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1
CHIPMAN, RUSSELL ATWOOD. "POLARIZATION ABERRATIONS (THIN FILMS)." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184051.
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Polarization aberrations are the variations of amplitude, phase, polarization and retardance associated with ray paths through optical systems. This dissertation develops methods for calculating the polarization aberrations of radially symmetric systems of weak polarizers, systems like lenses, telescopes and microscopes. The instrumental polarization in these systems arises from weak polarization effects occurring near normal incidence at glass, metal and thin film coated interfaces. Polarized light and polarizers are treated using the Jones calculus. Weak polarizers, optical elements with small polarization effects, are treated by expanding the Fresnel equations and thin film equations into a Taylor series. Methods are given for calculating the Taylor series coefficients for a multilayer coated interface whose polarization performance is known, for example from a thin film design program. Equations are derived for the propagation of polarized light through optical systems. Weak polarizers are shown to be very weakly order dependent; this greatly facilitates the calculation of the effect of a sequence of weak polarizers. The dominant terms are order independent polarization terms which are readily calculated. The order dependent portion can be systematically evaluated as higher order terms. The instrumental polarization, being a function of angle of incidence, is different for different rays through the system. Thus an optical system is a spatially varying polarizer. The instrumental polarization associated with a single surface is often well approximated as a "parabolic" polarizer. The instrumental polarization function is calculated as a Taylor series Jones matrix about the optical axis as a function of object and pupil coordinates. The resulting spatial variations of the instrumental polarization function bear a strong resemblance to the wavefront aberrations, since both arise from fundamental geometrical considerations. In particular, there are terms in the weak linear polarization and in the weak retardance of radially symmetric systems which strongly resemble defocus, tilt and piston error. A polarization aberration expansion is defined to second order in the object and pupil coordinates. A method is derived for calculating the polarization aberration coefficients for a sequence of radially symmetric surfaces from the Taylor series representation of the polarization associated with the individual interfaces.
2
Foster, James Jonathan. "Functions of animal polarization sensitivity." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685152.
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3
Pelaelo, Gaoboelwe. "Characterization of polarization dependent loss in optical fibres and optical components in the presence of polarization mode dispersion." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/695.
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In this study, the Jones matrix eigenanalysis (JME), optical spectrum analyzer (OSA) and polarization scrambling methods were used to investigate polarization dependent loss (PDL) in the presence of polarization mode dispersion (PMD) in optical components and fibres. The PDL measurements were conducted both in the laboratory and in the field. For field measurements, a buried link (28.8 km) and an aerial fibre (7.1 km) were extensively studied. The findings obtained from these studies are very important for network operators who must assess the impact of PDL on the network reliability. The three different PDL measurement methods (JME, OSA and polarization scrambling) were compared and their PDL values were found to agree very well at the selected wavelength of 1550 nm. Concatenation of PDL components showed that as expected, PDL increase as the number of PDL components were added. The interactions between PMD and PDL measurements were analyzed. A PMD/PDL emulator was constructed. We observed that PMD decreased while PDL increased. The PMD decrease was a result of the PMD vector cancellation enhanced by the randomly distributed mode coupling angles while PDL increase was a result of each PM fibre segments contributing to the overall global PDL. It was observed that the presence of PMD in a link containing PDL, results in PDL being wavelength dependent and this resulted in the extraction of the PMD information from the PDL data. PDL was found to be Maxwellian distributed when considering low values of PMD. High PMD values resulted in the PDL distribution deviating from Maxwellian. Long-term PDL and PMD (average DGD) measurements indicated that the PDL and PMD varied slowly with time and wavelength for both the laboratory and field measurements. It was observed that the BER increase as both PDL and PMD increased for simulated optical link.
4
Erlank, Warrick. "Constructing confidence intervals for polarization mode dispersion." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/951.
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Polarization mode dispersion (PMD) causes significant impairment in high bit-rate optical telecommunications systems. Knowledge of a fibre’s PMD mean value, and the relevant confidence interval, is essential for determining a fibre’s maximum allowable bit-rate. Various methods of confidence interval construction for time series data were tested in this dissertation using simulation. These included the autocovariance-matrix methods as suggested by Box and Jenkins, as well as the more practical and simpler batch means methods. Some of these methods were shown to be significantly better than the standard method of calculating confidence intervals for non time series data. The best of the tested methods were used on actual PMD data. The effect of using polarization scramblers was also tested.
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Xiong, Kunli. "Planar Plasmonic Devices for Controlling Polarization of Light." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177841.
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Planar nanostructures made of noble metal can efficiently control transmission of light, thanks to surface plasmon polaritons (SPPs) mediated through interaction between such a structure and incoming light. In this thesis, we numerically characterize, with a 3D finiteelement method, three types of plasmonic devices: plasmonic radial/azimuthal filter, plasmonic quarter-wave plate made of a periodic array of round holes in a thin metallic film, and a plasmonic quarter-wave plate with a periodic array of cross-shaped apertures. The plasmonic polarization filter is formed by a series of concentric equidistant gold rings, and it can transmit the radially polarized light and block the azimuthally polarized light. The quarter-wave plate with round holes has a different lattice constant along two Cartesiancoordinate directions that enable different phase retardations for two orthogonally polarized incident waves; hence, it can convert a linearly polarized light to a circularly polarized light. For the quarter-wave plate with an array of cross-shaped apertures, it utilizes the different lengths of horizontal/vertical arms to manipulate the phase retardations. All of these devices have sub-micron thicknesses, unlike their traditional counterparts that are bulky and inconvenient for integration purposes. Fabrication of the wave plate with cross-shaped apertures was attempted in collaboration with members in the Optics and Photonics unit at KTH.
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Kadambi, Achuta. "Computational light transport using space, time, and polarization." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115742.
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Thesis: Ph. D., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 261-273).
Understanding how light travels through macroscopic scenes can transform autonomous driving, medical imaging and consumer photography. Unfortunately, this understanding is difficult to achieve: trillions of light paths are measured by millions of pixels. The framework of computational light transport was introduced to model this complex interaction between light and matter in a tractable space. In this thesis, we study new methods to invoke space, time, and polarization into a computational light transport framework. First, we study how probing the time dimension enables cameras to separate bounces from multiple light paths. Our solutions are inspired by prior work on multipath in wireless and telecommunications. We then invoke both time and space to provide the first provable bound on resolution for seeing around corners or through scattering media. Finally, we jointly invoke space, time, and polarization to propose an ultra-high quality form of 3D imaging. This thesis contributes a few analytical theories, including: (1) provable bounds on multipath separation; (2) provable bounds on seeing around corners; and (3) proof of shape reconstruction from polarimetric measurements. The thesis also contributes new applications that span: (a) micron-scale 3D cameras; (b) real-time object tracking around corners; and (c) single-shot computational relighting of images. Future applications encompass equipping self-driving cars the ability to see through fog, or enabling doctors to see deeper inside the body using light.
by Achuta Kadambi.
Ph. D.
7
Ignace, Richard, K. Hole, J. Cassinelli, and G. Henson. "Linear Polarization Light Curves of Oblique Magnetic Rotators." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etsu-works/6276.
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The quality and quantity of polarimetric data being collected for stellar sources creates new opportunities for studying stellar properties and evolution, and also leads to new challenges for modeling and interpreting such data. Inspired by fresh prospects for detecting the Hanle effect to study photospheric magnetic fields, we have focused attention on purely geometrical aspects for polarimetric variability in the example of oblique magnetic rotators. In the case of axisymmetric fields, we highlight two key facts: (a) polarimetric lightcurves necessarily exhibit a certain time symmetry with rotation phase, and (b) variations in the polarization position angle can be modeled based on geometrical projection effects, independent of the photospheric magnetic field. These conclusions also have general applicability, such as to Thomson scattering and the transverse Zeeman effect. The authors gratefully acknowledge that funding for this work was provided by the National Science Foundation, grant AST-0807664.
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R, S. Umesh. "Algorithms for processing polarization-rich optical imaging data." Thesis, Indian Institute of Science, 2004. https://etd.iisc.ac.in/handle/2005/96.
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This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed their advantages.
Theoretically and through Monte-Carlo simulations, we have studied the performance of these schemes under white and coloured noise conditions, concluding that, in general, the PMI gives better estimates of all the parameters. Experimental results corroborate our theoretical arguments. PMI is shown to give asymptotically efficient estimates of these parameters, whereas PDI is shown to give biased estimates of the first two and is also shown to be incapable of estimating PO. Moreover, it is shown that PDI is a particular case of PMI. The property of PDI, that it can yield estimates at lower variances has been recognized as its major strength. We have also shown that the three visualization parameters can be fused to form a colour image, giving a holistic view of the scene. We report the advantages of analyzing chunks of data and bootstrapped data under various circumstances.
Experiments were conducted to image objects through calibrated scattering media and natural media like mist, with successful results. Scattering media prepared with polystyrene microspheres of diameters 2.97m, 0.06m and 0.13m dispersed in water were used in our experiments. An intensified charge coupled device (CCD) camera was used to capture the images. Results showed that imaging could be performed beyond optical thickness of 40, for particles with 0.13m diameter. For larger particles, the depth to which we could image was much lesser. An experiment using an incoherent source yielded better results than with coherent sources, which we attribute to the speckle noise induced by coherent sources. We have suggested a harmonic based imaging scheme, which can perhaps be used when we have a mixture of scattering particles. We have also briefly touched upon the possible post processing that can be performed on the obtained results, and as an example, shown segmentation based on a PO imaging result.This research was carried out with the support of Prof Hema Ramachandran of Raman Research Institute, Bangalore. Our thanks to her and RRI.
9
R, S. Umesh. "Algorithms for processing polarization-rich optical imaging data." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/96.
Full textAbstract:
This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed their advantages.
Theoretically and through Monte-Carlo simulations, we have studied the performance of these schemes under white and coloured noise conditions, concluding that, in general, the PMI gives better estimates of all the parameters. Experimental results corroborate our theoretical arguments. PMI is shown to give asymptotically efficient estimates of these parameters, whereas PDI is shown to give biased estimates of the first two and is also shown to be incapable of estimating PO. Moreover, it is shown that PDI is a particular case of PMI. The property of PDI, that it can yield estimates at lower variances has been recognized as its major strength. We have also shown that the three visualization parameters can be fused to form a colour image, giving a holistic view of the scene. We report the advantages of analyzing chunks of data and bootstrapped data under various circumstances.
Experiments were conducted to image objects through calibrated scattering media and natural media like mist, with successful results. Scattering media prepared with polystyrene microspheres of diameters 2.97m, 0.06m and 0.13m dispersed in water were used in our experiments. An intensified charge coupled device (CCD) camera was used to capture the images. Results showed that imaging could be performed beyond optical thickness of 40, for particles with 0.13m diameter. For larger particles, the depth to which we could image was much lesser. An experiment using an incoherent source yielded better results than with coherent sources, which we attribute to the speckle noise induced by coherent sources. We have suggested a harmonic based imaging scheme, which can perhaps be used when we have a mixture of scattering particles. We have also briefly touched upon the possible post processing that can be performed on the obtained results, and as an example, shown segmentation based on a PO imaging result.
10
Oktay, Onur. "Lorentz Group In Polarization Optics." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614773/index.pdf.
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The group theory allows one to study different branches of physics using the same set of commutation
relations. It is shown that a formulation of the polarization optics that depends on
the representations of the Lorentz group is possible. The set of four Stokes parameters, which
is a standard tool of polarization optics, can be used to form a four-vector that is physically
unrelated but mathematically equivalent to the space-time four-vector of the special relativity.
By using the Stokes parameters, it is also possible to generate four-by-four matrix representations
of the ordinary optical filters that are traditionally represented with the two-by-two Jones
matrices. These four-by-four matrices are treated as the entities of the Lorentz group. They
are like the Lorentz transformations applicable to the four-dimensional polarization space.
Besides, optical decoherence process can be formulated within the framework of the SO(3,2)
de Sitter group. The connection between the classical and quantum mechanical descriptions
of the polarization of light allows the extension of the Stokes parameters to the quantum domain.
In this respect, the properties of the polarization of the two-photon system can also be
studied within the framework of the Lorentz group.
11
Lahiri, Mayukh. "Contributions to the Theories of Coherence and Polarization of Light." UNIVERSITY OF ROCHESTER, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3498255.
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FARIA, GIANCARLO VILELA DE. "POLARIZATION OF LIGHT CONTROL IN MONOMODE OPTICAL FIBERS AND APLICATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14307@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROO controle de um estado de polarização, assim como o controle de todos os estados de polarização da luz transmitida através de uma fibra óptica monomodo, é realizado utilizando diferentes esquemas. O controle de polarização do sinal em um canal DWDM é realizado, utilizando sinais de referência em canais laterais em tempo contínuo. Uma troca de chave quântica codificada em polarização é discutida e realizada, no canal central, graças ao sistema de controle de polarização. A influência da distância espectral entre os canais e da PMD no controle também é estudada. Dois protótipos foram construídos, um sistema de controle de todos os estados de polarização e um compensador de PMD, e são apresentados e descritos inteiramente, incluindo os resultados dos seus testes. O compensador de PMD foi testado, e medidas de compensação de PMD em um enlace de 43Gb/s foram realizadas em diversos formatos de modulação, bem como, em diversas situações de embaralhamento de polarização, com e sem o uso de FEC, a fim de avaliar a eficiência dos formatos de modulação, e a compensação de PMD com linhas de atraso de secção simples e múltiplas.
The control of polarization state, as well as a control of all states of polarization of a light signal travelling through a singlemode optical fiber, is performed using different schemes. The polarization control of the signal in a DWDM channel is performed using reference signals in lateral channels in real time. A polarization encoded quantum key distribution scheme is discussed and performed in the central channel through the control system polarization. The influence of the PMD and the spectral distance between channels in control is also investigated theoretically and experimentally. Two prototypes were built, a full polarization control system and a PMD compensator is shown and totally described, as well their test results. Measurements of PMD compensation on a link at 43Gb / s were performed in different modulation formats and in different situations of polarization scrambling, with and without the use of FEC in order to evaluate the efficiency of modulation formats, and PMD compensation with single or multiple section delay lines.
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Mudau, Azwitamisi Eric. "Characterization of polarization effects on deployed aerial optical fibre in South Africa." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/1060.
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In this study, two polarization effects, namely the state of polarization (SOP) and polarization mode dispersion (PMD) in optical fibre cable are investigated. The change in polarization effects introduces errors in optical fibre communication system. We find that the SOP drifts slowly in buried cables, and rapidly in aerial cables. This is because buried cables are located in a static environment, whereas aerial cables are exposed directly to a dynamic environment. The SOP change in aerial cable shows significant correlation with its environment (the global radiation, temperature and wind). The autocorrelation function (ACF) was not performed in buried cable, since they do not satisfy the ACF assumption, whereas in aerial cable it is found that the ACF of the SOP decorrelates quite quickly during the day. The 50 percent decorrelation time during the day and night are 9.6 and 30.4 minutes, respectively. During the day the properties of the optical fibre change rapidly as a result of the rapidly changing environmental conditions, whereas at night the environmental conditions change relatively slowly. Fast Fourier Transform (FFT) of the SOP fluctuations show discrete peaks, which corresponds to the wind induced vibrational frequency of the cable. The PMD fluctuations for undeployed and deployed aerial optical fibre cable are monitored using the generalized interferometric technique (GINTY). It is found that the PMD measured with polarization scrambling is more scattered but more reliable than the PMD measured without polarization scrambling. This is because the PMD obtained with polarization scrambling is averaged over different input and output (I/O) SOP pairs. For deployed aerial cable, it is found that the PMD measured without polarization scrambling fluctuates rapidly during high wind speed conditions. Furthermore, there is a correlation between the measured PMD and the change in temperature. It is found that the change in temperature has a stronger influence than the wind on the PMD of the optical fibre link.
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Gamatham, Romeo Reginald Gunther. "Investigation of polarization mode dispersion measurement perfomance in optical fibre with a focus on the fixed analyzer technique." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/957.
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The work presented in this dissertation is a comparative study of polarization mode dispersion (PMD) measurement performance where the fixed analyzer (FA) technique was built and tested for the first time in South Africa. Techniques involved in the study are: the Jones matrix eigenanalysis (JME), generalised interferometric technique (GINTY) and the FA technique, with a particular focus on the FA technique. The FA PMD measurement technique determines the average differential group delay (DGD) from the transmitted intensity spectrum through a polarizer and has three analysis methods (extrema counting, mean level crossing and Fourier analysis) which were all evaluated. PMD measurements were performed in the laboratory on several different fibre types and in the field on buried deployed Telkom fibre links (28.8 km). The techniques showed good agreement in the measured PMD value, both in the laboratory and field measurements. In particular very good agreement was found between the JME average DGD and the extrema counting analysis PMD value. The GINTY and FA Fourier analysis method also gave very similar PMD values. It was found that the fibre birefringence and the mode coupling manifest in different ways on the intensity spectrum. By using the FA ratio method, the length regimes of the different fibre types were determined. Three characteristics of the FA technique were investigated, namely: wavelength window variation, sampling and input SOP scrambling. It was found that the wavelength window and the PMD are inversely proportional. Correct sampling plays a significant role in determining the correct measured PMD value. Lastly an average PMD value over the PMD values for different input SOPs serves as a better representation of the true PMD value. An additional study showed that the FA technique and a developed Poincaré sphere analysis method agree very well regarding the PMD value.
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Mankga, Maphuti Comfort. "Field and laboratory measurements of PMD using interferometric techniques." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/557.
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In this study, the generalized and traditional interferometric techniques (GINTY and TINTY) are used to investigate some of the important aspects of Polarization Mode Dispersion (PMD) phenomenon in optical fibres. Measurements of PMD and chromatic dispersion (CD) are performed on buried optical fibre cable in the Pretoria Telkom’s metropolitan network. The upgradeability of this network was investigated, and it was observed that just over a half of the fibres are upgradeable to 10 Gb.s-1 transmissions. Long-haul aerial network in the Northern Cape was also tested for upgradeability to 10 Gb.s-1. It was found that 41 percent of the fibres tested are upgradeable to 10 Gb.s-1. Long-term monitoring showed that PMD varies rapidly in aerial fibres and, on the other hand, it is relatively stable in buried cables. Investigations on the accuracy of the techniques showed that polarization scrambling is essential for the reduction of the measurements uncertainties. Furthermore, it was observed that TINTY underestimates the single scan PMD distributions. The study on the effect of the change in mode coupling on various fibre configurations was performed, and fibres showed a reduction in PMD after the introduction of mode coupling. Measurements of PMD conducted in the laboratory on cabled fibre with low PMD showed the floor sensitivity of TINTY. Comparison between GINTY and Jones Matrix Eigeanalysis (JME) PMD measurements methods were performed on an emulator, and the results showed a good agreement in the measured PMD.
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Grant, Robert Wallace. "A UV Zeeman-effect polarizer." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24674.
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It is shown that light emitted by mercury vapour at 253.7 nm can be polarized by passing the light through mercury absorption gas embedded in a magnetic field which is transverse to the direction of propagation of the light. The absorption lines of the mercury are split by the Zeeman effect, so that the absorber has an absorption coefficient which depends on both the polarization and wavelength of the transmitted light.
A complete theory for the Hg²⁰² isotope is presented and the results are compared to measurements made with a natural mercury emitter and absorber. The observations are in qualitative agreement with the theory once isotope and hyperfine structure of the isotopes in natural mercury are included in the theory. Quantitative analysis was not possible because the emission line profiles could not be measured with the available equipment.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Dolinska, Aska. "The investigation of quantum polarisation teleportation protocol." View electronic text, 2002. http://eprints.anu.edu.au/documents/disk0/00/00/07/87/index.html.
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Thesis (BSc. (Hons))--Australian National University, 2002.Available via the Australian National University Library Electronic Pre and Post Print Repository. Title from title screen (viewed Mar. 28, 2003). "A thesis submitted for the degree of Bachelor of Science in Physics, The Australian National University" Bibliography: p. 77-80.
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Bhandari, Purushottam. "The Design of a Polarimeter and its Use for the Study of the Variation of Downwelling Polarized Radiance Distribution with Depth in the Ocean." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/605.
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The spectral polarized radiance distribution provides the most complete description of the light field that can be measured. However, this is a very difficult parameter to measure near the surface because of its large dynamic range, dependence on incoming sky conditions, and waves at the air-sea interface. The measurement of the Stokes vector of the downwelling polarized light field requires the combination of at least four images, all of which must be obtained simultaneously. To achieve this, a new polarimeter (which we call DPOL) has been designed, characterized, calibrated and deployed. The description of the DPOL, its calibrations and characterizations are discussed. The uncertainties in the retrieval of Stokes vector and other derived parameters are also discussed. This instrument is equipped with four fish-eye lenses (180° field of view) with polarizers behind each lens in a different orientation, a coherent optical fiber bundle with 4 arms, a spectral filter changer assembly and a charged coupled-device (CCD) imaging camera. With this system, a single image contains 4 separate fisheye images, each a whole hemisphere of the same scene, each with different polarization information. Using these 4 images and applying appropriate calibration parameters allows us to calculate the four-element Stokes vector and then the total degree of polarization and the angle of plane of polarization of the incoming light field in a hemisphere of desired directions. Under the Office of Naval Research RaDyO (Radiance under a Dynamic Ocean) program, DPOL has been used in the Santa Barbara Channel and Hawaii field experiments. In most cases, data on sky polarization were collected with a separate camera (Sky-Cam) simultaneously with the DPOL. The data and results with these two camera systems in these experiments are presented and are compared. Data on the inherent optical properties of water from the same field experiments collected by collaborators will be shown. Our measurements show that very near the surface, for clear sky conditions, the dominant source of polarization is the refracted sky light. As one progresses in the water column, the polarization due to light scattering by the water increases and polarization due to the water becomes dominant. The dependence of the in-water light field polarization on the sky and surface wave conditions, solar zenith and azimuth angles, the depth of the instrument, the viewing angle, the wavelength of light, the inherent optical properties (IOP’s) of water are discussed.
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Baba, Justin Shekwoga. "The use of polarized light for biomedical applications." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1206.
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Polarized light has the ability to increase the specificity of the investigation of biomedical samples and is finding greater utilization in the fields of medical diagnostics, sensing, and measurement. In particular, this dissertation focuses on the application of polarized light to address a major obstacle in the development of an optical based polarimetric non-invasive glucose detector that has the potential to improve the quality of life and prolong the life expectancy of the millions of people afflicted with the disease diabetes mellitus. By achieving the mapping of the relative variations in rabbit corneal birefringence, it is hoped that the understanding of the results contained herein will facilitate the development of techniques to eliminate the effects of changing corneal birefringence on polarimetric glucose measurement through the aqueous humor of the eye.
This dissertation also focuses on the application of polarized light to address a major downside of cardiovascular biomechanics research, which is the utilization of toxic chemicals to prepare samples for histological examination. To this end, a polarization microscopy image processing technique is applied to non-stained cardiovascular samples as a means to eliminate, for certain cardiac samples, the necessity for staining using toxic chemicals. The results from this work have the potential to encourage more investigators to join the field of cardiac biomechanics, which studies the remodeling processes responsible for cardiovascular diseases such as myocardial infarct (heart attacks) and congestive heart failure. Cardiovascular disease is epidemic, particularly amongst the population group older than 65 years, and the number of people affected by this disease is expected to increase appreciably as the baby boomer generation transitions into this older, high risk population group. A better understanding of the responsible mechanisms for cardiac tissue remodeling will facilitate the development of better prevention and treatment regimens by improving the early detection and diagnosis of this disease.
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Fisher, Dave S. "Two-Photon Polarization Spectroscopy of Atomic Cesium Using Circularly Polarized Light." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1292444234.
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Jordan, Thomas M. "Disordered animal multilayer reflectors and the polarization and localization of light." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665176.
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Multilayer reflectors consisting of 'stacks' of alternating layers of guanine crystals with cytoplasm gaps are present in many different animals including fish and spiders. Common to these reflectors is high birefringence in the guanine crystals and disorder in thickness of the layers in the reflector. The central theme of this thesis is the development of a theoretical framework for understanding the physics of these structures based upon the optics of anisotropic stratified media, and the Anderson localization of light in one dimension. The thesis begins with an investigation of the physical origin of broadband, polarization-insensitive reflectivity from three species of 'silvery' teleost fish: Clupea harengus, Sardina pilchardus and Sprattus sprattus. Reflectance spectrophotometry is used to characterise the spectral, angular and polarization dependence of the reflectivity, and digital holographic microscopy is used to investigate the dielectric properties of the birefringent guanine crystals. It is discovered that there are two 'populations' of guanine crystal present in the fish stratum argenteum that have different alignments of their optic axes in the multilayer structure. An anisotropic model of birefringent-guanine isotropic-cytoplasm reflectors is developed using the 4x4 matrix method and is fitted to the two-crystal system. The model is then used to investigate numerically the production of a non-polarizing reflection, and the proposed camouflage function of the fish reflectors. An explanation for the broadband, polarization-insensitive reflectivity of the two-crystal system in fish reflectors is then developed from the perspective of Anderson localization and the structural property of the localization length. This is achieved by constructing an analytical model of a bio-inspired isotropic-birefringent random stack system. The model system is shown to exhibit the polarization-insensitive localization of light, which is in contrast to isotropic dielectric random stack systems that all have strong polarization-dependence to the localization length. Finally, the application of the theoretical framework of Anderson localization to random stack models of animal multilayer reflector is explored. This includes: a review of the thickness disorder for reflectors in fish, spiders and cephalopods; and investigations of the relationship between thickness disorder, localization length spectra and reflectivity spectra at normal and oblique incidence.
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Zirm, Andrew Wasmuth. "Stellar hosts, alligned light and polarization of high-redshift radio galaxies." Available to US Hopkins community, 2003. http://wwwlib.umi.com/dissertations/dlnow/3080807.
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Romain, Xavier. "Study of polarization of light through a stack of metallic metamaterials." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD038/document.
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Cette thèse a pour but l’étude théorique de métamatériaux métalliques empilés. Ces structures sont actuellement proposées pour améliorer et élargir les fonctionnalités des métamatériaux métalliques. Nous portons un intérêt particulier aux propriétés de polarisation de ces structures métalliques empilées.En premier lieu, nous précisons le type de métamatériaux que nous étudions et nous présentons la méthode modale qui nous permet de décrire les propriétés électromagnétiques de la structure. A l’aide d’un Formalisme de Jones Etendu (FJE), développé récemment dans notre équipe, nous faisons ressortir les principales propriétés de polarisation linéaire de ces métamatériaux métallique.En alliant le FJE à l’algorithme de propagation de la matrice S, nous étudions un empilement de deux métamatériaux vus comme un montage polariseur-analyseur. Nous établissons ensuite une expression de la transmission de la structure: la loi de Malus étendue. Cela nous permet notamment de démontrer les résonances de type Fabry-Perot qui ont lieu entre les métamatériaux.Pour des structures plus conséquentes, nous montrons qu’il est possible de réaliser une rotation de la polarisation, à très faible perte et spectralement agile, grâce aux résonances de type Fabry-Perot.Fondamentalement, nous révélons une nouvelle façon d’exciter des résonances Fano qui sont induites par les propriétés de polarisation des métamatériaux. Ces résonances peuvent être utilisées pour des applications de capteur ou de filtrage. De plus, ces résonances Fano induites par la polarisation ouvrent de nouvelles possibilités d’applications pour les empilement de métamatériaux métalliquesThis PhD thesis deals with the theoretical study of stacked metallic metamaterials. Such structures are currently investigated to extend the functionalities offered by single metallic metamaterials. We especially focus on the specific polarization properties of the stacked metallic metamaterials.We first present the type of metamaterial that we consider, and we describe the modal method that is used to model its electromagnetic properties. We outline the linear polarization properties characterizing the metamaterial thanks to an Extended Jones Formalism (EJF) recently developed by our team.In combination with the EJF, we apply the S-matrix algorithm to the study of a stack of two metallic metamaterials in a polarizer-analyzer configuration. We derive an analytical expression for the transmission response of the stacked structure: the Extended Malus Law. Mainly, it highlights the Fabry-Perot-like resonances located between the metamaterials.Using larger stacked structures, we demonstrate that spectrally tunable and low loss polarization rotation can be achieved owing to these Fabry-Perot-like resonances.In essence, we reveal a new way of realizing Fano resonances which are induced by the specific polarization properties of the metamaterials. We show that such resonances can be engineered for sensing or filtering applications. Moreover, the polarization-induced Fano resonances expand the possibilities of stacked metallic metamaterials
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Riffel, Richard W. "Characterization of dichroism and linear polarization effects on colorimetric properties of plastic transmitting materials /." Online version of thesis, 1992. http://hdl.handle.net/1850/11650.
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Tung, Yan Foo. "Testing and performance characterization of the split field polarimeter in the 3-5m̆ waveband /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FTung.pdf.
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Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, December 2003.Thesis advisor(s): Alfred W. Cooper, Gamani Karunasiri. Includes bibliographical references (p. 83-84). Also available online.
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Pearson, Ruth. "CMB lensing : polarization, large-scale structure and the primordial bispectrum." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/48418/.
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Gravitational lensing of photons in the Cosmic Microwave Background (CMB) can be described by an integrated potential along the line of sight, the CMB lensing potential. Covariances in maps of the CMB are generated by the lensing effect, and are used to reconstruct the lensing potential itself, which is a useful probe of the matter distribution. The CMB lensing potential has been measured to high significance with CMB temperature data. However, signal to noise for lensing reconstruction from CMB polarization data is expected to be much better due to the presence of the lensing B-mode. Upcoming data from ground based CMB polarization instruments will provide high resolution maps over small patches of the sky. This will provide much better lensing reconstruction, but also presents data analysis challenges. This thesis begins with an introduction to the field of CMB lensing and CMB lensing reconstruction. The second chapter details the biases present in reconstructing the lensing potential from CMB polarization maps considering first the full sky, and then small patches of sky. It also shows that using the pure-B mode formalism for the CMB polarization leads to improved lensing reconstruction over the naive case on the cut sky. Given the upcoming improvement in the CMB lensing reconstruction, it is expected that cross-correlations of the CMB lensing with other structure tracers, such as galaxies, will yield improved information for cosmology. It is also expected that the CMB lensing will become useful to help constrain uncertainties in the galaxy power spectrum, and provide information on the linear galaxy bias and redshift distribution. The third chapter of the thesis forecasts the power of cross correlation science for a number of galactic and non-galactic parameters. Finally, the CMB lensing effects the level of non-Gaussianity observed in the CMB. The fourth chapter of the thesis is a study of the lensing effect on the primordial squeezed bispectrum. We conclude in the fifth chapter.
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Muguro, Kennedy Mwaura. "Effects of polarization in a distributed raman fibre amplifier." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/d1014621.
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The need to exploit the large fibre bandwidth and increase the reach has seen the application of the Raman fibre amplifier (RFA) become indispensable in modern light wave systems. The success and resilience of RFAs in optical communication is deeply rooted in their unique optical properties and new technologies which have allowed the amplifier to come of age. However, the full potential of RFAs in optical communication and other applications are yet to be realized. More so are its polarization properties which still remain largely unexploited and have not been fully understood. In this work, fundamental issues regarding distributed RFA have been investigated with the aim of acquiring a better understanding of the amplifier polarization characteristics which have potential applications. In particular the effects of polarization mode dispersion (PMD) and polarization dependent loss (PDL) have been demonstrated both by simulation and experiment. The possibility of Raman polarization pulling in single mode fibres (SMFs) has also been addressed. Polarization sensitivity of RFA has been known for a long time but the clear manifestation of it has become evident in the advent of modern low PMD fibre. Unlike EDFAs which make use of special doped fibre, RFAs require no special fibre for operation. Besides, RFA uses a very long length of fibre and as such the fibre polarization characteristics come into play during amplification. In the demonstrations presented in this thesis a fibre of PMD coefficient < 0.05 pskm-1/2 was regarded as low PMD fibre while one having coefficient ≥ 0.05 pskm-1/2 was categorized to have high PMD unless otherwise stated. Several experiments were performed to evaluate the RFA gain characteristics with respect to fibre PMD and the system performance in the presence of noise emanating from amplified spontaneous emission (ASE). Analysis of Raman gain statistics was done for fibres of low and high PMD coefficients. The statistics of PDG and on-off gain were eventually used to demonstrate the extraction of PMD coefficients of fibres between 0.01- 0.1 pskm-1/2 using a forward pumping configuration. It was found that, at increasing pump power a linear relationship exists between forward and backward signal gain on a dB scale. The interaction of PDL and Raman PDG in the presence of PMD were observed at very fundamental level. It was found the presence of PDL serves to reduce the available on-off gain. It was also established that the presence of PMD mediates the interaction between PDG/PDL. When PMD is high it reduces PDG but the presence of PDL introduces a wavelength dependent gain tilting for WDM channels. Further analysis revealed that signal polarization is influenced by the pump SOP due to the pulling effect which is present even at moderate pump power.
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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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Ignace, Richard, M. Al-Malki, J. Simmons, J. Brown, D. Clarke, and J. Carson. "Scattering Polarization due to Light Source Anisotropy II. Envelope of Arbitrary Shape." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/6256.
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Aims. We consider the polarization arising from scattering in an envelope illuminated by a central anisotropic source. This work extends the theory introduced in a previous paper (Al-Malki et al. 1999) in which scattering polarization from a spherically symmetric envelope illuminated by an anisotropic point source was considered. Here we generalize to account for the more realistic expectation of a non-spherical envelope shape.Methods. Spherical harmonics are used to describe both the light source anisotropy and the envelope density distribution functions of the scattering particles. This framework demonstrates how the net resultant polarization arises from a superposition of three basic “shape” functions: the distribution of source illumination, the distribution of envelope scatterers, and the phase function for dipole scattering.Results. Specific expressions for the Stokes parameters and scattered flux are derived for the case of an ellipsoidal light source inside an ellipsoidal envelope, with principal axes that are generally not aligned. Two illustrative examples are considered: (a) axisymmetric mass loss from a rapidly rotating star, such as may apply to some Luminous Blue Variables, and (b) a Roche-lobe filling star in a binary system with a circumstellar envelope.Conclusions. As a general conclusion, the combination of source anisotropy with distorted scattering envelopes leads to more complex polarimetric behavior such that the source characteristics should be carefully considered when interpreting polarimetric data
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Fluegel, Brian Darrius. "Sub-relaxation and sub-dephasing dynamics of light-induced polarization in semiconductors." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185839.
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Using laser pulses of duration comparable to semiconductor relaxation and dephasing times, the coherent phenomena common to two-level systems have been demonstrated in II-VI and III-V semiconductors. These light-matter interactions are characterized by electrons and holes in their initially excited states and/or a macroscopic polarization that persists after the excitation. A nonthermal carrier distribution was observed in bulk CdSe, demonstrating the extremely fast energy relaxation possible when carrier-LO-phonon scattering is included. Quantum-confined CdSe microcrystallites were then employed to limit the available decay avenues. The one and two-pair transitions were characterized, and using spectral hole-burning, energy relaxation was shown to be substantially slower than in bulk. Dipole dephasing remained very rapid. Persistent macroscopic polarization was demonstrated in semiconductors through pump and probe experiments conducted on time scales faster than the inverse linewidth of the exciton. In the first set of experiments, it was found that the exciton optical Stark shift deviates from that predicted by a steady-state theory. The shift is smaller than expected and lasts longer than the pump pulse. Both effects are explained by free evolution of the exciton's polarization. Transient exciton bleaching is observed and shown to be a result of adiabatic following. In a second study of coherent polarization, spectral oscillations at negative delay times were studied. Oscillations were measured in a wide variety of semiconductors, temporally preceding several different pump-probe phenomena. By comparison with a semiclassical theory, it was shown that spectral oscillations in the spectral region of the exciton are evidence of persistent exciton polarization. Oscillations in the band are due to four wave mixing of the pump and probe beams.
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Stolker, T., C. Dominik, M. Min, A. Garufi, G. D. Mulders, and H. Avenhaus. "Scattered light mapping of protoplanetary disks." EDP SCIENCES S A, 2016. http://hdl.handle.net/10150/622692.
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Context. High-contrast scattered light observations have revealed the surface morphology of several dozen protoplanetary disks at optical and near-infrared wavelengths. Inclined disks offer the opportunity to measure part of the phase function of the dust grains that reside in the disk surface which is essential for our understanding of protoplanetary dust properties and the early stages of planet formation. Aims. We aim to construct a method which takes into account how the flaring shape of the scattering surface of an optically thick protoplanetary disk projects onto the image plane of the observer. This allows us to map physical quantities (e.g., scattering radius and scattering angle) onto scattered light images and retrieve stellar irradiation corrected images (r(2)-scaled) and dust phase functions. Methods. The scattered light mapping method projects a power law shaped disk surface onto the detector plane after which the observed scattered light image is interpolated backward onto the disk surface. We apply the method on archival polarized intensity images of the protoplanetary disk around HD 100546 that were obtained with VLT/SPHERE in the R' band and VLT/NACO in the H and K-s bands. \Results. The brightest side of the r(2)-scaled R-0 band polarized intensity image of HD 100546 changes from the far to the near side of the disk when a flaring instead of a geometrically flat disk surface is used for the r(2)-scaling. The decrease in polarized surface brightness in the scattering angle range of similar to 40 degrees-70 degrees is likely a result of the dust phase function and degree of polarization which peak in different scattering angle regimes. The derived phase functions show part of a forward scattering peak, which indicates that large, aggregate dust grains dominate the scattering opacity in the disk surface. Conclusions. Projection effects of a protoplanetary disk surface need to be taken into account to correctly interpret scattered light images. Applying the correct scaling for the correction of stellar irradiation is crucial for the interpretation of the images and the derivation of the dust properties in the disk surface layer.
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Li, Yanfang. "A study on the use of polarized light in application to noninvasive tissue diagnoistics /." See Full Text at OhioLINK ETD Center (Requires Adobe Acrobat Reader for viewing), 2005. http://www.ohiolink.edu/etd/view.cgi?toledo1134596719.
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Dissertation (Ph.D.)--University of Toledo, 2005.Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 106-120.
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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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Porter, Amber L., Mark D. Leising, G. Grant Williams, Peter Milne, Paul Smith, Nathan Smith, Christopher Bilinski, Jennifer L. Hoffman, Leah Huk, and Douglas C. Leonard. "ASYMMETRIES IN SN 2014J NEAR MAXIMUM LIGHT REVEALED THROUGH SPECTROPOLARIMETRY." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622057.
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We present spectropolarimetric observations of the nearby Type Ia supernova SN 2014J in M82 over six epochs: +0, +7, +23, +51, +77, +109, and +111 days with respect to B-band maximum. The strong continuum polarization, which is constant with time, shows a wavelength dependence unlike that produced by linear dichroism in Milky Way dust. The observed polarization may be due entirely to interstellar dust or include a circumstellar scattering component. We find that the polarization angle aligns with the magnetic field of the host galaxy, arguing for an interstellar origin. Additionally, we confirm a peak in polarization at short wavelengths that would imply R-V < 2 along the light of sight, in agreement with earlier polarization measurements. For illustrative purposes, we include a two-component fit to the continuum polarization of our +51-day epoch that combines a circumstellar scattering component with interstellar dust where scattering can account for over half of the polarization at 4000 angstrom. Upon removal of the interstellar polarization signal, SN 2014J exhibits very low levels of continuum polarization. Asymmetries in the distribution of elements within the ejecta are visible through moderate levels of time-variable polarization in accordance with the Si II lambda 6355 absorption line. At maximum light, the line polarization reaches similar to 0.6% and decreases to similar to 0.4% 1 week later. This feature also forms a loop on theqRSP-uRSP plane, illustrating that the ion does not have an axisymmetric distribution. The observed polarization properties suggest that the explosion geometry of SN 2014J is generally spheroidal with a clumpy distribution of silicon.
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Sridhar, Susmita. "Elliptically polarized light for depth resolved diffuse reflectance imaging in biological tissues." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/404053.
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Polarization gating imaging is a popular and widely used imaging technique in biomedical
optics to sense tissues, deeper volumes, and also selectively probe sub-superficial volumes.
Due to the "polarization memory" effect of polarized light, elliptical polarization-gating
allows access to tissue layers between those of accessible by linear or circular polarizations.
As opposed to the conventional linearly polarized illumination, we focus on polarization
gating methods that combine the use of elliptically polarized light to select polarization maintaining photons and eliminate the background while providing superior contrast and
depth information. With gating, it has also become possible to access user-defined depths
(dependent on optical properties) in biological tissues with the use of images at different
ellipticities. Furthermore, this investigation allowed the application of polarization gating
in spectroscopy to selectively quantify the concentration of tissue chromophores at userdesired depths. Polarization gating methods have been validated and demonstrated with in vivo experiments on abnormalities of human skin (nevus, burn scar) and also on the exposed cortex of an anaesthetized rat. Finally, as a first step towards the use of coherent illumination, adding the concept of polarimetry to laser-speckle imaging was demonstrated.
Preliminary tests on phantoms (solid and liquid) suggested evidence of the influence of
polarization ellipticity on the formation and behaviour of speckles, which could pave the
way for more insight in the study of blood flow in tissues.L’imagerie de filtrage en polarisation est une technique populaire largement utilisée en optique pour le biomédical pour le sondage des tissus superficiels, pour le sondage de volumes plus profonds, mais aussi pour l’examen sélectif de volumes sub-surfaciques. Du fait de l’effet de ’mémoire de polarisation’ de la lumière polarisée, l’imagerie de filtrage en polarisation elliptique est sensible à des épaisseurs de tissus différentes, depuis la surface, accessible avec la polarisation linéaire, jusqu’à une épaisseur critique accessible par la polarisation circulaire. Nous nous concentrons sur des méthodes utilisant des combinaisons de polarisations elliptiques afin de sélectionner la portion de lumi ère ayant maintenu son état de polarisation et éliminer le fond pour un meilleur contraste avec, de plus, une information sur la profondeur. Avec ce type de filtrage, il est possible d’accéder à des profondeurs de tissus biologiques bien définies (selon ses propriétés optiques) selon l’ellipticité de polarisation. De plus, ces travaux ont permis d’étendre la méthode à la spectroscopie pour quantifier sélectivement la concentration en chromophores à une profondeur spécifique. Les méthodes développées ont été validées in vivo à l’aide d’expériences réalisées sur des anomalies de la peau (grain de beauté, cicatrice de brûlure) et aussi sur le cortex exposé d’un rat anesthésié. Enfin, une étude préliminaire a été réalisée pour examiner la possibilité d’étendre la méthode à l’imagerie de tavelures (speckle). Des tests Préliminaires réalisés sur fantômes (solides et liquides) montrent l’influence de l’ellipticité de polarisation sur la formation et le comportement du speckle, ce qui offre la possibilité d’accéder à des informations sur le flux sanguin à des profondeurs spécifiques dans les tissus.
"Polarization gating imaging" es una técnica de imagen muy popular y ampliamente empleada en óptica biomédica con el fin de caracterizar tejidos y sondear volúmenes subsuperficiales de manera selectiva incluso a regiones profundas. Debido al efecto conocido como memoria de polarización de la luz polarizada, la técnica de "polarization gating" elíptica permite el acceso a capas de tejido que, de otro modo, no son accesibles mediante polarización lineal y circular. En contra de la iluminación linealmente polarizada convencional, nuestro estudio se centra en los métodos de "polarization gating" en combinación con luz elípticamente polarizada. Esto permite discriminar aquellos fotones que mantienen una polarización concreta, eliminando así el fondo al mismo tiempo que proporciona un mayor contraste y profundidad de campo, incrementando notablemente la información extraída. Gracias a esta técnica es posible el acceso a distintas profundidades en tejidos biológicos definidas por el usuario (dependiendo de las propiedades ópticas) mediante el empleo de imágenes a distinta elipticidad. Es más, este estudio ha permitido la aplicación del método "polarization gating" a la espectroscopia con el fin de cuantificar la concentración de ciertos cromóforos presentes en tejidos biológicos de manera selectiva y a distintas profundidades deseadas. Los métodos de "polarization gating" han sido validados, establecidos y demostrados en experimentos in-vivo sobre anomalías en tejidos epiteliales humanos (nervios, cicatrices por quemadura) y también en el córtex expuesto de una rata anestesiada. Finalmente, como primer paso en el uso de iluminación coherente, se ha añadido y demostrado el concepto de polarimetría a la técnica de speckle imaging por láser. Los test preliminares en "phantoms" (tanto en sólido como en líquido) arrojan indicios sobre una influencia de la polarización elíptica en la formación y comportamiento de la distribución de las motas (speckle), lo cual podría abrir nuevas puertas y dar un nuevo enfoque sobre la comprensión de la circulación de la sangre en los tejidos.
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Waswa, David Wafula. "Compensation for polarization mode dispersion and nonlinear birefringence in a multichannel optical fibre system." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/885.
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Polarization mode dispersion (PMD) is stochastic in nature and continues evolving in an unpredictable manner according to the changing environment. Nonlinear birefringence in multichannel systems alters the polarization states of the bits, so that they vary from one bit to the next in a way that is difficult to predict. These are the two major signal-impairment effects that are inherent in optical fibre transmission links which can seriously degrade network performance. It is therefore extremely challenging to compensate for both linear and nonlinear birefringence in multichannel systems. The purpose of this thesis is to investigate the interaction between PMD and nonlinear induced birefringence in a fibre with consideration of mode coupling. A sound knowledge of this interaction is necessary in designing a linear and nonlinear polarization mode dispersion compensator for WDM systems, as was successfully carried out in this study. The investigation shows that the effect of nonlinear birefringence alone depolarizes the signal, while in high PMD links where polarization mode coupling is high, the nonlinear birefringence effect couples with second-order PMD such that it may reduce the penalty and improve the signal DOP. Further investigation shows that when nonlinear birefringence becomes significant, asymmetry arises between the two principal axes of the fibre, such that it is only one axis which experiences the effect of nonlinear birefringence. It is found out that along this vii axis, there exists a critical point in pump power where the nonlinear birefringence cancels PMD in the link and improves the signal. An adaptive compensator to cancel PMD and nonlinear birefringence was designed based on feedforward DOP-monitoring signal. The compensator was tested both at laboratory level and on the Telkom buried fibre link and found to be functioning as intended. It was able to adaptively track and compensate PMD in the link in less than a second. The compensator was able to cancel PMD in the link up to a maximum of 30 ps. The compensator improved the DOP of the worst signal by more than 100 percent.
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Ovcharenko, A. P., V. I. Bilozertseva, and D. A. Gaman. "Specificity of Antireflective Coatings at Oblique Incidence of Light." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35369.
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The optical characteristics of a single-layer and double-layer antireflection coating for different substrates are considered. Methods of simultaneous blooming of s - and p - polarization component of light are shown. The refractive index and thickness of the layers necessary for blooming the substrates with a given refractive index at an arbitrary angle of light incidence are determined. The urgency of the task of creating new optical materials with low refractive index is shown.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35369
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Musara, Vitalis. "Polarization mode dispersion emulation and the impact of high first-order PMD segments in optical telecommunication systems." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1138.
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In this study, focus is centred on the measurement and emulation of first-order (FO-) and second-order (SO-) polarization mode dispersion (PMD). PMD has deleterious effects on the performance of high speed optical transmission network systems from 10 Gb/s and above. The first step was characterising deployed fibres for PMD and monitoring the state of polarization (SOP) light experiences as it propagates through the fibre. The PMD and SOP changes in deployed fibres were stochastic due to varying intrinsic and extrinsic perturbation changes. To fully understand the PMD phenomenon in terms of measurement accuracy, its complex behaviour, its implications, mitigation and compensation, PMD emulation is crucial. This thesis presents emulator designs which fall into different emulator categories. The key to these designs were the PMD equations and background on the PMD phenomenon. The cross product from the concatenation equation was applied in order to determine the coupling angle β (between 0o and 180o) that results in the SO-PMD of the emulator designs to be either adjustable or fixed. The digital delay line (DDL) or single polarization maintaining fibre (PMF) section was used to give a certain amount of FO-PMD but negligible SO-PMD. PMF sections (birefringent sections) were concatenated together to ensure FO- and SO-PMD coexist, emulating deployed fibres. FO- and SO-PMD can be controlled by altering mode coupling (coupling angles) and birefringence distribution. Emulators with PMD statistics approaching the theoretical distributions had high random coupling and several numbers of randomly distributed PMF sections. In addition, the lengths of their PMF sections lie within 20% standard deviation of the mean emulator length. Those emulators with PMD statistics that did not approach the theoretical distributions had limited numbers of randomly distributed PMF sections and mode coupling. Results also show that even when an emulator has high random mode coupling and several numbers of randomly distributed PMFs, its PMD statistics deviates away from expected theoretical distributions in the presence of polarization dependent loss (PDL). The emulators showed that the background autocorrelation function (BACF) approaches zero with increasing number of randomly mode coupled fibre sections. A zero BACF signifies that an emulator has large numbers of randomly distributed PMF sections and its presence means the opposite. The availability of SO-PMD in the emulators made the autocorrelation function (ACF) x asymmetric. In the absence of SO-PMD the ACF for a PMD emulator is symmetric. SO-PMD has no effect on the BACF. Polarization-optical time domain reflectometry (P-OTDR) measurements have shown that certain fibre sections along fibre link lengths have higher FO-PMD (HiFO-PMD) than other sections. This study investigates the impact of a HiFO-PMD section on the overall FO- and SO-PMD, the output state of polarization (SOP) and system performance on deployed fibres (through emulation). Results show that when the wavelength-independent FO-PMD vector of the HiFO-PMD section is greater than the FO-PMD contributions from the rest of the fibre link, the mean FO-PMD of the entire link is biased towards that of the HiFO-PMD section and the SO-PMD increases (β ≠ 0o or 180o) or remains fixed (β = 0o or 180o) depending on the coupling angle β between the HiFO-PMD section and the rest of the fibre link. In addition, the FO-PMD statistics deviates away from the theoretical Maxwellian distribution. However, experimental results show that the HiFO-PMD section has negligible influence on the SOPMD statistical distribution. An increase in the amount of FO-PMD on a HiFO-PMD section reduces the output SOP spread to a given minimum, in this study the minimum was reached when the HiFO-PMD ≥ 35 ps. However, the outcome of the output SOP spread depends on the location of the HiFO-PMD section along the fibre link length. It was found that when the HiFO-PMD section introduces SO-PMD, the bit error rate (BER) is much higher compared to when it does not introduce SO-PMD.
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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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Liu, ChangSheng. "A simple and accurate method to measure molecular hyperpolarizability with EFISH technique and photoluminescence of unpassivated and passivated GaAs /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9720549.
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Jin, Yang. "Dynamic polarization control using spatial light modulators for advanced ultrafast laser surface-structuring." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3007808/.
Full textAbstract:
Reflective liquid-crystal-based Spatial Light Modulators (SLM), addressed with optimised Computer Generated Holograms (CGH), have been integrated with two picosecond laser systems to control and manipulate the phase front and polarization states of laser beams, both statically and dynamically, for ultrafast laser surface microstructuring. Firstly, two SLMs were used in combination to structure the optical fields and wavefront of a 532 nm, 10-picosecond laser beam, producing planar or vortex wavefronts with radial or azimuthal polarization states. Multiple first-order cylindrical vector beams with vortex or planar wavefront have been generated and used to nano-structure a highly polished stainless steel metal surface. Then, synchronization of the two SLMs with the picosecond laser system was achieved for dynamic modulation of the polarization states of the laser beam. Consequently, for the first time, four states of polarization, linear horizontal and vertical, radial and azimuthal, all with a ring intensity distribution, were dynamically switched at a frequency up to ν = 12.5 Hz while synchronized with a motion control system and the 532 nm picosecond laser. Surface patterning with these 4 states resulted in ~ 0.5 μm pitch plasmonic structures, easily discernible when using white light diffraction. In separate experiments, CGH's applied to a single SLM were synchronised with a galvo scanner and a 1064 nm, 10 ps laser system for dynamic linear polarisation modulation. This real time polarisation control allowed complex laser surface patterning of polished metals with linear, periodic, ~ 1 μm pitch surface plasmonic structures. Hence, iridescent metal surface colouring with various geometric patterns was achieved. Finally, with an advanced digital scanner fully synchronized with the 532 nm, 10 ps laser system, high speed parallel multi-beam surface patterning of a 30 nm thick Aluminium thin film on a flexible Polyethylene Terephthalate (PET) was achieved. With laser repetition rate of 200 kHz and 8 diffracted first order beams, a film removal rate of R > 0.5 cm2/s was demonstrated with 5W average laser power delivered without damage to the PET substrate. The effective laser repetition rate was f ~ 1.3 MHz. During this work, the single pulse front and rear side single pulse ablation thresholds of the Al film on PET were determined to be Fth= 0.20±0.01 J.cm-2 and 0.15±0.01 J.cm-2 respectively, much lower than the PET ablation threshold, Fth=1.2 J.cm-2, providing a clear processing window.
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Lee, Yoonsik. "Hybrid photonic systems consisting of dielectric photonic crystals and plasmonic meta-atoms for nanoscale light manipulation." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188597.
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Runyon, Matthew. "Experimental Design and Implementation of Two Dimensional Transformations of Light in Waveguides and Polarization." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36881.
Full textAbstract:
Photonics, the technological field that encompasses all aspects of light, has been rapidly growing and increasingly useful in uncovering fundamental truths about nature. It has helped detect gravitational waves, allowed for a direct measurement of the quantum wave function, and has helped realize the coldest temperatures in the universe. But photonics has also had an enormous impact on day-to-day life as well; it has enabled high capacity and/or high speed telecommunication, offered cancer treatment solutions, and has completely revolutionized display and scanning technology. All of these discoveries and applications have required a superb understanding of light, but also a high degree of control over the sometimes abstract properties of light.
The work contained in this thesis explores two novel means of controlling and manipulating two different abstract properties of light. In Part I, the property under investigation is the polarization state of light – a property that is paramount to all light-matter interactions, and even some light-light interactions such as interference. Here, a liquid crystal on silicon spatial light modulator (LCOS-SLM)’s capabilities in manipulating the polarization state of light is theoretically examined and experimentally exploited, tested, and reported on. It is found through experimentation that, for an appropriate range of beam sizes and input polarizations, a single LCOS-SLM can be used to produce any light field with an arbitrary, spatially varying polarization profile. In Part II, the property under investigation loosely corresponds to light’s spatial degree of freedom – how light can move from one spot in space to another in a non-trivial manner. Here, control over light’s position through a waveguide array through the use of quantum geometric phase is theoretically examined, simulated, and experimentally designed. It is found through simulation that a threewaveguide array is capable of implementing two dimensional unitary transformations. The common theme between Part I and Part II is manipulating these properties of light to realize classes of general transformations. Moreover, if the light field is treated as a quantum state in the basis of either property under investigation, a two dimensional computational basis ensues. This is precisely the right cardinality for applications in quantum information.
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Broky, John. "Inverse Problems in Multiple Light Scattering." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5608.
Full textAbstract:
The interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the medium and a thorough analysis of the scattered light allows solving specific inverse problems. Traditional attempts to solve these kinds of inverse problems tend to rely on statistical average quantities and ignore the deterministic interaction between the optical field and the scattering structure. Thus, because ensemble averaging inherently destroys specific characteristics of random processes, one can only recover limited information about the medium. This dissertation discusses practical means that go beyond ensemble averaging to probe complex media and extract additional information about a random scattering system. The dissertation discusses cases in which media with similar average properties can be differentiated by detailed examination of fluctuations between different realizations of the random process of multiple scattering. As a different approach to this type of inverse problems, the dissertation also includes a description of how higher-order field and polarization correlations can be used to extract features of random media and complex systems from one single realization of the light-matter interaction. Examples include (i) determining the level of multiple scattering, (ii) identifying non-stationarities in random fields, and (iii) extracting underlying correlation lengths of random electromagnetic fields that result from basic interferences. The new approaches introduced and the demonstrations described in this dissertation represent practical means to extract important material properties or to discriminate between media with similar characteristics even in situations when experimental constraints limit the number of realizations of the complex light-matter interaction.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA /." Link to this resource, 2005. http://eprints.ru.ac.za/784/.
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Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005284.
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This thesis reports the calibration, imaging and analysis of one epoch of VLBI observations of the v (italics) = J (italics) = 1-0 transition of SiO towards VY CMa. Full polarisation information was recorded, allowing high resolution synthesis maps of each of the four Stokes parameters to be produced. A total of 81 maser components were extracted from the total intensity map, each approximately 1 mas in size. The emission spans approximately 100 x 80 mas in right ascension and declination and is concentrated to the east. The maser component positions were fitted to a ring of radius ~ 3.2R₊ (italics), or 7.2 x 1O¹⁴ cm for a stellar distance of 1.5 kpc. If the stellar position is assumed to be the centre of this ring then almost all of the maser components fall within the inner dust shell radius, which is at ~ 5R (italics)ϰ All of the maser components fall between 1.5R (italics)ϰ and 6R (italics)ϰ. A velocity gradient with position angle was observed in the sparsely filled western region of the maser ring. If interpreted as evidence of shell rotation, this gradient implies a rotational velocity of v (italics) rot (subscirpt) sin i (italics) = 18 km.s⁻¹. The fractional circular and linear polarisations of the maser spots were derived from the Stokes parameter maps. The mean fractional circular polarisation of the masers components was ~ 2 percent and the median fractional linear polarisation was ~ 6 percent, with many spots displaying over ~ 30 percent linear polarisation. The mean circular polarisation implies a magnetic field of ~ 4 G in the SiO maser region if the polarisation is due to Zeeman splitting. Two maser components display a rotation of linear polarisation position angle with velocity, possibly implying a connection between the magnetic field and the velocity field variations in the region of these components.
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Chang, Yuan-Pin. "Novel probes of angular momentum polarization." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:d3880edf-436a-415e-8a74-6b1c0fd26e65.
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New dynamical applications of quantum beat spectroscopy (QBS) to molecular dynamics are employed to probe the angular momentum polarization effects in photodissociation and molecular collisions. The magnitude and the dynamical behaviour of angular momentum alignment and orientation, two types of polarization, can be measured via QBS technique on a shot-by-shot basis. The first part of this thesis describes the experimental studies of collisional angular momentum depolarization for the electronically excited state radicals in the presence of the collider partners. Depolarization accompanies both inelastic collisions, giving rise to rotational energy transfer (RET), and elastic collisions. Experimental results also have a fairly good agreement with the results of quasi-classical trajectory scattering calculations. Chapter 1 provides the brief theories about the application of the QBS technique and collisional depolarization. Chapter 2 describes the method and instrumentation employed in the experiments of this work. In Chapter 3, the QBS technique is used to measure the total elastic plus elastic depolarization rate constants under thermal conditions for NO(A,v=0) in the presence of He, Ar, N2, and O2. In the case of NO(A) with Ar, and particularly with He, collisional depolarization is significantly smaller than RET, reflecting the weak long-range forces in these systems. In the case of NO(A)+N2/O2, collisional depolarization and RET are comparable, reflecting the relatively strong long-range forces in these systems. In Chapter 4, the QBS technique is used to measure the elastic and inelastic depolarization and total RET rate constants for OH(A,v=0) under thermal conditions in the presence of He and Ar, as well as the total depolarization rate constants under superthermal conditions. In the case of OH(A)+He, elastic depolarization is sensitive to the N rotational state, and inelastic depolarization is strongly dependent on the collision energy. In the case of OH(A)+Ar, elastic depolarization is insensitive to N, and inelastic depolarization is less sensitive to the collision energy, reflecting that the relatively strong long-range force in OH(A)+Ar system. The second part of this thesis describes the experimental studies of photodissociation under thermal conditions. Chapter 5 provides a brief introduction about several polarization parameter formalisms used for photodissociation, and the incorporation of the QBS technique to measure these polarization parameters. In this thesis, most polarization parameters of the molecular photofragments are measured using the LIF method, and the QBS technique is used as a complementary tool to probe these polarization parameters. In Chapter 6, rotational orientation in the OH(X,v=0) photofragments from H2O2 photodissociation using circularly polarized light at 193 nm is observed. Although H2O2 can be excited to both the A and B electronic states by 193 nm, the observed orientation is only related to the A state dynamics. A proposed mechanism about the coupling between a polarized photon and the H2O2 parent rotation is simulated, and the good agreement between the experimental and simulation results further confirms the validity of this mechanism. In Chapter 7, rotational orientation in the NO(X,v) photofragments from NO2 photodissociation using circularly polarized light at 306 nm (v=0,1,2) and at 355 nm (v=0,1) is observed. Two possible mechanisms, the parent molecular rotation and the coherent effect between multiple electronic states, are discussed. NOCl is photodissociated using circularly polarized light at 306 nm, and NO(X,v) rotational distributions (v=0,1) and rotational orientation (v=0) are measured. For the case of NOCl, the generation of orientation is attributed to the coherent effect.
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Zaghloul, Yasser A. "Polarization based digital optical representation, gates, and processor." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43675.
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A complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor could be implemented, was proposed. Following the new polarization-based representation, a new Orthoparallel processing technique
that allows for the creation of all-optical-processing gates that produce a unique output once in a truth table, was developed. This representation allows for the implementation of all basic 16 logic gates, including the NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented, which opens the door for reconfigurable optical processors and programmable optical logic gates. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information.
The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. The Rail Road (RR) architecture for polarization optical processors (POP) is presented. All the control inputs are applied simultaneously, leading to a single time lag, which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step design algorithm is provided for the POP, and design reduction methodologies are discussed. The algorithm lends itself systematically to software programming and computer-assisted design.
A completely passive optical switch was also proposed. The switch is used to design completely passive optical gates, including the NAND gate, with their operational speeds only bound by the input beams prorogation delay. The design is used to demonstrate various circuits including the RS latch.
Experimental data is reported for the NAND and the Universal gate operating with different functionality. A minute error is recorded in different cases, which can be easily eliminated by a more dedicated manufacturing process. Finally, some field applications are discussed and a comparison between all proposed systems and the current semiconductor devices is conducted based on multiple factors, including, speed, lag, and heat generation.
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Chen, Hongwei. "Directional Emission of Light in Hyperbolic Metamaterials and Its Application in Miniature Polarimeter." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1565630730775184.
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Aronson, Erik. "Modelling reflected polarized light from exoplanetary atmospheres." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173451.
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I present numerical simulations of intensity and degree of polarization of light reflected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few different phase angles and a few different points on the planet. At this stage the aim is to show the working code and test a few different set ups of the star-planet system in order to find preferable configurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneficial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.