UBC Theses and Dissertations
Integrated optical devices in lithium niobate Jaeger, Nicolas August Fleming
A class of integrated optical devices is based on light propagation in optical channel waveguides. It includes optical modulators such as the integrated Mach-Zehnder (IMZ). Many applications have been proposed for such integrated optical devices. The present work was motivated by a proposed application to voltage determination on high voltage lines, for example, SF₆ bus ducts in Hydro substations. For the voltage measurement application two device types were proposed. The first includes devices using capacitive voltage dividers. A novel divider for the SF₆ bus duct application was proposed using a LiNbO₃ wafer into which an IMZ could be built to give an integrated unit. Time permitted the divider to be tested only using a separate IMZ. The second type of device includes Immersion devices. Two novel immersion devices are proposed and their theory is developed. IMZs were made for the demonstrated, high voltage sensor, by diffusing Ti into LiNbO₃. Much effort was put into solving a sequence of experimental obstacles including the elimination of Li₂O out-diffusion (which causes a waveguide to be produced on the whole surface), the polishing of the LiNbO₃ crystals and optical fibers, and the butt coupling of the fibers to the crystals. In the end IMZs were fabricated with state-of-the-art extinction ratios. A third device, employing voltage induced waveguides, was proposed and was demonstrated. A mathematical treatment of the theory of the IMZ is provided.
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