Nonreciprocity is a fundamental property of networks. Unlike electronic networks theory, optical network theory is still a field to be investigated. Lightwave systems, including fiber optic and integrated optic, are becoming more and more complex, new function blocks ( or components) and networking strategies are very important for future highly integrated lightwave circuits. Several common nonreciprocal optical effects studied in this disseration and several basic applications to fiber components and fiber optic metrology systems analyzed. The common optical nonreciprocal phenomena include the Faraday effect, Sagnac effect, Fresnel drag effect, nonlinearity or asymmetric geometric structure-induced nonreciprocity, and some pseudo nonreciprocity. The best-known application of nonreciprocity to optical components is the isolator, and the known nonreciprocity-based fiber optic sensors are the fiber optic gyroscope and the fiber optic current sensor. The major difficulty in forming a general optical network theory is the complexity of optical signals compared to the electrical signal, because each light signal consists of four independent parameters, all of which changing during transmission. Fortunately, most optical signals can be classified into intensity-based and phase-based systems, and the Jones matrix technique is the ideal tool for describing the intensity-based system. Several reciprocity-insensitive structures designed and analyzed in chapter 3. The performance of the intensity-based reciprocity-insensitive structure (IRIS) was employed successfully in a fiber optic current sensor for stabilizing the signal from birefringence influences in chapter 5. A variable-loop Sagnac interferometer was designed and applied to distributed sensing in chapter 6, and the reciprocity-insensitive property of the Sagnac interferometer was preserved. Polarization independent isolators and wavelength division multiplexers were also realized by employing suitable nonreciprocal effects and were discussed in chapter 2 and chapter 4, and their feasibilities were verified by experiment. The primary contributions of this dissertation are the study of common nonreciprocal optical effects and demonstration of several basic applications to fiber components and fiber metrology systems. / Ph. D.

The purpose of this research is to study a new type of vibration isolator, utilizing the post-buckled stiffness of elastic struts (or columns). The advantage of the post-buckled state is that ideally it can support more static load with a relatively small static deflection than traditional vibration isolators such as springs or rubber mounts, but can also exhibit a low axial stiffness when dynamic excitation is introduced. Three models consisting of buckled or pre-bent struts serving as vibration isolators which support a rigid bar are examined in this research. The three cases studied are 1) two buckled struts supporting a symmetric rigid bar, 2) two buckled struts supporting an asymmetric rigid bar, and 3) two pairs of buckled struts with a bonded filler supporting a symmetric rigid bar. The models are subjected to a harmonic excitation at the base, and external damping is included. The struts in all cases are modeled as an elastica, and the boundary conditions are clamped/clamped for all cases. Because the purpose of the struts is to reduce unwanted vibrations, determining the displacement transmissibility of the system is the main goal of this research. Transmissibility versus frequency plots are generated for all cases, with varying parameters such as stiffness, damping, and location of center of mass, to determine how they affect the behavior of the struts. Models that produce a large range of frequencies at which the transmissibility is well below unity are the most effective. Vibration shapes are also determined for certain frequencies so that the physical behavior of the system can be studied. / Master of Science

The layered honeycomb lattice iridate Na2IrO3 is a novel candidate material for either a topological insulator or spin liquid. These states of matter are one possible starting point for the future realization of scalable quantum computation, but may also find application in magnetic memory or low-power electronic devices. This thesis reports on the pulsed laser deposition of high-quality heteroepitaxial (001)-oriented Na2IrO3 thin films with well-defined in-plane epitaxial relationship on 5-by-5 and 10-by-10 square millimeter single-crystalline sapphire, YAlO3 and zinc oxide substrates. Three-dimensional Mott variable range hopping is the dominant conduction mechanism between 40 and 300 K. Moreover, a signature of the proposed topological insulator phase is found in magnetoresistance by observation of the weak antilocalization effect that is associated with topological surafce states. Compared to single crystals, a smaller, 200-meV optical gap in Na2IrO3 thin films is found by Fourier-transform infrared transmission spectroscopy.

Dans les systèmes de télécommunications l'isolateur est le seul élément qui n'a pas encore été intégré, en raison du traitement thermique élevé (~ 700 °C) nécessaire à la cristallisation des matériaux magnétiques le constituant. Ce composant autorise le passage de la lumière dans une seule direction, en bloquant la propagation dans le sens retour et évite les risques des dommages ou d’instabilités. Il est basé sur l'effet non-réciproque de la rotation Faraday des matériaux magnéto-optiques. Pour surmonter ce problème de compatibilité tout en exaltant l'effet magnéto-optique, un matériau composite structuré en cristal photonique 3D a été élaboré par imprégnation d’un opale direct de polystyrène avec une solution de précurseurs métalliques dopés avec des nanoparticules magnétiques (CoFe2O4) à basse température en utilisant le procédé sol-gel. Premièrement, nous avons montré par le calcul, que l'utilisation d'un matériau magnétique diluée avec un indice de réfraction relativement faible dans un cristal photonique 1D, peut augmenter le facteur de mérite par rapport à une seule monocouche magnéto-optique. Pour obtenir une rotation Faraday suffisante, la fraction volumique de nanoparticules magnétiques dans la couche composite a tout d’abord été augmentée de quelques pour cent à une valeur aussi importante que 40%. Le résultat principal de cette thèse est enfin que la rotation de Faraday des cristaux magnéto-photoniques réalisés a montré une amélioration sur les bords de la bande interdite photonique en comparaison à la seule monocouche / For telecommunication systems the isolator is the only element, which has not been integrated yet, because of the high temperature (~700 °C) annealing process which is required for the crystallization of magnetic materials. Due to the non-reciprocal behavior of the magneto-optical effects, this device assures that the transmitted light passes in one direction, but it blocks the backward propagation into the laser and avoids damage risk or instabilities. To overcome this compatibility problem and increase the magneto-optical effect, a composite material arranged as 3D photonic crystal has been elaborated by impregnating polystyrene direct opals with magnetic nanoparticles(CoFe2O4) doped metallic precursor solution using low temperature sol-gel process. Firstly, we have shown by calculation, that the use of a dilute magnetic material with a relatively low refractive index in a 1D photonic crystal can increase the merit factor compared to a single magnetic monolayer. To obtain a sufficient Faraday rotation, the volume fiaction of magnetic nanoparticles had to be increased. We managed to reach 40%, whereas this rate was only a few percent at the beginning of this work. The main result of this thesis is that the Faraday rotation of the realized magneto-photonic crystals showed an enhancement at the edges of the photonic band gap comparing to the single monolayer

Neste trabalho apresenta-se uma alternativa para utilização de vidros laminados provenientes de rejeitos industriais ou pós-consumo. Reciclando o vidro laminado, por meio de uma série de moagens, pode-se obter dois tipos de rejeitos: vidros de partículas pequenas (200 e 325 mesh), que não conseguem ser reaproveitados pela indústria vidreira, e filme de poli(vinil butiral) - PVB - impregnado com uma pequena quantidade de carga, que tem como destino os aterros. No presente estudo, esses dois resíduos foram aproveitados na fabricação de vernizes curados por radiação ultravioleta empregados para proteção de pisos de madeira. O filme de PVB foi utilizado na formulação de um isolante, em razão de sua alta flexibilidade e boa aderência à madeira, e o vidro de baixa granulometria foi empregado como carga nos vernizes chamados de alto tráfego para o aumento da resistência à abrasão dos mesmos (propriedade fundamental de vernizes para pisos de madeira). Pelos resultados obtidos, verificou-se que o isolante preparado com o filme de PVB em solução alcoólica e misturado a um monômero acrílico trifuncional, como o trimetilolpropano triacrilato (TMPTA), quando aplicado sobre pisos de madeira, obteve-se bons resultados de aderência, arrancamento e flexibilidade, podendo assim substituir os isolantes utilizados atualmente, produtos com cura por radiação ultravioleta, em base aquosa, e que apresentam alto custo por serem preparados com resinas importadas. Foi observado que quanto maior a quantidade de solução de PVB, melhor a flexibilidade do filme e, conseqüentemente, melhor a resistência ao arrancamento do revestimento. Os vidros de baixa granulometria apresentaram resultados muito satisfatórios quando utilizados como carga nos vernizes de alto tráfego, especialmente ao se combinarem com o óxido de alumínio (carga atualmente utilizada nesses sistemas), aumentando ainda mais a resistência à abrasão dos vernizes e também a estabilidade dos vernizes (quanto à sedimentação e à geleificação). Para todas as combinações de cargas preparadas neste trabalho foram bons os resultados obtidos, podendo-se optar pela utilização daquelas com maior quantidade de vidro, uma vez que este, por tratar-se de um resíduo, torna tais combinações mais econômicas. / The present work features an alternative for the utilization of the windshield after its use. The recycling of the laminated glass, through a series of grindings, make possible to obtain two kinds of materials: glasses of small particles (200 and 325 mesh), that cannot be recovered in the glass industry, and a poly(vinyl butiral) - PVB - sheet impregnated with a small amount of filler, that has as final disposal the sanitary landfill. In this study these two materials were introduced in the formulation of ultraviolet curing varnishes used to the protection of wood flooring. The film of PVB was used in the formulation of a primer, due to its high flexibility and good adherence to the wood, and the glass of low granulometry was used as a filler in the so-called high traffic varnish, to increase the abrasion resistance (main property of these varnishes). The results obtained showed that the primer prepared with the PVB sheet in alcoholic solution, mixed with a trifunctional acrylic monomer, like TMPTA, when applied on wood flooring, obtained good results of adherence, scrape adhesion, flexibility and stability and could substitute the primers used nowadays that are UV curing products, however water based ones, and that has a high cost because of the imported resins that are used in their formulations. It was observed that larger the amount of solution of PVB, better the flexibility of the film and, consequently, better its scrape adhesion. The glasses of low granulometry also presented very satisfactory results when used as fillers in the high traffic varnishes, mainly when in combination with aluminium oxide (filler used in these systems), increasing more the abrasion resistance of the varnishes and also their stability (the sedimentation and geleification have showed better results). To all filler combinations studied in this work the results were good and the best one can be the ones that presented the largest amount of glass, since as a residue, make these combinations more economical.

This work aims at enhancing the understanding and to provideimproved models of the dynamic behavior of rubber vibrationisolators which are widely used in mechanical systems.Initially, a time domainmodel relating compressions tocomponent forces accounting for preload effects, frequency anddynamic amplitude dependence is presented. The problem ofsimultaneously modelling the elastic, viscoelastic and frictionforces are removed by additively splitting them, where theelastic force response is modelled either by a fully linear ora nonlinear shape factor based approach, displaying resultsthat agree with those of a neo-Hookean hyperelastic isolatorunder a long term precompression. The viscoelastic force ismodelled by a fractional derivative element, while the frictionforce governs from a generalized friction element displaying asmoothed Coulomb force. This is a versatile one-dimensionalcomponent model effectively using a small number of parameterswhile exhibiting a good resemblance to measured isolatorcharacteristics. Additionally, the nonlinear excitationeffects on dynamic stiffness and damping of a filled rubberisolator are investigated through measurements. It is shownthat the well-known Payne effect - where stiffness is high forsmall excitation amplitudes and low for large amplitudes whiledamping displays a maximum at intermediate amplitudes -evaluated at a certain frequency, is to a large extentinfluenced by the existence of additional frequency componentsin the signal. Finally, a frequency, temperature and preloaddependent dynamic stiffness model is presented covering theranges from 20 to 20 000 Hz, -50 to +50 °C at 0 to 20 %precompression. A nearly incompressible, thermo-rheologicallysimple material model is adopted displaying viscoelasticitythrough a time - strain separable relaxation tensor with asingle Mittag-Leffler function embodying its time dependence.This fractional derivative based function successfully fitsmaterial properties throughout the whole audible frequencyrange. An extended neo-Hookean strain energy function, beingdirectly proportional to the temperature and density, isapplied for the finite deformation response with componentproperties solved by a nonlinear finite element procedure. Thepresented work is thus believed to enlighten workingconditions’impact on the dynamic properties of rubbervibration isolators, while additionally taking some of thesemost important features into account in the presentedmodels.

Simulating wave propagation in microstrip lines with Gyrotropic magnetic substrate is considered in this thesis. Since the static internal field distribution has an important effect on the device behavior, accurate determination of the internal fields are considered as well. To avoid the losses at microwave frequencies it is assumed that the magnetic substrate is saturated in the direction of local internal field. An iterative method to obtain the magnetization distribution has been developed. It is applied to a variety of nonlinear nonuniform magnetic material configurations that one may encounter in the design stage, subject to a nonuniform applied field. One of the main characteristics of the proposed iterative method to obtain the static internal field is that the results are supported by a uniqueness theorem in magnetostatics. The series of solutions Mn,Hn, where n is the iteration number, minimize the free Gibbs energy G(M) in sequence. They also satisfy the constitutive equation M = χH at the end of each iteration better than the previous one. Therefore based on the given uniqueness theorem, the unique stable equilibrium state M is determined. To simulate wave propagation in the Gyrotropic magnetic media a new FDTD formulation is proposed. The proposed formulation considers the static part of the electromagnetic field, obtained by using the iterative approach, as parameters and updates the dynamic parts in time. It solves the Landau-Lifshitz-Gilbert equation in consistency with Maxwell’s equations in time domain. The stability of the initial static field distribution ensures that the superposition of the time varying parts due to the propagating wave will not destabilize the code. Resonances in a cavity filled with YIG are obtained. Wave propagation through a microstrip line with YIG substrate is simulated. Magnetization oscillations around local internal field are visualized. It is proved that the excitation of magnetization precession which is accompanied by the excitation of magnetostatic waves is responsible for the gap in the scattering parameter S12. Key characteristics of the wide microstrip lines are verified in a full wave FDTD simulation. These characteristics are utilized in a variety of nonreciprocal devices like edgemode isolators and phase shifters.

Simulating wave propagation in microstrip lines with Gyrotropic magnetic substrate is considered in this thesis. Since the static internal field distribution has an important effect on the device behavior, accurate determination of the internal fields are considered as well. To avoid the losses at microwave frequencies it is assumed that the magnetic substrate is saturated in the direction of local internal field. An iterative method to obtain the magnetization distribution has been developed. It is applied to a variety of nonlinear nonuniform magnetic material configurations that one may encounter in the design stage, subject to a nonuniform applied field. One of the main characteristics of the proposed iterative method to obtain the static internal field is that the results are supported by a uniqueness theorem in magnetostatics. The series of solutions Mn,Hn, where n is the iteration number, minimize the free Gibbs energy G(M) in sequence. They also satisfy the constitutive equation M = χH at the end of each iteration better than the previous one. Therefore based on the given uniqueness theorem, the unique stable equilibrium state M is determined. To simulate wave propagation in the Gyrotropic magnetic media a new FDTD formulation is proposed. The proposed formulation considers the static part of the electromagnetic field, obtained by using the iterative approach, as parameters and updates the dynamic parts in time. It solves the Landau-Lifshitz-Gilbert equation in consistency with Maxwell’s equations in time domain. The stability of the initial static field distribution ensures that the superposition of the time varying parts due to the propagating wave will not destabilize the code. Resonances in a cavity filled with YIG are obtained. Wave propagation through a microstrip line with YIG substrate is simulated. Magnetization oscillations around local internal field are visualized. It is proved that the excitation of magnetization precession which is accompanied by the excitation of magnetostatic waves is responsible for the gap in the scattering parameter S12. Key characteristics of the wide microstrip lines are verified in a full wave FDTD simulation. These characteristics are utilized in a variety of nonreciprocal devices like edgemode isolators and phase shifters.

<p>This work aims at enhancing the understanding and to provideimproved models of the dynamic behavior of rubber vibrationisolators which are widely used in mechanical systems.Initially, a time domainmodel relating compressions tocomponent forces accounting for preload effects, frequency anddynamic amplitude dependence is presented. The problem ofsimultaneously modelling the elastic, viscoelastic and frictionforces are removed by additively splitting them, where theelastic force response is modelled either by a fully linear ora nonlinear shape factor based approach, displaying resultsthat agree with those of a neo-Hookean hyperelastic isolatorunder a long term precompression. The viscoelastic force ismodelled by a fractional derivative element, while the frictionforce governs from a generalized friction element displaying asmoothed Coulomb force. This is a versatile one-dimensionalcomponent model effectively using a small number of parameterswhile exhibiting a good resemblance to measured isolatorcharacteristics. Additionally, the nonlinear excitationeffects on dynamic stiffness and damping of a filled rubberisolator are investigated through measurements. It is shownthat the well-known Payne effect - where stiffness is high forsmall excitation amplitudes and low for large amplitudes whiledamping displays a maximum at intermediate amplitudes -evaluated at a certain frequency, is to a large extentinfluenced by the existence of additional frequency componentsin the signal. Finally, a frequency, temperature and preloaddependent dynamic stiffness model is presented covering theranges from 20 to 20 000 Hz, -50 to +50 °C at 0 to 20 %precompression. A nearly incompressible, thermo-rheologicallysimple material model is adopted displaying viscoelasticitythrough a time - strain separable relaxation tensor with asingle Mittag-Leffler function embodying its time dependence.This fractional derivative based function successfully fitsmaterial properties throughout the whole audible frequencyrange. An extended neo-Hookean strain energy function, beingdirectly proportional to the temperature and density, isapplied for the finite deformation response with componentproperties solved by a nonlinear finite element procedure. Thepresented work is thus believed to enlighten workingconditions’impact on the dynamic properties of rubbervibration isolators, while additionally taking some of thesemost important features into account in the presentedmodels.</p>

Die elektronischen Transporteigenschaften von Polymerketten haengen sehr stark von deren strukturellen Eigenschaften und der Temperatur ab. Auf der Basis vorhandener Bandstrukturdaten wird ein empirischer Tight-Binding-Hamiltonoperator fuer ausgewaehlte Polyanilinstrukturen konstruiert. Mit den so erhaltenen Parametern ist es moeglich, Unordnung in die Polymerkette einzufuehren, wie sie durch Polaronen- Paarbildung und Bipolarondefekte bei niedrigen Temperaturen auftritt. Die Streukoeffizienten des Systems bestimmen die Transmission durch die Kette und damit den Leitwert des Systems im Rahmen der Landauer-Buettiker- Theorie. Der Einfluss von Dissipation auf die Transporteigenschaften des Polymers wird mit Hilfe zweier Modelle untersucht. Zum einen kann inelastische Streuung durch Kopplung des Systems an zusaetzliche Elektronenreservoire eingefuehrt werden, dies ist ein sehr phaenomenologisches Modell. Die Kopplung des zu untersuchenden Systems an Reservoire harmonischer Oszillatoren bietet die Moeglichkeit, dissipative Prozesse auf der Basis eines Hamiltonoperators einzufuehren. Beide Modelle lassen sich mit Hilfe der gleichen Greens-Funktionen-Methode loesen. Polyanilin kann sowohl in Form von einzelnen, in einer isolierenden Matrix eingebetteten Polymerketten als auch in groesseren Aggregaten von miteinander gekoppelten Ketten vorliegen. Zur Beschreibung dieser quasi-eindimensionalen Systeme wird das Tight-Binding-Modell auf drei Dimensionen erweitert und die Transporteigenschaften in Abhaengigkeit von der Systemgroesse diskutiert. Im Anschluss daran wird durch Einfuehrung dissipativer Prozesse das Material auf die Moeglichkeit eines Metall-Isolator-Ueberganges untersucht.