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published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

The optical transmission characteristics of dielectric optical waveguides having directional changes is considered in this study. Experimental and theoretical loss results are presented for two types of waveguide bends. First is the corner bend where two straight waveguides are joined together at some angle. The second type is a curved waveguide having some radius of curvature. The loss mechanism is different for each type of bend. The corner bend is basically a scattering loss due to a mismatch of the modes of the two joining waveguides. The loss in the curved waveguide is due to radiation of the energy away from the waveguide as it propagates around the bend. The waveguides were fabricated by diffusing 3 μm wide 200 Å thick titanium strips into LiNbO₃. All of the curved portions of waveguide were joined by straight waveguides at the input and output of the curved waveguides. Rayleigh scattering and absorption loss was measured in the straight waveguides to determine their optical quality which yielded about 1.4 dB/cm. The loss due to corner bends was measured for angles from 0.1° to 3.0° in steps of 0.1°. The loss ranged from about 0.1 dB to 23 dB for 0.1° and 3.0° respectively. The results are slightly dependent upon the polarization of the light and the orientation of the LiNbO₃ crystal. The curved waveguides were fabricated in two different geometries. The first geometry was a straight waveguide joined by a curved portion and then joined by another straight waveguide. The second geometry is different from the first by another curved portion joining the first curved portion in between the two straight waveguides. The two curved portions are equal but have opposite curvature which have an S shape. The radiation loss was measured for radius of curvatures from 1.0 cm to 3.0 cm. The results ranged from 41 dB/cm to 1 dB/cm for 1.0 cm and 3.0 radius of curvatures respectively. At each of the straight to curved and curved to curved junctions there exists a mode mismatch loss. The straight to curved mode mismatch loss was 1.65 dB for R = 1 cm and 0.5 dB for R = 3 cm. The curved to curved mode mismatch loss was 6 dB for R = 1 cm and 0.5 for R = 3 cm. The results for the corner bends and the curved bends were used to study the constraints on integrated optical devices. In many integrated optical devices, it is necessary for two different straight portions of a single mode channel waveguide to be connected with a given amount of transverse offset. The experimental and theoretical results showed that for small transverse offsets the corner bend approach yields smaller loss. The curved bend (S bend) approach was better for larger transverse offsets. Theory was developed for this study of bending loss in titanium diffused LiNbO₃ waveguides. In general all of the experimental results agreed quite well with the theoretical predictions.

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The purpose of this study was to analyze Canadian Citizenship Guides as a proxy for an official policy voice of the Canadian government about what it means to be a Canadian citizen and what is expected from a Canadian citizen. This study analyzed six Canadian Citizenship Guides in the English language developed between 1947 and 2012 and identified how the selection of historical, governmental and social topics, and the use of different words and rhetorical strategies within each contemporary historical context constructed a narrative about what constitutes a Canadian citizen. To construct the narratives of Canadian citizen present in each Canadian Citizenship Guide, the study analysed the narratives about Canada, adaption to Canadian culture, and expected citizenship participation present in each guide. The study also sought continuities and disruptions in the narratives to explore how the narratives changed over time. The study concluded that while the narratives constructed by each guide (good character citizen, responsible citizen, wholesome citizen, politically active citizen, citizenship student, and loyal citizen) had unique elements, at the macro-level it could be said that from 1947 to 2012 there seemed to be more continuities than disruptions in the construction of the narratives of the Canadian citizen, and the narratives about Canada, adaption to Canadian culture, and expected citizenship participation.

Couplers that can couple light vertically between stacked waveguides are finding importance in the push towards higher density and lower cost optoelectronics. A compact grating coupler (12.8mum) designed by a former student is implemented in this project. The device is patterned by reactive-ion-etch into silicon-on-insulator with a 250 nm thick device layer, ensuring single mode operation. Alignment marks are patterned into the backside so that aligned bonding can be carried out. A die bonding recipe is developed using an intermediate adhesive film of SU-8-2. A novel approach to creating optically smooth input facets is included in the final steps of the process. Optical testing remains to be done.

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No description available.

The purpose of this study was to analyze Canadian Citizenship Guides as a proxy for an official policy voice of the Canadian government about what it means to be a Canadian citizen and what is expected from a Canadian citizen. This study analyzed six Canadian Citizenship Guides in the English language developed between 1947 and 2012 and identified how the selection of historical, governmental and social topics, and the use of different words and rhetorical strategies within each contemporary historical context constructed a narrative about what constitutes a Canadian citizen. To construct the narratives of Canadian citizen present in each Canadian Citizenship Guide, the study analysed the narratives about Canada, adaption to Canadian culture, and expected citizenship participation present in each guide. The study also sought continuities and disruptions in the narratives to explore how the narratives changed over time. The study concluded that while the narratives constructed by each guide (good character citizen, responsible citizen, wholesome citizen, politically active citizen, citizenship student, and loyal citizen) had unique elements, at the macro-level it could be said that from 1947 to 2012 there seemed to be more continuities than disruptions in the construction of the narratives of the Canadian citizen, and the narratives about Canada, adaption to Canadian culture, and expected citizenship participation.

No description available.