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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Molecular beam epitaxial growth of CdTe and HgCdTe for new infrared and optoelectronic devices

Wagner, Brent K. 08 1900 (has links)
No description available.
32

Crosslinkable Light Emitting Conjugate and Metallocene Polymers: Synthesis, Properties and Application

McDowell, Jeffrey 13 January 2014 (has links)
Numerous semiconductive organic materials are actively being pursued for application in sensing and electronics. Chapter one introduces conjugated polymers (CPs) and their many useful properties, including electroluminescence, which has helped foster growing demand for these materials in low-power organic light emitting diodes (OLED) for solid state lighting and additionally polychromatic displays. In the second chapter of this dissertation, we develop the concept of digrignard scavengers for use in nickel catalyst transfer polymerization of diarylmagnesate monomers into conjugate polymers within a unique mixed THF/1,4-Dioxane solvent system. Our initial findings include a polymerization method which permits the formation of an electronics grade copolymer with molecular weights in excess of Mn = 50 kg/mol within 15 minutes using a scalable, room temperature method. In chapter three, we discuss the synthesis and characterization of Polysilafluorenes (PSFs), which are an important class of light-emitting conjugate polymers noted for their characteristic brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and improved thermal stability. In chapter four, we present a protocol for photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 10 μm. The resultant crosslinked material possess characteristic blue photoluminescence with solid state quantum yields > 80%. In chapter five, we present a protocol for 3-D photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 200 nm using two photon direct laser writing techniques. In chapter six, we present a unique deep blue emitting copolymer, poly(3,6-dimethoxy-9.9`-dihexylsilafluorene-co-3.6-dimethoxy-2’,3’,6’,7’-tetrahexyloxy-9,9-spiro-9-silabifluorene) (PHSSF-co-PDHSF), which exhibits brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and thermal stability. In chapter seven, we explore crosslinked conductive metallocene polymer networks that mediate chemical, electronic and mechanical signals.
33

Crosslinkable Light Emitting Conjugate and Metallocene Polymers: Synthesis, Properties and Application

McDowell, Jeffrey 13 January 2014 (has links)
Numerous semiconductive organic materials are actively being pursued for application in sensing and electronics. Chapter one introduces conjugated polymers (CPs) and their many useful properties, including electroluminescence, which has helped foster growing demand for these materials in low-power organic light emitting diodes (OLED) for solid state lighting and additionally polychromatic displays. In the second chapter of this dissertation, we develop the concept of digrignard scavengers for use in nickel catalyst transfer polymerization of diarylmagnesate monomers into conjugate polymers within a unique mixed THF/1,4-Dioxane solvent system. Our initial findings include a polymerization method which permits the formation of an electronics grade copolymer with molecular weights in excess of Mn = 50 kg/mol within 15 minutes using a scalable, room temperature method. In chapter three, we discuss the synthesis and characterization of Polysilafluorenes (PSFs), which are an important class of light-emitting conjugate polymers noted for their characteristic brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and improved thermal stability. In chapter four, we present a protocol for photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 10 μm. The resultant crosslinked material possess characteristic blue photoluminescence with solid state quantum yields > 80%. In chapter five, we present a protocol for 3-D photopatterning derivatives of poly(3,6-dimethoxy-9,9-dialkylsilafluorenes) with resolutions exceeding 200 nm using two photon direct laser writing techniques. In chapter six, we present a unique deep blue emitting copolymer, poly(3,6-dimethoxy-9.9`-dihexylsilafluorene-co-3.6-dimethoxy-2’,3’,6’,7’-tetrahexyloxy-9,9-spiro-9-silabifluorene) (PHSSF-co-PDHSF), which exhibits brilliant solid state blue luminescence, high quantum efficiency, excellent solubility and thermal stability. In chapter seven, we explore crosslinked conductive metallocene polymer networks that mediate chemical, electronic and mechanical signals.
34

Alignment of lines in space (with particular reference to laser-fibre coupling)

Opono-Moyahi-Okello, John A. January 1987 (has links)
The object of this work (featuring the study of alignment of lines in space) is to produce a novel system for automatic production of optoelectronic components. It begins by reviewing the different components associated with optical fibre transmission and examines the existing laser-fibre coupling methods. The manual alignment technique adopted by STC to align a laser beam with a monomode optical fibre is then presented. The various interpretations of alignment are explored. The results obtained from the analysis determine the type of manipulator required for laser to optical fibre coupling. The central axis of a divergent beam emitted by a semi-conductor laser diode is manipulated for alignment with the axis of the fibre. Such an alignment places stringent displacement tolerance and accuracy demands on the manipulator. To construct a manipulator, actuators need to be coupled together. The coWling methods are studied and presented. Prior to this study, commercially available actuators are surveyed leading to the selecticin of the Oriel Encoder Mike actuator. This actuator exhibits some inherent control problems but meets the laser-fibre coupling accuracy demands. Various types of couplings are also examined based on the expansion of the Kelvin coupling for the construction of a four degree of freedom manipulator. A computational algorithm analogous to that used to solve two plane balancing problems is sucessfully tested on this manipulator for alignment of a conventional He-Ne laser beam with the centres of two transparent screens. This algorithm requires linearity for its success. For this reason and for purposes of completeness, spatial displacement characteristics of the manipulator are analysed and confirmed experimentally. This work ends with the ocnstruction. and testing of a program based on a hill climbing technique for the control of a three degree of freedom (Oriel Encoder Mike) manipulator to align a laser beam emitted by a semi-conductor laser diode with a monomode optical fibre.
35

Development of an optoelectronic holographic otoscope system for characterization of sound-induced displacements in tympanic membranes

Hulli, Nesim. January 2009 (has links)
Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: tympanic membrane; optoelectronic holography; otoscope; stroboscopic holography; interferometry. Includes bibliographical references (leaves 62-68).
36

Optical properties of intermixed quantum wells and its application in photodetectors /

Lee, Siew-wan, Alex. January 1999 (has links)
Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 201-202).
37

High-performance ultraviolet photodetectors fabricated on single-crystal GaN /

Carrano, John Con, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 171-186). Available also in a digital version from Dissertation Abstracts.
38

Optimization of charge collection efficiency in MSM photodetector

Kache, Sravanthi. January 2005 (has links)
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 12, 2006) Includes bibliographical references.
39

Investigation into the monitoring of microwaves in microwave cavities using optical techniques

Matasane, Matasane Clement January 2002 (has links)
Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002. / Tne purpose of this research or study was to perform an investigation in the use of optical fibers as sensor elements in order to develop a millimetre wave instrument capable of measuring microwave power within microwave cavities. Included in the scope of the project was an investigation of microwaves and microwave power measurements techniques. The emphasis of the research work was to develop expertise in photonics, by modeling and developing a measuring technique using optical techniques. This was deemed to be highly beneficial in laboratory experimentation and for possible use by microwave technicians. The implementation was amongst others, done by means of computer simulation and associated hardware, together with fiber-optic accessories. In order to conduct this research a literature and technology survey of current non-optical microwave power measurement technique was done. With this a review different power measurements systems and their relationship towards microwave power measurements was conducted. Within the scope of the project, a study of fiber optics sensors and its components was also conducted, which enabled models for a Mach-Zehnder microwave sensor to be developed. This resulted in the development of inexpensive electronic signal conditioning and detection techniques to enable measurements that employed a Mach-Zehnder Interferometer for this sensor technique. Finally, as microwaves are difficult to measure with pure electronic equipment, different approaches were made to investigate the temperature changes and other parameters on optical fiber to avoid damage to it. The specifications of hardware and circuitry suitable to measure these effects were determined.
40

Improving the performance of organic optoelectronic devices by optimizing device structures

Kwong, Chung-yin, Calvin., 鄺頌賢. January 2004 (has links)
published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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