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 25 for “"fibre bragg grating"”.
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Resonant cavity Fibre Bragg grating sensor interrogation
… approach 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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Advanced fibre Bragg grating structures: design and application
… and computational 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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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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Low-cost interrogation of optical fibre Bragg grating sensors
… compare different algorithms for resolving the Bragg wavelength from a low resolution discrete representation of the reflected spectrum, and present optimal processing methods for providing a high integrity measurement from the reflection image. Our second sensing scheme uses a novel network of …
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Fibre Bragg grating temperature sensors for high-speed machining applications
… greater performance. The optical sensors are fibre Bragg grating based and the optical techniques used to interrogate that sensor include DWDM, WDM, athermic grating, tuneable grating and coupler. Optical fibre devices are simpler to place in situ prior to the machining tests and they offer …
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Gamma irradiation response of photonic crystal and standard optical fibre Bragg grating sensors for radiation dosimetry
This study investigates the use of Optical Fibre Bragg Grating Sensors (FBGs) for Gamma Radiation Dosimetry. A comparative analysis of responses to gamma irradiation between standard commercial FBGs and new generation FBGs written in Photonic Crystal fibre (PCF) were examined under similar regimes …
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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 …
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Interrogation of fibre optic sensors
… thesis was to investigate the interrogation of fibre optic sensors using "off the shelf optical components and equipment developed mainly for the telecommunications industry. This provides a cost effective way of bringing fibre optic sensor systems to within the price range of their …
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Applications of superstructure fibre Bragg gratings for optical code division multiple access and packet switched networks
… and recognition based on superstructure fibre Bragg grating (SSFBG) for use in Optical Code Division Multiple Access (OCDMA) systems and also in high-speed all-optical packet switched networks.These results highlight the precision and flexibility of the continuous grating writing process …
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On a dual wavelength optical sensor system for measuring strain and temperature simultaneously in tokamak port plug
… and radiation effects. An optical fibre sensor was constructed to a strain resolution of ±10uε and temperature resolution of ±5°C. The fibre sensor is an off the shelf solution dual-wavelength fibre Bragg grating. The thesis proposes a method of coating the fibre in layers of silver …
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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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Thulium-doped fibre laser in the 2 μm wavelength region for gas sensing
… features of the gases of interest. Well-designed fibre laser-based systems, however, can overcome this limitation by offering potentially much wider wavelength ranges, coupled with their distinctive and valuable features such as stability, narrow linewidth and high tuneability at room temperature. …
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Fibre gratings in novel optical fibres for applications in sensing
This thesis presents the fabrication of fibre gratings in novel optical fibres for sensing applications. Long period gratings have been inscribed into photonic crystal fibre using the electric-arc technique. The resulting sensing characteristics were found to depend on the air-hole geometry of the …
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Investigation of code reconfigurable fibre Bragg gratings for Optical Code Division Multiple Access (OCDMA) and Optical Packet Switching (OPS) Networks
… and all-optical packet switching nodes based on fibre Bragg grating (FBG) technology. My research work involves characterizing the performance of various gratings, specifically high reflectivity, short chip duration, long code sequences, multiple phase level and tunable superstructured fiber …
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Measurement of the local optical phase and amplitude in photonic devices using scanning near-field microscopy
… The optical field distribution within a fibre Bragg grating is investigated as a function of wavelength. This work details the direct observation of the spatial shift of the standing wave across the stop band of a fibre grating. The shift is an explicit feature of fibre Bragg gratings and …
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All-optical nonlinear signal processing devices and their applications within fibre-optic communication systems
… into the development of a range of all-optical fibre based nonlinear devices for optical communication applications. The research can he divided into two main themes. The first concerns the use nf superstructured fibre Bragg grating technology together with fibre based nonlinear devices to …
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Distributed feedback fibre laser strain and temperature sensors
… types of polarimetric distributed feedback (DFB) fibre laser sensors for simultaneous strain and temperature measurements. These fibre Bragg grating (FBG) based sensors offer strain and temperature measurement accuracies of ±0.3 - ±15 µ.epsilon and ±0.04 - ±0.2°C which are suitable for many …
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Structural health monitoring of onshore wind turbine foundations
… thesis demonstrates the application of optical fibre Bragg grating (FBG) strain sensors for crack displacement monitoring on an operational wind turbine foundation. The primary original contribution to knowledge of this work is the development of a novel methodology in order to categorize and …
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Exploitation of fibre characteristics in temperature sensing and radio-over-fibre applications
… development of microelectronic sensors, optical fibre sensors are widely investigated because of their advantageous properties over the electronics sensors such as their wavelength multiplexing capability and high sensitivity to temperature, pressure, strain, vibration and acoustic emission. …
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