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dc.contributor.advisorHarrison, Barry
dc.contributor.authorPowell, Ollyen_US
dc.date.accessioned2018-01-23T02:20:25Z
dc.date.available2018-01-23T02:20:25Z
dc.date.issued2004en_US
dc.identifier.doi10.25904/1912/1215
dc.identifier.urihttp://hdl.handle.net/10072/365595
dc.description.abstractThe conventional large radii bends used in large cross section silicon-on-insulator waveguides were replaced with novel wet etched corner mirrors, potentially allowing much smaller devices, therefore lower costs. If such corners had been based on reactive ion etch techniques they would have had the disadvantage of rougher surfaces and poor alignment in the vertical direction. Wet etching overcomes these two problems by providing smooth corner facets aligned precisely to the vertical {100} silicon crystallographic planes. The waveguides obtained had angled walls, and so numerical analysis was undertaken to establish the single mode condition for such trapezoidal structures. To show the relationship between fabrication tolerances and optical losses a three dimensional simulation tool was developed, based on expansion of the incident mode into plane waves. Various new fabrication techniques were are proposed, namely: the use of titanium as a mask for deep silicon wet anisotropic etching, a technique for aligning masks to the crystal plane on silicon-oninsulator wafers, a corner compensation method for sloping sidewalls, and the suppression of residues and pyramids with the use of acetic acid for KOH etching. Also, it was shown that isopropyl alcohol may be used in KOH etching of vertical walls if the concentration and temperature are sufficiently high. As the proposed corner mirrors were convex structures the problem of undercutting by high order crystal planes arose. This was uniquely overcome by the addition of some structures to effectively convert the convex structures into concave ones. The corner mirrors had higher optical losses than were originally hoped for, similar to those of mirrors in thin film waveguides made by RIE. The losses were possibly due to poor angular precision of the lithography process. The design also failed to provide adequate mechanisms to allow the etch to be stopped at the optimal time. The waveguides had the advantage over thin film technology of large, fibre-compatible cross sections. However the mirror losses must be reduced for the technology to compete with existing large cross section waveguides using large bends. Potential applications of the technology are also discussed. The geometry of the crystal planes places fundamental limits on the proximity of any two waveguides. This causes some increase in the length of MMI couplers used for channel splitting. The problem could possibly be overcome by integrating one of the mirrors into the end of the MMI coupler to form an L shaped junction.en_US
dc.languageEnglishen_US
dc.publisherGriffith Universityen_US
dc.publisher.placeBrisbaneen_US
dc.rights.copyrightThe author owns the copyright in this thesis, unless stated otherwise.en_US
dc.subject.keywordssilicon-on-insulator waveguidesen_US
dc.subject.keywordssilicon optical waveguidesen_US
dc.subject.keywordsmicro-mirrorsen_US
dc.subject.keywordswet etchingen_US
dc.subject.keywordsreactive ion etchingen_US
dc.titleFabrication of Micro-Mirrors in Silicon Optical Waveguidesen_US
dc.typeGriffith thesisen_US
gro.rights.copyrightThe author owns the copyright in this thesis, unless stated otherwise.
gro.hasfulltextFull Text
dc.rights.accessRightsPublicen_US
gro.identifier.gurtIDgu1316474293800en_US
gro.identifier.ADTnumberadt-QGU20040719.115224en_US
gro.source.ADTshelfnoADT0en_US
gro.source.GURTshelfnoGURTen_US
gro.thesis.degreelevelThesis (PhD Doctorate)en_US
gro.thesis.degreeprogramDoctor of Philosophy (PhD)en_US
gro.departmentSchool of Microelectronic Engineeringen_US
gro.griffith.authorPowell, Oliver J.


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