This dissertation addresses several aspects pertaining to polarization in optical fibers and optical waveguide devices. In particular, the analysis and design of fibers that maintain polarization over long lengths, provide zero polarization-mode dispersion, and function as polarizers or mode filters are presented. First, optimum designs for high-birefringence as well as single-polarization single-mode fibers are studied. For high-birefringence fibers, several index profiles were obtained that provided high birefringence while achieving zero or very small dispersion in 1.3 μm and 1.55 μm windows. Also, few index profiles were found that resulted in single-polarization single-mode operation with zero or very small dispersion at about 1.3 μm and 1.55 μm. A wavelength range of 100 nm to 500 nm was achieved for truly single-mode operation. Second, a comprehensive analysis of polarization-mode dispersion in a multiple-clad fiber due to ellipticity of fiber cross-section is carried out. The analysis results are then used to design large effective area single-mode dispersion-shifted fiber that provides zero polarization-mode dispersion at the wavelength 1.55 μm. Effective area on the order of 122 μm² with mode-field diameter of about 10 μm have been attained for this design. Tolerance analysis on the transmission parameters due to ±1% and ±2% variations in the radii of the fiber layers is carried out. Finally, a wedge-shape dielectric waveguides bounded by conducting planes is introduced and analyzed. Conductor and dielectric losses for the fundamental mode in waveguides with wedge angle of π/n; n ≥ 1, and 2π/3 as a special case with noninteger azimuthal number have been evaluated. These waveguides generally support fewer number of modes for smaller wedge angles and the modes cannot be of TM type. They find applications as mode filters and polarizers.. / Ph. D.

This research presents the first use of side-polished Panda fiber in the fabrication of slab-coupled optical sensors (SCOS). It is determined that the Panda SCOS provides a sensor that is comparable to the D-fiber SCOS in cases of electric field sensing. It exhibits greater power transfer and higher bandwidth than a typical D-SCOS. The Panda SCOS is also less costly and easier to splice than the D-fiber alternative. This comes at a cost of slightly decreased sensitivity and a more fragile fabrication process. This research also demonstrates the use of the Panda-SCOS as means of voltage characterization across both the spark gap of an ignition coil circuit along with the spark gap of an automobile. This paper demonstrates the use of a Panda SCOS to measure the voltages and time delays across the spark gaps at different stages of a Marx generator setup .

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. / 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.

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.

birefringance, degreeofpolarization, polarization, Stokesvectors, Poincarésphere, state of polarization, optical power, sensoric fibre, polarization-maintaining fiber, polaroid, poalrimeter