Modifying terahertz waveguide geometries: Bends, tapers, and grooves

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dc.contributor.advisorMittleman, Daniel M.en_US
dc.creatorAstley, Victoriaen_US
dc.date.accessioned2013-03-08T00:32:51Zen_US
dc.date.available2013-03-08T00:32:51Zen_US
dc.date.issued2012en_US
dc.description.abstractTerahertz waveguides are the focus of considerable research interest due to their potential for sensing, imaging and communications applications. Two of the most promising designs are the metal wire waveguide and the parallel-plate waveguide. The metal wire waveguide exhibits excellent low loss and low dispersion characteristics. However, the radiation is only weakly coupled to the wire and the beam extends a great distance from the waveguide, which can lead to high bending loss. In my research I show that this large beam extent also gives a high degree of flexibility in the geometry required to couple radiation into the waveguide or between waveguide sections. I also show that the traditional formalism of bending loss is incomplete, and that there is an optimum radius of curvature to reduce loss. The relationship between the beam extent and the radius of the wire presents the possibility of a tapered waveguide to confine the radiation as it propagates. I here present experimental data and simulations results to verify this subwavelength confinement at the tip of a tapered metal wire waveguide, which is of great interest for near-field imaging applications. The parallel-plate waveguide is another design frequently employed due to its low loss and low dispersion characteristics. Resonant structures may also be easily incorporated into the waveguide for sensing and filtering applications. One such structure is a single rectangular groove, which serves as a notch filter with a very narrow linewidth when the transverse-electric (TE) mode of the waveguide is excited, though its physical origin is poorly understood. In this work I present a detailed experimental and theoretical study of the rectangular resonant cavity in a TE-mode parallel-plate waveguide, particularly with respect to its potential as a microfluidic refractive index sensor. This study is extended to include the possibility of two grooves, in both coupled and non-coupled geometries, and their efficacy as multichannel or high-resolution single-channel microfluidic sensors.en_US
dc.format.extent209 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS PHYS. 2012 ASTLEYen_US
dc.identifier.citationAstley, Victoria. "Modifying terahertz waveguide geometries: Bends, tapers, and grooves." (2012) Diss., Rice University. <a href="https://hdl.handle.net/1911/70206">https://hdl.handle.net/1911/70206</a>.en_US
dc.identifier.digitalAstleyVen_US
dc.identifier.urihttps://hdl.handle.net/1911/70206en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectPure sciencesen_US
dc.subjectTerahertz waveguidesen_US
dc.subjectTapersen_US
dc.subjectBendsen_US
dc.subjectGroovesen_US
dc.subjectResonant cavityen_US
dc.subjectMode-matching analysisen_US
dc.subjectSommerfeld waveen_US
dc.subjectSuperfocusingen_US
dc.subjectPhysicsen_US
dc.subjectElectromagneticsen_US
dc.subjectOpticsen_US
dc.titleModifying terahertz waveguide geometries: Bends, tapers, and groovesen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentPhysicsen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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