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Fabrication, Characterization, and Application of Microresonators and Resonant StructuresCohoon, Gregory A. January 2016 (has links)
Optical resonators are structures that allow light to circulate and store energy for a duration of time. This work primarily looks at the fabrication, characterization, and application of whispering gallery mode microresonators and the analysis of organic photonic crystal-like structures and simulation of their resonant effects. Whispering gallery mode (WGM) microresonators are a class of cylindrically symmetric optical resonator which light circulates around the equator of the structure. These resonators are named after acoustic whispering galleries, where a whisper can be heard anywhere along the perimeter of a circular room. These optical structures are known for their ultra high Q-factor and their low mode volume. Q-factor describes the photon lifetime in the cavity and is responsible for the energy buildup within the cavity and sharp spectral characteristics of WGM resonators. The energy buildup is ideal for non-linear optics and the sharp spectral features are beneficial for sensing applications. Characterization of microbubble resonators is done by coupling light from a tunable laser source via tapered optical fiber into the cavity. The fabrication of quality tapered optical fiber on the order of 1-2 μm is critical to working on WGM resonators. The measurement of Q-factors up to 2x10⁸ and mode spectra are possible with these resonators and experimental techniques. This work focuses on microdisk and microbubble WGM resonators. The microdisk resonators are fabricated by femtosecond laser micromachining. The micromachined resonators are fabricated by ablating rotating optical fiber to generate the disk shape and then heated to reflow the surface to improve optical quality. These resonators have a spares mode spectrum and display a Q factor as high as 2x10⁶. The microbubble resonators are hollow microresonators fabricated by heating a pressurized capillary tube which forms a bubble in the area exposed to heat. These have a wall thickness of 2-5 μm and a diameter of 200-400 μm. Applications in pressure sensing and two-photon fluorescence of dye in microbubble resonators is explored. Photonic crystals can have engineered resonant properties by tuning photonic band gaps and introducing defects to create cavities in the photonic structure. In this work, a natural photonic crystal structure is analyzed in the form of diatoms. Diatoms are a type of phytoplankton which are identified by unique ornamentation of each species silica shell, called a frustule. The frustule is composed of a quasi-periodic lattice of pores which closely resembles manmade photonic crystals. The diatom frustules are analyzed using image processing techniques to determine pore-to-pore spacing and identify defects in the quasi-periodic structure which may contribute to optical filtering and photonic band gap effects. The data gathered is used to simulate light propagation through the diatom structure at different incident angles and with different material properties and to verify data gathered experimentally.
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Den fabricerande människan : Om bedrägeri som vardaglig interaktionsform / The Fabricating Human Being : Deception as an Everyday Form of InteractionArvidson, Markus January 2007 (has links)
<p>The present dissertation takes the multi-faceted phenomenon of deception as its point of departure. The aim is to make a case for deception as a social phenomenon, and to frame theoretically and define the skills and abilities that make deception possible.</p><p>A theoretical model based on a number of ideal types is constructed. The purpose of the model is to differentiate particular aspects of deception, and the model is illustrated with examples of actions of more or less well-known impostors. The examples were collected from a variety of sources, such as autobiographies and television programs.</p><p>As a first step, the legal definition of deception, i.e. fraud, and statistics on crimes of deception in Sweden are presented. Different theoretical approaches are also discussed; deception as a personality trait, and deception as communication and interaction.</p><p>In order to illuminate the social dimensions, it is emphasized that deception constitutes a particular type of relationship between deceiver and deceivee. This particular form of interaction exploits elementary forms, and it is also asymmetrical in terms of the intentions of the parties involved.</p><p>The concept of social competence is used to describe the skills and abilities required for successful acts of deception. It is argued that the social competence of deceivers consists of three types: strategic, normative, and dramaturgic competencies. The strategic competency involves being goal-rational and strategic, for example, the ability to predict the actions of the potential addressee. In the normative competency, norms and reference to norms are used strategically. The dramaturgic competency represents an operationalization and enactment of the two other competencies, and resembles the preparation and performance of an actor.</p><p>The different contexts in which deception can occur are also discussed. A preliminary typology is presented, with the aim of demonstrating the difficulties in drawing clear lines between various types of deception. The extended approach to deception also means that it can be viewed as a part of everyday social interaction.</p><p>Finally, some thoughts on deception in the light of societal changes are presented. It is argued that the increasing demands on people to promote themselves in various ways in today’s society can be perceived as an invitation to deception and fabrication. These demands can generate feelings of inferiority and a fear of eventually being unmasked as an impostor, or a phony.</p>
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Fabrication and Characterization of Superconductive Coplanar Waveguide Resonators : Fabrication and Characterization of Superconductive Coplanar Waveguide ResonatorsErgül, Adem January 2009 (has links)
<p>The objective of this thesis is to evaluate a generic process for fabrication and characterization of the Superconductive coplanar waveguide (CPW) resonators. Superconductive CPW resonators with various lengths and shapes are designed to investigate their electrical and magnetic properties as well as resonance properties and sensitivities. In the first part of thesis, two different models are introduced in order to estimate the nonlinear kinetic inductance of a superconducting CPW resonator. The first model is based on Bean critical-state model and the second one is based on current dependence of London penetration depth. The existence of a shift in resonant frequency of Superconductive CPW resonator caused by a non-linear kinetic inductance is also shown experimentally. Simulations were carried out to estimate the nonlinear kinetic inductance due to the self- induced magnetic field penetration.</p><p>The rest of the thesis is concerned with development of very smooth Aluminum (Al) thin films with RMS (Root Mean Square) roughness 1~nm and CAD (Computer Aid Design) of superconductive CPW resonators. Experimental investigation of a generic fabrication technique for superconductive CPW resonator is carried out. Many resonators are fabricated with different design parameters, such as centerline or gap width, film thickness and gap capacitors length. The fabrication process is described in detail. Electron Beam Lithography is used to fabricate Nb and Al CPW resonators which are coupled to outer conductors via gap capacitors. We have fabricated GHz frequency CPW resonators with quality factors, Q up 5X10^5.</p>
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Étude d'un problème posé par les chaînes de fabricationQuilichini, Paul 28 June 1961 (has links) (PDF)
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The fabrication and evaluation of diamond cold cathodes for field emitter display applicationsFox, Neil Anthony January 1998 (has links)
No description available.
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Characterization of Optical Surface Grinding using Bound and Loose AbrasivesJohnson, James Ballard January 2011 (has links)
Large optical systems fabrication is a demanding task due to the tight requirements and big scales. To make mirrors up to 8.4m in diameter necessitates technological development in materials, tooling, and metrology. These advancements are designed to not only produce optics on a near-unheard of scale, but to improve fabrication methods with each piece.For an optical surface to be properly polished, the amount of material removed during polishing must be greater than the volume of damage left behind by the grinding process. Mixed-mode grinding, which combines bound abrasives with a compliant binder material, is a valuable tool at this stage as it creates less damage while maintaining a fast and uniform cutting rate than traditional loose abrasive grinding.These materials are challenging for large optical surfaces due to the honeycomb structures used to lightweight the mirrors. Development is done to adapt the abrasive to handle the very low pressures and speeds required to avoid imprinting structure on the optical surface.We take a comprehensive approach in measuring mixed-mode behavior using 3M Trizact™. Prior works on bound abrasives have focused on specific properties: removal rates, subsurface damage, etc. None have yet to look at the entire scope of the material and its benefits. These properties will be analyzed along with different behaviors regarding surface scattering, Twyman effect bending moments, glazing, manufacturing expenses, and failure mechanisms. This comprehensive understanding of the abrasive allows manufacturers to create better grinding schedules and reduce overall expenses in fabrication.Trizact shows up to a three times faster removal rate while producing 30\% less subsurface damage than loose abrasives of similar size. Additionally, the surface has scatters less light which can be adapted through changes in processing to create a specular reflection for optical surface metrology.Based on our findings, this type of abrasive integrates into current optical fabrication processes as a pre-polishing material. Here, the transition to these abrasives becomes cost effective by rapidly eliminating damage created during the generating of the surface and reducing the amount of polishing required.
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Fabrication of electron sources for a miniature scanning electron microscopeChen, Li January 1999 (has links)
No description available.
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InGaAs/GaAs self-organised quantum dot lasers : fabrication and characterisationBhattacharyya, Debabrata January 1999 (has links)
No description available.
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Preparation and characterization of superconducting Bi-2212/Ag composite tapesHuang, Sun-Li January 1996 (has links)
No description available.
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A critical appraisal of the design, fabrication and assessment of photonic structures in III-V semiconductorsRigby, Pauline January 1998 (has links)
No description available.
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