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Keeling, David. "Novel thin film optical modulator/tunable retarder." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/29595.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.Committee Chair: A. Rahman Zaghloul ; Committee Members: W. Russell Callen and Doug Yoder. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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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.
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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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Dasgupta, Abhijeet. "High efficiency S-Band vector power modulator design using GaN technology." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0021/document.
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L’évolution des systèmes de télécommunications, liée à une demande sans cesse croissante en termes de débit et de volume de données, se concrétise par le développement de systèmes proposant des bandes passantes très larges, des modulations à très hautes efficacités spectrales, de la flexibilité en puissance et en fréquence d’émission. Par ailleurs, la mise en œuvre de ces dispositifs doit se faire avec un souci permanent d’économie d’énergie d’où la problématique récurrente de l’amplification de puissance RF qui consiste à allier au mieux rendement, linéarité et bande passante. L’architecture conventionnelle d’une chaine d’émission RF consiste dans une première étape à réaliser l’opération de modulation-conversion de fréquence (Modulateur IQ) puis dans une deuxième étape l’opération de conversion d’énergie DC-RF (Amplificateur de Puissance), ces deux étapes étant traditionnellement traitées de manière indépendante. L’objectif de ces travaux de thèse est de proposer une approche alternative qui consiste à combiner ces deux opérations dans une seule et même fonction : le modulateur vectoriel de puissance à haute efficacité énergétique. Le cœur du dispositif, conçu en technologie GaN, repose sur un circuit à deux étages de transistors HEMT permettant d’obtenir un gain en puissance variable en régime de saturation. Il est associé à un modulateur de polarisation multi-niveaux spécifique également en technologie GaN. Le dispositif réalisé a permis de générer directement, à une fréquence de 2.5 GHz, une modulation vectorielle 16QAM (100Msymb/s) de puissance moyenne 13 W, de puissance crête 25W avec un rendement global de 40% et une linéarité mesurée par un EVM à 5%The evolution of telecommunications systems, linked to a constantly increasing demand in terms of data rate and volume, leads to the development of systems offering very wide bandwidths, modulations with very high spectral efficiencies, increased power and frequency flexibilities in transmitters. Moreover, the implementation of such systems must be done with a permanent concern for energy saving, hence the recurring goal of the RF power amplification which is to combine the best efficiency, linearity and bandwidth. Conventional architectures of RF emitter front-ends consist in a first step in performing the frequency modulation-conversion operation (IQ Modulator) and then in a second step the DC-RF energy conversion operation (Power Amplifier), these two steps being usually managed independently. The aim of this thesis is to propose an alternative approach that consists in combining these two operations in only one function: a high efficiency vector power modulator. The core of the proposed system is based on a two-stage GaN HEMT circuit to obtain a variable power gain operating at saturation. It is associated with a specific multi-level bias modulator also design using GaN technology. The fabricated device generates, at a frequency of 2.5 GHz, a 16QAM modulation (100Msymb/s) with 13W average power, 25W peak power, with an overall efficiency of 40% and 5% EVM
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Zhou, Sichao. "Complex Optical Fields Generation Using a Vectorial Optical Field Generator." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461689435.
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Hällstig, Emil. "Nematic Liquid Crystal Spatial Light Modulators for Laser Beam Steering." Doctoral thesis, Uppsala University, Quantum Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4693.
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Laser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. Physical constraints set limitations to the SLM and an ideal phase distribution can usually not be realised. In order to understand how such components can be used for non-mechanical beam control three nematic liquid crystal (NLC) SLMs have been thoroughly characterised and modelled.
The pixel structure and phase quantisation give a discrepancy between ideal and realised phase distributions. The impact on beam steering capability was examined by measurements and simulations of the intensity distribution in the far-field.
In two of the studied SLMs the pixel period was shorter than the thickness of the LC layer giving the optical phase shift. This results in a so-called “fringing field”, which was shown to degrade the phase modulation and couple light between polarisation modes. The deformation of the LC was simulated and a finite-difference time-domain (FDTD) algorithm was used to calculate how polarised light propagates through the optically anisotropic SLM.
Non-mechanical beam steering and tracking in an optical free-space communication link were demonstrated. Continual optimisation of the steering angle was achieved by feedback from a video camera.
The optical properties of the SLM in the time period right after a voltage update were studied. It was shown how light is redistributed between orders during the switching from one blazed grating to another. By appropriate choice of the blazed gratings the effects on the diffraction efficiency can be minimised.
The detailed knowledge of the SLM structure and its response to electronic control makes it possible to predict and optimise the device performance in future systems.
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Tang, Yongbo. "Study on electroabsorption modulators and grating couplers for optical interconnects." Doctoral thesis, KTH, Mikroelektronik och tillämpad fysik, MAP, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24178.
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Decades of efforts have pushed the replacement of electrical interconnects by optical links to the interconnects between computers, racks and circuit boards. It may be expected that optical solutions will further be used for inter-chip and intra-chip interconnects with potential benefits in bandwidth, capacity, delay, power consumption and crosstalk. Silicon integration is emerging to be the best candidate nowadays due to not only the dominant status of silicon in microelectronics but also the great advantages brought to the photonic integrated circuits (PICs). Regarding the recent breakthroughs concerning active devices on silicon substrate, the question left is no longer the feasibility of the optical interconnects based on silicon but the competitiveness of the silicon device compared with other alternatives. This thesis focuses on the study of two key components for the optical interconnects, both especially designed and fabricated for silicon platform. One is a high speed electroabsorption modulator (EAM), realized by transferring an InP-based segmented design to the hybrid silicon evanescent platform. The purpose here is to increase the speed of the silicon PICs to over 50 Gb/s or more. The other one is a high performance grating coupler, with the purpose to improve the optical interface between the silicon PICs and the outside fiber-based communication system. An general approach based on the transmission line analysis has been developed to evaluate the modulation response of an EAM with a lumped, traveling-wave, segmented or capacitively-loaded configuration. A genetic algorithm is used to optimize its configuration. This method has been applied to the design of the EAMs on hybrid silicon evanescent platform. Based on the comparison of various electrode design, segmented configuration is adopted for the target of a bandwidth over 40 GHz with as low as possible voltage and high extinction ratio. In addition to the common periodic analysis, the grating coupler is analyzed by the antenna theory assisted with an improved volume-current method, where the directionality of a grating coupler can be obtained analytically. In order to improve the performance of the grating coupler, a direct way is to address its shortcoming by e.g. increasing the coupling efficiency. For this reason, a nonuniform grating coupler with apodized grooves has been developed with a coupling efficiency of 64%, nearly a double of a standard one. Another way is to add more functionalities to the grating coupler. To do this, a polarization beam splitter (PBS) based on a bidirectional grating coupler has been proposed and experimentally demonstrated. An extinction ratio of around -20 dB, as well as a maximum coupling efficiency of over 50% for both polarizations, is achieved by such a PBS with a Bragg reflector underneath.QC 20100906
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Lin, Yi-Hsin. "POLARIZATION-INDEPENDENT LIQUID CRYSTAL DEVICES." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4199.
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Liquid crystal (LC) devices can be operated as amplitude modulators and phase modulators. LC amplitude modulation is commonly used in liquid crystal display (LCD) while phase-only modulation is useful for laser beam steering, tunable grating, prism, lens, and other photonic devices. Most LC devices are polarization dependent and require at least one polarizer. As a result, the optical efficiency is low. To enhance display brightness, a power hungry backlight has to be used leading to a high power consumption and short battery life. In a LC phase modulator, the polarization dependent property complicates the laser beam steering system. It is highly desirable to develop new operating mechanisms that are independent of the incident light polarization. In this dissertation, we have developed eight polarization-independent liquid crystal operation principles: three of them are aimed for displays and the other five are for phase modulators. For amplitude modulations, a new polymer-dispersed liquid crystal (PDLC) and two new dye-doped LC gels are polarizer-free by combining light scattering with dye-absorption effects. In phase modulation, we explore five device concepts: PDLC and Polymer-Stabilized Cholesteric Texture (PSCT), homeotropic LC gels, thin polymer film separated double-layered structure, and double-layered LC gels. In the low voltage regime, both PDLC and PSCT have a strong light scattering. However, as the voltage exceeds a certain level, the phase modulation is scattering-free and is independent of polarization. The homeotropic LC gels do not require any biased voltage and the response time is still fast. Although the remaining phase in these devices is small, they are still useful for micro-photonic device applications. To increase the phase change, thin polymer film separated double-layered structure is a solution. The orthogonal arrangement of top and bottom LC directors results in polarization independence. However, the response time is slow. Similarly, double-layered LC gels are not only polarization independent but also fast response due to the established polymer network.Ph.D.
Optics and Photonics
Optics
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Stoller, Patrick C. "Polarization-modulated second harmonic generation microscopy in collagen /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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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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LaCasse, Charles. "Modulated Imaging Polarimetry." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/247279.
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In this work, image processing algorithms are presented for an advanced sensor classification known collectively as imaging modulated polarimetry. The image processing algorithms presented are novel in that they use frequency domain based approaches, in comparison to the data domain based approaches that all previous algorithms have employed. Under the conditions on the data and imaging device derived in this work, the frequency domain based demodulation algorithms will optimally reduced reconstruction artifacts in a least squared sense. This work provides a framework for objectively comparing polarimeters that modulate in different domains (i.e. time vs. space), referred to as the spectral density response function. The spectral density response function is created as an analog to the modulation transfer function (or the more general transfer function for temporal devices) employed in the design of conventional imaging devices. The framework considers the total bandwidth of the object to be measured, and then can consider estimation artifacts that arise in both time and space due to the measurement modality that has been chosen. Using the framework for objectively comparing different modulated polarimeters (known as the spectral density response function), a method of developing a Wiener filter for multi-signal demodulation is developed, referred to as the polarimetric Wiener filter. This filter is then shown to be optimal for one extensive test case. This document provides one extensive example of implementing the algorithms and spectral density response calculations on a real system, known as the MSPI polarimeter. The MSPI polarimeter has been published extensively elsewhere, so only a basic system description here is used as necessary to describe how the methods presented here can be implemented on this system.
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Dumenil, Arnaud. "Polarization dependent loss in next-generation optical networks : challenges and solutions." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAS006.
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La demande de débit en augmentation constante requiert des canaux de communication fiables et robustes. Les réseaux optiques terrestres ainsi que les liens sous-marins représentent le cœur de l'infrastructure des télécommunications au niveau mondial, et transportent des centaines de canaux fréquentiels modulés à haut débit. Ces liens se composent non seulement de kilomètres de fibre mais aussi de composants optiques comme les amplificateurs à fibre dopée à l'erbium (EDFA) pour relever régulièrement la puissance des signaux atténués, ou encore des commutateurs sélectifs en longueur d'onde (WSS) qui routent le signal vers leur destination. Dans cette thèse, nous nous intéressons à une pénalité spécifique qui survient dans ces systèmes et qui réduit le débit d'information dans une propagation optique. Les composants optiques discrets présentent typiquement une anisotropie en polarisation : un déséquilibre de perte (ou gain) apparaît entre les deux polarisations d'un signal optique multiplexé en polarisation. Cet effet non unitaire appelé pertes dépendant de la polarisation (abrégé PDL en anglais) dégrade la qualité de transmission dans les systèmes optiques actuels et futurs.Dans le cadre des transmissions multiplexés en polarisation, nous caractérisons la perte de capacité induite par la PDL. Pour commencer, des modèles de canal sont attentivement étudiés et deux approches sont présentées : un canal avec des éléments PDL distribués avec un bruit également distribué, ou alors un canal équivalent simplifié en un seul élément. Nous analysons les limites fondamentales de communication associées à ces modèles. Nous montrons en outre que la capacité d'un canal PDL dépend en pratique de l'orientation de l'état de polarisation du signal incident. Nous passons ensuite en revue l'état de l'art de schémas de modulation atténuant l'effet de PDL puis nous proposons deux nouveaux schémas de modulation multi-dimensionnels qui augmentent la performance minimum et moyenne du canal. Ces deux modulations sont des transformations unitaires de symboles M-QAM qui n'utilisent pas de degrés de liberté autres que les quatre déjà utilisés pour chaque longueur d'onde (encodage en phase et quadrature de phase sur les deux états de polarisation). Nous proposons succinctement une extension de ces premiers résultats à des communications optiques plus généralement multiplexés en dimension spatiale et impactées par des pertes dépendantes de mode, qui présentent un déséquilibre de gain identique. Au-delà de la construction de modulations au niveau du transmetteur, nous étudions la perte de performance en présence de PDL d'une chaîne de traitement de signal conventionnelle et séquentielle par comparaison avec une égalisation et décodage joint. Cette perte additionnelle de capacité résultant du traitement séquentiel non optimal est évaluée pour différents formats de modulations ainsi que différents points de fonctionnement. Enfin, nous exposons une validation expérimentale des deux schémas de modulation proposés, aussi bien sur un élément de PDL seul ou sur un canal PDL distribué, et montrons comme attendu une robustesse augmentée vis-à-vis de la PDLLarge amounts of ever-increasing global data traffic require sound and reliable communication channels. Optical terrestrial networks and submarine links are at the very heart of the global telecom infrastructure, and carry hundreds of frequency channels modulated at very high rates. These links include not only kilometers of fiber but also optical elements such as Erbium-Doped Fiber-Amplifiers (EDFA) to amplify periodically the attenuated signals and Wavelength Selective Switches (WSS) to route the signals to their assigned destinations. In this thesis, we explore a specific rate-degrading impairment of the optical propagation that raises in those systems. Discrete optical elements often exhibit a polarization anisotropy that emerges as a gain or loss imbalance between the two polarization tributaries of the polarization-multiplexed optical signals. This non-unitary effect called Polarization Dependent Loss (PDL) impairs the quality of transmission in current and next-generation optical systems.In the context of polarization-multiplexed signals, we assess the capacity loss induced by PDL. First, channel models are carefully studied and two approaches are described: a channel with distributed PDL elements and distributed noise or a simplified single-element equivalent channel. Making use of these models, we then analyze their fundamental limits of communications. We show that the PDL channel capacity depends in practice on the state-of-polarization orientation of the incident signal. We then review the state-of-the art of PDL-mitigating modulation schemes and propose two new multi-dimensional signaling schemes that enhance worst-case and average performance. These two modulations are unitary transforms of M-QAM symbols and do not make use of additional degrees of freedom apart from the four already-used dimensions per wavelength (in-phase and quadrature channels of two polarization states). We briefly extend these first results to space-division-multiplexed optical communications impaired by mode dependent loss (MDL) that present a similar gain imbalance. Beyond signal shaping at the transmitter side, we study the performance loss of a conventional, sequential signal processing chain at the receiver side in presence of PDL, in comparison with a joint equalization-decoding scheme. The additional capacity loss due to the mismatch sequential processing is evaluated for several modulation formats and at different operating points. Finally, we report an experimental validation of the two proposed signaling schemes, both on a single PDL element and on a distributed PDL channel, demonstrating the predicted enhanced robustness to PDL
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Lee, Christina K. "Modulation of Neutrophil Functions and Anti-Tumor Immune Responses by Innate Suppressors." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/98571.
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Neutrophils are known to be key innate defenders through performing vital and diverse functions such as degranulation, oxidative burst, and generation of extracellular trap (NET). Recent data suggest that neutrophils may also play key roles in modulating tissue inflammatory/immune environment by secreting soluble mediators as well as surface-attached co-activators. Furthermore, neutrophils may adopt distinct functional states either conducive or detrimental for tumor-growth through cellular contact with cancer cells and/or other immune cells such as T helper cells. However, molecular mechanisms that modulate functional adaptations of neutrophils are not well understood. The objective of my thesis is to identify the role of Tollip, a novel TLR signaling adaptor molecule, in modulating neutrophil functions by suppressing the inflammatory signaling pathway. Preliminary data from our lab suggest Tollip deficient neutrophils may be programed to exhibit enhanced anti-tumor activities. Based on these novel findings, I tested the hypothesis that neutrophils also have subsets with different functions similar to monocyte/macrophages, and Tollip deficient neutrophils may be programmed into an enhanced anti-tumor state through upregulating inflammatory signaling processes and mediators.Ph. D.
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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/.
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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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Kuhn, Jeffrey Russell. "Modulated polarization microscopy : a new instrument for visualizing cytoskeletal dynamics in living cells /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Bryan, Sean Alan. "Half-wave Plates for the Spider Cosmic Microwave Background Polarimeter." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1392115856.
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Ozensoy, Emrah. "Polarization modulation infrared reflection absorption spectroscopy for heterogeneous catalytic applications at elevated pressures." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2201.
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This dissertation focuses on bridging the pressure and complexity gap between heterogeneous catalysis and surface science by introducing new instrumental tools that can operate under catalytically relevant conditions (i.e. atmospheric pressures and temperatures higher than room temperature). Thus, some of the few detailed examples of the polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) as an in situ vibrational spectroscopic tool for the elevated-pressure investigation of gas/solid interfaces on planar single crystal model catalyst systems were presented in this work. Furthermore, for the first time in the literature, PM-IRAS technique was applied to study complex multi-component model catalyst structures exhibiting three dimensional morphologies such as metal nanoparticles deposited on a metal-oxide thin film. In order to achieve a molecular understanding of the properties of CO+NO catalytic reaction at elevated temperatures and pressures on Pd based catalysts, adsorption trends of each of the reactant molecules were studied separately on Pd (111). The adsorption properties of CO/Pd (111) and NO/Pd (111) systems both under UHV conditions and at elevated pressures were discussed in a comparative manner to highlight the pressure dependent behavioral differences between these two probe molecules by emphasizing the risks of extrapolating UHV trends to elevated pressure regimes. CO+NO reaction mechanism and kinetics was also studied on Pd (111) by in situ PM-IRAS. Factors affecting the conversion and the selectivity of the Pd (111) model catalyst towards CO+NO reaction at elevated pressures were discussed. Formation of isocyanate containing species?? was also observed and the catalytic implications of this observation was elaborated. Finally, design and characterization of a complex model catalyst composed of supported Pd nano-particles was investigated using CO adsorption at elevated pressures. Catalytic activity of the defect sites on the supported Pd nano-particles towards CO dissociation was demonstrated and compared with Pd (111) to elucidate the significance of the surface morphology of the active sites in a catalytic reaction.
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Borasio, Marta. "Polarization modulation infrared reflection absorption spectroscopy on Pd model catalysts at elevated pressure." [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/351/index.html.
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Rahmatian, Farnoosh. "High-speed guided-wave electro-optic modulators and polarization converters in III-V compound semiconductors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25142.pdf.
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Vaughn, Israel Jacob. "Bandwidth and Noise in Spatio-temporally Modulated Mueller Matrix Polarimeters." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/595816.
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Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is improved by 300% over a conventional dual rotating retarder Mueller matrix polarimeter. Reconstruction results from the physical instrument are presented, and issues with the implemented system design are discussed.
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Chagnon, Mathieu. "Digital signal processing assessment for optical coherent receiver using dual-polarization Quadrature phase shift keying modulation." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97202.
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In this work, we evaluate different approaches of digital signal processing applied after a coherent receiver in order to recover the binary information of an optical signal modulated in Dual-Polarization Quadrature Phase Shift Keying. We explain in details the functioning of a coherent receiver as well as the optical and electrical signals travelling inside. We present the criteria of the two lasers employed for modulation and demodulation, i.e., the signal and local oscillator lasers, as a function of the modulation format and the binary rate. We expose all the required signal processing for information recovery out of a coherent receiver and mention those who will be assessed in this work, along with the reason of their selection. Subsequently, the metric to assess the different methods is introduced. The latter is twofold and consists of the computational complexity and the final bit error rate that each approach yields. The schematics of the test bed follows in parallel with the parameter space of our setup. The computational complexity and the bit error rate of ten different approaches are presented, and an optimal configuration of methods and parameters to use for such modulation and receiver is deduced.Dans ce travail, nous évaluons différentes approches de traitement de signaux numériques pour un récepteur cohérent optique dans le but de recouvrir l'information binaire d'un signal modulé sur double polarization et quatre niveaux de phase, ou « Dual-Polarization QPSK ». Nous expliquons en détail le fonctionnement d'un récepteur cohérent ainsi que les signaux optiques et électriques qui s'y propagent. Nous présentons les critères des deux lasers utilisés pour la modulation et la démodulation cohérente, i.e., les lasers signal et oscillateur local, en fonction du format de modulation utilisé et du taux binaire. Nous exposons tous les traitements de signaux numériques requis pour recouvrir l'information sortant d'un récepteur cohérent et mentionnons ceux qui seront évalués dans ce travail ainsi que les raisons de leur sélection. Par la suite, nous introduisons la métrique d'évaluation des différentes approches. Cette dernière comporte deux facettes, soit la complexité de calcul des différents algorithmes et paramètres utilisés ainsi que le taux d'erreur binaire final que l'ensemble des processus produisent lorsqu'une certaine approche est employée. La présentation schématique du banc de test suit de concert avec l'espace des paramètres du montage. La complexité de calcul et le taux d'erreur binaire de dix différentes approches sont présentés et une configuration optimale des paramètres et méthodes pour un tel format de modulation et receveur est déduite.
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Winski, David Nathaniel. "Design and construction of a polarization modulated infrared reflection absorption spectrometer and validation with carbon monoxide adsorption on a platinum (100) surface." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 96 p, 2009. http://proquest.umi.com/pqdweb?did=1889078511&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Vieira, Pedro Manuel Assis Loureiro Limão. "Control of functional T helper cell polarization by dendritic cells regulation and modulation by inflammatory factors, pathogens and drugs /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/85747.
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Lachance, Zachary Thomas. "Polarization Modulated-Infrared Reflectance Absorbance Spectroscopy Of Orientation And Binding Mode Of Pentafluorobenzyl Acid Modifiers On Indium Zinc Oxide." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/556967.
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Understanding the orientation of small organic acid modifiers on metal oxide electrodes is important in advancing the field of organic photovoltaics (OPVs). In this work, the orientation of a group of these small organic acid modifiers will be investigated on indium zinc oxide (IZO). Polarization modulation-infrared reflectance-absorbance spectroscopy (PM-IRRAS) is the primary technique used to determine these orientations. In order to determine orientations from PM-IRRAS data, other chemical and physical properties of the modifiers, such as density and surface coverage, must be experimentally determined. Neutral buoyancy is used to determine the density of the modifiers, while X-ray photoelectron spectroscopy (XPS) is used to estimate surface coverage of these modifiers on IZO. These techniques are also used to determine binding mode of these modifiers on IZO. The tilt angles (θ) were found to be 50 ± 3°, 64 ± 2°, and 43 ± 3° for F₅BnPA, F₅BnCA, and F₅BnHA, respectively, meaning that the phenyl ring in F₅BnHA is more perpendicular to the surface while the phenyl ring in F₅BnCA more parallel to the surface. All three modifiers were also found to bind to IZO in a bidentate manner. In contrast, F₅BnSA etches away significant portions of the IZO substrate.
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Venkatachalam, Anusha. "Investigation of self-heating and macroscopic built-in polarization effects on the performance of III-V nitride devices." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29669.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Yoder, Douglas; Committee Member: Graham, Samuel; Committee Member: Allen, Janet; Committee Member: Klein, Benjamin; Committee Member: Voss, Paul. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Degboé, Yannick. "Modulation thérapeutique du phénotype du macrophage dans la polyarthrite rhumatoïde." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30085/document.
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La polyarthrite rhumatoïde (PR) est le rhumatisme inflammatoire chronique le plus fréquent. Cette maladie est caractérisée par une auto-immunité et une synovite hypertrophique, responsables d'une destruction des articulations périphériques. Les macrophages contribuent aux phénomènes inflammatoires de la PR. Ces cellules peuvent présenter différents états d'activation ou " polarisation ", réversibles, dépendant de leur environnement, notamment cytokinique. Les biothérapies (bDMARDs) ont représenté une avancée majeure dans la prise en charge des manifestations inflammatoires des formes sévères de PR. Toutefois, peu d'études ont évalué si ce bénéfice était lié à une action spécifique sur le macrophage. L'objectif de ce travail de transversal était : (i) d'évaluer in vitro l'effet des principales biothérapies de la PR (anti-TNF : etanercept, adalimumab, certolizumab ; anti-IL- 6R : tocilizumab ; CTLA4-Ig : abatacept) sur la différenciation et l'activation de macrophages dérivés de monocytes issus de patients atteints de PR et de sujets sains, (ii) d'identifier des marqueurs de polarisation du macrophage, corrélés à l'activité de la maladie (DAS28). Parmi les bDMARDs évalués, seuls les anti-TNF ont montré une action sur la polarisation des macrophages. En contexte de différenciation avec M-CSF, les bDMARDs anti-TNF ont induit un biais vers une polarisation non inflammatoire dite alternative. En contexte d'activation inflammatoire, les bDMARDs anti-TNF ont induit une préservation sélective des marqueurs de polarisation liés à l'IL-10 (CD16, CD163, MerTK) et une inhibition des marqueurs inflammatoires (CD40, CD80). Nous avons montré que ce changement phénotypique s'accompagnait : (i) d'un changement fonctionnel concordant avec une polarisation induite par l'IL-10, (ii) d'une inhibition de la production des cytokines de l'inflammation (TNF, IL-6, IL-12), (iii) et d'une majoration de la phagocytose. Nous avons montré que ce mécanisme était dû à une production précoce d'IL-10 et dépendant de STAT3. De plus, nous avons pu montrer que le certolizumab, un anti-TNF, induisait une réponse anti-inflammatoire, impliquant le facteur de transcription NRF2 (nuclear factor erythroid-2-related factor 2), un régulateur central dans la réponse au stress oxydatif. Enfin, nous avons observé que l'expression de CD16, à la surface des macrophages non activés, était corrélée négativement à l'activité de la PR. Ces travaux concourent à montrer l'intérêt du ciblage du macrophage dans la PR et nous ont d'identifier de potentielles cibles théranostiques dans le traitement de la PR par anti-TNFRheumatoid arthritis (RA) is the most frequent chronic inflammatory rheumatism. This disease is characterized by an auto-immunity and a hyperplasic synovitis, both responsible for peripheral joints destruction. Macrophages contribute to inflammatory aspects of RA. This cell type can present various states of activation or "polarization", reversible and dependent on its environment, notably cytokines. Biologics (bDMARDs) represented a revolution in severe RA treatment. However, data regarding their specific action on macrophage are scarce. The aim of our translational work was: (i) to assess the in vitro effect of RA bDMARDs (anti-TNF: etanercept, adalimumab, certolizumab; anti-IL-6R: tocilizumab; CTLA4-Ig: abatacept) on the phenotype of monocytes-derived-macrophages from RA patients and healthy volunteers, during differentiation and activation phases, (ii) to identify polarization markers correlated with disease activity (DAS28). Among bDMARDs, only anti-TNF modulated macrophage polarization. During differentiation, anti-TNF bDMARDs induced a bias toward the so-called alternative non-inflammatory polarization. In inflammatory context, anti-TNF bDMARDs induced a selective preservation of markers associated with IL-10 (CD16, CD163, MerTK) and an inhibition of inflammatory markers (CD40, CD80). We showed that these changes in phenotype were associated with changes in functions consistent with: (i) a polarization induced by IL10, (ii) a decrease in inflammatory cytokines production (TNF, IL-6, IL-12), (iii) and an increase in phagocytosis. We showed that this mechanism was dependant on early IL-10 production and STAT3 signaling. Moreover, we have showed that certolizumab, an anti-TNF agent, induced an anti-inflammatory response, implicating the transcription factor NRF2 (nuclear factor erythroid-2- related factor 2), a central regulator of the response to oxidative stress. We observed that CD16 expression on non-activated macrophages was negatively correlated with RA activity. This work contributes to demonstrate the relevance of macrophage targeting in RA, and enabled us to identify theranostic targets for RA treatment with anti-TNF bDMARDs
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Gilles, Marin. "Effets de modulation de phase croisée dans les fibres à dispersion normale et leurs applications." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK036/document.
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Dans ce manuscrit, les effets émergeant de la modulation de phase croisée entredeux signaux polarisés orthogonalement dans des fibres optiques à dispersionnormale sont étudiés et leurs applications approfondies.En premier lieu, un générateur d’impulsions cadencées à 40-GHz a été développéen injectant deux ondes sinusoïdales en opposition de phase polariséesorthogonalement au sein d’une fibre optique à dispersion normale. Une grandedifférence de puissance entre les deux ondes induit un potentiel de phasepériodique pour la réplique de plus faible énergie, induisant ainsi dans régimede dispersion normale une dynamique de compression, comprimant ainsi l'ondesinusoïdale en impulsions courtes et correctement séparées.Un échantillonneur et amplificateur est ensuite démontré en utilisant le mêmePrincipe. Une pompe sinusoïdale de forte puissance et à haute fréquence estinjectée dans une fibre optique sur un axe de polarisation, orthogonalement àun long pulse de forme arbitraire et de faible énergie. Nous avons alorsdémontré un échantillonnage à 40-GHz ainsi qu'une amplification jusqu'à unfacteur 4.Nous rapportons ensuite la première observation de solitons en parois dedomaine de polarisation dans des fibres à dispersion normale en transmettanttout d'abord des trains d’impulsions périodiques anticorrélés et polarisésorthogonalement dans une fibre de 10 km, puis en encodant le mot 'PETAL' enASCII sur les ondes lumineuses et le transmettant dans une fibre de 2x25km.L'information encodée est correctement décodée après propagation.L'apparition spontanée de ces parois de domaine en polarisation est ensuiteétudiée en observant le processus de ségrégation de polarisation entre deuxondes incohérentes et décorrélées. Une approche thermodynamique est ensuiteutilisée afin d'expliquer le comportement observé. L'origine de ces parois dedomaine, liée théoriquement à l'instabilité de modulation de polarisationisotrope est ensuite étudiée. En injectant des impulsions de fortes puissancesdans de courts segments de fibre de très faible biréfringence, nous avonsobservé l'apparition des bandes théoriques d'instabilité modulationnellejusqu'à des longueurs de 200m, et mettons en avant leur extinction dans de pluslongues fibres. Enfin, une extension au modèle de Manakov est apportée enprenant en compte le processus de fabrication (spun) pour les fibres utiliséespour les expériences précédentesIn this Ph.D., physical effects arising from cross-phase modulation between twoorthogonally polarized signals propagating in normal dispersion fibers arestudied and some of their applications investigated.First, a 40-GHz pulse generator is designed by sending two orthogonallypolarized out-of-phase sinusoidal waves in a normally dispersive optical fiber.A large power imbalance between the two waves induces a periodic phasepotential for the weak replica which turns the normal dispersive defocusingregime into a focusing dynamics, thus compressing the sinusoidal wave intoshort and well-separated pulses.A signal sampler and magnifier was then designed using the same principle,sending a high power high frequency sinusoidal pump on one axis ofpolarization, orthogonally to a long arbitrary shaped pulse with low power. Wethen report a 40-GHz sampling as well as a magnification factor up to 4.We then report the first observation of polarization domain walls in normaldispersion fibers by first transmitting anticorrelated orthogonally polarizedperiodic signals in a 10-km long fiber, and then encoding the word 'PETAL' asASCII on the light waves and transmitting the signal in 2x25km fibers. Theinformation encoded was properly decoded after propagation.Spontaneous apparition of such polarization domain walls was then studied byobserving a polarization segregation process of two incoherent and uncorrelatedsignal. A thermodynamic approach was then used to explain the observedbehaviour. The origin of those domain walls, which was theoretically relatedto isotropic polarization modulation instability, was then investigated.Injecting high power pulses in short segments of very low birefringence fibers,we were able to observe the growth of the theoretical bands in a up to200m-long fibers, and highlight their extinction for longer strands, while newand unexplained side-bands appeared. Finally, an extension to the Manakovmodel is explicited taking into account the manufacturing process for thefibers used in the previous experiments
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Sargeant, H. "PREDETECTION RECORDING TECHNIQUES FOR GPS SIGNALS." International Foundation for Telemetering, 1986. http://hdl.handle.net/10150/615545.
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International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, NevadaPredetection recording of spread-spectrum (SS) signals such as GPS transmissions is a desirable objective for both users and developers of equipment designed to receive such signals. (GPS user-equipment development is a lengthy process during which signal simulators are only partially useful.) Upon playback, GPS signals are used by the same or modified receivers so that acquisition, processing, detection and tracking loops can be altered to optimize the receiver parameters. Development of predetect SS signal recording systems is difficult to achieve in practice. Such systems not only must be of suitable phase linearity to preserve the signal content to be extracted but sometimes must also preserve the exact signal-to-noise ratio (SNR) characteristics of the recorded signals. Existing conventional test equipment is unsuitable for deriving value judgments of the quality of a predetect recording system’s output because the SS signal has a negative SNR. This paper reveals that it is possible to use, for this purpose, tape recorders now available on many test ranges in combination with auxiliary equipment similar to that designed for the U.S. Navy’s TRIDENT Program (recording C/A-code data from in-flight missile translators). The basic techniques are described in some detail to enable potential users to understand the necessary equipment concepts and evaluate the author’s approach in terms of their own applications.
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Maluenda, Niubó David. "Síntesi de camps vectorials de llum amb polarització tridimensional no uniforme mitjançant holografia digital." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/348557.
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La introducció dels feixos amb polaritzacions no uniformes ha aportat grans avenços en multitud d'àrees. En un nivell més fonamental, ha permès entendre la naturalesa de la llum d'una manera més amplia, estenent les teories òptiques conegudes, com ('escalar, a d'altres més precises com la vectorial.
La síntesi de feixos amb una distribució no uniforme de la polarització segueix sent una tasca desafiant. Mentre que algunes tècniques utilitzen sistemes totalment òptics, en aquesta tesi, s'ha optat per incorporar dispositius optoelectrònics per modular la llum, obtenint així una major flexibilitat a la hora de dissenyar el feix. Per altra banda, el muntatge òptic utilitzat està basat en un interferòmetre de Mach-Zehnder per tal de manipular les dues components del feix, d'una manera independent, en cada braç de l'interferòmetre. D'aquesta manera, utilitzant en cada braç de l'interferòmetre un modulador de cristall líquid, tenim la capacitat de modular ambdues components del feix incident. Aquests moduladors són els proporcionats per Holoeye, concretament el model HEO 0017, els quals treballen en transmissió. Compten amb una configuració pixelada, dotant-nos d'una capacitat de modulació espacial amb una resolució de 32gm. Complementant aquesta modulació amb una tècnica d'holografia digital, som capaços de modular tant l'amplitud com la fase d'ambdues components del camp i, per tant, d'esculpir qualsevol forma amb qualsevol distribució de la polarització. Per tal de mostrar aquesta flexibilitat, s'ha sintetitzat un conjunt de feixos amb diversos perfils i diverses distribucions de la polarització.
Els feixos generats s’han avaluat mitjançant un analitzador, compost d’una làmina retardadora λ/4 i un polaritzador lineal, enfront d’una càmera CCD de 14 bits de rang dinàmic del model Stingray F080B A5G. D’aquesta manera, s’han obtingut les distribucions dels paràmetres d’Stokes en el pla de la càmera.
Aprofitant aquesta capacitat de modulació, s’ha dissenyat una tècnica d’encriptació hologràfica utilitzant el mateix sistema òptic amb lleugeres modificacions. Les claus secretes, que garanteixen la seguretat en la codificació, són màscares de polarització. Per incrementar el nivell de seguretat del sistema, s’han afegit dos paràmetres físics necessaris per poder desencriptar la informació. A més, s’ha simulat, sobre els resultats experimentals obtinguts, la resposta del sistema sota condicions de molt baixa il·luminació. Aquestes condicions, sovint utilitzades en treballs previs, augmenten significativament la robustesa del mètode d’encriptació.
Un cop garantida la correcta manipulació d’ambdues components d’un feix paraxial, s’ha procedit a desenvolupar un marc teòric per sintetitzar feixos altament focalitzats amb una polarització tridimensional arbitrària. Per tal d’obtenir aquests feixos, s’ha utilitzat un objectiu de microscopi amb una obertura numèrica de NA=0.85, on s’ha modulat el camp en la pupil·la d’entrada mitjançant el mètode hologràfic anterior. El disseny del camp en la zona focal, en funció de la distribució de la polarització en la pupil·la d’entrada, s’ha realitzat en el marc de la teoria vectorial desenvolupada per B. Richards i E. Wolf. Per avaluar el funcionament del sistema, s’ha sintetitzat un feix altament focalitzat amb polarització circular en qualsevol pla, i s’ha comparat els resultats obtinguts experimentalment amb els extrets numèricament.
La definició del grau de polarització en feixos altament focalitzats, encara ara, genera certs debats degut a que no es pot expandir d’una manera inequívoca com una suma directa del camp totalment polaritzat i del camp totalment despolaritzat. En aquesta tesi, hem fet l’estudi en el marc dels paràmetres d’Stokes generalitzats, obtenint una correspondència entre la distribució del paràmetres d’Stokes en la pupil·la d’entrada i la distribució del paràmetres d’Stokes de la contribució transversal del camp focalitzat. S’ha proposat un feix paraxial, que, un cop focalitzat, genera un camp amb les components transversals despolaritzades i que compta amb una component longitudinal no nul·la. Aquests tipus de feixos són de gran utilitat, entre d’altres camps, en la confecció de capes de invisibilitat.Non uniformly polarized beams have provided great strides in many areas. The synthesis of arbitrary polarized beams remains a challenging task. While some techniques use full optics systems, in this dissertation we introduce a system where optoelectronic devices modulate the light, providing more flexibility in the beam design. Complementing this modulation with a digital holography method, we modulate both amplitude and phase of the field. Moreover, the optical assembly is based on a Mach-Zehnder interferometer where the two components of the field can be independently manipulated in each arm of the interferometer. Applying an arbitrary modulation in both compontents, we can sculpt any profile with any distribution of polarization. To show this flexibility, a set of beams with multiple profiles and polarization distribution have been presented. In addition, taking this modulation capability, we introduce an holographic encryption technique where the secret keys are polarization masks. Two physical parameters are necessary to decrypt the information, increasing the security of the system. We have simulated the system response under very low illumination. Once guaranteed the flexibility in the design of paraxial beams with arbitrary polarization distribution, a theoretical framework to synthesize highly focused beams with an arbitrary three-dimensional polarization has been developed. The B. Richards y E. Wolf theory relates the polarization distribution on the entrance pupil of a microscope objective with the vectorial structure of the field in the focal region. To evaluate the performance of the system we have implemented a highly focused beam (NA=0.85) with circular polarization in any plane. The definition of the degree of polarization in highly focused beams even now generates some discussion because it can not be expanded unequivocally as a direct sum of completely polarized fields and completely depolarized fields. In this thesis, we have made the study within the frame of generalized Stokes parameters. We have obtained a correspondence between the distribution of the Stokes parameters in the entrance pupil and the distribution of the transverse Stokes parameters in the focused field. We have proposed a paraxial beam, which once focused, it generates a field with the transverse components depolarized and a non-zero longitudinal component.
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Zhou, Renjie. "DEVELOPMENT OF HIGH POWER FIBER LASER TECHNOLOGIES." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1271970621.
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Briand, Elisabeth. "Fonctionnalisation de surfaces d'or et greffage de protéines pour l'élaboration d'un immunocapteur." Paris 6, 2007. http://www.theses.fr/2007PA066013.
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Un immunocapteur consiste à utiliser les propriété de reconnaissance d'un anticorps pour détecter spécifiquement un analyte cible dans un milieu complexe. L'immobilisation de des anticorps (IgG) est cruciale et doit aboutir à un nombre optimal d'IgG accessibles. Ce travail a porté sur l'étude de l'interface biomolécules/surface d'or par quatre techniques d'analyse (PM-IRRAS, QCM, XPS et AFM). Trois modes d'immobilisation des IgG ont été testés, et leur liaison orientée par la protéine A (PrA) répond le mieux aux critères définis. Puis, l'influence de la première couche de thiols (ou SAM) sur l'activité des PrA a été étudiée. Trois SAM ont été comparées (une SAM pure et deux SAM mixtes). La nature chimique du thiol diluant influence l'adsorption des protéines et leur activité. Une couche hydrophile hétérogène favorise l'espacement des PrA, avec une couverture en anticorps optimale. Enfin, ce capteur a été testé pour détecter une toxine marine, l'acide okadaïque.
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Retournard, Alain. "Étude et réalisation d'un canal de double résonance adapté aux expériences de RMN multi-impulsionnelles." Nancy 1, 1989. http://www.theses.fr/1989NAN10478.
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Dispositif de double résonance, couvrant la même gamme de fréquence que le canal d'émission principal et présentant la même souplesse d'utilisation quant au contrôle des amplitude, fréquence et phase. Ce dispositif, normalement placé sous contrôle du calculateur, intègre intégralement des séquences d'impulsions préprogrammées, réalisées dans le mode hardware, qui seraient difficilement générées directement par le calculateur. L'ensemble a été conçu de manière à pouvoir être utilisé de façon très souple et de permettre par conséquent la mise en œuvre de toute nouvelle séquence d'impulsions, si compliquée soit-elle
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Rios, Clauson Sales do Nascimento. "ImplementaÃÃo de portas lÃgicas atravÃs da modulaÃÃo de pulsos por posiÃÃo (PPM) em filtros acÃstico-Ãpticos sintonizÃveis." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2097.
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FundaÃÃo de Amparo à Pesquisa do Estado do CearÃNesta dissertaÃÃo foi estudada a aplicaÃÃo do filtro AcÃstico-Ãptico SintonizÃvel (AOTF), com a ModulaÃÃo de Pulsos por PosiÃÃo (PPM), objetivando implementar, utilizando o mÃtodo de Runge-Kutta de 4a ordem, portas lÃgicas (OR-OU e AND-E) Ãpticas operando com pulsos de luz ultracurtos (2ps). Neste trabalho à investigado o desempenho das portas considerando vÃrios comprimentos do filtro ( L) que integra a sua estrutura interna, com o intuito de obter o comprimento de filtro mais adequado para uma operaÃÃo satisfatÃria, em regime dispersivo, nÃo linear, sem perdas e com modulaÃÃo de fase cruzada (XPM). Esta investigaÃÃo à realizada em duas situaÃÃes: primeiramente, sÃo considerados filtros com automodulaÃÃo de fase (SPM) e GVD (dispersÃo da velocidade de grupo). Em um segundo momento, as mesmas portas sÃo obtidas com efeitos SPM, XPM e GVD agindo juntos no AOTF. Foi observado que para pulsos do tipo sÃliton, os efeitos da dispersÃo, da nÃo linearidade e da modulaÃÃo de fase cruzada exercem juntos uma forte influÃncia na propagaÃÃo do mesmo, provocando a quebra do pulso na saÃda do dispositivo quando utilizamos um comprimento maior para os filtros. Para dispositivos mais curtos, o pulso chaveado apresentou compressÃes e alargamentos temporais e espectrais, bem comodeslocamentos temporais nos dois modo de propagaÃÃo (TE e TM). ApÃs a escolha de um comprimento de filtro adequado, foi selecionado um deslocamento temporal Ãtimo a ser aplicado nos pulsos de entrada para conseguirmos, na saÃda da porta lÃgica, deslocamentos temporais satisfatÃrios (acertos) na aplicaÃÃo da modulaÃÃo PPM. Em seguida, introduzimos fases em um dos pulsos de entrada (TM), provocando um defasamento entre os pulsos TE e TM, reduzindo ainda mais a margem de erro PPM de operaÃÃo das portas. Finalmente, ao analisarmos as fases aplicadas no pulso TM (0 a 2), definirmos o melhor Ãngulo de fase para que as portas operem na regiÃo de acerto da modulaÃÃo PPM.
In this dissertation it was studied the application of the Acoustic Optical Tunable Filter (AOTF), with Pulse Position Modulation (PPM), aiming at to implement, using the method of Runge-Kutta of 4a order, logical gates (OR and AND) optical operating with pulses of light ultra shorts (2ps). In this work the acting of the gates is investigated, considering several lengths of the filter ( L) that integrates your internal structure, with the intention of obtaining the length of more appropriate filter for a satisfactory operation, in dispersion regime, nonlinear, without losses and with Cross Phase Modulation (XPM). This investigation is accomplished in two situations: firstly, filters are considered with Self Phase Modulation (SPM) and GVD (group-velocity dispersion). In a second moment, the same gates are obtained with effects SPM, XPM and GVD, acting together in AOTF. It was observed that for pulses of the type soliton, the effects of the dispersion, of the nonlinearity and of the cross phase modulation exercise together a strong influences in the propagation of the same, provoking the break of the pulse in the exit of the device when we used a larger length for the filters. For shorter devices, the switched pulse presented temporary and spectral compression and spread, as well as, displacement in the time in the two propagation modes (TE and TM). After the choice of a length of appropriate filter, a great temporary displacement was selected to be applied in the input pulses for us to get, in the exit of the logical gate, satisfactory temporary displacements (successes) in the application of the PPM modulation. Soon after, we introduced phases in one of the entrance pulses (TM), provoking a phase displacement among TE and TM pulses, still reducing more the margin of error PPM of operation of the gates. Finally, to the we analyze the applied phases in the pulse TM (0 to 2), we defined the best phase angle for the gates to operate in the success area of the PPM modulation.
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Kyselák, Martin. "Disperzní vlivy optických vláken na multiplexní přenosy." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233474.
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This doctoral thesis deals with present trend to turn up the bit rate of the optical fibres making use of wavelenght multiplex systems. There are new theoretical and practical problems caused by the new technologies. Except the known modal dispersion there exist problems caused by chromatical and polarization mode dispersion. In the opening of the thesis the known effects, which influence the payload signal, are introduced. The polarization mode dispersion has the main attention. Within the scope of this thesis there has been programmed the statistical calculator which can analyses the measured values of differential group delay by Monte Carlo calculation. Next meaningful output is the designating application of the optical routes. It is possible to mathematicaly unambiguously define the polarization mode dispersion by Jones, Stokes and Poynting vectors. This complicated calculations are mechanized and in the simulation application make possible to simulate the signification of the PMD influence at different input parameters. The thesis includes the study of the PMD modulation format impact with the results of simulations and confrontation with other scientists results. The significant output are the final practical results examinations, which can be implemented thanks to the possibility of using the FTB-5500B measuring device.
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Frisquet, Benoit. "Ondes scélérates complexes dans les fibres optiques." Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS056/document.
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Ce manuscrit de thèse présente l’étude d’instabilités non-linéaires et la génération d’ondes scélérates complexes liées à la propagation de la lumière dans des fibres optiques standards des télécommunications optiques. Un rappel est tout d’abord présenté sur les phénomènes physiques linéaires et non-linéaires impliqués et qui peuvent présenter une analogie directe avec le domaine de l’hydrodynamique. Les différentes formes d’ondes scélérates liées au processus d’instabilité de modulation, aussi appelées « breathers », sont alors présentées, elles sont obtenues par la résolution de l’équation de Schrödinger non-linéaire. À partir de ces solutions exactes, divers systèmes expérimentaux sont alors conçus par simulation numérique à partir de deux méthodes d’excitation d’ondes scélérates. La première est une génération exacte à partir des solutions analytiques en effectuant une mise en forme spectrale en intensité et en phase d’un peigne de fréquence optique. La seconde méthode est basée sur des conditions initiales approchées avec des ondes continues modulées sinusoïdalement. Les mesures expérimentales réalisées avec ces deux méthodes démontrent parfaitement la génération d’ondes scélérates complexes (solutions d’ordre supérieur du système) issues de la superposition non-linéaire ou collisions de « breathers » de premier ordre. Enfin, nous avons également étudié un système non-linéaire équivalent au modèle de Manakov, qui fait intervenir la propagation de deux ondes distinctes avec des polarisations orthogonales dans une fibre optique. L’analyse de stabilité et des simulations numériques de ce système multi-variable mettent en évidence un nouveau régime d’instabilité de modulation vectorielle ainsi que de nouvelles solutions d’ondes scélérates noires et couplées en polarisation. Un nouveau système expérimental mis en place a permis de confirmer ces prédictions théoriques avec un excellent accord quantitatifThis manuscript presents the generation of complex rogue waves related to nonlinear instabilities occurring through the propagation of light in standard optical fibers. Linear and nonlinear physical phenomena involved are first listed, in particular some of them by analogy with the field of hydrodynamics. The different forms of rogue waves induced by the modulation instability process are then presented. They are also known as "breathers", and they are obtained by solving the nonlinear Schrödinger equation. From these exact solutions, various experimental systems were designed by means of numerical simulations based on two rogue-wave excitation methods. The first one is an exact generation of mathematical solutions based on the spectral shaping of an optical frequency comb. The second method uses approximate initial conditions with a simple sinusoidal modulation of continuous waves. For both cases, experimental measurements demonstrate the generation of complex rogue waves (i.e., higher-order solutions of the system) arising from the nonlinear superposition or collision of first-order breathers. Finally, we also studied a nonlinear fiber system equivalent to the Manakov model, which involves the propagation of two distinct waves with orthogonal polarizations. The stability analysis and numerical simulations of this multi-component system highlight a novel regime of vector modulation instability and the existence of coupled dark rogue-wave solutions. A new experimental system setup was conceived and theoretical predictions are confirmed with an excellent quantitative agreement
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Perny, Sébastien. "Alignement de cristaux liquides par irradiation en lumière linéairement polarisée de film minces de polymères photoréticulables." Cachan, Ecole normale supérieure, 1998. http://www.theses.fr/1998DENS0042.
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L'objectif de ce travail de thèse a été en premier lieu de concevoir et de synthétiser quatre polymères photosensibles utilisables industriellement comme films d'alignement des cristaux liquides. Dans un deuxième temps, des études par spectroscopie UV et IR ont permis de caractériser l'anisotropie et l'évolution de la composition de ces matériaux en cours d'irradiation en lumière linéairement polarisée. Dans le cas général, il a ainsi été possible de mettre en évidence la compétition de deux photo réactions : la cycloaddition 2+2 et l'isomérisation trans/cis. Ainsi, trois espèces cohabitent au sein du film de polymère irradié : les dimères, produits de la cycloaddition de chromophores agrégés ; les isomères cis, issus de l'isomérisation des chromophores isoles ; les chromophores initiaux qui n'ont pas réagi. De plus, nous avons pu constater que l'orientation préférentielle des chromophores inchangés était perpendiculaire a l'axe de polarisation et que, dans certains cas, les dimères étaient préférentiellement formes parallèlement a l'axe de polarisation. Enfin les propriétés d'alignement de ces matériaux ont été étudiés en confinant des cristaux liquides entre deux films de photopolymères irradies. Leur comportement a ensuite été compare a ceux du pvci et du poly(7-methacryloyloxycoumarine) afin de clarifier le mécanisme de photo alignement. Deux mécanismes ont du être envisages. Dans un cas, la sélectivité axiale des réactions photochimiques en lumière polarisée consomme les chromophores préférentiellement orientes le long de l'axe de polarisation. L'anisotropie du film est donc uniquement due à la présence de chromophores inchangés, initialement perpendiculaires à l'axe de polarisation, et le film induit un alignement homogène planaire suivant cet axe. Dans le deuxième cas, l'anisotropie du film est essentiellement due à la formation de dimères le long de l'axe de polarisation, et le film induit un alignement homogène planaire suivant l'axe de polarisation.
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Fu, Shih-Fong, and 傅士峰. "Multi-service Access Networks Using Polarization Modulator." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/u5zb6f.
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碩士國立臺北科技大學
光電工程系研究所
100
In recent times, wireless communication has become more important in our lives, making the high demand for the high-speed services. But the large transmission loss of millimeter-wave signal in free space limits the range of signal transmission. Transmitting millimeter-wave signal with Radio over Fiber system can extend the transmission distance of the mm-wave signal. In addition, if the Radio over Fiber system used in multi-service access network can provide more signal applications and more convenience. Therefore, this study presents a multi-service access network, which transmits both wire-line and wireless signals simultaneously. In the scheme, three lasers were used as three users'' optical carriers to transmit hybrid signals via a optical fiber simultaneously. Experimental results shows that the quality of wire-line and wireless signal can be achieved all user''s requirements. The system is sufficient to meet the standard of future communication network.
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Frazão, João Carlos dos Reis. "Quantum communications system using qubits with polarization encoding." Master's thesis, 2020. http://hdl.handle.net/10316/92563.
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Trabalho de Projeto do Mestrado Integrado em Engenharia Física apresentado à Faculdade de Ciências e TecnologiaCompreende-se criptografia como a prática de princípios e técnicas que permitem uma comunicação segura, na presença de terceiros. Com o desenvolvimento dos computadores quânticos, a utilização de um algoritmo quântico muito eficiente (algoritmo de Shor) para atacar a atual criptografia assimétrica pode transformar-se numa realidade. Isso comprometeria a segurança dos sistemas atuais e futuras trocas de informações. Nesta dissertação, é estudada uma implementação do protocolo quântico BB84, que utiliza variáveis discretas com codificação na polarização de fotões.Na primeira parte deste trabalho, foi estudado o recetor já implementado no laboratório do Instituto de Telecomunicações de Aveiro. De forma a otimizar o processo de recolha e processamento de informação, foi desenvolvida uma solução baseada no Arduino. Conforme foram realizados alguns testes, percebeu-se que seria necessário adicionar um novo Arduino e uma placa periférica para gerir quatro valores de tensão de um controlador de polarização. Foram ainda obtidos resultados testes do Quantum Bit Error Rate (QBER), onde se verifica a estabilidade do sistema.Por último, de forma a obter ritmos de operação elevados, estudou-se uma solução baseada em moduladores IQ (In-phase Quadrature. Para se conseguir gerar os seis estados de polarização nas três bases não ortogonais (base padrão, base diagonal e base circular) propusemos uma estrutura Dual-IQ. Nesta estrutura, o sinal ótico é dividido em duas partes iguais, cada uma passando por um modulador IQ. Aqui, uma diferença de fase é introduzida em cada um dos sinais, e com a ajuda de um rotador de polarização é possível gerar vários estados de polarização. Foram realizadas simulações de forma a demonstrar que esta estrutura é capaz de gerar os seis estados de polarização necessários.
Cryptography can be understood as the practice of principles and techniques, that allows secure communications, in the presence of unwanted parties. With the development of quantum computers, the use of a very efficient quantum algorithm (Shor algorithm) to attack the current asymmetric cryptography can become a reality. This would compromise the security of current systems and future information exchanges.In this dissertation, an implementation of the BB84 quantum protocol is studied, which uses polarization encoding on single photons.In the first part of this work, the already implemented receiver, in the laboratory of Instituto de Telecomunicações de Aveiro was studied. To optimize the process of collecting and processing information, a solution based in the Arduino was developed. As some tests were carried out, it was perceived that the system needs two Arduinos and a peripheral board to manage four voltage values of a polarization controller. The Quantum Bit Error Rate (QBER) tests results were also obtained, where the stability of the system can be analyzed.Finally, in order to obtain high operation rates, a solution based on IQ (In-phase Quadrature) modulators was studied. To generate the six polarization states, in the three non-orthogonal bases (standard base, diagonal base and circular base), we proposed a Dual-IQ structure. In this structure, the optical input signal is divided into two equal parts, each passing on the IQ modulator. Here, a phase difference is introduced in each of the signal, and with the help of a polarization rotator it is possible to generate several polarization states. Simulations have been performed to demonstrate that this structure is capable of generating the six required polarization states.
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Yang, Wei-Yuan, and 楊維元. "Applications of Polarization Modulator for Multi-service Signal Generation Module." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/wq8e97.
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碩士國立臺北科技大學
光電工程系研究所
102
In this work, we propose and experimentally demonstrated a multi-service signals generation module based on polarization modulator for RoF communication system. With the assistance of a polarization beam splitter, the pol-x and pol-y sidebands of optical polarization modulated multi-service signals can be separated colorlessly to achieve optical double/quadruple frequency. 3-band services are integrated and delivered simultaneously. After transmitting over 25 km single mode fiber, three band signals include OFDM and OOK are successfully achieved the qualities of radio-over-fiber communication.
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Liao, Xinqing. "Surface Plasmon Polariton Based Polarization Modulators Using Metal-polymer Waveguides." Thesis, 2012. http://hdl.handle.net/1807/32256.
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A tunable polarization modulator based on the periodic metal strips embedded in a polymer waveguide is presented. The periodic metallic structure is analyzed by Finite Element simulation (COMSOL). The calculation results show that the giant birefringence is formed by the selective cut-off of TE polarization over TM polarization, which makes it possible to design an efficient polarization modulator with a short conversion length. The metallic strips are made by using four-layer lift-off fabrication technology. The transmission and group indices of TE and TM modes are measured. However, it is observed that TE and TM modes cut off at same time, which does not agree with our predictions. The reason for failure is that the change in refractive indices is different from what we expected, which makes the device perform in opposite way. Finally, further suggestions are provided to modify the design so that the device can achieve its expected function.
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Hsu, Chia-Wei, and 許嘉維. "Design and Fabrication of Polarization-Independent Lithium Niobate Electro-Optic Modulator." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16643859274295568418.
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碩士國立臺灣大學
電子工程學研究所
100
Novel polarization-independent lithium niobate electro-optic modulators operating at 1.55um are successfully designed and fabricated for demonstration. The proposed device, based on the structure of Mach-Zehnder interferometer, is an integration of a polarization splitter and two single-polarization electro-optic modulators. On the same Z-cut lithium niobate, the TE mode waveguide is fabricated by Zn and Ni co-diffusion, whereas the TM mode waveguide is fabricated only by Ga diffusion. Though three types of metal (Zn, Ni, and Ga) are deposited, only one diffusion step is needed, which greatly simplifies the device fabrication process. For the polarization splitter, the measured extinction ratios are 27.5dB and 24.3dB for the TE and TM modes, respectively. For the single-polarization electro-optic modulator, the device length is 3cm, and the polarization dependent loss is less than 0.69dB when the applied voltage is within the range of 0-100V, and it becomes as low as 0.05dB at two specific applied voltages 26V and 95V. These results show the proposed polarization-independent electro-optic modulator has good potential for practical application.
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Chang, Jia-hon, and 長家弘. "Study of Polarization Independent Spatial Light Modulator and Optical Vortex Applications." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/7n6653.
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碩士國立中山大學
光電工程學系研究所
103
Spatial light modulator (SLM) is an electro-optic device possessing high spatial resolution of birefringent pixels. Each pixel can be controlled individually by the signals sent from the computer. Therefore, SLM is capable of modulating the spatial distribution of phase, amplitude and polarization of the incident beam, leading to plenty applications in optics and photonics, such as micro-projection and optical tweezers. This study aims to improve SLM particularly for the use in phase modulation and explore their possible applications in spatial control of optical field. Most of the liquid-crystal-on-silicon (LCoS) based SLMs utilize nematic liquid crystals as their host media. Nematic liquid crystals nevertheless possess intrinsic restrictions including polarization-dependent modulation and slow electro-optic response. Polymer-stabilized blue phase (PSBP) liquid crystals emerge as a promising candidate for SLM because of their optical isotropy and sub-millisecond switching. However, the required operating voltage of current commercially available PSBP materials is still too high for SLMs. In this work, we optimized the recipe and polymerization conditions of PSBP and finally demonstrated diffraction experiments using the phase grating generated by a PSBP-based SLM. The experimental findings revealed polarization-independent and ultrafast phase modulation. The latter part of the thesis describes simultaneous investigations on complex optical vortices generation exploiting the ability of SLM in spatial phase modulation. An optical vortex is a beam carrying an orbital angular momentum and so exhibiting helical wavefront. Using a high-resolution SLM, we were able to convert a Gaussian beam to a vortex beam carrying various orbital angular momenta. Interferometric measurements were applied to verify the vortex nature of the generated beams. In such vortex beams, different orbital angular momenta interfere with each other, thereby forming complex spatial intensity distribution. This makes SLM a more powerful technique in spatial shaping of light fields. The experimental findings agree well with the simulation results. We also demonstrate signal processing of the vortex beams with the SLM acting as both coding and decoding tools. It is believed that further development of the host PSBP materials and complex optical vortices will lead SLMs to a much wider range of practical applications in both the industries and academics.
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Liu, Juin-Ming, and 呂俊明. "Design of Polarization-Independent Electro-absorption Modulator Using Strain Coupled Quantum Well." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/45030865192887483766.
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碩士國立清華大學
電機工程學系
85
A new alternative-strain compensated InP/InGaAs/InP/InAsP/InP polarization independent anti-symmetric coupled-quantum-well (CQW) structure with both blue and red quantum-confined Stark shift for the first heavy-hole-to-electron (or the first light- hole-to-electron) excitonic transition is studied theoretically in this thesis. In the anti-symmetric coupled-quantum-well (CQW), an anti-symmetric-like pair of potential profile between the shallow-deep conduction band profile and the deep-shallow valence band profile is formed. The subband eigenenergies and the associated envelope wave functions in the CQW structures with or without applied electric field are calculated by the transfer matrix method. The effects of the strain on the pseudomorphic layers has been taken into account. The influence of various anti-symmetric CQW structure parameters such as the total well width, the individual well width, the central barrier thickness and the composition of the strained layer on transition energy, QCSE, the envelope wavefunction overlap, and on/off ratio are studied systematically. In addition, the tradeoff between the polarization-independent requirement and the strength of the blue Stark Effect has been discussed. Results indicated that: First, the use of the tensile-strained well is to help to meet the polarization-insensitive condition while that of the remaining compressive-strained well and middle barrier is to help tuning the transition energy to the desired wavelength and simultaneously achieving larger blue shift and wavefunction overlap. Second, in either blue- or red- shift applications, the alternative-strain compensated anti-symmetric polarization-independent CQW structure could gather around superior properties to design the polarization independent electroabsorption modulator because the novel structure could give large enhancement of both blue and red Stark Effect. The design of the novel polarization-independent electroabsorption modulator operated at 1.3mm utilizing either blue or red Stark Effects in the alternative-strain compensated polarization-independent anti-symmetric couple quantum well (CQW) is proposed and studied theoretically in this thesis. The InP/In0.379Ga0.621As(40A)/InP(6A)/InAs0.4P0.6(40A)/InP alternative-strain compensated polarization-independent anti- symmetric CQW is adopted. A value of as high as 5.7 can be achieved by either blue or red Stark Effects shift of the anti- symmetric CQW in the electric field range of 0 to 125kV/cm for blue-shift and 0 to -250kV/cm for red-shift applications. Also, we use In0.409Ga0.591As(52A)/InP operated at 1.3 mm to design the modulator for comparison. Our result shows that in virtue of our novel strain compensated polarization independent anti- symmetric CQW structure, the performance of our novel device, such as switching energy, drive voltage, and the net strain in the device, could be dramatically improved in comparison with the conventional InGaAs/InP SQW modulator.
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Huang, Chin-Wang, and 黃金旺. "Frequency Quadrupling Technique Based on Polarization Modulator for Radio-over-Fiber System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/mwzucn.
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碩士國立臺北科技大學
光電工程系研究所
102
We propose and experimentally demonstrate a frequency quadrupling technique based on polarization modulator for radio-over-fiber system. The scheme is based on a polarization modulator and a following intensity modulator. Frequency-quadrupled signal is generated through optical carrier suppression. The qualities of the system could be achieved after transmitting over single-mode-fiber. The system has good potential applications in the radio-over-fiber systems in the future
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吳欣庭. "Theoretical and experimental analysis of polarization mode dispersion in an electro-optic modulator." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/55037950458816037689.
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Yu, Tsung-Chih, and 尤崇智. "Optical Polarimeter for the Measurement of Glucose Concentration using a new Liquid Crystal Polarization Modulator." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/90865324482081412918.
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碩士國立成功大學
機械工程學系碩博士班
92
Optical activity which is a character of some substances can be applied to many domains, such as the measurement of glucose concentration. In this report, we firstly developed a new liquid-crystal (LC) polarization modulator consisting of one LC variable retarder and two quarter wave plates. This modulator could be used to replace the Faraday modulator in modulating the polarization angle of light. We passed a linearly polarizing light through the LC modulator and an analyzer to obtain a modulated signal. After demodulating the signal by using the new demodulation system, the rotation angle caused by optical activity would be derived. This polarimeter has simpler structure, less optical elements, and a cheaper modulator than traditional one. To be integrated and non-invasive glucose sensor will be the purpose of this system.
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Nan-Ying, Lin, and 林男穎. "The Bit Error Rate Evaluation of an Electrooptic Modulator under the Influence of Polarization Mode Dispersion." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/23278368473161139345.
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碩士國立臺灣科技大學
電子工程系
93
In high-speed optical fiber communication systems, polarization mode dispersion (PMD) becomes a major factor which degrades the quality of the system and limits the capability of transmission. The electro-optic (E-O) modulator which modulates optical carrier by means of electro-optic effect is an essential component in optical fiber communication systems. In this thesis, the phenomenon of PMD in the E-O modulator is investigated and the theoretical model is developed. The differential group delay (DGD) of the output light which passes through the E-O modulator PMD is estimated and verified by the experimental data. The E-O modulator which is fabricated by an inhomogeneous crystal with an anisotropic property is used generally in modern optical communication systems. Assuming the incident lightwave with an arbitrary state of polarization, the coupled-wave equations can be derived from the three dimension Maxwell's equations. A theoretical model which is used to estimate the PMD can be developed. The theoretical mode is verified by the eye diagrams simulated by the Virtual Photonics Incorporated (VPI) ActivePhotonics software and is confirmed by the a set of experimental deviations measured by synchronous and asynchronous amplitude histogram techniques.
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譚漢民. "A Study of Polarization Insensitive Electro-Optic Modulators." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/23893322296214924870.
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Wang, Li-chann, and 王儷娟. "Wavelength Converters Based on Cross-Polarization Modulation." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/cf9x8u.
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碩士國立臺灣科技大學
電子工程系
94
The wavelength converter is a key component in all optical networks. The function of a wavelength converter is to convert the original signal from one wavelength to another wavelength. It can reduce the wavelength blocking problems and provide flexible services for optical networks. In this thesis, we utilize the cross-polarization modulation (CPM) mecha-nism in a semiconductor optical amplifier (SOA) to realize high-perfor-mance wavelength converters. We first investigate the operation conditions and power dynamics for CPM wavelength converters. A CPM wavelength converter can have about 6-dB and 5-dB dynamic ranges for 1:1 and 1:2 wavelength conver-sion, respectively. The performance of XGM wavelength converters is also investigated for comparison with CPM wavelength converters. From the transmission experiments, we obtain the clear eye patterns with less than 1-dB power penalty when the signal is CPM-converted and transmitted over 40-km distance. On the other hand, the signal converted by the XGM mechanism can only transmit for a short distance due to the positive chirp that enhances the dispersion effect via a SMF. In order to improve the performance of a XGM converter, we insert a CPM con-verter after the XGM converter in order to use the negative chirp to com-pensate the XGM converted signal. With this scheme, the XGM con-verted signal can be transmitted over 30-km transmission.
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Yen, Li-Hsing, and 顏利興. "Radio-over-Fiber Systems Based on Polarization Modulation Technique." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/pdabe7.
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碩士國立臺北科技大學
光電工程系研究所
99
In recent years, wireless communication generally used, radio-over-fiber (RoF) system is highly discussed. This study proposed two radio-over-fiber systems based on polarization modulation technique, integrating fiber-to-the-home (FTTH) and RoF system, are promising for multi-service access networks. These schemes can transmit both wireless and wireline signals on a single wavelength over a single fiber, which serves these two applications simultaneously. According to the experimental results, the signals meet the standard. Polarization modulation technique satisfied the demand of high quality transmission in the future.
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Hsieh, Ying-Hui, and 謝孆慧. "Modulation of Electrical Polarization in Complex Oxides via Strain." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/nuwp3c.
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博士國立交通大學
材料科學與工程學系所
105
In this thesis, we study how the polarization in complex oxides are affected by the strain. It is discussed in two parts: in the first part, the reversal of the ferroelectric polarization of multiferroic BiFeO3 (BFO) is constrained to enhance the ferroelectric retention, and in the second part flexoelectricity is created through a compositional gradient. Firstly, Non-volatile electronic devices based on magnetoelectric multiferroics have triggered new possibilities of outperforming conventional devices for applications in information storage, the emerging field of spintronics, and sensors. However, ferroelectric reliability issues, such as imprint, retention, and fatigue, must be solved before the realization of practical devices. In this study, everlasting ferroelectric retention in the heteroepitaxial constrained multiferroic mesocrystal is reported, suggesting a new approach to overcome the failure of ferroelectric retention. Studied by scanning probe microscopy and transmission electron microscopy, and supported via phase-field simulations, the key to the success of ferroelectric retention is to prevent the crystal from ferroelastic deformation during the relaxation of the spontaneous polarization in a ferroelectric nanocrystal. On the other hand, complex oxides present versatile properties, such as ferroelectricity, superconducting, and colossal magnetoresistance (CMR), and have been widely studied. To improve or manipulate the properties, complex oxides are designed and well grown into different structures, from the thin film of a single material to hetero-structures combining at least two materials. With the advance of growth techniques, the accuracy of growth is controlled on the scale of a unit cell via the assistance of reflection high-energy electron diffraction (RHEED). Utilizing the ability to control the growth at the atomic scale, a non-uniformity with compositional gradient along the out-of-plane (OOP) direction is created. The model system is constituted by SrTiO3 (STO) and LaAlO3 (LAO). Under this circumstance of an OOP compositional gradient, a strain gradient ensues. Polarity discontinuities between STO and LAO are also expected compared to the bi-layer system. Through the coupling among the charge, orbital, and lattice, a spontaneous polarization is created. Since the spontaneous polarization is induced and manipulated by the strain gradient, the behavior is named “flexoelectricity”.