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Fosuhene, Samuel Kofi. "Single-end reflectometric measurements of polarization-mode dispersion in single-mode optical fibres." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/6280.
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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.
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Cottle, Paul Wesley. "Aerosol type analysis with single wavelength, dual polarization elastic LIDAR." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57069.
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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
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Damato, Ralph. "Polarization control of plasmonic modes in single nanoparticles and nanostructures." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527542.
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<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 (λ= 9–11 µm) 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–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 ≈10 nm) is described and quantified. </p>
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Suarez, Yana Elmer Eduardo. "Topological phases generated with single photons entangled in polarization and momentum." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/7437.
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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
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Robinson, Risa J. "Polarization modulation and splicing techniques for stressed birefringent fiber /." Online version of thesis, 1995. http://hdl.handle.net/1850/12228.
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Sun, Xiaohu. "Top polarization measurement in single top quark production with the ATLAS detector." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY081/document.
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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
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Li, Tiesheng. "Optical properties of CdTe/Cd1-xZnxTe strained-layer single quantum wells." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1173760803.
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DeGrush, Adam (Adam Jon). "Single and double polarization observables in the electrodisintegration of the deuteron from BLAST." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62644.
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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.
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Sala, Vera Giulia. "Coherence, dynamics and polarization properties of polariton condensates in single and coupled micropillars." Paris 6, 2013. http://www.theses.fr/2013PA066712.
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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
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Kolano, Michael [Verfasser]. "Design and characterization of a single-laser polarization-controlled optical sampling system / Michael Kolano." München : Verlag Dr. Hut, 2019. http://d-nb.info/1198542748/34.
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Hoover, Diana Kay Yousaf Muhammad. "Electroactive nanoarrays for the biospecific-ligand mediated study of single cell adhesion and polarization." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2591.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry Analytical Chemistry. " Discipline: Chemistry; Department/School: Chemistry.
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Maletinsky, Patrick. "Polarization and manipulation of a mesoscopic nuclear spin ensemble using a single confined electron spin /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17815.
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SOUZA, KAROLINE DE. "IMPACT OF THE EFFECTS OF PMD IN THE LIGHT POLARIZATION CONTROL IN SINGLE-MODE FIBERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35252@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Este trabalho apresenta o estudo e a realização de experimentos a fim de investigar os efeitos da PMD (Polarization Mode Dispersion) no controle de polarização implementado em um enlace de fibra óptica monomodo. Esse estudo permitirá a otimização de controladores de polarização em sistemas de transmissão que venham a utilizar multiplexação em polarização (PolMux) combinado a técnicas de UDWDM (Ultra Dense Wavelength Division Multiplexing), possibilitando o aumento da taxa de transmissão em um canal. Para tanto, foram realizadas medidas experimentais que demonstrem o desvio angular da polarização devido à descorrelação entre canais, através da análise da evolução da polarização do sinal óptico em função da PMD, do comprimento de onda e do espaçamento espectral; foram analisadas duas propostas para se utilizar no controle de polarização; estatísticas referentes à atenuação dos canais utilizados foram realizadas e também o cálculo da correlação com intuito de analisar como esses canais se relacionam.<br>This work presents the study and conducting experiments to investigate the PMD (Polarization Mode Dispersion) effects in polarization control implemented in a single-mode fiber optic link. This study will allow the optimization of polarization controllers in transmission systems that will use polarization multiplexing (PolMux) combined with techniques like UDWDM (Ultra Dense Wavelength Division Multiplexing), and thereby to increase the transmission rate in a channel. Therefore, we performed experimental measurements showing the angular displacement of the polarization due to decorrelation between channels by analyzing the evolution of the polarization of the optical signal as a function of PMD, wavelength and the spectral spacing, analyzed using two proposals for the control of polarization, statistics of the fading channels used and also performed the calculate the correlation with the aim to analyze how these channels are related.
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Wu, Jingwei, Xiushan Zhu, Valery Temyanko, LaComb L. Valery, R. A. Norwood, and N. Peyghambarian. "Power scaling of single-frequency fiber amplifiers at 976 nm." IEEE, 2016. http://hdl.handle.net/10150/622788.
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Cladding pumped single-frequency Yb3+-doped fiber amplifiers at 976 nm were investigated. Over 4 W output power was obtained and further power scaling can be achieved by reducing the cladding diameter of the Yb3+-doped fiber.
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Liao, Chen-Ting, and Arvinder Sandhu. "XUV Transient Absorption Spectroscopy: Probing Laser-Perturbed Dipole Polarization in Single Atom, Macroscopic, and Molecular Regimes." MDPI AG, 2017. http://hdl.handle.net/10150/624358.
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We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is monitored in dilute helium, dense helium, and sulfur hexafluoride (SF6) molecules. We observe and quantify the time-dependence of various transient phenomena in helium atoms, including laser-induced phase (LIP), time-varying (AC) Stark shift, quantum path interference, and laser-induced continuum structure. In the case of dense helium targets, we discuss nonlinear macroscopic propagation effects pertaining to LIP and resonant pulse propagation, which account for the appearance of new spectral features in transient lineshapes. We then use tunable NIR photons to demonstrate the wavelength dependence of the transient laser induced effects. In the case of molecular polarization experiment in SF6, we show suppression of XUV photoabsorption corresponding to inter-valence transitions in the presence of a strong NIR field. In each case, the temporal evolution of transient absorption spectra allows us to observe and understand the transient laser induced modifications of the electronic structure of atoms and molecules.
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Pumpa, Martin. "Single Molecule Diffusion in Liquid Crystals." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-157717.
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The present work introduces a new method that is used to explore the connection between molecular order and molecular dynamics in liquid crystals. In liquid crystals, the building blocks show a liquid like disorder in at least one dimension of space with an otherwise crystalline like positional or orientational long range order. A new microscope is introduced that combines polarization measurements with the ability to track single fluorescent probe molecules in a thin sample of ordered liquid crystal. A new method for the analysis of orientation dependent diffusion is also introduced. It can be used to spatially resolve the anisotropic diffusion of the probe molecules. With this setup, molecular structure and molecular dynamics can be directly compared on a μm scale.
Three different kinds of liquid crystal samples are analyzed with the new experimental method. First, twisted nematic liquid crystal cells are used to verify a proposed model for the connection between molecular structure and the dynamics in twisted nematic cells. Second, the liquid crystal structure and probe mobility are analyzed in homogeneous samples in a temperature regulated environment. The third experiment focuses on the combination of both of these scenarios. Different domains in a heterogeneous section of a sample are analyzed with different methodical approaches at various temperatures.
The results display the close connection between molecular order and molecular dynamics in the samples. It is also found that the probe molecules introduce local distortions in the director field of the host material. Despite this realization, only the absolute value of the probes mobility seems to be effected. The anisotropy of the translational diffusion of the probe molecules resembles the results found in the literature on the self-diffusion of the liquid crystal molecules. The anisotropy also follows the same temperature dependence as the order of the host molecules. Using these results and the new method of analyzing single molecule tracking data, it is shown that the structure of a heterogeneous sample can be spatially resolved, only by means of single probe molecule tracking.
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Esteban, i. Ferrer Daniel. "Electric polarization properties of single bacteria measured with electrostatic force microscopy. Theoretical and practical studies of Dielectric constant of single bacteria and smaller elements." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284622.
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The present thesis is included in the field of nanobioelectricity. That is, understanding the electrical properties of biological specimens at the nanoscale (< 200 nm).
To do so we used an electrical variation of the Atomic Force Microscope called Electrostatic Force Microscope (EFM). By the application of a novel methodology (experimental and theoretical) we were able to obtain electrical polarization properties of single bacteria.
Firstly the methodology was applied to calibration samples were the dielectric constant was already known. The obtained value for a silicon nitride sample was 7.6 and the nominal value for this material is 6-8 (depending on stoichometry). Also a silicon oxide sample was studied obtaining a dielectric constant of 3.9 while the nominal value is 4. Both calculations validate the used methodology.
Moving to bacteria we found that the effective dielectric constant, for the four bacterial types investigated (Salmonella typhimurium, Escherchia coli, Lactobacilus sakei, and Listeria innocua) is around 3-5 under dry air conditions. Under ambient humidity, it increases to 6-7 for the Gram-negative bacterial types (S. typhimurium and E. coli) and to 15-20 for the Gram-positive ones (L. sakei and L. innocua). We show that the measured effective dielectric constants can be consistently interpreted in terms of the electric polarization properties of the biochemical components of the bacterial cell compartments and of their hydration state. These results demonstrate the potential of electrical studies of single bacterial cells.
Finally a comparison of these results with smaller ones (namely nanoparticles and viruses) was performed in the theoretical side obtaining that the geometrical factors of the sample have a larger influence in the small objects. Also it was concluded that while there exist some analytical approximations to work with them, these are not applicable to larger objects like bacteria.
This work confirms that dielectric measurements of single bacterial cells can be correlated with the electric polarization response of their biochemical constituents and their internal structure, thus opening interesting possibilities for analytical studies based on the biological electric polarization properties (also with smaller biological entities).<br>La present tesi està inclosa en l'àmbit de la nanobioelectricitat. És a dir, la comprensió de les propietats elèctriques de les mostres biològiques a escala nanomètrica (< 200 nm ).
Per a això es va utilitzar una variant elèctrica del Microscopi de Força Atòmica (AFM) anomenat Microscopi de Força Electrostàtica (EFM). Mitjançant l'aplicació d'una metodologia nova (experimental i teòrica) hem estat capaços d'obtenir propietats de polarització elèctrica de bacteris individuals.
En primer lloc es va aplicar la metodologia a certes mostres de calibratge amb constant dielèctrica ja conegudes. El valor obtingut per a una mostra de nitrur de silici va ser de 8.2 i el valor nominal d'aquest material és de 7-8 (depenent de la estoicometria).
Passant als bacteris, es va trobar que la constant dielèctrica efectiva, per als quatre tipus de bacteris investigats (Salmonella typhimurium, Escherichia coli, Lactobacilus sakei, i Listeria innocua) és al voltant de 3-5 en condicions d'aire sec. En virtut de la humitat ambiental, aquesta augmenta a 6-7 per als tipus de bacteris Gram-negatius (S. typhimurium i E. coli) i a 15-20 per als Gram-positius (L. sakei i L. innocua). Es demostra que les constants dielèctriques eficaces mesurades poden ser interpretades consistentment en termes de les propietats de polarització elèctriques dels components bioquímics dels compartiments cèl•lulars i del seu estat d'hidratació.
Finalment una comparació d'aquests resultats amb objectes més petits (és a dir, nanopartícules i virus) en el seu aspecte teòric va concloure que els factors geomètrics de la mostra tenen una major influència en els objectes petits. També es va concloure que, si bé hi ha algunes aproximacions analítiques per treballar amb ells, aquestes no són aplicables a objectes més grans, com ara els bacteris.
Aquest treball confirma que les mesures dielèctriques de cèl•lules bacterianes individuals es poden correlacionar amb la resposta de polarització elèctrica dels seus constituents bioquímics i la seva estructura interna, obrint així possibilitats interessants per als estudis analítics sobre la base de les propietats biològiques de polarització elèctrica (cosa també certa en entitats biològiques més petites).
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Harwood, Peter, Christopher Wilson, Arthur Sullivan, and Eugene Augustin. "LOW COST, HIGHLY TRANSPORTABLE, TELEMETRY TRACKING SYSTEM FEATURING THE AUGUSTINE/SULLIVAN DISTRIBUTION AND POLARIZATION, FREQUENCY AND SPACE DIVERSITY." International Foundation for Telemetering, 1996. http://hdl.handle.net/10150/608364.
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International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California<br>The tracking system is part of a telemetry ground station being developed for the UK
Ministry of Defence. The design objective is a self-contained transportable system for
field use in a vehicle or workshop environment, so that the system components are
required to be man portable. Comprehensive facilities are required for the reception,
display and analysis of telemetry data from a remote 1430-1450MHz airborne source at
ranges of up to 205km. Since tracking over water is a prime requirement the system
must accommodate severe multipath fading.
A detailed analysis of the link budget indicates that there is a major conflict between
cost, portability, antenna size and the receiver complexity required to achieve a
satisfactory performance margin. A baseline system is analysed using a four foot
antenna. Methods for improving the performance are then considered including
polarisation, frequency and space diversity coupled with alternative antenna types and
configurations.
The optimum solution utilises two six foot diameter shaped beam single axis antennas
of unique design in conjunction with a receiving system which economically combines
the elements of polarisation, frequency and space diversity.
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Sudradjat, Faisal. "50%-50% Beam Splitters Using Transparent Substrates Coated by Single- or Double-Layer Quarter-Wave Thin Films." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/376.
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A pair of light beams that have orthogonal polarizations and equal intensity can be generated through reflection and refraction of a monochromatic light at a dielectric surface. Sytematic procedures to design beam splitters which can produce such output light beams are described in this thesis. Two designs that are of particular interest are prismatic substrates coated by a single layer and a double layer of thin films. Specific examples of each beam splitter in the visible and infrared are included. The performance of each beam splitter as a function of incidence angle, film thickness, and wavelength is also discussed.
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Critchley, Jacques R. (Jacques Rigby). "Employment, gender and household polarization in a single industry town : the social impacts of economic restructuring in Windsor, Quebec." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59659.
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This thesis, from a "locality studies" perspective, examines the impact of industrial restructuring and employment decline on the relationship between locality, gender and patriarchy at the household level in Windsor, a pulp and paper mill town in South-Eastern Quebec. A detailed questionnaire/survey was deployed in May and June 1987, during a period of massive reorganization and automation of production by Domtar Fine Paper Mill, the dominant local employer. The primary empirical focus of this work is on the household impacts of job losses, incurred directly or indirectly by this restructuring. Particular attention is paid to the relationship between gender, employment and income and how this relationship is manifested among the differing material circumstances of Windsor households, and to attempts to adapt to the socio-economic impacts of restructuring via self-conscious "coping strategies". A secondary focus is communal coping strategies aimed at combatting declining industrial employment. Findings indicate an exacerbation of economic polarization between economically stable households of the remaining Domtar employees and households enmeshed in unstable economic and employment conditions.
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Nasse, Michael Johannes. "Development of a Confocal and Near-field Scanning Optical Microscope for Polarization-resolved Temporal Studies of Single Nano-objects." Université Joseph Fourier (Grenoble), 2004. http://www.theses.fr/2004GRE10235.
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Nous présentons le développement et les applications d'un microscope dual fonctionnant soit en mode confocal soit en champ proche optique à ouverture et opérant en mode réflexion. Il a été conçu pour travailler à basse température et sous atmosphère contrôlée. De plus, il permet de séparer les deux directions de polarisation de la fluorescence récoltée. Nous avons étudié comme nano-objets des molécules et nanosphères fluorescentes ainsi que des nanocristaux semi-conducteurs. Comme échantillons moléculaires nous avons utilisé des molécules diI-C18 et des molécules dérivées d'anthracène. Les spectres d'absorption et d'émission de ces dernières ainsi que leur section efficace d'absorption et leur efficacité quantique de fluorescence ont été mesurés en solution pour la première fois. Nous avons réalisé une mesure résolue en temps de l'émission suggérant la présence de différentes conformations pour ces molécules en solution. Notre instrument a été employé en mode confocal afin d'imager, et d'enregistrer des traces temporelles et des spectres de nano-objets uniques. Des nanosphères uniques (Ø 27 nm) ont été utilisées pour cartographier la distribution du champ optique autour du foyer d'un objectif de microscope. Les images ainsi obtenues sont comparées qualitativement à un modèle scalaire. Le montage en champ proche est validé par l'utilisation des nanosphères fluorescentes (Ø 500 nm). Le comportement dynamique temporel est étudié à l'aide des traces temporelles, par autocorrélation pour des molécules uniques, et par analyse statistique pour les nanocristaux uniques. Dans ce dernier cas, une loi de puissance est observée pour la distribution des temps " brillant " et " noir "<br>We present the development and application of a hybrid confocal and aperture near-field scanning optical microscope operating in reflection mode. It has been designed to work at cryogenic temperatures and in vacuum or with an exchange gas. Furthermore, it permits to split the fluorescence into two perpendicular polarization channels. We have studied various single nano-objects, such as molecules, CdSe/ZnSe nanocrystals, CdSe/ZnS nanorods and fluorescent nanospheres. As molecular samples we used diI-C18 molecules and molecules derived from anthracene. The ensemble absorption and emission spectra of the latter were measured, as well as their absorption cross-section and quantum yield in solution for the first time. Furthermore, we used time correlated fluorescence decay experiments that suggest the presence of different conformations in solution, already observed with similar molecules. We used our instrument in confocal mode to image, record time traces, and acquire some spectra of single nano-objects. Single nanospheres with a diameter of 27 nm are used to map the optical field distribution in the vicinity of the focal point of a microscope objective. The experimentally obtained images are qualitatively compared with a scalar model. The near-field scanning optical microscopy setup is validated using nanospheres with a diameter of 500 nm. The dynamic temporal behavior is examined with the help of time traces. The study is based on the autocorrelation function for single molecules, and using an on-off statistics for single nanocrystals/-rods. In the latter case a power law distribution of the on- and off-time probabilities is observed
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Liu, Tieqi. "Electromechanical Behavior of Relaxor Ferroelectric Crystals." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4881.
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Relaxor ferroelectric PZN-xPT and PMN-xPT single crystals exhibit extraordinary electromechanical properties. They are under development for applications in sensors, actuators and transducers. The polarization switching and phase transition behavior of PZN-4.5%PT and PMN-32%PT single crystals under external loading has been investigated. Experimental investigation elucidates the polarization switching and phase transition behavior of relaxor ferroelectric crystals at different orientation cuts under combined temperature, electric field and stress loading. These crystals exhibit strong orientation dependence of electromechanical properties, and the applied fields all affect the poling and phase states of the crystals. Based on experimental investigation, crystal variant modeling was developed to compute the piezoelectric properties of multi-domain crystals at different orientation cuts from a set of properties for the single domain. Thermodynamics and work-energy analysis of field induced phase transitions in these single crystals sheds light on the phase transition mechanism of ferroelectric crystals. Fracture behavior of relaxor single crystals under non-uniform electric fields at a partial electrode edge has also been measured and analyzed.
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Sturm, Chris, Rüdiger Schmidt-Grund, Vitaly Zviagin, and Marius Grundmann. "Temperature dependence of the dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 1.0–8.5 eV." American Institute of Physics, 2017. https://ul.qucosa.de/id/qucosa%3A25613.
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The full dielectric tensor of monoclinic Ga2O3 (β-phase) was determined by generalized
spectroscopic ellipsometry in the spectral range from 1.0 eV up to 8.5 eV and temperatures in the
range from 10K up to 300K. By using the oriented dipole approach, the energies and broadenings of
the excitonic transitions are determined as a function of the temperature, and the exciton-phonon coupling
properties are deduced.
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Chiarello, Fabrizio. "Analysis and application of nonlinear amplification effects in single-mode optical fibers." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423797.
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This thesis focuses on all-optical signal generation and processing through nonlinear amplification phenomena in single-mode fibers.
Three different nonlinear fiber optical oscillators are investigated and experimentally demonstrated. A continuous-wave pump for fiber Raman amplifiers, developed with the goal of achieving high degree of polarization, tunability and suppression of stimulated Brillouin scattering, is presented, discussed and used to achieve nonlinear polarization attraction. A fast and widely tunable fiber optical oscillator based on stimulated Raman scattering and on broad- and narrow-band fiber optical parametric amplification, and exploiting the time-dispersion-tuning technique, is demonstrated and characterized. Each nonlinear effect dominates in a different spectral region, so that the fiber optical oscillator achieves a tuning range of 160 nm. Through the same time-dispersion-tuning method, a fast tunable optical frequency comb, based on cascaded four-wave mixing, is obtained by using a single pump, avoiding the limitations in spectral purity and frequency and phase stability given by double pump systems.
Finally, the control of the state of polarization and of the degree of polarization through nonlinear polarization attraction in counter-propagating fiber Raman amplifiers in standard, randomly birefringent, single-mode fibers is studied, analyzed and characterized. The analysis, including the effects of pump depletion, nonlinear polarization rotation and orthogonal Raman gain, shows that counter-propagating fiber Raman amplifiers are effective in attracting the signal toward a predetermined state of polarization settled by the pump input state of polarization. Moreover, the importance of the role of pump depletion in achieving signal repolarization in fibers with moderately-high polarization-mode dispersion is discussed. The performances and the limits of repolarization efficiency are determined, leading to a quantitative relationship between the degree of polarization and the gain of the fiber Raman amplifier, which is then confirmed to represent an upper bound on the maximum achievable degree of polarization.<br>Questa tesi è focalizzata sulla generazione e sull’elaborazione completamente ottiche di segnali attraverso fenomeni di amplificazione non lineare in fibre ottiche a singolo modo.
Tre diversi oscillatori non lineari in fibra ottica sono investigati e dimostrati sperimentalmente. Una pompa ad onda continua per amplificatori Raman in fibra, sviluppata con l’obiettivo di ottenere un alto grado di polarizzazione, sintonizzabilità e soppressione dell’effetto Brillouin, è presentata, discussa e utilizzata al fine di ottenere attrazione di polarizzazione non lineare. Un oscillatore in fibra ottica con sintonia veloce su un’ampia banda basato sugli effetti di amplificazione Raman e di amplificazione parametrica a banda stretta e a banda larga, che sfrutta la tecnica di sintonia mediante dispersione temporale (time-dispersion tuning), è dimostrato e caratterizzato. Ciascuno degli effetti non lineari domina in una diversa regione spettrale, cosicché l’oscillatore raggiunge un intervallo di sintonia di 160 nm. Attraverso lo stesso metodo di sintonia mediante dispersione temporale, un comb ottico in fibra con sintonia veloce, basato sull’effetto di miscelazione a quattro onde a cascata, è ottenuto usando una singola pompa, evitando così i limiti di purezza spettrale e di stabilità di frequenza e di fase dei sistemi a doppia pompa.
Infine, il controllo dello stato e del grado di polarizzazione, attraverso l’attrazione di polarizzazione non lineare in amplificatori Raman in fibra ottica standard con birifrangenza aleatoria, è studiato, analizzato e caratterizzato. L’analisi, che include gli effetti di svuotamento della pompa, della rotazione non lineare di polarizzazione e di guadagno Raman ortogonale, mostra che gli amplificatori Raman contro-propaganti sono efficaci nell’attrarre il segnale verso uno stato di polarizzazione predeterminato e imposto dallo stato di polarizzazione di ingresso della pompa. Viene inoltre discussa l’importanza del ruolo dello svuotamento della pompa nell’ottenere la ripolarizzazione del segnale in fibre con dispersione dei modi di polarizzazione moderatamente alta. Le prestazioni e i limiti dell’efficienza di ripolarizzazione vengono determinati portando ad una relazione quantitativa tra il grado di polarizzazione e il guadagno dell’amplificatore Raman, relazione che rappresenta un limite superiore sul massimo grado di polarizzazione raggiungibile.
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Feng, Fu. "Coupling between optical Tamm states and fluorescent nanocrystals ; determination of the dipole nature of single colloidal nanoplatelets." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066564/document.
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Ce travail de thèse porte sur le couplage d’émetteurs fluorescents (en l’occurrence des nanostructures semi-conductrices colloïdales) à leur environnement optique. Il se décompose en deux parties : dans la première, des structures photoniques (modes de Tamm optiques) sont caractérisées par le biais de la fluorescence de nanocristaux insérés dans ces structures. Dans la seconde, des nanoplaquettes individuelles de CdSe/CdS sont caractérisées par des études de microphotoluminescence sur différents types de substrats. Dans ces deux études, la mesure du diagramme de rayonnement par imagerie dans le plan de Fourier joue un rôle important, et son principe sera présenté en détail. Le mode optique de Tamm est un mode électromagnétique confiné entre un miroir de Bragg et une couche métallique. Nous avons couplé une couche de nanocristaux de CdSe/CdS avec des modes de Tamm optiques 2D et 0D. Le confinement latéral dans le cas du mode 0D est mis en évidence. Nous avons étudié la relation de dispersion de l’émission issue de différentes portions du disque et comparé ces résultats avec les simulations numériques. Enfin, en excitant différentes position sur le disque, nous avons montré que la direction d’émission dépend fortement de la position de la source au sein de la structure. D’autre part, nous avons mis en place une méthode fine pour déterminer la nature dipolaire (dipôle 1D ou 2D) et l’orientation d’un nano-émetteur individuel. L’idée principale est de mesurer à la fois, pour un seul émetteur, le diagramme de rayonnement et la polarisation d’émission. En choisissant un substrat adapté (de l’or ou du verre), ces mesures donnent des résultats théoriques très différents selon la nature et l’orientation du dipôle. Nous avons ensuite appliqué cette méthode sur les émetteurs nanoplaquettes de CdSe/CdS (dimensions 20x20x2 nm). Un accord parfait entre les mesures et les calculs analytiques nous confirme que l’émission d’une plaquette carrée peut être décrite par un dipôle 2D orienté dans le plan de la plaquette. Nous avons ensuite étudié l’émission d’une plaquette rectangulaire et montré une asymétrie dans le dipôle émetteur. Cette étude montre le rôle de la forme de la plaquette sur son dipôle d’émission, qui pourrait être expliqué par un effet d’antenne diélectrique<br>Technological progress in the recent 30 years for reducing the size of semi-conductor materials offers the possibility to fabricate devices in which the electrons and holes are confined in a very small volume in three dimensions. When the dimension of the material is small (a few nanometers), the charges experience quantum confinement effects. This kind of nanomaterial is called nanocrystal or quantum dot [1]. These structures have the remarkable property that the energy levels are discretized, in a sense making them artificial atoms. At the beginning of 1980s, Efros, Ekimov et al. started the growth of II/VI semi-conductor nanocrystals in a vitreous matrix [2]. A few years later, colloidal synthesis methods were developed and nanocrystals with increasingly good optical properties were obtained [3-5]. These emitters have drawn intense attention because of their versatile manipulation in solution and biochemical functionalization, high quantum effciency, and photostability, tunable emission wavelength and broad absorption spectrum. By fluorescence microscopy, it is possible to study the optical properties of individual nanocrystals ; non classical effects such as single photon emission (even for nanocrystals at room temperature) are evidenced. Studying individual nano-emitters offers new ways to test the concepts of electromagnetics in the visible domain. Other manipulations are possible by nano structuring the environment around an emitter ; for instance, the use of antennas, which is ubiquitous in the radio and microwave domains, can be extended to nano-photonics, provided that sufficiently precise nano-fabrication techniques are available. The group "Nanophotonics and quantum optics" at the Institut de NanoSciences de Paris (INSP) studies how to manipulate light by coupling fluorescent emitters (individually or collectively) with their optical environment. The emission properties of nanoemitters depend strongly on their optical environment. This is expressed, as for the decay time of a radiating dipole, by Fermi's golden rule: where the initial and final state of the nanoemitter transition are taken into consideration; the polarization of these states can infuence highly the emission properties (determined by the symmetries of the transition and its associated orientation). The local state density which is mainly determined by the optical environment around the emitter and depends on the emission angular frequency. The electric field at the emitter position is included in the Hamiltonian (for a dipolar electric transition). Previously, our team has studied the coupling between the nanocrystal and different nanophotonic structures such as photonic crystals, plasmonic structures, plasmonic patch antennas etc
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Yurdanur, Tasel Elif. "Elemental Analysis Of Materials Including Silicon (100) And (111) Crystals With Single And Double Pulsed Libs." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12614304/index.pdf.
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Laser Induced Breakdown Spectroscopy (LIBS) which is used to determine the elemental content of various samples, inspects the emission spectroscopy of samples of interest for searching certain elements or identifying the unknown content.
In this study, spectroscopic analyses of various kinds of metals, namely, Cu, Fe, Mo, Ti, W, some compounds such as CuBe, ZnSe, ZnS, GaSe, some semimetals like Si, Ge and even gases were investigated by means of a compact-commercial portable LIBS system and an independently constructed experimental set-up consisting of a single pulse system and
various kinds of double pulse configurations using Nd:YAG lasers.
The contributions of this thesis to the LIBS community can be classified into two main groups- which are experimental and code development. One of the experimental contributions was the investigation of the different crystal surfaces of silicon in which dangling bond density were taken into account for
a more precise comparison of atomic emissions. The second experimental contribution was the polarization experiments by which polarization dependency, to some extent, was demonstrated. The third and final one was the orthogonal double pulse configuration with a 45 o incidence angle for both
lasers in opposite directions by which it was shown that the positioning becomes straightforward yielding the desired reproducible results. The second major contribution was to develop a basic code for analyzing the experimental data more accurately.
In conclusion, by means of the different experimental approaches, factors relating to the enhancement in intensity were investigated and as a result of developing the code, flexibility in upgrading the constraints of element searching was obtained and the updating of the database was accomplished.
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Koehler, Jana [Verfasser]. "Studying large-scale structures and polarization of the Northern sky facilitating single-station data of the Low Frequency Array (LOFAR) / Jana Koehler." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1113688378/34.
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Schäfer, Philip Sudadyo. "Tuning of color and polarization of the fluorescence of nano-ribbons using laser microscopy and controlled self-assembly." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0435/document.
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Des matériaux ayant des propriétés émissives spécifiques peuvent être obtenus par l'organisation contrôlée de fluorophores aux échelles moléculaire, nano- et micro-métrique. Dans ce travail, l'émission de lumière bleue polarisée est obtenue par l'auto-assemblage hautement anisotrope de n-acènes alcoxylés en nano-rubans. Des techniques de microscopie de fluorescence ont été utilisées pour déterminer le mécanisme de leur croissance et ont été combinées à la cristallographie aux rayons X pour déterminer l'empilement moléculaire dans les nano-objets. L'étude a révélé que la formation des nano-rubans est induite non seulement par le mécanisme de maturation d'Ostwald très commun, mais aussi par une croissance par attachement orienté rarement démontré dans des systèmes organiques. En plus des techniques plus courantes, la microscopie en polarisation de fluorescence de molécules uniques a contribué à caraxctériser l'emplilement moléculaire, bien que les nano-objets à haute densité en chromophore constituent des échantillons très difficiles à étudier. Dans ce travail, les propriétés des nano-rubans ont été contrôlées au niveau microscopique par les conditions de croissance, ainsi que par l'addition de dopants. Ainsi, en combinant différentes molécules et une réaction photochimique sous microscopie, des rubans à motifs colorés sub-micrométriques ont été obtenus. Par ailleurs, l'assemblage orthogonal a été exploité pour développer des réseaux interpénétrés. Ces derniers se distinguent par une émission à double couleur, un transfert d'énergie entre objets et une électroluminescence aux jonctions<br>Materials with specific emissive properties can be obtained by the controlled organization of fluorophores at the molecular, nano- and microscales. In this work, polarized blue light emission is achieved by the highly anisotropic self-assembly of alkoxylated n-acenes into nano-ribbons. Fluorescence microscopy techniques were used to determine the growth mechanism and were combined to X-ray crystallography to determine the molecular packing in the nano-objects. The study revealed that the formation of the nano-ribbons is induced not only by the very common Ostwald ripening mechanism but also by an oriented attachnment growth, rarely observed with such evidence in organic systems. Besides more common techniques, single molecule fluorescence polarization microscopy contributed to characterize the molecular packing, although the nano-objects with high chromophore density represent very challenging samples. In this work, the properties of the nano-ribbons have been controlled at the microscopic level by the growth conditions, as well as by the addition of dopants Thereby, combining different molecules and photochemistry at the sub-micrometer scale under the microscope, colorful patterned ribbons could be obtained. In addition, orthogonal assembly was exploited to grow interpenetrated networks. The latter demonstrated dual color-emission, as well as inter-object energy transfer and electroluminescence at junctions
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Kaassamani, Shatha. "Polarization Spectroscopy of High Order Harmonic Generation in Semiconductors Orbital angular momentum from semiconductor high-order harmonics All semiconductor enhanced highharmonic generation from a single nanostructured cone." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP091.
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Depuis sa première observation, la génération d'harmonique d'ordre élevé (HHG) dans les cristaux s'est avérée d'être une source efficace, contrôlable et compacte de rayonnement XUV cohérent. Dans cette thèse, nous étudions la génération d'harmonique d'ordre élevé (HHG) dans le graphène, et dans différents semi-conducteurs principalement oxyde de zinc, silicium, arséniure de gallium et oxyde de magnésium. Nous observons que les propriétés du laser, notamment l'intensité, polarisation et ellipticité ainsi que les propriétés du cristal impactent de manière corrélée au processus de génération d'harmonique. De plus, nous surlignons le rôle important des effets de propagation linéaire et non linéaire, surtout l'effet Kerr, qui peut modifier l'efficacité de génération d'harmonique. Bien que ceux-ci induisent des limitations, dans certaines conditions ils présentent un avantage. Finalement, nous démontrons la possibilité d'augmenter localement l'intensité du laser par confinement dans un cône nanostructuré et ainsi d’accroître le flux harmonique généré. Enfin, nous démontrons une application en imagerie par diffraction cohérente de la source harmonique nanostructurée<br>Since its first observation, a decade ago, high harmonic generation (HHG) in crystals has proved to be an efficient, controllable and compact source of coherent XUV radiation. In this thesis, we investigate HHG in 2D materials, particularly graphene, and in different semiconductor crystals mainly zinc oxide, silicon, gallium arsenide and magnesium oxide. We find that the laser properties, such as its intensity, polarization and ellipticity, and the crystal properties are interrelated. Moreover, we shed the light on the role of the linear and nonlinear propagation effects mainly the Kerr effect, upon laser interaction with the crystal, which can significantly influence the high harmonic generation efficiency. Although this presents major limitations, we show that in some cases it turns out to be an advantage. Finally, we demonstrate the manipulation of the harmonic radiation at the source of the emission by patterning nanostructures to confine and enhance nanojoule laser pulses, and generate harmonic beams carrying orbital angular momentum. Lastly, we successfully image a micrometer-sized sample by the coherent diffractive imaging (CDI) technique based on solid-state harmonics
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Luo, Yun. "Crystal Chemistry of U and Th in Apatite." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1272635731.
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Almeida, Álvaro José Caseiro de. "Quantum communications in optical fibers." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16306.
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Doutoramento em Engenharia Física<br>This thesis begins by proposing the implementation of a probabilistic photon source based on the stimulated four-wave mixing (FWM) process. This source was implemented experimentally and characterized in terms of its statistical distribution. Next, the impact of the stimulated FWM process in a co-propagating quantum signal was studied experimentally. Finally, the violation of Clauser-Horne-Shimony-Holt (CHSH) inequality was experimentally verified using polarization-entangled photon pairs, which were obtained from the spontaneous FWM process in a Sagnac loop. The experimental evolution of the quantum-bit error rate (QBER) in a system without control of polarization, using this degree of freedom to encode information, was studied. It was found out that the QBER increases with the length of the transmission fiber. It was also verified that the increase in the QBER was due to the random rotation of photon’s polarization. A model for the rigorous estimation of the QBER was derived and developed an automatic method to compensate the random rotations of polarization. The method was validated numerically and experimentally, in a transmission system with 40km, showing that it can compensate for the rotations that photons suffer during propagation in optical fibers. Finally, a quantum bit commitment (QBC) protocol between two untrusted entities was implemented. The encoding was performed using two nonorthogonal states of polarization (SOPs). As quantum channel between the two entities, it was first assumed that the transmitter and the receiver were side by side, and after that, they were separated by 8 km and finally, that they were 16km from each other. The implementation of the protocol was performed with a success rate in measurements exceeding 93%, well above the theoretical security limit of 85%. The best strategy for deceiving the commitment was also implemented, and its security experimentally confirmed with a confidence of 7 standard deviations.<br>Nesta tese começou-se por propor a realização de uma fonte de fotões probabilística baseada no processo estimulado de mistura de quatro ondas (FWM). Implementou-se essa fonte no laboratório e caracterizou-se experimentalmente a sua distribuição estatística. Depois, estudou-se experimentalmente o impacto do processo estimulado de FWM num sinal quântico que se propaga na mesma fibra ótica. Por fim, foi verificada experimentalmente a violação da desigualdade de ClauserHorne-Shimony-Holt (CHSH) usando pares de fotões entrelaçados, que foram obtidos a partir do processo espontâneo de FWM num ciclo de Sagnac. Estudou-se a evolução da taxa de erro de bits quânticos (QBER) num sistema sem controlo de polarização, quando este grau de liberdade é usado para codificar a informação. Verificou-se que a QBER aumenta com o comprimento da fibra de transmissão. Verificou-se ainda que o aumento da QBER era devido às variações aleatórias da polarização dos fotões. Derivou-se um modelo para a estimativa rigorosa da QBER e desenvolveu-se um método automático de compensação das rotações aleatórias da polarização. O método foi validado numericamente e experimentalmente, num sistema de transmissão com 40km, verificando se que consegue compensar as rotações que os fotões sofrem durante a sua propagação em fibras óticas. Finalmente, implementou-se um protocolo de compromisso quântico entre duas entidades não confiávéis. Na codificação foram usados dois estados de polarização (SOPs) não ortogonais. Como canal quântico entre as duas entidades foi primeiro considerado que o emissor e o recetor se encontravam lado a lado, depois que estes estavam separados por 8km e finalmente que se encontravam a 16km um do outro. A implementação do protocolo foi feita com uma taxa de sucesso nas medidas superior a 93%, muito acima do limite teórico mínimo de 85%. Implementou-se ainda a melhor estratégia para que o compromisso pudesse ser falseado, tendo sido confirmada experimentalmente a sua segurança com uma confiança de 7 desvios padrão.
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Sarabia, Francisco J. "Interfacial studies of Pt and Cu single-crystal electrodes modified by transition metal deposition." Doctoral thesis, Universidad de Alicante, 2021. http://hdl.handle.net/10045/118535.
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El conocimiento de las características interfaciales es de suma importancia para poder desarrollar materiales que sean capaces de dar lugar a reacciones electrocatalíticas eficientes. Por esta razón, en esta tesis se muestran diferentes estudios interfaciales sobre superficies monocristalinas de platino y cobre en diferentes electrolitos. Además se estudian las características de la interfase electrodoldisolución con superficies de platino modificadas con adátomos de hierro, cobalto y níquel. Para ello, se han empleado las técnicas de voltametría cíclica, espectroscopía infrarroja con transformada de Fourier, desplazamiento de carga con CO y salto de temperatura inducido por láser. Los resultados muestran cómo varía el campo eléctrico interfacial disminuye al aumentar el recubrimiento de hierro y níquel en la superficie de platino. Este efecto tiene un gran impacto en la reacción de evolución de hidrógeno, ya que la mejora electrocatalítica de esta reacción está relacionada con la energía de reorganización de las moléculas de agua, la cual, depende de la fortaleza del campo eléctrico interfacial. Los estudios realizados en medio alcalino para las diferentes superficies de cobre y platino sin modificar muestran una correlación entre el potencial de máxima entropía y las funciones de trabajo para cada una de las diferentes orientaciones atómicas superficiales. Por otro lado, debido a la aplicabilidad de las nanopartículas en los sistemas reales de conversión de energía, se realizaron experimentos de sincrotrón empleando la técnica de Bragg coherent difraction imaging con el objetivo de estudiar el deterioro de las nanopartículas en condiciones operando.
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Tomba, Caterina. "Primary brain cells in in vitro controlled microenvironments : single cell behaviors for collective functions." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY039/document.
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Du fait de sa complexité, le fonctionnement du cerveau est exploré par des méthodes très diverses, telles que la neurophysiologie et les neurosciences cognitives, et à des échelles variées, allant de l'observation de l'organe dans son ensemble jusqu'aux molécules impliquées dans les processus biologiques. Ici, nous proposons une étude à l'échelle cellulaire qui s'intéresse à deux briques élémentaires du cerveau : les neurones et les cellules gliales. L'approche choisie est la biophysique, de part les outils utilisés et les questions abordées sous l'angle de la physique. L'originalité de ce travail est d'utiliser des cellules primaires du cerveau dans un souci de proximité avec l'in vivo, au sein de systèmes in vitro dont la structure chimique et physique est contrôlé à l'échelle micrométrique. Utilisant les outils de la microélectronique pour un contrôle robuste des paramètres physico-chimiques de l'environnement cellulaire, ce travail s'intéresse à deux aspects de la biologie du cerveau : la polarisation neuronale, et la sensibilité des cellules gliales aux propriétés mécaniques de leur environnement. A noter que ces deux questions sont étroitement imbriquées lors de la réparation d'une lésion. La première est cruciale pour la directionalité de la transmission de signaux électriques et chimiques et se traduit par une rupture de symétrie dans la morphologie du neurone. La seconde intervient dans les mécanismes de recolonisation des lésions, dont les propriétés mécaniques sont altérées., Les études quantitatives menées au cours de cette thèse portent essentiellement sur la phénoménologie de la croissance de ces deux types de cellules et leur réponse à des contraintes géométriques ou mécaniques. L'objectif in fine est d'élucider quelques mécanismes moléculaires associés aux modifications de la structure cellulaire et donc du cytosquelette. Un des résultats significatifs de ce travail est le contrôle de la polarisation neuronale par le simple contrôle de la morphologie cellulaire. Ce résultat ouvre la possibilité de développer des architectures neuronales contrôlées in vitro à l'échelle de la cellule individuelle<br>The complex structure of the brain is explored by various methods, such as neurophysiology and cognitive neuroscience. This exploration occurs at different scales, from the observation of this organ as a whole entity to molecules involved in biological processes. Here, we propose a study at the cellular scale that focuses on two building elements of brain: neurons and glial cells. Our approach reachs biophysics field for two main reasons: tools that are used and the physical approach to the issues. The originality of our work is to keep close to the in vivo by using primary brain cells in in vitro systems, where chemical and physical environments are controled at micrometric scale. Microelectronic tools are employed to provide a reliable control of the physical and chemical cellular environment. This work focuses on two aspects of brain cell biology: neuronal polarization and glial cell sensitivity to mechanical properties of their environment. As an example, these two issues are involved in injured brains. The first is crucial for the directionality of the transmission of electrical and chemical signals and is associated to a break of symmetry in neuron morphology. The second occurs in recolonization mechanisms of lesions, whose mechanical properties are impaired. During this thesis, quantitative studies are performed on these two cell types, focusing on their growth and their response to geometrical and mechanical constraints. The final aim is to elucidate some molecular mechanisms underlying changes of the cellular structure, and therefore of the cytoskeleton. A significant outcome of this work is the control of the neuronal polarization by a simple control of cell morphology. This result opens the possibility to develop controlled neural architectures in vitro with a single cell precision
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Romagnoli, Priscila. "Modelamento, fabricação e caracterização de seções polarizadoras em fibras de cristal fotônico altamente birrefringentes." Universidade Presbiteriana Mackenzie, 2013. http://tede.mackenzie.br/jspui/handle/tede/1426.
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Previous issue date: 2013-01-24<br>Photonic crystal fibers have been proposed as single-polarization (or polarizing) fibers with important applications being demonstrated, for example, in telecommunications, sensing and georeferencing. Although the vast majority of reported studies have focused on the numerical analysis of the performance of PCFs with specific and unconventional designs, post-processing PCFs also allows for great flexibility in altering the characteristics of guidance. In this work, the structure of a commercial, highly birefringent, PCF, with different holes diameters, has been locally changed using a tapering technique, which reduces the transverse dimensions of the fiber, with the application of pressure in the holes. This process was implemented to create 1-cm-long sections with a 66% reduction in their cross-sectional dimensions, through the application of pressure using two different schemes. It is numerically and experimentally shown that the two resulting structures are polarizing. In the first scheme, the same pressure is applied to all holes, resulting in a polarizing PCF at a wavelength of 633 nm, with an experimentally obtained polarization extinction ratio (PER) of 6.44 dB. In the second scheme, the applied pressure was different for the large and small holes, resulting in a polarizing PCF for the 1510-1590 nm wavelength range, with an experimentally obtained PER of more than 30 dB. Both the simplicity of the method and the resulting PER compares favorably with alternative methods to create polarizing conventional and photonic crystal fibers.<br>Fibras de cristal fotônico (PCFs, do inglês photonic crystal fibers) vêm sendo propostas como fibras polarizadoras, com importantes aplicações sendo demonstradas, por exemplo, em telecomunicações, sensoriamento e georreferenciamento. Apesar da vasta maioria dos trabalhos reportados analisarem numericamente o desempenho de PCFs com designs específicos e não convencionais, o pós-processamento em PCFs comerciais permite grande flexibilidade na alteração das características de guiamento. Neste trabalho, a estrutura de uma PCF altamente birrefringente comercial, com capilares de diferentes diâmetros, foi alterada localmente utilizando uma técnica de afilamento (tapering), que reduz as dimensões transversais da fibra, com aplicação de pressão nos capilares. Este processo foi implementado para criar seções de 1 ���� de extensão com uma redução nas dimensões transversais de 66%, aplicando-se pressão de duas formas diferentes. Demonstra-se numérica e experimentalmente que as duas estruturas resultantes são polarizadoras. Na primeira forma, aplicou-se uma única pressão em todos os capilares, resultando em uma PCF polarizadora no comprimento de onda de 633 ����, com uma razão de extinção de polarização (PER) experimentalmente obtida de 6,44 ����. Já na segunda forma aplicaram-se pressões diferentes nos capilares grandes e pequenos, o que resultou em uma PCF polarizadora para a faixa de comprimentos de onda que se estende de 1510 ���� a 1590 ����, com uma PER experimentalmente obtida superior a 30 ����. Tanto a simplicidade do método quanto a PER resultante possuem resultados positivos em comparação a métodos alternativos para a produção de fibras convencionais e fibras de cristal fotônico polarizadoras.
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Shakya, Mahendra Man. "Generation of intense high harmonics : i) to test and improve resolution of accumulative x-ray streak camera ii) to study the effects of carrier envelope phase on XUV super continuum generation by polarization gating." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/408.
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大智, 東., та Daichi Higashi. "リフレクトアレーアンテナの広帯域化および偏波特性制御のための高性能共振素子形状に関する研究". Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13128124/?lang=0, 2019. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13128124/?lang=0.
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本研究は, 広帯域直交偏波共用低交差偏波特性, 偏波変換特性および任意の反射位相差を有する高性能・高機能リフレクトアレー共振素子の開発を行い, 設計・試作したリフレクトアレーアンテナの放射特性の数値的及び実験的検討の研究成果をまとめたものである.<br>博士(工学)<br>Doctor of Philosophy in Engineering<br>同志社大学<br>Doshisha University
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Ahmed, Haitham Ahmed Shaban. "Quantitative molecular orientation imaging of biological structures by polarized super-resolution fluorescence microscopy." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4323.
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Dans cette thèse, nous avons construit et optimisé des méthodes de microscopie de fluorescence super-résolue stochastique, polarisée et quantitative qui nous permettent d'imager l'orientation moléculaire dans des environnements dynamiques et statiques a l’échelle de la molécule unique et avec une résolution nanoscopique. En utilisant un montage de microscopie super-résolue à lecture stochastique en combinaison avec une détection polarisée, nous avons pu reconstruire des images d'anisotropie de fluorescence avec une résolution spatiale de 40 nm. En particulier, nous avons pu imager l'ordre orientationnel d'assemblages biomoléculaires et cellulaires. Pour l'imagerie cellulaire, nous avons pu étudier la capacité d'étiquettes de marquer fluorophoresde reporter quantifier l'orientation moléculaire dans l'actine et les microtubules dans des cellules fixées. Nous avons également mis à profit la meilleure résolution et la détection polarisée pour étudier l'ordre moléculaire d’agrégats d’amyloïdes a l’échelle nanoscopique. Enfin, nous avons étudié l'interaction de la protéine de réparation RAD51 avec l'ADN par microscopie de fluorescence polarisée super-résolue pour quantifier l'ordre orientationnel de l'ADN et de la protéine RAD51 afin de comprendre la recombinaison homologue du mécanisme de réparation de l'ADN<br>.In this thesis we built and optimized quantitative polarized stochastic super-resolution fluorescence microscopy techniques that enabled us to image molecular orientation behaviors in static and dynamic environments at single molecule level and with nano-scale resolution. Using a scheme of stochastic read-out super resolution microscopy in combination with polarized detection, we can reconstruct fluorescence anisotropy images at a spatial resolution of 40 nm. In particular, we have been able to use the techniques to quantify the molecular orientationalorder in cellular and bio-molecular assemblies. For cellular imaging, we could quantify the ability of fluorophore labels to report molecular orientation of actin and microtubules in fixed cells. Furthermore, we used the improvements of resolution and polarization detection to study molecular order of amyloid aggregates at a nanoscopic scale. Also, we studied repair protein RAD51` s interaction with DNA by using dual color polarized fluorescence microscopy, to quantify the orientational order of DNA and RAD51 to understand the homologous recombination of DNA repair mechanism
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Ferrage, Fabien. "Spectroscopie du proton en RMN hétéronucléaire des biomolécules : la polarisation croisée de transitions uniques et les échos stimulés hétéronucléaires." Paris 6, 2002. http://www.theses.fr/2002PA066139.
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Hase, Michal. "Návrh antény s kruhovou polarizací pro kmitočtové pásmo 2,4 GHz." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217597.
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In this thesis, I introduce two types of circularly polarized rectangular microstrip antennas at 2.44 GHz. First type has direct fed and the second has two inputs for fed. In first case is used a stub to make the frequency with minimum return loss and equal to the frequency with minimum axial ratio. In second case is use the power splitter to divide the wave in to two lines with phase shift 90° for feeding the patch. In this thesis is described, how to get the best results of Axial Ratio.
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Sulaiman, Mohamad Ismail. "Design and analysis of singly-fed dielectric resonator antennas with a wideband circular polarization." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578033.
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The proliferation of mobile communications technology increases the demands for faster and more robust services, in addition to the ever decreasing sizes of antennas. These demands can be satisfied using circularly polarized (CP) dielectric resonator antennas (DRAs) exhibiting wide operational bandwidth capability. By utilizing such antennas, the probability of linking the transmitted and received signals is higher, and the system is more reliable since the CP wave is transmitted in all planes and less susceptible to unwanted reflections and absorptions. As CP system is insensitive to the transmitter and receiver orientation, the time consuming practice of continuously aligning the antennas can be avoided. Furthermore, the antennas profile can be reduced simply by using dielectric material with higher permittivity. The thesis focuses on the design and analysis of singly-fed regular-shaped DRAs with a wideband circular polarization. Two new single-point excitation schemes that can be easily used to excite an arbitrarily shaped DRA are introduced, where a square spiral and a rectangular open half-loop are used for DRA excitation. These proposed feeding methods are based on employing conformal conducting metal strips that are placed on the DRA surface. Additionally, two different approaches are employed onto the DRA design to enhance the CP bandwidth. The first approach is based on using a multilayer dielectric, and the second introduces a parasitic half-loop inside the feeding element. The generated broad CP bands have been achieved in conjunction with sufficient impedance matching bandwidths. The studied geometries have been modeled using a comprehensive self developed MoM code that employs the volume surface integral equation (VSIE). The computed results have been validated against those obtained from measurements as well as CST microwave studio simulations. Theoretical and experimental results demonstrate a several folds enhancement in the CP bandwidths compared to those reported in the literature for identical DRA geometries.
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Darwich, Dia. "Gestion des effets thermiques dans des fibres actives à très grande aire modale pour la montée en puissance des sources laser à 2μm". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0085/document.
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Ce travail concerne le développement d’une fibre optique à structure originale permettant la montée en puissance moyenne et crête dans les systèmes lasers à 2μm. La gestion des effets thermiques est devenue aujourd’hui un enjeu primordial notamment pour essayer de repousser le seuil d’apparition des instabilités modales transverses. Le principe mis en avant ici est basé sur la rupture de symétrie de la gaine microstructurée de la fibre afin d’améliorer la délocalisation des modes d’ordre supérieur vers l’extérieur du milieu à gain. Ainsi une propagation quasi-monomode est obtenue dans une fibre apériodique passive avec un coeur de 140μm à 2μm. Un travail de modélisation a été mené de manière à proposer d’autres structures basées sur une modulation contrôlée de l’indice de réfraction dans le milieu à gain afin de repousser encore plus le seuil du régime multimode. En outre, la fabrication de la première fibre dopée thulium à large aire modale (Dcoeur = 18μm) par la méthode REPUSIL a montré une efficacité de 50%. Ensuite, la fabrication de la première fibre rigide complètement apériodique à gaine réduite dopée thulium a été réalisée. Une fibre avec un coeur de 29μm et un diamètre extérieur de 769μm et une longueur de 86cm a été caractérisée en configuration laser et a permis d’obtenir une émission laser à 2μm de 3,8W (puissance limitée par la puissance de la diode de pompe disponible) avec un rendement de 20% et une qualité de faisceau quasi-monomode. De plus, une fibre passive complètement apériodique à polarisation unique avec un coeur de 140μm a également été réalisée et a permis d’obtenir un ratio d’extinction de polarisation de 16,5dB à 2μm<br>This work deals with the development of an original leaky structure of optical fiber aiming at generating a high power laser radiation at 2μm in CW and pulsed regimes. The management of thermal effects in high power/energy regime became a major issue, in particular to push further the transverse modal instabilities threshold. Our approach consists in breaking the symmetry of the microstructured fiber cladding for to improve the delocalization of the high order modes outside of the gain medium. Thus, an effective single-mode propagation at a 2μm operating wavelength was first demonstrated into a passive aperiodic fibers whose the core diameter reaches up to 140 μm. After implementing some Stress Applying Parts over our aperiodic design, a PER of 16.5dB was achieved at 2μm using a single polarization passive FA-LPF with a core of 140 μm. Thence, a numerical study on the tailoring the active core refractive index has been carried out so as to fend off the threshold of multimodedness. Additionally, the first LMA Tm-doped fiber (Dcoeur = 18μm) fabricated by the REPUSIL method and showing an efficiency of 50% is demonstrated. Thereafter, the fabrication of the first rod-type Tm-doped FA-LPF with reduced cladding is shown. A 29 μm core FA-LPF was characterized in laser configuration, leading to an effective single-mode emission of 3.8W of average power at 2μm strictly restricted by the available pump power and an efficiency of 20%
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Bin, Ngah Lufti Arif. "Synchronisation toute optique d’un réseau de communication quantique." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4141/document.
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Ce manuscrit expose le développement de ressources fondamentales pour les communications quantiques à longues distances basées sur les technologies des fibres optiques télécoms et des guides d'onde optiques non linéaires. Après une introduction générale sur les communications quantiques, cette thèse est structurée en trois parties principales. La première partie illustre le développement de deux sources pour la génération de paires de photons intriqués en polarisation et émis à une longueur d'onde télécom via conversion paramétrique spontanée (SPDC) dans des guides d'ondes non linéaires intégrés sur niobate de lithium périodiquement polarisé. Les sources s'appuient respectivement sur un accord de phase de type-II et un accord de phase de type-0 et sur des solutions de filtrage et d'interférométrie mises en place après le cristal non linéaire. Dans la seconde partie, sont discutées les réalisations de deux sources de photons uniques annoncés haut débit. La première s'appuie sur le multiplexage spatial sur puce de photons uniques annoncés. La seconde exploite le multiplexage temporel passif grâce à l'utilisation d'un laser télécom cadencé à 10 GHz. Enfin, nous présentons une approche tout-optique visant la synchronisation de sources distantes de paires de photons intriqués, agencées selon une architecture de type relais quantique distribué. Cette technique innovante repose sur l'utilisation d'un laser télécom impulsionnel en tant qu'horloge optique de référence. Cette horloge autorise la synchronisation de l'émission de paires de photons dans la bande C des télécoms en deux lieux distants. Des résultats préliminaires d'interférence à deux photons sont montrés et discutés<br>This manuscript reports the development of fundamental resources for long distance quantum communication based on fibre telecom technology and non-linear optical waveguides. After a general introduction on quantum communication, the thesis is structured along three parts. The first part illustrates the development of two photonic polarization entanglement sources suitable for quantum networking. Both sources generate paired photons at telecom wavelength via spontaneous parametric down conversion (SPDC) in periodically poled lithium niobate waveguides (PPLN/W). They rely on type-II and type 0 phase matching, respectively. In the second part, two high quality heralded single photon sources are highlighted. The first one relies on on-chip generation and spatial multiplexing of heralded single photons towards achieving higher bit rates. The second one takes advantage of passive temporal multiplexing of a single SPDC process. Finally, an all-optical approach towards efficient and accurate synchronization of remote entangled photon pair sources within quantum relay architecture over long distances is presented. This particular synchronization technique highlights the use of ultra-fast picosecond pulsed telecom fiber laser, operating at 2.5 GHz repetition rate, acting as a master optical clock, enabling to accurately synchronize the emission of photon pairs in the telecom C-band of wavelengths at two remote locations. This innovative approach is applied for synchronizing two remote PLLN/W based sources operated at 2.5 GHz, and preliminary results on two-photon interference obtained with single photons coming from each source are shown and discussed
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Czerwińska, Urszula. "Unsupervised deconvolution of bulk omics profiles : methodology and application to characterize the immune landscape in tumors Determining the optimal number of independent components for reproducible transcriptomic data analysis Application of independent component analysis to tumor transcriptomes reveals specific and reproducible immune-related signals A multiscale signalling network map of innate immune response in cancer reveals signatures of cell heterogeneity and functional polarization." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB075.
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Les tumeurs sont entourées d'un microenvironnement complexe comprenant des cellules tumorales, des fibroblastes et une diversité de cellules immunitaires. Avec le développement actuel des immunothérapies, la compréhension de la composition du microenvironnement tumoral est d'une importance critique pour effectuer un pronostic sur la progression tumorale et sa réponse au traitement. Cependant, nous manquons d'approches quantitatives fiables et validées pour caractériser le microenvironnement tumoral, facilitant ainsi le choix de la meilleure thérapie. Une partie de ce défi consiste à quantifier la composition cellulaire d'un échantillon tumoral (appelé problème de déconvolution dans ce contexte), en utilisant son profil omique de masse (le profil quantitatif global de certains types de molécules, tels que l'ARNm ou les marqueurs épigénétiques). La plupart des méthodes existantes utilisent des signatures prédéfinies de types cellulaires et ensuite extrapolent cette information à des nouveaux contextes. Cela peut introduire un biais dans la quantification de microenvironnement tumoral dans les situations où le contexte étudié est significativement différent de la référence. Sous certaines conditions, il est possible de séparer des mélanges de signaux complexes, en utilisant des méthodes de séparation de sources et de réduction des dimensions, sans définitions de sources préexistantes. Si une telle approche (déconvolution non supervisée) peut être appliquée à des profils omiques de masse de tumeurs, cela permettrait d'éviter les biais contextuels mentionnés précédemment et fournirait un aperçu des signatures cellulaires spécifiques au contexte. Dans ce travail, j'ai développé une nouvelle méthode appelée DeconICA (Déconvolution de données omiques de masse par l'analyse en composantes immunitaires), basée sur la méthodologie de séparation aveugle de source. DeconICA a pour but l'interprétation et la quantification des signaux biologiques, façonnant les profils omiques d'échantillons tumoraux ou de tissus normaux, en mettant l'accent sur les signaux liés au système immunitaire et la découverte de nouvelles signatures. Afin de rendre mon travail plus accessible, j'ai implémenté la méthode DeconICA en tant que librairie R. En appliquant ce logiciel aux jeux de données de référence, j'ai démontré qu'il est possible de quantifier les cellules immunitaires avec une précision comparable aux méthodes de pointe publiées, sans définir a priori des gènes spécifiques au type cellulaire. DeconICA peut fonctionner avec des techniques de factorisation matricielle telles que l'analyse indépendante des composants (ICA) ou la factorisation matricielle non négative (NMF). Enfin, j'ai appliqué DeconICA à un grand volume de données : plus de 100 jeux de données, contenant au total plus de 28 000 échantillons de 40 types de tumeurs, générés par différentes technologies et traités indépendamment. Cette analyse a démontré que les signaux immunitaires basés sur l'ICA sont reproductibles entre les différents jeux de données. D'autre part, nous avons montré que les trois principaux types de cellules immunitaires, à savoir les lymphocytes T, les lymphocytes B et les cellules myéloïdes, peuvent y être identifiés et quantifiés. Enfin, les métagènes dérivés de l'ICA, c'est-à-dire les valeurs de projection associées à une source, ont été utilisés comme des signatures spécifiques permettant d'étudier les caractéristiques des cellules immunitaires dans différents types de tumeurs. L'analyse a révélé une grande diversité de phénotypes cellulaires identifiés ainsi que la plasticité des cellules immunitaires, qu'elle soit dépendante ou indépendante du type de tumeur. Ces résultats pourraient être utilisés pour identifier des cibles médicamenteuses ou des biomarqueurs pour l'immunothérapie du cancer<br>Tumors are engulfed in a complex microenvironment (TME) including tumor cells, fibroblasts, and a diversity of immune cells. Currently, a new generation of cancer therapies based on modulation of the immune system response is in active clinical development with first promising results. Therefore, understanding the composition of TME in each tumor case is critically important to make a prognosis on the tumor progression and its response to treatment. However, we lack reliable and validated quantitative approaches to characterize the TME in order to facilitate the choice of the best existing therapy. One part of this challenge is to be able to quantify the cellular composition of a tumor sample (called deconvolution problem in this context), using its bulk omics profile (global quantitative profiling of certain types of molecules, such as mRNA or epigenetic markers). In recent years, there was a remarkable explosion in the number of methods approaching this problem in several different ways. Most of them use pre-defined molecular signatures of specific cell types and extrapolate this information to previously unseen contexts. This can bias the TME quantification in those situations where the context under study is significantly different from the reference. In theory, under certain assumptions, it is possible to separate complex signal mixtures, using classical and advanced methods of source separation and dimension reduction, without pre-existing source definitions. If such an approach (unsupervised deconvolution) is feasible to apply for bulk omic profiles of tumor samples, then this would make it possible to avoid the above mentioned contextual biases and provide insights into the context-specific signatures of cell types. In this work, I developed a new method called DeconICA (Deconvolution of bulk omics datasets through Immune Component Analysis), based on the blind source separation methodology. DeconICA has an aim to decipher and quantify the biological signals shaping omics profiles of tumor samples or normal tissues. A particular focus of my study was on the immune system-related signals and discovering new signatures of immune cell types. In order to make my work more accessible, I implemented the DeconICA method as an R package named "DeconICA". By applying this software to the standard benchmark datasets, I demonstrated that DeconICA is able to quantify immune cells with accuracy comparable to published state-of-the-art methods but without a priori defining a cell type-specific signature genes. The implementation can work with existing deconvolution methods based on matrix factorization techniques such as Independent Component Analysis (ICA) or Non-Negative Matrix Factorization (NMF). Finally, I applied DeconICA to a big corpus of data containing more than 100 transcriptomic datasets composed of, in total, over 28000 samples of 40 tumor types generated by different technologies and processed independently. This analysis demonstrated that ICA-based immune signals are reproducible between datasets and three major immune cell types: T-cells, B-cells and Myeloid cells can be reliably identified and quantified. Additionally, I used the ICA-derived metagenes as context-specific signatures in order to study the characteristics of immune cells in different tumor types. The analysis revealed a large diversity and plasticity of immune cells dependent and independent on tumor type. Some conclusions of the study can be helpful in identification of new drug targets or biomarkers for immunotherapy of cancer
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Panascí, Marco. "Vliv dlouhých optovláknových tras na polarizační stav světla a jejich využití pro napájení polarizačních senzorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442367.
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This diploma thesis deals with the influence of long fiber optic paths on the polarization state of light and their use for powering polarization sensors. The aim of the diploma thesis was to design the arrangement of optical fiber components so that the polarization properties of light at the end of the path are further usable for sensory purposes. Four partial measurements with a long path (in a laboratory setting, laying in the ground, on a curtain, under the influence of external influence) and one measurement without a path under the influence of external influence were designed. The overall measurement results demonstrate that for the functional power supply of long-distance sensor systems, an existing single-mode fiber can be used (laid by laying in the ground), into which a light source for a given sensor system would be multiplexed. In the discussion, all types of measurements are analyzed and compared with each other. Finally, the overall result is summarized and applications are described in which such a sensor system could be used.
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Martinod, Marc-Antoine. "Développement et exploitation scientifique d’un nouvel instrument interférométrique visible en optique guidée." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4215/document.
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L'interférométrie visible longue base est une technique d'observation en astronomie permettant de sonder les objets avec une résolution spatiale qu'il est impossible d'atteindre avec un télescope seul. La mise en œuvre au sol de cette méthode est limitée en sensibilité et précision de mesure à cause de la turbulence atmosphérique. Or les nouveaux besoins scientifiques, tels que la détermination des paramètres fondamentaux, l'étude de l'environnement proche ou de la surface des étoiles, requièrent la capacité d'observer des objets de moins en moins brillants et de faire des mesures de plus en plus précises, en interférométrie visible. Pour s'affranchir de la turbulence, l'interférométrie multimode a été développée en reprenant le concept de l'interférométrie des tavelures utilisée sur un seul télescope. Aujourd'hui, pour améliorer davantage les performances des futurs instruments, cette instrumentation évolue vers l'utilisation de la nouvelle génération de détecteur, l'Electron Multiplying Charge-Coupled Device (EMCCD), et de l'emploi des fibres optiques interfacées avec des optiques adaptatives. Cette avancée est motivée par le succès de l'utilisation conjointe de l'optique adaptative et du suivi de franges pour s'affranchir partiellement de la turbulence en interférométrie infrarouge, en 2017 avec l'instrument GRAVITY (Gravity Collaboration et al. 2017). Le prototype FRIEND (Fibered and spectrally Resolved Interferometer - New Design) a été conçu pour caractériser et évaluer les performances de la combinaison de ces éléments, dans le domaine visible. L'amélioration de la précision des instruments interférométriques est apportée par les fibres optiques et par la dynamique du signal délivré par une EMCCD. L'inconvénient de l'emploi des fibres dans le visible est une perte de la sensibilité du fait que le taux d'injection du flux dans celles-ci est très faible à cause de la turbulence atmosphérique. Mais il se trouve que l'optique adaptative et l'EMCCD permettent d'améliorer la sensibilité. En effet, l'optique adaptative maximise l'injection en réduisant l'influence de la turbulence atmosphérique, et l'EMCCD est capable de détecteur de faibles flux. FRIEND prépare ainsi le développement du futur instrument SPICA, recombinant jusqu'à six télescopes (Mourard et al. 2017, 2018). Celui-ci devra explorer la stabilisation des interférences grâce au suivi de franges. Cet aspect n'est pas abordé dans cette thèse. Je présente dans cette thèse le prototype FRIEND, capable de recombiner jusqu'à trois télescopes, opérant dans la bande R en franges dispersées. Il est doté de fibres optiques gaussiennes monomodes à maintien de polarisation et d'une EMCCD. Il est installé sur l'interféromètre visible Center for High Angular Resolution Astronomy (CHARA), au Mount Wilson, en Californie, qui est en train de s'équiper d'optiques adaptatives. J'ai développé des estimateurs de visibilité et de clôture de phase, la méthode de réduction des données de ce prototype et une stratégie d'observation. Grâce à ces outils, j'ai montré que les optiques adaptatives améliorent le taux d'injection dans les fibres. Il est alors apparu que la stabilisation de l'injection est importante pour maximiser le rapport signal-à-bruit dans chaque image. La biréfringence des fibres dégrade les performances de l'instrument mais elle a pu être compensée. J'ai montré qu'un instrument, basé sur la conception de FRIEND, permet d'accéder à des mesures de visibilité faibles avec une précision, inatteignable avec la génération actuelle, grâce au développement et l'utilisation d'un modèle de rapport signal-à-bruit. L'instrument a enfin été testé dans son intégralité sur le système binaire connu ζ Ori A. Cette observation montre la fiabilité et la précision des mesures interférométriques obtenues avec ce prototype, montrant l'intérêt de cette association de technologies pour les futurs interféromètres visibles<br>Long baseline visible interferometry in astronomy is an observing technique which allows to get insights of an object with an outstanding angular resolution, unreachable with single-dish telescope. Interferometric measurements with ground-based instrumentation are currently limited in sensitivity and precision due to atmospheric turbulence. However, the new astrophysical needs, particularly the determination of fundamental parameters or the study of the closed environment and the surface of the stars, require to observe fainter objects with a better precision than now in visible interferometry. Ought to overcome the atmospheric turbulence, multispeckle interferometry has been developed by adapting speckle imaging technics used on single-dish telescope. Today, in order to improve the performance of the future combiners, instrumentation progresses to the use of a new generation detector called EMCCD, and the use of optical fibers which are coupled with adaptive optics. This path is chosen thank to the success of the use of the adaptive optics with the fringe tracking in the infrared interferometry in 2017 (Gravity Collaboration et al. 2017), in order to compensate turbulence. FRIEND prototype (Fibered and spectrally Resolved Interferometer - New Design) has been designed to characterize and estimate the performance of such a combination of technologies, in the visible spectral band. The improvement of the precision of the measurements from interferometric instruments is due to optical fibers and the dynamical range of the EMCCD. The counterpart of using the optical fibers is a loss in sensitivity due to a low injection rate of flux into the fibers because of the atmospheric turbulence. On the other hand, sensitivity is improved thanks to adaptive optics and EMCCDs. Indeed, adaptive optics increases the injection rate and EMCCDs can measure low fluxes. Lastly, FRIEND is a pathfinder for the future instrument SPICA which should recombine up to 6 telescopes (Mourard et al. 2017, 2018). Fringe-tracking aspects will have to be studied for SPICA; this topic is not dealt with in this thesis. In this work, I present the FRIEND prototype, which can recombine up to three telescopes and operates in the R band with dispersed fringes. It has Gaussian polarization-maintaining single mode optical fibers and an EMCCD. It is set up at the Center for High Angular Resolution Astronomy (CHARA), at Mount Wilson, in California. CHARA is currently being equipped with adaptive optics. I develop estimators of visibility modulus and closure phase, the data reduction software and an observing strategy. Thanks to that, I am able to show that adaptive optics improves the injection rate. I also demonstrate how important the stabilization of injection is to maximize the signal-to-noise ratio (SNR) per frame. Birefringence of the fibers decreases the performance of the instrument but we manage to compensate it. I show how such an instrument can measure low visibility with a better precision than now by developing and using a SNR model of FRIEND. Finally, FRIEND has entirely been tested on the known binary system ζ Ori A. These observations demonstrate how reliable and accurate the measurements of FRIEND are
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Prade, Bernard. "Quelques aspects theoriques et experimentaux de la propagation des ondes electromagnetiques dans l'atmosphere et dans une fibre optique monomode." Paris 6, 1987. http://www.theses.fr/1987PA066061.
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Cette these, menee dans le cadre d'un travail sur la transmission d'informations par voie optique, comporte deux parties; la premiere traite du bruit de polarisation introduit par l'atmosphere au repos ou en ecoulement; la seconde partie traite du couplage par champ evanescent dans les fibres monomodes
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Kirik, Mustafa Sancay. "Design, Analysis, And Implementation Of Circular Disk - Annular Ring (cdar) Antenna." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12609156/index.pdf.
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In satellite applications, a circularly polarized satellite antenna is desirable with a pattern that results in constant received power while the distance between the transmitter and the receiver is changing. The Circular Disk - Annular Ring (CDAR) antenna satisfies these requirements along with other requirements for the satellite antenna. The CDAR antenna is a combination of a Circular Disk and an Annular Ring patch antennas. In this thesis, a circularly polarized CDAR antenna that is fed from a single point is designed at the center frequency of 8.2 GHz. This antenna is investigated and optimized to ease the fabrication process. The design parameters are defined on this report and optimized by using an Electromagnetic Simulation software program. In order to verify the theoretical results, Circular Disk - Annular Ring Antenna is produced as a prototype. Measurements of antenna parameters, electromagnetic field and circuit properties are interpreted to show compliance with theoretical and simulation results. The values of deviation between theoretical and experimental results are also discussed.
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Yu-Chia, Chang. "The Single-molecule Fluorescence Polarization Detecting System." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2806200417144200.
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LI, ZHENG-LI, and 李政立. "The polarization in single-mode optical fibers." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/11218916274704203445.
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Chang, Yu-Chia, and 張瑜家. "The Single-molecule Fluorescence Polarization Detecting System." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/96600796697395987965.
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碩士<br>國立臺灣大學<br>物理研究所<br>92<br>A single-molecule fluorescence polarization (SMFP) detecting system enables us to investigate the time evolution of the dipole orientation of a chromophore. It has applications for a variety of studies such as determine the protein structure, detecting the rotational motion of a protein, characterizing the properties of a membrane, and so on. Within the framework of this thesis, we have successfully developed a SMFP detecting system by employing a polarization beamsplitter cube into a double-port scanning confocal microscope. The intensity ratio of the two linearly perpendicular polarization states emerging from the two ports of this system is 1:3 when a circular polarized light was incident into the system.
Thin polystyrene films containing isolated DiIC18(3) small molecules which are commonly used in the membrane study consisting of only one chromophore were prepared to test the SMFP detecting system. As to the single-molecule detection, reducing background fluorescence and increasing signal to noise (S/N) ratio are two crucial issues. Cleaner implements used in the sample preparation not only can enlarge the S/N ratio but also can prevent quenching effect from taking place. With the effort on the removal of the contaminants introduced in the sample preparation processes we found out that polluted pipette may easily contaminate solvents in use, even when disposable tips are used and presumably the solvents wouldn’t have contact with the inner of the pipette. To examine the background intensity of the sample, it has been found out that the incident light with 1 �巰 for the raster scanning is more efficient than that with 33 nW as we did previously. After eliminating possible contaminations, the background intensity of the sample amounts to a value of three counts per 10ms which is very close to the dark count rate of the detecting system has been achieved.