Academic literature on the topic 'SINGLE POLARIZATION'

In this thesis two novel single-end methods are applied to measure and characterize polarization mode dispersion in single mode optical fibres. Polarization mode dispersion (PMD) is an important factor negatively affecting the successful implementation of high speed long haul optical fibre networks operating at bit rates of 10Gb/s and above. PMD measurements are thus important for quality control during manufacturing and cabling processes. It is also useful for network operators planning to upgrade bitrates in existing networks to 10Gb/s and beyond. In an optical fibre link, sections with particularly high PMD may act to increase the entire PMD of the link. Identifying and replacing such sections can greatly reduce the PMD of the link. PMD measurements can be forward or single-end. In forward measurements, both ends of the fibre are used for input and detection. In single-end configuration, only one end of the fibre is used. For this reason, single-end measurements are more practical for the field where fibre ends are situated several kilometres apart. Single-end techniques can be implemented with a continuous wave for non-local PMD measurements (by Fresnel reflection). If a pulsed wave is used, local measurements can be achieved (by total power due to Rayleigh scattering). Two single-end schemes, one based on Fresnel reflection and the other due to Rayleigh scattering have been applied to measure non-local and local PMD of standard single mode optical fibres. For the non-local PMD measurements, the general interferometric technique (GINTY) was modified to operate in a round-trip configuration. In this configuration, the fibre was treated as a concatenation of two identical fibre segments. Three different sets of fibres were investigated, each set representing a particular mode coupling regime. For polarization maintaining fibres, (PMFs), with no mode coupling, a factor of two was found between forward and single-end measurements. For long single mode fibres in the long length regime, the factor was 1.4. For a combination of PMF and single mode fibres, a factor of 1.6 was obtained. The method which is accurate, repeatable, low cost and robust is very suitable for field applications. The second method is the polarization optical time domain reflectometric (P-OTDR) technique. This technique performs local birefringence measurements by measuring the evolution of the states of polarization (SOP). The birefringence information from such measurements was extracted and analysed to characterise four different fibres. Beat lengths and correlation lengths extracted from the P-OTDR were used to calculate the differential group delay (DGD) of the fibres. Next an expression for the root-mean-square differential group delay was derived and applied to the birefringence measurements to calculate the DGDs at a single wavelength. This method which operates at a single wavelength has a huge advantage. Firstly it is able to measure completely all the fibre characteristic parameters. Secondly it can measure mean DGD, root mean square DGD and instantaneous DGD. A plot of instantaneous DGD vs. length enables one to identify and eliminate sections with particularly high DGD. Finally since the P-OTDR system operates with a single wavelength, real time monitoring of PMD is possible via multiplexing. The results obtained are repeatable, accurate and are in good agreement with the standard Jones Matrix Eigenanalysis (JME) technique.

Aerosols play an important role in many atmospheric processes but their highly heterogeneous nature makes them difficult to study. Thus, new advancements in the field frequently focus on finding ways to more accurately determine more information about aerosols as they occur. LIght Detection And Ranging (LIDAR) systems have become an important tool in the study of aerosols because they can provide high resolution vertical profiles of quantities of interest (including aerosol concentrations, temperature, and wind speed, among others) over several kilometres of altitude. But on the other hand, the data can be ambiguous or difficult to correctly interpret and LIDAR systems can be costly and usually require a great deal of technical expertise to maintain and operate. In recent years, technological developments in lasers and detectors have led to the development of relatively inexpensive LIDAR systems that are robust and simple to operate, but to date these single-wavelength elastic LIDARs have provided only basic analysis products, such as determining the heights of clouds or qualitative monitoring of aerosol layers. There is a need for more extensive analyses using these simpler LIDARs. To this end, an algorithm has been developed that employs ground-based, single-wavelength elastic LIDAR to create high resolution maps of aerosol and cloud types as well as backscatter and extinction coefficients. Applications for maps such as these include studies of long-range transport of aerosols, air quality within the planetary boundary layer, cloud-aerosol interactions, and visibility. Algorithms similar to this have been developed in the past, but they have required either multi-wavelength LIDAR systems or have stopped short of differentiating between aerosol and cloud types. This algorithm also includes a novel utilization of depolarization ratio profiles for sub-layer discrimination. Thus far, the algorithm has been applied to limited number of cases, resulting in a high degree of uncertainty compared to some more complex systems. The algorithm is thus merely a first step, and further refinements are suggested as a way to continue to improve its performance.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

<p> This thesis investigates the fundamental nanoscale near-field light matter interaction between a probe tip and plasmonic antenna nanostructures. The thesis is focused on polarization control of metallic plasmon modes using scattering-type scanning near-field optical microscopy (s-SNOM). Part of the thesis is dedicated to spectroscopic near-field comparison of coated and bare single plasmonic particles in the infrared wavelength range (&lambda;= 9&ndash;11 &micro;m) using s-SNOM. By tuning the wavelength of the incident light, we have acquired information on the spectral polarization dependence plasmon modes and plasmon/phonon&ndash;polariton resonant near-field interactions. The enhanced near-field coupling between the probe tip and high index Au nanostructures and Au-core thin silica coating (thickness &ap;10 nm) is described and quantified. </p>

El entrelazamiento puede abordarse desde dos perspectivas diferentes: como un recurso esencial para las tecnologías cuánticas y como un fenómeno fundamental que está íntimamente relacionado con nuestra comprensión de la naturaleza misma. Por otro lado, la teoría cuántica se formula en el marco teórico de los espacios de Hilbert, para los que el entrelazamiento juega un papel importante en la determinación de su geometría y topología. Las características topológicas que puedan exhibirse al utilizar estados entrelazados son largamente independientes de la realización física particular del entrelazamiento: puede afectar a un solo grado de libertad poseído por dos partículas diferentes, o bien puede implicar dos grados diferentes de libertad que se cohesionan a una misma partícula o entidad física, por ejemplo, un campo electromagnético. Resulta que la manipulación de los grados de libertad de polarización y momentum (camino) ya sea de forma independiente el uno del otro o mediante la aplicación de evoluciones unitarias no separables es muy versátil. Con esto en mente, la presente tesis apunta hacia el diseño e implementación de arreglos experimentales que se pueden utilizar para estudiar fases geométricas y topológicas en sistemas de dos qubits mediante el uso de los grados de libertad de momentum (camino) y polarización de un solo fotón. Finalmente mostramos el diseño de un experimento, apuntado a exhibir la fase topológica, y los resultados obtenidos.<br>Tesis

La polarisation du quark top produit par interaction électrofaible (single-top) en voie-t permet de tester la structure du vertex Wtb: le couplage vecteur gauche prévu dans le cadre du Modèle Standard (MS), ainsi que les couplages anormaux vecteur ou tenseur introduits par plusieurs théories au-delà du Modèle Standard. Le lot de données correspondant à une luminosité integrée de 4,7 fb-1 recolté dans les collisions proton-proton à une énergie de 7 TeV dans le centre de masse offre une chance de mesurer la polarisation du quark top. Cette thèse traite de la mesure de la polarisation du quark top grâce à l'étude des distributions angulaires polarisées dans des bases spécifiques avec les événements single-top produits en voie-t. Au début du document, le contexte théorique de production du quark top par interaction forte et électrofaible au LHC est introduit. Ensuite, le détecteur, les performances de reconstruction ainsi que la sélection d'événements avec une signature single-top en voie-t, sont décrits. Les méthodes d' "unfolding" et de "folding" sont présentées et testées avec différentes configurations afin de mesurer la polarisation du quark top. Les résultats obtenus, ainsi que les incertitudes théorique, expérimentales et statistiques, sont examinées. Il s'agit de la première mesure de polarisation du quark top avec le détecteur ATLAS. Les résultats sont compatibles avec les prédictions MS, et contribuent donc à contraindre de maniére significative les couplages anormaux sur le vertex Wtb<br>The top quark polarization in electroweak production for single top t-channel allows to test the structure of the Wtb vertex: the left-handed vector coupling of the Standard Model (SM) as well as the anomalous couplings including the right-handed vector, the left-handed tensor and the right-handed tensor couplings. The 4.7 fb-1 data recorded by the ATLAS detector at the LHC with the center of mass energy at 7 TeV in 2011 provides a chance to measure the top polarization. This thesis discusses the measurement of the top polarization by studying the polarized angular distributions in specific bases with t-channel single top events. In the beginning of the thesis, a theoretical context of the top quark production via the strong interaction and the electroweak interaction at the LHC is introduced. Then the detector, the reconstruction performances as well as the event selections with a single top t-channel event signature are described. To measure the top polarization, the unfolding and folding methods are constructed and tested with different configurations. In the end, the measured results are examined with the estimated uncertainties from the theory, the detector response and modeling as well as the statistics. This is the first measurement of the top polarization with the ATLAS detector. The results are compatible with the SM predictions and contribute signicantly to constrain the anomalous couplings in the Wtb vertex

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 217-221).<br>Understanding the underlying mechanisms involved in the interactions between nucleons is one of the fundamental problems in nuclear physics. Over roughly the last 70 years, this question has been approached on many different fronts. We believe that the theory underlying the interaction between nucleons is that between quarks and gluons described by Quantum Chromodynamics; however, a complete solution to the nucleon-nucleon interaction within this framework has yet to emerge. In parallel, the advent of polarization experiments involving both polarized beams and targets has provided new experimental avenues to test our understanding the reaction mechanisms involved in the nucleon-nucleon interaction. One important example is the electrodisintegration of the deuteron, ... (e[over-arrow], e'p)n, in particular the measurement of the beam-vector asymmetry, AV, and the tensor asymmetry, AT. Both of these asymmetries are sensitive to the d-wave components of the deuteron and are thus measurements of the effects of the tensor force in the nucleon-nucleon interaction. This work reports on measurements of AV and A T in the electrodisintegration of the deuteron that were performed by the BLAST collaboration at the Bates Linear Accelerator Center involving two data runs during 2004 and 2005. The measurements consisted of cross sections and asymmetries vs. missing momentum for a Q2 range of 0.1(GeV/c) 2 < Q2 < 0.5(GeV/c) 2 . Comparisons between Monte Carlo simulations based on a particular theoretical framework are made, and conclusions are drawn.<br>by Adam DeGrush.<br>Ph.D.

Microcavity polaritons are mixed light-matter quasiparticles arising from the strong coupling between quantum well excitons and photons confined in a Fabry-Perot microcavity. Their bosonic nature along with the strong interparticle interactions makes polaritons an excellent solid-state platform to study the nonlinear properties of bosonic condensates, with the advantage of being addressable using standard optical techniques. An important degree of freedom in the study of polaritons is the possibility to introduce a lateral confining potential. The growth and etching techniques developed at LPN allow obtaining low dimensional structures of different geometries, preserving high optical properties, opening the way to the study of polariton nonlinearities in at-will potential landscapes. During my PhD, my research has focused mostly on the experimental study of 0D structures, consisting of single micropillars and polaritonic molecules made of coupled micropillars. I studied the coherence properties of polariton condensates in single micropillars, by measuring the g2 function of the emission with a streak camera technique providing a time resolution of ~ 4 ps. I studied the Josephson physics in diatomic molecules made of two coupled micropillars, with particular attention to the nonlinear regimes. In particular the macroscopic self-trapping regime has been observed. Finally I studied a more complex molecule made of six coupled micropillars in a hexagonal shape, where an effective spin-orbit coupling for polaritons has been realized. These results highlight microcavity polaritons in micropillars as a platform where nonlinear effects can be studied, in combination with nontrivial topologies<br>Les polaritons de microcavité sont des particules mixtes lumière-matière issues du couplage fort entre les excitons dans un puits quantique et les photons confinés dans une microcavité Fabry-Pérot. Leur nature bosonique et les fortes nonlinéarités font des polaritons une excellente plateforme où l’on peut étudier les propriétés nonlinéaires des condensats des bosons, avec l’avantage de pouvoir les manipuler avec des techniques optiques. Un degré de liberté important est la possibilité d’introduire un potentiel latéral de confinement. Les techniques de croissance et de gravure développées au LPN permettent d’obtenir des géométries différentes qui préservent de hautes propriétés optiques. Cela ouvre la voie à l’étude des nonlinéarités dans les polaritons dans des potentiels sur mesure. Pendant mon doctorat, ma recherche a été focalisée sur l’étude expérimentale des structures 0D, en particulier des micropiliers simples et des molécules formées de piliers couplés. J’ai étudié les propriétés de cohérence des condensats de polaritons dans des piliers simples, en mesurant la fonction g2 de l’émission avec une streak camera possedant un temps de résolution de 4 ps. J’ai étudié la physique de Josephson dans des molécules polaritoniques faites de deux piliers couplés, avec une attention particulière au régime nonlinéaire. En particulier le régime de self-trapping a été observé. J’ai étudié une molécule plus complexe composée de six piliers couplés dans une structure hexagonale, où un couplage spin-orbite effectif a été réalisé. Ces résultats etablissent les polaritons de microcavité comme une plateforme où les effets nonlinéaires peuvent être étudiés en combinaison avec des topologies non triviales