Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 444 for “"Bragg"”.
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Microscopic characterisation of fibre Bragg gratings
… characterization of optical fibres and fibre Bragg gratings, by the use of a non-invasive microscopic technique, namely differential interference contrast microscopy. The thesis aims to provide detailed information on the structural and optical properties of optical fibres and fibre Bragg …
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Bragg grating filters for optical networks
This thesis focuses on the exploitation of fibre Bragg gratings in optical communication networks. New designs, as well as procedures for dynamically altering grating characteristics are proposed for several important functions. We begin with designing gratings for flattening the gain profile of an …
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Strain sensor using fiber bragg grating interrogation
… a novel design of strain sensor using Fiber Bragg Grating (FBG) interrogation. Studies on fiber optic sensors reported have mainly focused on FBG wavelength-based monitoring method by using optical spectrum analyzers (OSA). Although FBG has better strain sensitivity measurement, however there …
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Optofluidic Bragg grating sensors for chemical detection
… and potential applications of direct UV written Bragg grating refractometers for detection of chemical analytes. The technique of direct UV writing uses the localised refractive index increase of a photosensitive planar glass layer upon exposure to a tightly focussed UV beam to fabricate a wide …
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Monitorización estructural SHM mediante redes de Bragg.
… de disponibilidad tecnológico de las redes de Bragg como sensor principal en sistemas de monitorización de estructuras aeronáuticas. Se trata de sensores precisos, fiables, “embebibles”, inertes a la radiación electromagnética, fácilmente multiplexables, etc. La monitorización mediante redes de …
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Integrated Fiber Bragg Sensors for aersoapce applications
L'abstract è presente nell'allegato / the abstract is in the attachment
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Integrated chirped Bragg gratings for dispersion control
… device for this purpose. A monolithic chirped Bragg grating is presented with dispersion and bandwidth characteristics coinciding with the previously mentioned regimes. The device, based on a deeply etched tapered waveguide design, may be fabricated fully post-growth, lending it a significant …
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Fabrication and applications of fibre Bragg gratings
The consequences of fabricating Bragg gratings in various fibres, with or without hydrogen loading, and with varying laser power levels are explored. Three new techniques for fabricating chirped gratings are presented. Beams with dissimilar wavefront curvatures are interfered to give chirped …
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Resonant cavity Fibre Bragg grating sensor interrogation
… to time-division-multiplexing (TDM) fibre Bragg grating (FBG) optical sensors, known as the resonant cavity architecture. A background theory of FBG optical sensing includes several techniques for multiplexing sensors. The limitations of current wavelength-division-multiplexing (WDM) …
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Intragrating sensing using chirped optical fibre Bragg gratings
… sensing systems employing chirped fibre Bragg gratings (CFBGs) are investigated. Intragrating sensing is the process of obtaining a continuous profile of a measurand over the grating length from either the amplitude or phase, or both the amplitude and phase of its measured reflection …
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Passive and active Bragg gratings for optical networks
This thesis investigates fibre Bragg grating (FBG) devices. Specifically, it consists of the developments and applications of two groups of devices: the optical phase en/decoders and the tunable fibre Bragg gratings based on an S-bending technique. The advantage of an S-bending tuning FBG is that …
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Advanced fibre Bragg grating structures: design and application
… work on a variety of advanced fibre Bragg grating structures covering long dispersion compensating chirped Bragg gratings, superstructured Bragg gratings for identical multiple channel operation, Bragg gratings for pulse-shaping applications and Bragg gratings for add-drop …
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Chloride Selective Gold Coated Fiber Bragg Grating Sensor
… aims at a chloride-sensitive gold-plated Fiber Bragg Grating (FBG) sensor that can detect chloride with good resolution. This sensor is designed for applications in water treatment plants and swimming pools where safety and quality matter. And for better results, we use Atomic Layer Deposition …
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Fibre bragg gratings for microwave photonics and sensing
… of microwave transversal filters using fibre Bragg grating arrays and the building of fibre Bragg grating based magnetic-field sensors. Some theoretical background about fibre Bragg gratings, photosensitivity, fibre Bragg grating sensors and filters are presented. Fibre Bragg grating sensors …
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Advanced Fibre Bragg Grating fabrication systems and devices
This thesis address the creation of fibre Bragg grating based sensors and the fabrication systems which are used to manufacture them. The information is presented primarily with experimental evidence, backed up with the current theoretical concepts. The issues involved in fabricating high quality …
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Theory and fabrication of colloidal-crystal Bragg filters
… parameters, is developed for colloidal-crystal Bragg filters. The coupling constant, for coupled-wave equations, is derived to produce filter spectra. The spectra are modified by convolving with a Gaussian function to represent crystal defects. Scattering losses are calculated to attenuate the …
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Fiber Bragg Gratings Strain Sensors for Railway Applications
… to their electrical counterparts. A fiber Bragg grating (FBG) strain sensor has been employed for this study to detect and distinguish normal and lateral loads on rail tracks. A theoretical analysis of the relationship between strain and displacement under vertical and horizontal strains on …
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Integrated optical filters using Bragg gratings and resonators
… study of optical filters made using integrated Bragg gratings and Bragg resonators. Various topologies for making add/drop filters using integrated gratings are outlined. Each class of devices is studied in detail and the theoretical tools needed for designing the add/drop are developed. …
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Microscopic and spectral characterisation of optical Fibre Bragg gratings
Fibre Bragg gratings (FBGs) have found extensive application in lasers, amplifiers, signal filtering in telecommunications and sensing. The underlying mechanisms and fundamental properties of FBGs are not completely understood, which stands in the way of full exploitation of FBG-based devices …
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