In this study, a novel technique (TO-Butterfly package) for butterfly-type laser module packaging based on the coaxial type structure is proposed. By applying the low cost TO packaging technique, the cost and fabrication time can be reduced, and the yield rate can be increased. The achievement can be employed to package the novel butterfly-type laser module in the fiber optics communication. In traditional butterfly-type module package, the PWS was large while saddle clip and fiber ferrule being jointed by laser welding after the fiber ferrule and laser being aligned. Therefore, the coupling efficiency and the yield rate are low with long fabrication time. On the contrary, the TO-Butterfly package, similar to TO-Can laser module, includes upper part and lower part. The direction of the main PWS in TO-Butterfly laser module parallels to the optical axis, in which direction the components are constrained. Therefore, the PWS takes less influence on the coupling efficiency. Furthermore, the aligning process between the fiber and the laser and laser welding process is completed on Newport LW4000 workstation to build up a TO-Butterfly TOSA. After that, the TO-Butterfly TOSA is taken out of the workstation and combined with the case through solder. As a result, the fabrication time can be reduced to one-third. And the coupling efficiency and yield rate can also be improved. After several times of process modification, the coupling efficiency of the 19 TO-Butterfly TOSA modules by applying the novel packaging technology was all over 70%. The average and the highest coupling efficiency were 81.3% and 95.7%, respectively, and the standard deviation was 6.5%.

No description available.

The coaxial aperture structure has been under intensive study in recent years, particularly since it exhibits electromagnetic transmission resonances that are stronger than its circular aperture counterpart. In our work, we study the resonance properties of a coaxial aperture in a perfect electric conductor (PEC) and in a real metal. For PEC, The dielectric constant is in finite and for real metal the dielectric constant is fi nite. We develop theory for reflection phase and amplitude in coaxial aperture at the end of a metal plate. While most of the past works of coaxial aperture focused on the propagation of light within the aperture structure and ignore the reflection at end-face,we fi nd that the reflection properties at the end-face are critical to determine both the wavelength and quality of Fabry-Perot resonant transmission of coaxial structure. Finite-di fference time-domain calculations agree well with our theory. We fi rst consider the PEC case, and later to develop the theory to account for real metal case. In real metal, the phase and amplitude of reflection are quantitatively diff erent from PEC because of plasmonic e ffects. Such di fference arises from the new physics associated with surface plasmons. This work is of interest to ongoing studies of coaxial structures in metal fi lms, which could impact many fields including filter e ffect,optical sensing, optical trapping, near- field spectroscopy and metamaterials. / Graduate

Thesis (M.S.)--Ohio University, August, 1989. / Title from PDF t.p.

Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (December 19, 2006) Includes bibliographical references.

Las redes híbridas de fibra óptica y cable coaxial, HFC, fueron implementadas en un principio por operadores de TV Cable, los que posteriormente incluyeron servicios como Video-on-Demand, Pay-Per-View, etc. Con el avance de la tecnología, las redes de TV Cable fueron capaces de ofrecer otros servicios multimedia como telefonía y acceso a Internet de Banda Ancha. Para esto, modificaron las mismas redes existentes, transformándose en Operadores Multi-Servicio, MSO. La red sufrió modificaciones importantes, pasando de ser una red prácticamente unidireccional a ser una red bidireccional desbalanceada. En la discusión actual sobre telecomunicaciones se encuentran habitualmente términos como convergencia IMS (IP Multimedia Subsystem) y Redes de Nueva Generación, NGN (Next Generation Networking). HFC representa un bloque fundamental en la comprensión de estos conceptos. Un factor clave para el éxito de los operadores de cable que pretenden adecuar sus redes para la próxima generación de arquitecturas de comunicaciones, será la capacidad del personal técnico para evaluar las diversas opciones disponibles. Por otro lado, los MSO, se enfrentan a otras consideraciones como el manejo de la compatibilidad de las diversas normas de próxima generación con las arquitecturas existentes y cómo determinar el momento óptimo para realizar este cambio. El objetivo de esta memoria fue diseñar un curso teórico y práctico sobre servicios soportados por redes HFC de nueva generación, basándose en los atributos de escalabilidad y disponibilidad que esta tecnología presenta frente a otras. Para guiar el desarrollo de este proyecto se utilizó una metodología que consiste en la recopilación de información sobre tecnología HFC en la etapa inicial, seguido de un análisis de los datos obtenidos. Con esta información se generó un programa docente y una planificación que permitió desarrollar el curso. En este proyecto de título se diseñó e implementó un curso de servicios teórico y práctico. En lo teórico se cubren temas como: Broadcasting de TV, Internet/Datos, Telefonía, IPTV, eTV, Video-on-Demand, Pay-Per-View, VoIP, videoconferencias y Juegos On Line. En lo práctico, se presenta una propuesta preeliminar de laboratorio docente, que contempla una red HFC a escala y guías prácticas sobre la evaluación de servicio y la vía de retorno. El curso se diseñó para hacer uso de recursos docentes presenciales e interactivos a través de Internet. Este curso representa un aporte, tanto fuera como dentro del Departamento de Ingeniería Eléctrica de la Universidad de Chile, al tratar temáticas actuales con un enfoque orientado a la industria de los servicios ofrecidos por los MSO. El curso diseñado es una propuesta orientada a completar la instrucción de un ingeniero civil electricista.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / RF and microwave filters can be implemented using ceramic coaxial resonators. This technology has been widely employed in nanosatellite communications systems recently, owing to its large quality factor (Q), permitting them to have low loss and narrow bandwidth. Features such as high selectivity, high power handling, excellent rejection, and low passband insertion loss are just a few of the key performance areas offered by ceramic coaxial resonators. This feature makes them suitable for use in bandpass filters. Applications with demanding specifications requiring low volume and mass make use of this technology. Fulfilling the required performance goals can be challenging, given the size and weight restriction. Difficulties such as finding the correct length of resonators and the coupling capacitors’ structure to meet the size restriction, limit the type of ceramic coaxial resonators to use. This thesis presents the design of a bandpass filter using ceramic coaxial resonators, which provides evidence of the concept for F’SATI’s future needs. This design will be used in an imminent space mission and the intention is to mount the bandpass filter in the receiver communications system. An intensive investigation was conducted into the use of filters for nanosatellite communication systems. The Chebyshev LC ladder low pass prototype was used to derive the conventional bandpass filter. Thereafter, the coupled resonator bandpass filter was derived using the conventional bandpass filter topology combined with the admittance inverter. Following this, using the ceramic coaxial resonators datasheet and information provided by the manufacturers, the coupled resonator bandpass filter was converted into a 3D model for further simulations, using CST Microwave Studio®. The ceramic coaxial resonator filter fabricated using Rogers’s material provided satisfactory results at its operating frequency between 2.2 GHz and 2.3 GHz. A radiation level test was performed on the filter to justify the use of the metallic enclosure. The test presented a low level of radiation measured at the filter operating frequency (2.25 GHz). The filter was also subjected to temperature cycling. / French–South African Institute of Technology (F’SATI) National Research Foundation (NRF)

Este trabalho faz um estudo sistemático de fibras óticas coaxiais de quatro camadas de índices de refração no regime linear e não linear. Para o estudo no regime linear deduzimos as equações transcendentais para a constante de propagação utilizando a aproximação LP, para quatro diferentes perfis de índice de refração. A partir destas equações transcendentais estudamos as propriedades da constante de propagação e da freqüência de corte dos modos como função dos parâmetros da fibra. Mostramos que existem situações em que duas das fibras estudadas (as estruturas W2 e M2), apresentam modos fundamentais cuja freqüência de corte pode ser diferente de zero. Em seguida, utilizamos as equações transcendentais deduzidas para a constante de propagação para otimizar uma fibra ótica coaxial que pode funcionar como compensadora de dispersão de segunda ordem no comprimento de onda de 1.55 m. Mostramos que podem ser obtidos valores da ordem de 12000 ps/(nm.Km) para o parâmetro D no comprimento de onda anterior. Por fim, propomos um novo método numérico para resolver um sistema de equações diferenciais parciais que será utilizado no estudo da propagação de um pulso ao logo de um taper. Para esse último estudo, desenvolvemos um modelo que permitiu gerar uma equação diferencial válida para estudar a propagação de um pulso ao longo de um taper adiabático / In this work a systematic coaxial optical fibers study was done to four layers of refraction indexes in the lineal and not lineal regime. For the study in the lineal regime deduced the transcendental equations for the propagation constant using the approach LP, for four different profiles of refraction index. Starting from these transcendental equations we studied- the properties of the propagation constant and the cut-off as function of the parameters of the fiber. We showed that situations exist in that two of the studied fibers (the structures W2 and MZ), they present fundamental mode whose cut-off can be different from zero. Soon after, we used the transcendental equations deduced for the propagation constant for optimized a coaxial optical fiber that can work as compensation of dispersion of second order in the length of wave of 1.55 p. We showed that can be obtained values of the order of -12000 ps/(nm.Km) for the parameter D in the previous wavelength. Finally, we propose a new numeric method to solve a system of equations for differentiate partial that will be used in the study of the propagation of a pulse to the therefore of a taper. For that last study, we developed a model that allowed to generate an differential equation valid to study the propagation of a pulse along an adiabatic taper

Abstract In the first part of this study, determination of the dielectric properties of the low loss microwave ceramic material, barium nonatitanate (Ba2Ti9O20), around 1 GHz is discussed. The structures under test were coaxial resonators, the cores of which were made of barium nonatitanate and the metallization was realised by thick film silver. The measured value of the real part of the relative dielectric constant was εr = 37 and that of the loss tangent was tan σ = 0.00014. The change of the resonance frequency of the coaxial resonators with temperature, in the range -20 … +80 C, was 4 ppm/ C. In addition, realisation of compact interdigital and comb-line bandpass filters was demonstrated for the 900 MHz mobile phone band. Besides Ba2Ti9O20, Ba(Sm,Nd)2Ti5O14 ceramic material with a dielectric constant of εr = 78 was also employed in order to improve the miniaturisation. The volume of the smallest filter was 2 cm3 and the weight was 9 g. In the second part of this study, various measurement methods have been demonstrated to determine the real part of the relative permittivity of FR4 fibreglass circuit board. Test structures were straight asymmetric open-circuited strip lines. It was found that the real part of the relative permittivity decreased slightly with frequency. At 0.72 GHz and 4.5 GHz, εr values of 4.3 and 4.1, respectively, were measured. All the characterisation methods used gave consistent values for εr, and electromagnetic simulators were used to verify the results. In the third part of this study, the structures under test were microstrip or strip line transmission lines, the S parameters of which were measured by using on-wafer measurement techniques. It was found that the insertion loss of the 10 mm long etched Cu microstrip was slightly less than that of the Ag microstrips which were manufactured by etching and gravure offset printing techniques, respectively. The performance of the Ag microstrips was, however, similar. In addition, a theoretical basis was established for the determination of εr of the dielectric substrate and the attenuation coefficient of the transmission lines under test. The calculations were based on signal flow diagrams. The method was applied to determine the dielectric and loss properties of a commercial, Kyocera, Japan, LTCC (Low Temperature Cofired Ceramic) material up to 50 GHz. The measured value of the real part of the relative permittivity was εr = 5.7, and the loss tangent was approximately tan σ = 0.003. The essential idea behind the studies reported in this thesis was twofold. First, the studies aimed at characterising dielectric media which find usage in the realisation of UHF, microwave or millimetre wave circuits. Second, the studies aimed to obtain data of immediate value in practical design work. For this reason, the structures under test were transmission lines having extensive usage in practical high frequency circuit design.

Plasma railguns are electromagnetic accelerators used to produce controlled high velocity plasma jets. This thesis discusses the design and characterization of a small coaxial plasma railgun intended to accelerate argon-helium plasma jets. The railgun will be used for the study of plasma shocks in jet collisions. The railgun is mounted on a KF-40 vacuum port and operated using a 90 kA, 11 kV LC pulse forming network. Existing knowledge of coaxial railgun plasma instabilities and material interactions at vacuum and plasma interfaces are applied to the design. The design of individual gun components is detailed. Jet velocity and density are characterized by analyzing diagnostic data collected from a Rogowski coil, interferometer, and photodiode. Peak line-integrated electron number densities of approximately 8 × 10¹⁵ cm^-2 and jet velocities of tens of km/s are inferred from the data recorded from ten experimental pulses. / Master of Science / Plasma is a gaseous state of matter which is electrically conductive and interacts with electric and magnetic fields. Plasmas are used in many everyday objects such as fluorescent lights, but some of the physics of plasmas are still not entirely understood. One set of plasma interactions that have not been fully explored are those which occur during high-velocity collisions between plasmas. Experiments aimed to further the understanding of these interactions require the generation of plasmas with specified properties at very high velocities. A device known as a plasma railgun can be used to produce plasmas which meet these experimental demands. In a plasma railgun, a short pulse of current is passed through a plasma located between two parallel electrodes, or "rails". This current generates a magnetic field which propels the plasma forward. The plasma is accelerated until it leaves the muzzle of the railgun. In coaxial plasma railguns, the electrodes are concentric. This paper discusses the design and testing of a small, relatively low power coaxial plasma railgun. Specific elements of the design are examined and the inherent physical and material difficulties of a coaxial design are explored. The experiment which was performed to confirm the properties of the plasma jets produced by the coaxial plasma railgun is explained. The results of this experiment confirm that the design succeeds in producing plasmas which meet targets for plasma properties.