Planar optical waveguides fabricated by K$ sp+$-Na$ sp+$ ion-exchange in soda-lime glass substrates are investigated. / Experimental characterizations of planar waveguide with respect to a wide range of fabrication conditions have been carried out, including detailed measurements of the refractive index anisotropy resulting from the large induced surface stresses. / Parallel to this, the non-linear diffusion process of ion-exchange was simulated numerically to provide, along with the results of the characterizations, a complete description of the refractive index profile from any set of fabrication conditions. / The magnitude of the maximum surface index change observed was shown theoretically to be almost entirely due to the induced stress at the surface of the substrate, arising from the presence of the larger potassium ions. / Finally, a novel class of single-mode channel waveguides, made by a "two-step" ion-exchange was analyzed. A simple model for these waveguides was developed and used in the design of two directional coupler structures which were fabricated and measured. / The two-step process was conceived because it relaxes waveguides' dimensional control, yielding single-mode guides of larger size, better suited for low-loss connections to optical fibers. It also provides an additional degree of freedom to adjust device properties.

This thesis presents the design of radio-frequency (RF) tunable active inductors (TAIs) with independent inductance (L) and quality factor (Q) tuning capability, and their application in the design of RF tunable phase shifters and directional couplers for wireless transceivers. The independent L and Q tuning is achieved using a modided gyrator-C architecture with an additional feedback element. A general framework is developed for this Q- enhancement technique making it applicable to any gyrator-C based TAI. The design of a 1.5V, grounded, 0.13um CMOS TAI is presented. The proposed circuit achieves a 0.8nH-11.7nH tuning range at 2GHz, with a peak-Q in excess of 100. Furthermore, printed and integrated versions of tunable positive/negative refractive index (PRI /NRI) phase shifters, are presented in this thesis. The printed phase shifters are comprised of a microstrip transmission-line (TL) loaded with varactors and TAIs, which, when tuned together, extends the phase tuning range and produces a low return loss. In contrast, the integrated phase shifters utilize lumped L-C sections in place of the TLs, which allows for a single MMIC implementation. Detailed experimental results are presented in the thesis. As an example, the printed design achieves a phase of -40 to +34 degrees at 2.5GHz. As another application for the TAI, a reconfigurable CMOS directional coupler is presented in this thesis. The proposed coupler allows electronic control over the coupling coefficient, and the operating frequency while insuring a low return loss and high isolation. Moreover, it allows switching between forward and backward operation. These features, combined together, would allow using the coupler as a duplexer to connect a transmitter and a receiver to a single antenna. Finally, a planar electronically steerable patch array is presented. The 4-element array uses the tunable PRI/NRI phase shifters to center its radiation about the broadside direction. This also minimizes the main beam squinting across the operating bandwidth. The feed network of the array uses impedance transformers, which allow identical interstage phase shifters. The proposed antenna array is capable of continuously steering its main beam from -27 to +22 degrees of the broadside direction with a gain of 8.4dBi at 2.4GHz.

The Multimode Interference (MMI) mechanism is a powerful toool used in the analysis and design of a certain class of optical, microwave and millimeter wave devices. The principles of the MMI method and the self-imaging principle is described. Using this method, NXM MMI couplers, MMI splitter/combiners are analyzed. Computer simulations for illustrating the &quot / Multimode Interference Mechanism&quot / are carried out. The MMI approach is used to analyze overmoded &#039 / rectangular metallic&#039 / and &#039 / dielectric slab&#039 / type of waveguides and devices. The application of the MMI technique is investigated experimentally by using a metallic waveguide structure operating in the X-band. The construction of the related structure and the related experimental work are reported.

Thesis (Ph. D.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 102-110). Also available on the World Wide Web.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-03-08T12:15:41Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertaçãoDaviLira.pdf: 3636018 bytes, checksum: a3d66cf7d5a7e3e102b2d49abcabf422 (MD5) / Made available in DSpace on 2017-03-08T12:15:41Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertaçãoDaviLira.pdf: 3636018 bytes, checksum: a3d66cf7d5a7e3e102b2d49abcabf422 (MD5) Previous issue date: 2016-04-13 / O presente trabalho introduz um novo método para confecção de acopladores híbridos do tipo branch-line que sejam de banda dupla, ou seja, que são projetados para operar em duas frequências desejadas quaisquer com a mesma resposta. Este método faz uso de uma nova estrutura de linha de transmissão artificial (LTA) implementada em microfita, a qual é composta por três linhas de transmissões conectadas em cascata, com estubes em aberto inseridos em paralelo entre as linhas de transmissão. Foram obtidas expressões algébricas que determinam, em função das frequências das bandas desejadas, os valores de impedância característica e comprimento elétrico de cada um dos segmentos e estubes para que, em ambas as frequências, a LTA tenha os mesmos parâmetros de espalhamento que, e portanto seja equivalente a, um único segmento de linha de transmissão convencional com impedância característica e comprimento elétrico quaisquer especificados. Para obter o acoplador híbrido do tipo branch-line com banda dupla, portanto, substituímos cada linha de transmissão do acoplador por uma ATL com os parâmetros calculados de acordo com as expressões encontradas. Essa técnica foi usada para projetar, simular, fabricar e medir um acoplador híbrido branch-line que funcionasse nas frequências GSM de 925MHz e ISM 5.8GHz. Essa técnica tem como principal vantagem a capacidade e a flexibilidade de obter acopladores branch-line com bom desempenho em duas bandas quaisquer. / This work deals with a new method for the design of dual band branch-line hybrid couplers with arbitrary central frequencies, in other words, branch-line couplers which operate in two desired frequencies. This method makes use of a new artificial transmission line (ATL) structure, which is composed of the cascade connection of three transmission lines segments with parallel open stubs between them. Algebraic expressions were obtained that specify, in function of the central frequencies, the values for the characteristic impedance and electric length of the segments, so that the ATL has, for both frequencies, the same scattering parameters, hence the same behavior, as an ordinary transmission line with any chosen characteristic impedance and electric length. To obtain a dual band branch line coupler, the desired frequencies are chosen and the expressions are evaluated to find out the characteristic impedances and electric lengths of the ATL’s to replace all transmission lines that make up the coupler. This technique was used to design, simulate, fabricate and measure a branch-line hybrid coupler that works on the 925MHz GSM and 5.8GHz ISM frequencies. This technique has as it’s main advantage the ability and flexibility to yield couplers with good performance in two arbitrary bands.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-20T14:10:52Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação_Leonardo_digital.pdf: 8248572 bytes, checksum: 8eaff05e901397f38f65a651841ef367 (MD5) / Made available in DSpace on 2017-07-20T14:10:52Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação_Leonardo_digital.pdf: 8248572 bytes, checksum: 8eaff05e901397f38f65a651841ef367 (MD5) Previous issue date: 2015-01-22 / CAPES / O presente trabalho aborda o desenvolvimento e a implementação de acopladores híbridos em quadratura mais compactos e com largura de banda e desempenho similares as do acoplador branch-line convencional. Para isso, fez-se uso de uma classe de estruturas denominadas linhas de transmissão artificiais (LTA). Uma nova estrutura desse tipo, composta por três linhas de transmissão conectadas em cascata, é analisada e utilizada neste trabalho. Foram derivadas equações matemáticas para o projeto deste tipo de estrutura que podem ser utilizadas para obter LTAs com uma matriz de espalhamento idêntica, para uma dada frequência de operação, a de uma linha de transmissão com uma impedância característica e comprimento elétrico quaisquer. Essa técnica foi aplicada no projeto de acopladores híbridos em quadratura em microfita para as bandas GSM em 920 MHz e ISM em 2.45 GHz usando-se o substrato FR-4 com espessura de 1.6 mm. Obteve-se dispositivos com áreas aproximadamente 70% menor do que a área do acoplador branch-line convencional operando em 920 MHz e aproximadamente 50% menor do que o acoplador de 2.45 GHz. Os acopladores obtidos foram simulados, fabricados e medidos, mostrando que os seus desempenhos são comparáveis aos dos acopladores convencionais. A técnica desenvolvida neste trabalho é geral o suficiente para ser aplicada ao projeto de outros dispositivos que usem trechos de linhas de transmissão. / This thesis is concerned with the design and implementation of compact hybrid couplers with similar bandwidth and performance to the conventional branch-line coupler. To achieve this, a class of structures, called artificial transmission line (ATL), was used. A new structure of this type, made of three transmission lines connected in cascade, is analyzed and used. Mathematical equations have been derived for the design of this type of structure that can be used to obtain ATLs with an identical scattering matrix, for a given frequency of operation, to that of a transmission line with a given characteristic impedance and electrical length. This technique was applied in the design of microstrip quadrature hybrid couplers for the 920 MHz GSM band and for the 2.45 GHz ISM band using a 1.6 mm-thick FR-4 substrate. These couplers have surface areas approximately 70% smaller than the area of the conventional branch-line coupler operating at 920 MHz and approximately 50% for the 2.45 GHz coupler. The couplers obtained were simulated, manufactured and tested, showing that their performances are comparable to the conventional coupler. The technique developed here is general enough to be applied to the design of other devices using transmission line sections.

In this present world there is a huge requirement for high data rates and less powerconsumption in mobile networking. To achieve this one need to build a highly efficientpower amplifiers which is the most power consuming component in transmitterfront end. Most of the power amplifiers are highly efficient at higher output powerlevels and achieving the similar efficiency at average or back-off power levels is challenging.Efficient PA architectures have been proposed in recent decades and onesuch architecture is the Load Modulated Balanced Amplifier (LMBA). All the existingLMBA designs have been implemented using the discrete components and GaNbased PA’s using Transmission Line (TL) for base-station applications which has adisadvantage of larger footprint. The main purpose of this thesis is to implementthe same idea in CMOS by replacing the discrete components with their lumpedcounterparts. In this work cascode amplifiers biased in deep class AB were implementedas the main and control amplifiers of LMBA. The circuit was implementedin TSMC 0.18 μm process. With on-chip inductor losses, for LMBA with controlsource, at 9 dB back-off and at center frequency of 2 GHz, the PAE is 22% with outputpower of 17 dBm and at maximum power of 23 dBm the PAE was close to 32%while PAE was 16% without load modulation. For LMBA with control amplifier, at6 dB back-off, the PAE is 27% compared to 19% for a reference amplifier and withload modulation, maximum power of 25.6 dBm. For DLMBA with inductor lossesat 6 dB OBO, a PAE of 25.3% was achieved compared to 20.2% for a referenceamplifier without load modulation, and load optimized for peak PAE, a absolutePAE improvement of 5.1% or a relative PAE improvement of 25.2%. / I dagens värld finns det stora krav på höga datahastigheter och lägre strömförbrukningi mobilnätverk. För att uppnå detta måste man bygga en mycket effektiveffektförstärkare (power amplifier, PA), som är den komponent i sändaren medhögst strömförbrukning. De flesta PA är mycket effektiva vid högre uteffektnivåermen att uppnå samma effektivitet vid genomsnittliga eller neddragna (back-off) effektnivåerär utmanande. Effektiva PA-arkitekturer har föreslagits under de senastedecennierna och en av de senaste arkitekturen är den last-modulerade balanseradeförstärkaren (Load Modulated Balanced Amplifier, LMBA). Alla befintliga LMBAkonstruktionerhar implementerats med diskreta komponenterna och GaN-baseradePA för basstationer och använder transmissionsledare som upptar stor yta, en nackdel.Huvudsyftet med denna avhandling är att implementera samma idé i CMOSgenom att ersätta de diskreta komponenterna med deras lumpade motsvarigheter.I detta arbete användes kaskodförstärkare, förspända i deep-class AB, som huvudochstyrförstärkare för en LMBA. Kretsen implementerades i TSMC 0.18 m-process.För en LMBA med styrkälla och induktorförluster på chip, 9 dB back-off och vidcenterfrekvensen 2 GHz, uppnåddes 22 % PAE vid 17 dBm uteffekt och 32 % PAEvid den maximala uteffekt på 23 dBm. Utan lastmodulering var PAE 16 %. För enLMBA med kontrollförstärkare och 6 dB back-off, uppnåddes 27 % PAE jämförtmed 19 % för en referensförstärkare, och med lastmodulering en maximal effekt på25,6 dBm. För en DLMBA med induktorförluster uppnåddes vid 6 dB back-off 25,3% PAE jämfört med 20,2 % för en referensförstärkare utan lastmodulering och lastoptimerad för högsta PAE, vilket gör en absolut PAE-förbättring på 5,1 % eller enrelativ PAE-förbättring på 25,2 %.

No description available.

One of the major purposes of this project was to demonstrate optical components which will be used in fibre optic distribution systems. These include the fibre itself, couplers, connectors, splices, sources and detectors. All components used are state-of-the-art, the star coupler and fusion splice technique being developed by the author during the completion of the project. The star coupler has proved to have one of the lowest insertion losses of any such component to date. Although the telephone system demonstrated has only 3 stations, very similar or identical components would be used in an expanded network. / Thesis / Master of Engineering (MEngr)

Aiming to reduce research and development times in the field of silicon photonics, this paper presents a method for automatized device testing. Focus lies on automatic optical coupling between the grating couplers on a chip and optical fibers and efficient switching between devices when performing laboratory tests on silicon photonic chips. A lab setup with high precision motorized stages has been built and an algorithm for finding the best optical coupling between fiber and chip, based on the light distribution properties of the fiber, has been implemented. The project results shows that, while these methods have the potential of considerable time savings, further testing is needed.