui, été conçu avec la technologie 55 nm SiGe BiCMOS de ce même fondeur. Le démonstrateur proposé dans ces travaux offre un débit de 100 Gbits/s avec une modulation NRZ sur une unique voie optique. Pour cette configuration, ce prototype offre un débit binaire au-delà de l’état de l’art (pour une unique voie de transmission optique) avec une énergie par bit de 80 pJ/bit. / The sustained development of software applications including mass storage, intensive computing and broadband communication, motivates the emergence of novel communication technologies. On one hand, communications through metallic interconnections approach their inherent limitations in term of energy, area and cost per bit. On the other hand, conventional hybrid photonics, based on discrete 2D/3D photonic assemblies of III-V photonic devices, cannot be integrated. The rising silicon photonic technology, thanks to its high level of integration, overcomes the shortcomings of the two previous approaches and promises a low cost solution allowing close proximity integration of photonics with electronics.The design of a very high data rate electro-optic modulator on silicon is reported in this thesis manuscript. In a first section, the state of the art of optic systems is presented with a focus on the main technological challenges limiting performances. Then, a silicon based topology is introduced to achieve a 100 Gbs Mach Zehnder modulator. It was implemented with the STMicroelectronics PIC25G technology. The driver of this modulator was designed with the 55 nm SiGe BiCMOS technology of the same founder. The demonstrator introduced in this work offer a 100 Gbs data rate with an NRZ modulation on a single optical channel. For this configuration, this prototype provides a data rate beyond the state of the art (for a single optical transmission path) with an energy per bit of 80 pJ/bit.

We have harnessed the power of various programmable photonics devices for an interferometric measurement technique. Distortion-free laser-based velocity measurements through a dynamic gas-liquid interface are enabled by a closed-loop optoelectronic system. We are employing electrically tunable lenses and micro mirrors to correct low-order wavefront distortions effectively. Our work represents a paradigm shift in interferometric velocity measurement techniques from using static to dynamic optical elements.

This thesis addresses basic scientific research in the field of transmitter front-end circuits for electro-optical data communication. First, the theoretical fundamentals are presented and analyzed. Based on the theoretical considerations, conceptual circuit designs are studied. Finally, in order to prove the described concepts, the circuits were experimentally characterized and subsequently compared to other works in the literature. The analysis covers key theoretical aspects regarding transmitter front-end circuits. It starts from the basic physical effects inside a transistor and ends with the design of high-swing modulator drivers. Furthermore, it comprises the fundamentals of optical modulators as well as the integration of the electrical driver with the modulator. First, the concept of a basic monolithically integrated transmitter consisting of a Mach-Zehnder modulator (MZM) and an electrical driver is presented. The circuit reaches a bit-error-free data rate of 37 Gb/s, which is a record among other monolithically integrated transmitters reported in the literature. It was shown that by employing a high-swing driver, high extinction ratios (ER) can be achieved (namely 8.4 dB at 25 Gb/s and 7.6 dB at 35 Gb/s) while using short-length phase shifters (2 mm of length). It was therefore proved that one of the main drawbacks of the MZM-based transmitters, namely their large chip area, can be mitigated by using high-swing drivers, however without sacrificing the ER. Next, an improved modulator driver design is investigated, the focus of the study being the linearity. In addition to a high peak-to-peak differential output voltage swing of 7.2 Vpp,d, the driver achieves record-low total harmonic distortion (THD) values of 1% (at 1 GHz, for the output swing of 6.5 Vpp,d) and 1.7% (at 1 GHz, for the output swing of 7 Vpp,d). Moreover, the driver reaches a bandwidth of 61.2 GHz and shows a high power efficiency when relating its DC power consumption to its output voltage swing. The achievement of a high linearity and bandwidth without an increased power consumption is due to the fact that the bias currents of the emitter-follower (EF) stages are provided by means of resistors instead of the conventional current sources. The two approaches were first analyzed mathematically and subsequently compared by means of circuit simulations. It was shown that the proposed approach for the realization of the EFs – i.e. by means of resistors – allows a reduction of the DC power consumption by 19% compared to the current-source approach for an equivalent performance in terms of linearity and bandwidth. Finally, a modulator driver concept suitable for higher-order modulation formats is studied, namely the 8-level pulse amplitude modulation (PAM-8). The circuit was realized as a 3-bit digital-to-analog converter (DAC), thus being able to yield 8-level output signals. Moreover, the circuit is able to function as a PAM-4 driver as well, thanks to the tunable tail currents of the DAC core. It achieves a symbol rate of 50 Gbaud, which corresponds to a bit rate of 150 Gb/s for the PAM-8 modulation and 100 Gb/s for PAM-4. The study showed that a modulator driver can be realized that is able to switch between different modulation formats (namely PAM-8 and PAM-4), without requiring extra power or additional circuit parts. Moreover, the use of on-chip single-to-differential converters (SDCs) targets the relaxation of the requirements on the stages that precede the driver. Finally, relating its DC power consumption (590 mW, including the SDCs) to its output voltage swing (4 Vpp,d), the driver shows one of the highest power efficiencies among PAM modulator drivers in the literature.

The purpose of this thesis is the theoretical study of interference and correlation effects in multimode and continuum mode quantum systems. We are concerned with interference effects in multiport devices which in a sense are generalised Mach-Zehnder interferometers. It is shown how these multimode devices can be employed for the study of negative result and interaction free measurements. Interference and coherence effects are also studied in relation to the radiation fields generated by atoms through the process of spontaneous emission. Besides first order interference, higher order coherence effects are investigated with the aid of Glauber's photodetection theory and it is found that detectors that lie in spacelike regions may display nonclassical correlations under certain conditions. It is well known that the vanishing of field commutators between regions that cannot be connected by subluminal signals reflects the locality of quantum field theory. But is it possible that these spacelike regions exhibit correlations that violate Bell type inequalities? This is the main question and principal concern of the thesis and the answer is affirmative, nonclassical correlations between spacelike regions are indeed possible. A scheme of four detectors that lie in spacelike points was also studied. In this case we do not consider the radiation field but a free scalar field in vacuum state. Nevertheless the virtual quanta of this field may induce nonclassical correlations if the intervals between the detectors are spacelike but small enough. The fundamental reason for this fact is the nonvanishing of the Feynman propagator outside the light cone. Since this propagator is decaying expotentially with the distance it is demonstrated that for large spacelike intervals field correlations obey classical inequalities. We should also note that different inertial observers will agree on the violation or not of these inequalities since the results are manifestly Lorentz invariant.

No description available.

This thesis describes the development of a Mach-Zehnder interferometric filter based planar Doppler velocimetry (MZI-PDV) flow measurement technique. The technique uses an entirely new optical system, an unbalanced MZI incorporating glass blocks for wavefront-matching, to replace the iodine cell currently used in conventional PDV. The free spectral range of the interferometric filter can be selected by adjusting the optical path difference of the MZI. This allows the velocity measurement range, sensitivity and resolution to be varied. This system offers no restricts to the choice of laser wavelength of operation which is not the case with most techniques. Two techniques to process the interference fringe images are presented. The first uses the shift of the fringe pattern to determine the Doppler frequency shift along profiles. The second provides a full-field measurement by normalising the received light intensity at each pixel in the image. With the single camera MZI-PDV scheme, exact alignment of the two output images on the active area of the camera is automatic. This eliminates the pixel-matching problem in conventional two camera PDV systems. The technique allows the measurement of up to three components of the flow velocity across a plane defined by a laser light sheet. The construction of a single velocity component MZI-PDV system that incorporates a phase-locking system designed to stabilise the filter is described. Measurements are made on the velocity field of a rotating disc with maximum velocities of ~±70ms-1 and an axis-symmetric air jet (with a nozzle diameter of 20mm) with an exit velocity of ~85ms-1. Standard deviations in the measured velocities were found to be about 2.9 and 2ms-1 for the two processing methods respectively. The system was then modified to make 3-component velocity measurements using imaging fibre bundles to port multiple views to a single detector head, and the standard deviation of the velocity error is around ±3ms-1 for a maximum velocity of ~±30ms-1 in the field of view. The factors that will affect the quality of the interference fringe image are investigated including polarisation sensitivity of the two beam splitters and flatness of the optical components. The inclination angle and the optical path deviation have little effect on the contrast of the interference fringes since collimated light beams, rather than divergent ones, are used in the interferometer.

Este trabalho apresenta um estudo da transmissão de sinais de micro-ondas baseada em enlaces ópticos com modulação externa. Após contextualizar os enlaces ópticos e discutir sobre as características gerais de seus principais componentes, tais como fonte laser, modulador, fibra óptica e fotodetector é apresentada uma análise detalhada da função de transferência de um modulador óptico do tipo Mach-Zehnder (MZM), com apenas uma entrada de RF (single drive). A análise realizada serviu de base para a implementação de uma ferramenta computacional no ambiente MATLAB. O programa desenvolvido, permitiu analisar diversos parâmetros do enlace, tais como ganho de potência, figura de ruído e faixa dinâmica livre de espúrios em função do valor de tensão VDC, usado para ajustar o ponto de operação do modulador MZM ao longo da sua função de transferência. Com uma potência óptica entre 10 mW e 15 mW e usando sinal de teste de 1 GHz é apresentada a verificação experimental em termos dos parâmetros analisados. Foram obtidos valores de ganho de potência da ordem de -33 dB e faixa dinâmica livre de espúrios de 84 dB.Hz2/3. Em termos da aplicação do enlace óptico de micro-ondas o presente trabalho teve como aplicação um sistema dedicado para modulação por deslocamento de fase binária (BPSK).

Ce travail est consacré à l'étude des processus de décohérence dans le régime Hall quantique entier. Le transport électronique se fait alors par un ou plusieurs canaux unidimensionnels chiraux le long du bord de l'échantillon, contrôlés par des lames séparatrices mésoscopiques ou contacts ponctuels quantiques. Un réglage fin de ces contacts ponctuels quantiques permet d'obtenir des interférences de la conductance. L'étude de la visibilité de ces oscillations nous permet de sonder la cohérence du système. Dans un premier temps, nous avons étudié la visibilité en fonction de la tension drain source lorsque le canal interne est réfléchi et avons observé une structure en lobe. Nous avons montré qu'en présence d'un seul lobe, une moyenne gaussienne de la phase permettait de comprendre cette structure en lobe. Lorsque le canal interne est transmis la visibilité en fonction de la tension devient monotone: on comprend ce résultat en tenant compte du couplage entre le canal externe et interne. Dans un deuxième temps nous avons étudié la dépendance en température de la visibilité sur des MZI de différentes tailles, avons extrait pour la première fois une mesure de la longueur de cohérence de phase en régime Hall quantique et avons montré qu'elle était proportionnelle à 1/T. Nous nous sommes ensuite intéressés à l'origine de cette longueur finie de cohérence de phase. Nous avons montré que les fluctuations thermiques du canal interne combinées au couplage entre canaux étaient la source de décohérence. Enfin dans une troisième expérience, nous avons obtenu la première réalisation expérimentale quantitative d'un objet largement utilisé en théorie: la "sonde en tension".