Made available in DSpace on 2016-08-18T18:19:25Z (GMT). No. of bitstreams: 1 Nivea Fernanda Correa.pdf: 9488427 bytes, checksum: d432cb6753ed95396a5af400756eea91 (MD5) Previous issue date: 2009-02-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / in chains of coupled guides. These chains can serve of model for the propagation of solitons optics in directional couplers or micro-structuralized optics fibers. Systems of linearly coupled non linear Schrödinger equations had been used as theoretical model for these chains. The used numerical methods had been the split- step Fourier method and the orthogonal collocation method. The process of transference of energy between guides was characterized by the transmittance in function of the coupling factor, length of the guide and the power of entrance. In the mapping of the transmittance the diverse regions of parameters with its different behaviors had been identified. The threshold of power and the length of coupling had been gotten. The conclusions on the chains had been made on the basis of the analysis of the results in function of the total number of guides, the number of intermediate and peripheral guides and of the arrangement of couplings. For coupling arrangement the changes in the transmittances had the same been significant when the total number of guides varies, therefore it diminished the coupling length and the power threshold increased with the number of guides. Chains with same total number of guides, but with arrangements of distinct couplings had presented transmittances with clear differences in the chains of the type opened in relation to too many. The increase of the number of couplings between the guides led to an increase of the value of the power threshold, while the values of coupling length had not presented significant variations. / ópticos em cadeias de guias acoplados. Essas cadeias podem servir de modelo para a propagação de solitons ópticos em acopladores direcionais ou fibras ópticas micro-estruturadas. Sistemas de equações não lineares de Schrödinger acopladas linearmente foram utilizados como modelo teórico para essas cadeias. Os métodos numéricos utilizados foram o método de Fourier com passo dividido e o método da colocação ortogonal. O processo de transferência de energia entre guias foi caracterizado pela transmitância em função do fator de acoplamento, comprimento do guia e da potência de entrada. No mapeamento da transmitância foram identificadas as diversas regiões de parâmetros com seus diferentes comportamentos. O limiar de potência e o comprimento de acoplamento foram obtidos. As conclusões sobre as cadeias foram feitas com base na análise dos resultados em função do número total de guias, do número de guias intermediários e periféricos e do arranjo de acoplamentos. Para o mesmo arranjo de acoplamento as mudanças nas transmitâncias foram significativas quando o número total de guias varia, pois diminuiu o comprimento de acoplamento e o limiar de potência aumentou com o número de guias. Cadeias com mesmo número total de guias, mas com arranjos de acoplamentos distintos apresentaram transmitâncias com nítidas diferenças nas cadeias do tipo aberta em relação às demais. O aumento do número de acoplamentos entre os guias levou a um aumento do valor do limiar de potência, enquanto os valores de comprimento de acoplamento não apresentaram variações significativas.

This diploma thesis deals with optical and optoelecronic components. The first part of the work describes the optical paths and methods of their measurement. The second part describes the coupler, circulator and isolator. Further described is a laser diode, a photodetector and a modulator. The third part describes the measurement procedure of the coupler, circulator, isolator, laser diode, photodetector and modulator. The measured values are compared with the catalog values.

This Diploma thesis solves a quick coupler design for a loader. In introduction of the Diploma thesis are mentioned two potential designes and convenient solutions. Subsequently are outlined two practicable designes of a quick coupler for a original bucket, as a data componant of the second construction design is enclosed basic strength calculation. The ending point of the thesis deals and compare with the force decrease in use of a quick coupler and appraisals achieved ascertainment.

This diploma thesis describes the function of commonly used elements among optical network, with an emphasis on fiber optic sensors. The basics of optical transmission and types of fibers are described, in addition to active and passive optical components, optical splitters and couplers. Optical fiber sensors are divided in two groups: intrinsic and extrinsic. Interferometric types of sensors are described in detail. The thesis compares theoretical assumptions and practical measurements of two serially-connected couplers. A~new module fulfilling real optical coupler function was made using Matlab. This module can be implemented into the VPIphotonics library. Finally, interferometric function of two serially-connected couplers was tested.

An array of grating couplers is studied to be used for beam steering in a wireless optical communication system. This structure is designed using a rib waveguide with a silicon thickness of 220nm and an etch depth of 70nm using 2μm silica substrate. TE polarized input light with wavelength of 1550nm is coupled into the feed waveguide. The structure is optimized based on the angular coverage, directed power, and beam efficiency of the radiated main beam of an individual grating coupler. The main beam radiated by optimized grating coupler has a beamwidth of 10.3°×30.7°. The designed 1-D array of the fifteen grating couplers provides tunability in the range of around 30 degrees which is required for a point to pint wireless optical communication transmitter.

Plusieurs standards de téléphonie mobile ont été définis et sont utilisés actuellement. Dans un avenir proche, avec le développement de la 5G de nouveaux standards et de nouvelles bandes de fréquence faire leur apparition. De ce fait, avec l'utilisation de nombreux circuits dédiés à un standard et donc à une bande de fréquence, des difficultés d'intégration et desproblèmes de coûts apparaissent. Il est donc devenu nécessaire pour les concepteurs de proposer des circuits intégrés reconfigurables pour plusieurs gammes de fréquences avec des modes de fonctionnement différents.Dans un système d'émetteur récepteur, le duplexeur permet l'établissement d'une communication simultanée en utilisant une seule antenne pour la transmission et la réception de données, sans que celles-ci soient corrompues. C'est un composant vital, surtout pour la chaine de réception car la réception du signal désiré dépend de ses caractéristiques. Ce dispositif est conçu sur du matériau piézoélectrique, qui ne permet pas d'obtenir un filtre agile en fonction de la fréquence. Dans ce contexte, il est intéressant de rechercher une nouvelle architecture de duplexeur, permettant une réalisation intégrée et un fonctionnement agile.Plusieurs architectures de duplexeur ont été retenues en se basant sur des études récentes menées dans différentes équipes de recherche. Un classement de ces architectures a été proposé, avec des améliorations pour les rendre intégrables et reconfigurables. Parmi toutes les solutions de duplexeurs passifs étudiées, le duplexeur à coupleur hybride 3dB est unesolution permettant d'obtenir des performances attractives. Les simulations pour différentes bandes de fréquences ont montré qu’il était difficile de respecter les spécifications de l’isolation Tx/Rx. Des solutions possibles ont été présentées et des modifications de la structure d'un amplificateur du LNA ont été évaluées en simulation. Ainsi, les performancesd’isolation peuvent être améliorées grâce à des structures actives d’annulation du signal résiduel Tx.La conception, la réalisation et le test de coupleurs hybrides et duplexeurs sont présentés. Le circuit a été implémenté en utilisant la technologie SOI 0.13 micromètre de ST Microelectronics et mesuré avec un boitier BT soudé sur un support de test PCB. Les performances RF du duplexeur peuvent être ajustées en fonction de la bande de fréquence désirée grâce aux capacités commutées. Les performances RF du coupleur hybride 3dB permettent d’envisager l’application de la structure proposée pour les futurs développements de systèmes de téléphonie. / Several standards have been defined and are currently used on mobile phones. With the high request for the broadband, several new standards are developed and introduced in 5G. This results in the use of many circuits, dedicated to one standard and thus one frequency band, which increase the difficulty of integrating these dedicated circuits and therefore costly. It hasbecome necessary for designers to propose tunable integrated circuit that can address several frequency ranges with different operating modes.The duplexer allows the establishment of simultaneous communications, using a single antenna for sending and receiving data, without any interferences. It is a vital component, especially for receiver. In fact, the quality of the received signal depends greatly on the duplexer characteristics. This device is designed on the piezoelectric material, which does not allow to achieve a tunable filter according to the frequency. In this context, it seems interesting to study a new architecture of duplexer. Therefore, it is necessary to define the duplexer function based on studies and system simulations, thus identify the constraints and technology limitations. Several duplexer architectures were selected based on recent studies in different research teams.A classification of these architectures was proposed and also improvements to make them integrated and tunable. Among all the solutions studied, the duplexer using hybrid 3dB coupler shown the most attractive performance. Simulations for different frequency bands showed that it's difficult to achieve Tx/Rx isolation requirements. Different solutions have been presented and LNA structure have been changed and thus evaluated by simulations. Thanks to that, the Tx/Rx isolation can be improved through active cancellation structures.The final chapter presents the design, implementation and testing of hybrid 3dB coupler and duplexer. It has been implemented using SOI 0.13 micrometer from ST Microelectronics and tested on BT-resin substrat. The RF performance of the duplexer can be corrected according to the desired frequency band through the switched capacitor. The RF performance of the hybrid 3dB coupler is in the line with expectations and allows to consider its integration in future system developments.

This thesis presents novel radio frequency microelectromechanical (RF MEMS) circuits based on the three-dimensional (3-D) micromachined coplanar transmission lines whose geometry is re-configured by integrated microelectromechanical actuators. Two types of novel RF MEMS devices are proposed. The first is a concept of MEMS capacitors tuneable in multiple discrete and well-defined steps, implemented by in-plane moving of the ground side-walls of a 3-D micromachined coplanar waveguide transmission line. The MEMS actuators are completely embedded in the ground layer of the transmission line, and fabricated using a single-mask silicon-on-insulator (SOI) RF MEMS fabrication process. The resulting device achieves low insertion loss, a very high quality factor, high reliability, high linearity and high self actuation robustness. The second type introduces two novel concepts of area efficient, ultra-wideband, MEMS-reconfigurable coupled line directional couplers, whose coupling is tuned by mechanically changing the geometry of 3-D micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. The coupling is achieved by tuning both the ground and the signal line coupling, obtaining a large tuneable coupling ratio while maintaining an excellent impedance match, along with high isolation and a very high directivity over a very large bandwidth. This thesis also presents for the first time on RF nonlinearity analysis of complex multi-device RF MEMS circuits. Closed-form analytical formulas for the IIP3 of MEMS multi-device circuit concepts are derived. A nonlinearity analysis, based on these formulas and on  measured device parameters, is performed for different circuit concepts and compared to the simulation results of multi-device  conlinear electromechanical circuit models. The degradation of the overall circuit nonlinearity with increasing number of device stages is investigated. Design rules are presented so that the mechanical parameters and thus the IIP3 of the individual device stages can be optimized to achieve a highest overall IIP3 for the whole circuit.The thesis further investigates un-patterned ferromagnetic NiFe/AlN multilayer composites used as advanced magnetic core materials for on-chip inductances. The approach used is to increase the thickness of the ferromagnetic material without increasing its conductivity, by using multilayer NiFe and AlN sandwich structure. This suppresses the induced currents very effectively and at the same time increases the ferromagnetic resonance, which is by a factor of 7.1 higher than for homogeneous NiFe layers of same thickness. The so far highest permeability values above 1 GHz for on-chip integrated un-patterned NiFe layers were achieved. / <p>QC 20140328</p>

The rapidly expanding wireless market requires low cost, high integration and high performance of wireless communication systems. CMOS technology provides benefits of cost effectiveness and higher levels of integration. However, the design of highly efficient linear CMOS power amplifier that meets the requirement of advanced communication standards is a challenging task because of the inherent difficulties in CMOS technology. The objective of this research is to realize PAs for wireless communication systems that overcoming the drawbacks of CMOS process, and to develop design approaches that satisfying the demands of the industry. In this dissertation, a cascode bias technique is proposed for improving linearity and reliability of the multi-stage cascode CMOS PA. In addition, to achieve load variation immunity characteristic and to enhance matching and stability, a fully-integrated balanced PA is implemented in a 0.18-m CMOS process. A triple-mode balanced PA using switched quadrature coupler is also proposed, and this work saved a large amount of quiescent current and further improved the efficiency in the back-off power. For the low losses and a high quality factor of passive output combining, a transformer-based quadrature coupler was implemented using integrated passive device (IPD) process. Various practical approaches for linear CMOS PA are suggested with the verified results, and they demonstrate the potential PA design approach for WCDMA applications using a standard CMOS technology.

Nowadays, silicon photonics is a widely studied research topic. Its high-index-contrast and compatibility with the complementary metal-oxide-semiconductor technology make it a promising platform for low cost high density integration. Several general problems have been brought up, including the lack of silicon active devices, the difficulty of light coupling, the polarization dependence, etc. This thesis aims to give new attempts to novel solutions for some of these problems. Both theoretical modeling and experimental work have been done. Several numerical methods are reviewed first. The semi-vectorial finite-difference mode solver in cylindrical coordinate system is developed and it is mainly used for calculating the eigenmodes of the waveguide structures employed in this thesis. The finite-difference time-domain method and beam propagation method are also used to analyze the light propagation in complex structures. The fabrication and characterization technologies are studied. The fabrication is mainly based on clean room facilities, including plasma assisted film deposition, electron beam lithography and dry etching. The vertical coupling system is mainly used for characterization in this thesis. Compared with conventional butt-coupling system, it can provide much higher coupling efficiency and larger alignment tolerance. Two novel couplers related to silicon photonic wires are studied. In order to improve the coupling efficiency of a grating coupler, a nonuniform grating is theoretically designed to maximize the overlap between the radiated light profile and the optical fiber mode. Over 60% coupling efficiency is obtained experimentally. Another coupler facilitating the light coupling between silicon photonic wires and slot waveguides is demonstrated, both theoretically and experimentally. Almost lossless coupling is achieved in experiments. Two approaches are studied to realize polarization insensitive devices based on silicon photonic wires. The first one is the use of a sandwich waveguide structure to eliminate the polarization dependent wavelength of a microring resonator. By optimizing the multilayer structure, we successfully eliminate the large birefringence in an ultrasmall ring resonator. Another approach is to use polarization diversity scheme. Two key components of the scheme are studied. An efficient polarization beam splitter based on a one-dimensional grating coupler is theoretically designed and experimentally demonstrated. This polarization beam splitter can also serve as an efficient light coupler between silicon-on-insulator waveguides and optical fibers. Over 50% coupling efficiency for both polarizations and -20dB extinction ratio between them are experimentally obtained. A compact polarization rotator based on silicon photonic wire is theoretically analyzed. 100% polarization conversion is achievable and the fabrication tolerance is relatively large by using a compensation method. A novel integration platform based on nano-epitaxial lateral overgrowth technology is investigated to realize monolithic integration of III-V materials on silicon. A silica mask is used to block the threading dislocations from the InP seed layer on silicon. Technologies such as hydride vapor phase epitaxy and chemical-mechanical polishing are developed. A thin dislocation free InP layer on silicon is obtained experimentally. / QC20100705

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