High efficient optical spot size converter (SSC) is one of the most important building blocks for dense optical interconnection network and high-speed optical fiber communications due to efficient optical power transfer between different optical modules. Using tapered optical direction coupler (TODC) as SSC can reduce the dimension with high efficiency because of resonant condition and tapered structure. However, the strong dependence of operation on wavelength leads to narrow band operation, reducing the usage of wavelength division multiplexer (WDM) technique for upgrading optical data capacity through optical spectrum. In this work, based on multi- resonant points of TODC, a broadband SSC integrated with optical electroabsorption modulator (EAM) is proposed, designed, and fabricated. By tapering quantum well of the top active waveguide (AW), the integration with bottom passive waveguide (PW) can form a TODC. With the tapered structure, the gradually varied effective index forms a resonant point along wave propagation, inducing strong coupling, collecting optical power after resonant point, and thus leading to high efficient coupling. With multi-section of resonant conditions and also tapered structure, broadband operation can be realized. Through 3 section of tapered AW of TODC, the calculated coupling efficiency from bottom PW with larger than 70% is found for the regime of 1530nm~1550nm wavelength. The EAM-integrated SSC is also fabricated. With counter direction of optical coupling, the measured photocurrent in EAM shows a broadband of flap coupling from 1570nm~1585nm is observed, suggesting the multi-section TODC can bring out broadband operation.

This research uses Transmissivity Index (TI) and other transmission indices to analyze the transmission performance by applying those indices to coupler-driven mechanisms with sliders. Other estimative transmission indices include Total Transmission Index (TTI) and Transmissible Mechanical Advantage (TMA). The point with best transmission performance is ¡§Effective Point,¡¨ and the combination of the effective points becomes ¡§Locus of Effective Points¡¨. In addition, this research puts the influence of mechanisms with sliders including slider-friction into consideration, and also analyzes two inverses of mechanisms with sliders. Then we can extend to study the transmission performance of six-bar mechanisms. Finally, we apply the research result into some examples, such as ping pong table mechanism, four-bar and six-bar windows operator mechanisms, rowing exercise mechanism, so that we can find the better transmission performance of those mechanisms.

This thesis includes the study of hybrid microwave integrated circuits (HMIC), miniaturization techniques applied on HMICs and its application on a frequency modulated continuous wave (FMCW) range sensor transceiver. In the scope of study, hybrid and monolithic microwave integrated circuits (HMIC and MMIC) are introduced, advantages and disadvantages of these two types are discussed. Large size of HMICs is the main disadvantage especially for military and civil applications requiring miniature volumes. This thesis is mainly devoted on miniaturization work of HMICs in order to cope with this problem. In this scope, miniaturization techniques of some HMICs such as 3 dB hybrid couplers and stubs are examined and analyzed. Their simulation and measurement results cohere with original circuit results. Nevertheless, considerable size reduction up to 80% is achieved. Moreover, planar interdigital capacitors (IDC), spiral inductors (SI) and their equivalent circuit models are introduced. Design technique is discussed with illustrative electromagnetic (EM) simulations. Furthermore, FMCW radar is introduced with its basic operation principles, brief history and usage areas. In addition, FMCW range sensor transceiver is designed with its sub&amp / #8208 / parts / power amplifier, low noise amplifier (LNA), coupler and front end. Multi technology based on chip transistors, interdigital capacitors, spiral inductors and hybrid couplers with wire&amp / #8208 / bond connections is used in the design. As the result of using hybrid miniaturized components small layout size is achieved for the transceiver system with its all components.

This article is based on several nouns about transmission performance such as limiting positions, manipulation angle, transmission angle and mechanical advantage. In order to analyse the transmission performance of the coupler-driven and crank-output linkage mechanism, this article has developed an index called Transmissivity of Mechanical Advantage (TMA) for designers, besides this useful index, this article has identified a new noun as Total Transmission Coupler Point, that means after acting a force on the same direction of coupler point moving instantly, then the output force on the crank will act on it¡¦s moving direction and make the Transmissivity Index be the best as 1. For the designers of the coupler-driven linkage mechanisms, the transmission performance and the position where the force acts on involves to coupler curves very much. Based on the result of this research, the designers are able to choose the most proper coupler curves, and the best position of the coupler point would be designed. The designers are able to pick the best one among several similar coupler curves, and also they can certainly get a best range of either the length or the angle of the coupler designed when they were designing the coupler-driven type 4-bar linkage or the Stephenson¡¦s III 6-bar linkage. The applying force must change the direction all the time when a coupler-driven mechanism is driven, and it makes this type of mechanism seems to be uncommon, but it doesn¡¦t mean this kind of mechanism is not worth of application. On the other hand, the short of research about this type of mechanism makes the designers feel helpless when they were trying to analyse the transmission performance of mechanisms were designed. This article develops not only the theorem of analysis but also builds computer programs to help the designers to analyse the transmission performance quickly and correctly

A single-mode fused biconical 2¡Ñ2 coupler for polarization beamsplitting is fabricated in this thesis. We use simple fused and tapered method to fabricate the polarization beamsplitter(PBS) stably, and then we can get polarization maintaining in the output fibers. Without changing the manufacturing process, we design the device with special combination of fabrication parameters. We have achieved an extinction ratio of 25.78dB at the throughput port and 27.16dB at the coupled port. A usable spectral window as broad as 37nm and 27nm with an extinction ratio larger than 15dB for both ports is obtained. The excess loss is about 0.3dB. Based on a full-wave numerical approach, the performance of the PBS can be well modeled. We get good agreement between the measured and simulated results.

This thesis focuses on the forensic analysis of ten full-scale post-tensioned beam specimens after four years of aggressive exposure testing. The research was funded by FHWA and TxDOT. Post-tensioned structures have been under scrutiny due to their vulnerability to corrosion damage. Recent corrosion failures have been traced to inadequate materials and construction procedures. The purpose of this research project is to evaluate the corrosion performance of new and upcoming post-tensioning materials and systems and to determine their suitability for preventing durability issues which were found in older structures. The following variables were tested in the full-scale beam specimens: strand type, duct type, duct coupler type, anchorage type, tendon encapsulation. Non-destructive and destructive testing methods for evaluating corrosion damage were examined. Cost analysis of each material was conducted using tendon quantities from a typical post-tensioned bridge for comparison. Galvanized steel ducts performed poorly, showing substantial pitting and area loss. Plastic ducts were intact, but elevated grout chloride levels indicate that moisture was able to enter the ducts at the locations of couplers and grout vents. Strand corrosion was minor and uniform for all the types which were examined, suggesting that chloride traveled the length of the tendons through strand interstices. Stainless steel strands were nearly corrosion-free. Pourback quality was found to protect anchorages more than galvanization of bearing plates. The electrically isolated tendon did not completely prevent strand corrosion, but the system resulted in much lower chloride concentrations along the tendon than the conventional systems. / text

The advent of Substrate Integrated Circuit (SIC) technology, and specifically Substrate Integrated Waveguide (SIW) technology has made it feasible to design and fabricate low loss and high quality factor (Q-factor) microwave and millimeter wave structures on a compact and integrable layout and at a low cost. The SIW structure is the planar realization of the conventional rectangular waveguide (RWG). In this technology, the side walls of the waveguide are replaced with two rows of metallic vias, which are connecting two conductor sheets, located at the top and bottom of a dielectric slab. The motivation for this thesis has been to develop an analytical method to efficiently analyze SIW structures, and also design different types of passive microwave components based on this technology. As SIW structures are imitating waveguide structures in a planar format, the field distributions inside these structures are very close to those in waveguides. However, due to the very small substrate height in conventional planar technologies, and also the existence of a row of vias, instead of a solid metallic wall, there is a reduced set of modes in SIW compared to regular waveguide. This fact has given us an opportunity to deploy efficient modal analysis techniques to analyze these structures. In this thesis, we present a Mode Matching Techniques (MMT) approach for the analysis of H-plane SIW structures. One of the areas of application, which can significantly benefit from having an efficient analytical method, is designing and optimizing new circuits. Having such an analytical tool, which is faster than commercially available field solvers by an order of magnitude, new components can be designed, analyzed and optimized in a fast and inexpensive manner. Based on this technique, various types of passive microwave components including filters, diplexers, power dividers and couplers, some of which are among the first to be reported in SIW technology, are designed and analyzed in this thesis. Also based on this technique, the most accurate formula for the effective waveguide width of the SIW is presented in this thesis. In order to provide means to excite and measure SIW components, transitions between these structures and other planar topologies like microstrip and coplanar waveguide (CPW) are needed. More importantly, low-reflection transitions to microstrip are required to integrate SIW circuits with active components, and therefore it is vital to provide low-reflection transitions so that the component design is independent of the influences of the transitions. In this thesis, a new wideband microstrip-to-SIW transition, with the lowest reported reflection coefficient, is also introduced. / Graduate / 0544 / zkordi@ece.uvic.ca

With the rapid and ongoing developments in telecommunication and electronic warfare technology, faster and more flexible systems are in demand. Wideband signal processing is thus needed to implement such systems. Microwave photonics has been introduced as a tool for achieving such ultra broadband signal processing. Instantaneous Frequency Measurement (IFM) receivers play an important role in electronic warfare. They have been developed as a means of obtaining a rapid indication of the presence of a threat and to roughly identify the frequency of the threat signals. They also have the advantages of low-cost, compactness and moderate to good sorting capability in an interference-free environment. The main limitation of the traditional RF IFM receivers is constrained bandwidth. Microwave Photonic IFMs have been considered, but the main disadvantages of photonic realization of the recent IFM receiver is cost. This work aims to propose and demonstrate low-cost photonic IFM receivers with a broad frequency measurement range. The proposed methods are based on the use of photonic mixing to down-convert the RF modulated optical signals to DC. In a RADAR warning receiver, usually a bank of IFMs is required. Increasing the numbers of IFMs requires an increase in the number of photo-detectors. Thus if low-frequency, low-cost detectors can be used, then the net system cost will be reduced significantly. The concept is proven and the issues arising are analyzed. In the proof of concept system, measurement of the RF frequency required advance knowledge of the RF power. Secondly, the use of co-axial RF cables as delay elements limited the bandwidth and increased bulk. Using a photonic hybrid approach to achieve orthogonal measurements was demonstrated as a means of dentifying both RF frequency and power simultaneously and independently. Employing all optical mixing removed the need for co-axial RF cables delays using non-linear optical devices such as Semiconductor Optical Amplifier (SOA) and Highly Non-Linear Fiber (HLNF). The last investigation is to improve the sensitivity of the implemented IFM system. The sensitivity of the implemented system is characterized first and a lock-in technique is employed to improve the sensitivity of the system. The final system achieves a sensitivity of -41 dBm which is comparable with the traditional RF IFM receivers.

A microwave reflectometer is an instrument to measure a complex ratio between reflected and incident waves at an input port of a uniform transmission line that is terminated in a Device Under Test (DUT). The conventional reflectometer is formed by a four-port network with two ports connected to a microwave source and DUT, and the remaining ports coupled to a heterodyne receiver which acts as a Complex Ratio Detector (CRT). By using the heterodyne receiver technique, the two microwave signals at the input to CRT are converted in the linear manner to an Intermediate Frequency (IF) of hundreds of kHz where they are processed using digital means. As the ratio of two original microwave signals has to be preserved at IF, a very advanced electronic circuitry is required to accomplish the linear conversion process. This complicated electronic circuitry leads to a large size of the conventional reflectometer and its high price tag. Many applications require compact-size and low-cost reflectometers. They can be built using N-port networks, with N being greater than 5, equipped only in scalar (power) detectors. The thesis describes the concept of a multi-port reflectometer which determines the complex reflection coefficient of DUT with the use of scalar detectors instead of the complex ratio detector. It is shown that this device can be designed using an assembly of linear circuits in the form of quadrature (Q) and/or divider (D) hybrids. Assuming ideal operation of these components, it is shown that the reflection coefficient of DUT can be determined using simple mathematical operations on the power values measured by scalar detectors. Alternatively, it can be obtained from the intersection of power circles in a complex reflection coefficient plane. These simple mathematical expressions can be used to obtain an approximate real-time operation of reflectometer. For more accurate results, the multi-port has to be calibrated using calibration standards. A review of full calibration methods for a multi-port reflectometer is presented. In order to obtain wideband performance, the multi-port reflectometer has to be formed by components all having wideband performance. To obtain its low manufacturing cost, these components should preferably be of planar format and lead to a full integration of reflectometer. The thesis investigates a variety of planar couplers and dividers which can offer wideband performances. However, not all of them can lead to a fully integrated multi-port reflectometer. In order to overcome this shortfall, a multilayer microstrip-slot technique is proposed and investigated to obtain wideband components that can lead to a full integration of multi-port reflectometer. It is demonstrated that through the use of multilayer microstrip-slot technique, ultra wideband microwave 3-dB couplers and two-way dividers of in-phase or out-of-phase type can be designed. It is shown that the chosen configurations of dividers are compatible with the 3-dB couplers so that a fully integrated reflectometer can be formed. This compatibility is accomplished through the use of suitably designed microstrip to slotline transitions. An attractive feature of the designed couplers and dividers is that they are of sub-wavelength size and thus are very compact. A fine operation of these components is demonstrated via full electromagnetic wave simulations and experimental tests over and ultra wide frequency band of 3.1 to 10.6 GHz. Rogers substrate RO4003 featuring a relative dielectric constant of 3.38 and a loss tangent of 0.0027 is chosen as a microwave substrate for the design of these components. The design and analysis are carried out with the commercially available full EM simulator CST Microwave Studio while the experimental tests are done with the Vector Network Analyser, HP8510C. By using these components, an ultra wideband complex ratio measuring unit (CRMU), which is the heart of a multi-port reflectometer, is designed. This CRMU is fully integrated and of compact size. Its operation over an ultra wide frequency band is demonstrated via simulations. A particular attention is paid to its real-time mode of operation. Using this mode of operation, the complex ratio of two waves can be displayed on an oscilloscope using an analog electronics performing simple mathematical operations on the measured powers by detectors. While discussing the operation of CRMU, the attention is paid to the location and spacing of power circles centres (q-points) which are used for geometrical interpretation of operation of this device. Good operation of CRMU in this approximate operation mode indicates that the device will operate very well when it is fully calibrated. For simulations of CRMU, CST Microwave Studio, Agilent’s Advanced Design System (ADS) and MATLAB software are applied. Having accomplished the successful design of CRMU, the last step includes the formation of a fully integrated multi-port reflectometer. To this purpose an extra circuitry including multilayer microstrip-slot 3-dB couplers is added to CRMU. The purpose of this additional circuitry is to reroute the incident and reflected signals from the DUT to the input ports of CRMU. A few configurations of multi-port relectometer formed by multilayer microstrip-slot couplers or dividers are investigated via simulations with respect to real-time mode of operation. Then, the best performing configuration is selected for the final development. The device is manufactured in Rogers RO4003 substrate. Its S-parameters are measured with HP8510C analyser and compared with the simulated values. Having obtained a relatively good agreement between the simulated and measured results, the device is calibrated using multiple calibration standards. Its operation is verified for selected DUTs by comparing the measured reflection coeffcients with those obtained using the conventional VNA (HP8510C) over an ultra wide frequency band. A relatively good agreement is obtained between the two sets of measured results. The obtained results prove that the multilayer microstrip-slot technology can successfully be used for the development of a compact low-cost and fully integrated UWB multi-port reflectometer. Because of its compact size and good electrical performance, this device can be used in many microwave sub-systems offering a limited space for implementation of microwave measurements. The thesis shows that the accomplished multi-port device can also be used to build UWB communication transceivers. The concept of such UWB transceivers is addressed in the final sections of this thesis.

FRAGA, Wilton Bezerra de. Estudo do desempenho de acoplador direcional não linear duplo assimétrico de fibras ópticas operando portas lógicas. 2006. 82 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2006. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-05-25T22:01:57Z No. of bitstreams: 1 2006_dis_wbfraga.pdf: 1352410 bytes, checksum: c457ff6e820ccb3f66eac0052dfa0e61 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-05-27T18:56:36Z (GMT) No. of bitstreams: 1 2006_dis_wbfraga.pdf: 1352410 bytes, checksum: c457ff6e820ccb3f66eac0052dfa0e61 (MD5) / Made available in DSpace on 2015-05-27T18:56:36Z (GMT). No. of bitstreams: 1 2006_dis_wbfraga.pdf: 1352410 bytes, checksum: c457ff6e820ccb3f66eac0052dfa0e61 (MD5) Previous issue date: 2006 / We investigate the performance of three different non linear directional assymmetrical fibers couplers that include a profile of self-modulation of increasing and decreasing phase. The asymmetry is associated with the profile of self-modulation of phase of one of the chanels. Initially, we investigate the performance of the considered coupler using ultrashort pulses, type sóliton with 2ps of width and later operating with signal CW. Observing the characteristics of transmission of the device, through the direct chanel and cross chanel, we made a study of the extinction ratio (Xratio) of the devices. The extinction ratio of a switching on-off is the relation among the exit power in the state on and the power of exit in the state off. It was observed that the performance of gates AND, XOR, OR are dependents of the profile of non linearity. In the profile of constant it was not verified that logics AND and XOR present one better performance with the device operating in CW, while logic OR present better with the coupler operating in pulse regime. We conclude that coupler to operate it as logic gate we can control the non-linearity profile to optimize the characteristics of transmission through the extinction ratio. / Nós investigamos o desempenho de três diferentes acopladores direcionais nãolineares duplo assimétrico que incluem um perfil de auto modulação de fase crescente e decrescente. A assimetria está associada ao perfil de auto modulação de fase de um dos canais. Inicialmente, investigamos o desempenho do acoplador proposto utilizando pulsos ultracurtos, tipo sóliton com 2ps de largura e posteriormente operando com sinal CW. Observando as características de transmissão do dispositivo, através do canal direto e cruzado, fizemos um estudo do coeficiente de extinção (Xratio) dos dispositivos. O coeficiente de extinção de um chaveamento on-off é a relação entre a potência de saída no estado on e a potência de saída no estado off . Foi observado que a performance de portas AND, XOR, OR são dependentes do perfil de não linearidade. No perfil de não linearidade constante verificou-se que as lógicas AND e XOR apresentam um melhor desempenho com o dispositivo operando em CW, enquanto a lógica OR mostra-se melhor com o acoplador operando em regime pulsado. Concluímos que para o acoplador operar como porta lógica nós podemos controlar o perfil de não linearidade para otimizar as características de transmissão através do coeficiente de extinção.