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Polarization characteristics of 1D plasmonic grating measurement and discussionLiou, Jia-Hua 23 June 2011 (has links)
The birefringence of one-dimension PMMA surface gratings on a gold film substrate is investigated. The grating served as a coupler to facilitate the incoming light coupled to surface plasmon wave (SPW) which possesses high propagation wave vector. Since surface plasmon waves(SPWs) have a special dispersion relation, the birefringence £Gneff (£Gneff =nx-ny, where grating k-vector is along x axis) of this structure is relatively large and can be changed from positive to negative by changing the operation wavelength.
The obtained the four Stokes parameters at 515nm and 633nm are marked on the Poincare sphere. £Gneff is
2£k/7 and -£k/8 at 515nm and 633nm respectively. Further, by
changing the form factor of PMMA gratings, we found that the maximum £Gneff occurred when PMMA stripe width : air gap=1:1.
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Electrooptic electric field sensor for dc and extra-low-frequency measurementBordovsky, Michael January 1998 (has links)
The thesis reports the results of the research carried out towards the development of an electrooptic sensor for DC and extra low frequency electric field measurement. Available cubic electrooptic crystals were compared from the sensor sensitivity point of view. A new figure of merit was used taking into account the attenuation of the electric field in the dielectric crystal and its shape. The effect of optical activity in 23 cubic crystals was analyzed using the concept of Poincare sphere. The cubic crystals were further characterised for the charge relaxation time constant to estimate their performance in DC field measurements. Crystals of Bismuth Germanate and Lithium Niobate were identified as suitable materials for the DC field sensor. The selected crystals were found suitable at extra-low-frequencies. DC field measurements, without the rotation of the crystal, were possible only with Lithium Niobate. However, its performance was influenced to a great extent by the effect of stimulated conductivity. The quarter-wave plate and the crystal of Lithium Niobate were identified as the main sources of temperature instability. A new method of temperature compensation of the quarter-wave plate is proposed. Due to the temperature instability of Lithium Niobate, mainly attributed to the pyroelectric effect and natural birefringence, it is difficult to use the sensor in practical applications. The performance of the sensor is significantly affected by the presence of an external space charge. The proposed method of its elimination using an artificial extension of the sensing element did not reduce the space charge effect adequately. The response of the sensor in a space charge environment was found to be linear and independent of the space charge density. This enabled measurements of static fields in a unipolar environment. The direct field measurements in bipolar environment suffered from a drift which is intolerable in practical measurements. The minimum detectable electric field of this sensor in the frequency range from 1 to 200Hz was 1V/m, with a signal to noise ratio equal to 0dB and a resolution of 1V/m. The static field measurements were limited to measurements of pulses with a duration of 200s, due to a long term drift of photodetectors. The minimum detectable level of DC electric field was 2.4kV/m.
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[en] STATE OF POLARIZATION CONTROL IN LIGHTWAVE SYSTEM / [pt] CONTROLE DE ESTADO DE POLARIZAÇÃO DA LUZ EM SISTEMAS ÓPTICOSJULIANA BARROS CARVALHO 03 January 2013 (has links)
[pt] Este trabalho apresenta em sua etapa inicial os conceitos básicos de polarização da luz descritos através da Esfera de Poincaré, Vetores de Jones, Parâmetros de Stokes, Matrizes de Mueller e Fórmula da Rotação de Rodrigues. Em seguida, as diversas técnicas utilizadas para as transformações dos SOPs (States of Polarization) são introduzidas. A partir destas etapas, é apresentada a seleção, o desenvolvimento e a realização prática de um sistema capaz de ativar o controle de polarização de sinais ópticos em uma fibra monomodo. Um segundo sistema capaz de controlar sinais ópticos multiplexados em frequencia é também realizado e apresentado. Ambos os sistemas são ativados através de uma ferramenta computacional dedicada baseada na linguagem de programação gráfica LabVIEW. / [en] This work presents initially a set of light polarization concepts using the Poincaré Sphere, Jone’s Vectors, Stoke’s Parameters, Mueller Matrices, Rodrigues’ Rotation Formula, and several SOPs (States of Polarization) transformations. Through these concepts and after a careful components selection, a SOP control system in monomode optical fiber is realized and presented. A second system able to implement the SOP control when multiplexed optical signals are employed is also realized and described. A dedicated computer tool using the software LabVIEW is developed to both systems.
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Využití optického vlákna jako senzoru pro měření teploty / Use of optical fiber as a temperature sensorProcházka, Jakub January 2016 (has links)
This diploma thesis is focused on use of polarization mode dispersion for measurement of temperature. It also deals with representation of polarization mode dispersion in Poincaré sphere and a mathematical description of polarization mode dispersion by using Stokes and Jones vectors. Here are described basic alternatives of settings, selected temperature relationships and dependence and relationship between coherency and polarization. The practical portion of the diploma thesis examines behavior of the temperature sensor at different temperatures for wavelength 1550 nm and 633 nm.
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Etude de la réalisation d'un isolateur optique intégré sur verre / Study of the realization of a glass-integrated optical isolatorGarayt, Jean-Philippe 31 October 2017 (has links)
L’essor des télécommunications par fibre optique nécessite l’insertion en sortie des lasers d’un isolateur optique intégré protégeant celui-ci des réflexions qui le déstabilisent. Ce composant existe à l’heure actuelle sous forme massive, mais son intégration sur la même plaquette que le laser pose problème du fait de la difficulté à intégrer les bons matériaux magnétooptiques sur les substrats usuels de l’optique guidée. Dans cette perspective, l’intégration de nanoparticules magnétiques dans un sol-gel déposé sur les guides optiques est une voie prometteuse, développée par le laboratoire Hubert Curien. Cette thèse a eu pour but d’étudier de manière plus systématique le composant non-réciproque qui entre dans la fabrication des isolateurs à conversion de mode, à savoir le rotateur non-réciproque. Deux études poussées, l’une théorique, l’autre expérimentale, recoupées entre elles par des modèles numériques, ont été mises en oeuvre au cours des années de cette thèse. L’étude théorique a permis de tenir compte tous les paramètres ayant une influence sur l’état de polarisation de la lumière dans un guide magnétooptique, y compris les dichroïsmes souvent négligés. L’étude pratique, à partir d’échantillons sur verre réalisés en collaboration avec l’IMEP-LAHC et le laboratoire PHENIX, a abouti à une caractérisation quasi complète des effets magnétooptiques — longitudinaux et transverses — dans les guides et de l’influence des paramètres de fabrication sur ceux-ci. Au final, ces résultats nous ont donné une compréhension plus complète du fonctionnement des guides magnétooptiques, et nous ont permis de prédire les paramètres optimaux qu’il faudra mettre afin de fabriquer, dans un futur proche, l’isolateur complet sur une seule plaque de verre / The development of optical-fiber telecommunications requires the insertion of optical isolator between lasers and fibers, in order to protect them against perturbating reflexions. This component is currently inserted in a bulk form, but the goal is to integrate it on the same wafer than the laser; nevertheless, this is problematic due to the difficulty to integrate good magnetooptical materials on usual substrates as glass or silicon. One of the promising way to achieve this, developped by the Laboratoire Hubert Curien, is the embedding of magnetic nanoparticles into a sol-gel matrix deposited above the optical guides. This thesis aimed at studying more deeply the main non-reciprocal component of integrated mode conversion optical isolators: the non-reciprocal rotator. A theorical and a practical study have both been performed, with numerical simulations to confront them. The theorical study aimed at describing the evolution of propagation in magnetooptical waveguides with respect to all effects, even absorption and dichroïsm. Then a practical study was performed on glass samples engineered in collaboration with IMEP-LAHC and the PHENIX laboratory, and lead to a full measurement of longitudinal and transverse magnetooptical effects, and their evolution related to the fabrication parameters of the samples. Finally, these results gave us a comprehensive view of how magnetooptical waveguides behave, and we were able to predict the good parameters to choose in order to construct, in a close future, a glass-integrated optical isolator
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