{"id":{"repo_id":"unm","oai_identifier":"oai:digitalrepository.unm.edu:ose_etds-1015"},"canonical_url":"https://search.dev.ndltd.org/etd/unm/oai:digitalrepository.unm.edu:ose_etds-1015","repository":{"repo_id":"unm","name":"University of New Mexico","base_url":"https://digitalrepository.unm.edu/do/oai/"},"display":{"title":"Ultrafast Broadband Terahertz Spectroscopy","abstract":"This dissertation centers on broadband terahertz spectroscopy and is arranged in four main sections. In the first section, we describe terahertz generation from a two-color laser air breakdown plasma. This is modeled with a plasma current that includes plasma density and dispersion in propagation. The terahertz spatial profile has a ring-like structure with a frequency dependent radius. Parameters for optimal terahertz generation are also presented. The next two sections discuss broadband terahertz detection techniques: optically biased coherent detection and electro-absorption in a semiconductor. The subject of the fourth section is terahertz imaging with electroabsorption. Optically biased coherent detection is distinguished from air-breakdown coherent detection by replacing the electrical bias for an optical field. The importance of phase control in this technique is demonstrated. In addition, we found the terahertz-induced second harmonic to be spectrally delay-dependent. This is due to the phase matching condition and is discussed in detail. Terahertz-induced electro-absorption is performed in GaAs/AlGaAs multiple double quantum wells and an AlGaAs bulk semiconductor. To the best of the author's knowledge, this is the first demonstration of large modulation induced by a single cycle terahertz pulse in such structures. The underlying mechanism is identified as the Franz-Keldysh effect that has been successfully modeled in both the temporal and spectral regimes. Terahertz imaging of the plasma profile is accomplished with electro-absorption in these structures. The observed ring pattern is reproduced with the model described in the first section of this dissertation. Terahertz raster scan imaging of a large object is also presented.","abstract_html":"This dissertation centers on broadband terahertz spectroscopy and is arranged in four main sections. In the first section, we describe terahertz generation from a two-color laser air breakdown plasma. This is modeled with a plasma current that includes plasma density and dispersion in propagation. The terahertz spatial profile has a ring-like structure with a frequency dependent radius. Parameters for optimal terahertz generation are also presented. The next two sections discuss broadband terahertz detection techniques: optically biased coherent detection and electro-absorption in a semiconductor. The subject of the fourth section is terahertz imaging with electroabsorption. Optically biased coherent detection is distinguished from air-breakdown coherent detection by replacing the electrical bias for an optical field. The importance of phase control in this technique is demonstrated. In addition, we found the terahertz-induced second harmonic to be spectrally delay-dependent. This is due to the phase matching condition and is discussed in detail. Terahertz-induced electro-absorption is performed in GaAs/AlGaAs multiple double quantum wells and an AlGaAs bulk semiconductor. To the best of the author's knowledge, this is the first demonstration of large modulation induced by a single cycle terahertz pulse in such structures. The underlying mechanism is identified as the Franz-Keldysh effect that has been successfully modeled in both the temporal and spectral regimes. Terahertz imaging of the plasma profile is accomplished with electro-absorption in these structures. The observed ring pattern is reproduced with the model described in the first section of this dissertation. Terahertz raster scan imaging of a large object is also presented.","abstract_has_math":false,"creators":["Li, Chia-Yeh"],"institution":null,"degree_name":"Optical Science and Engineering","degree_level":"Doctoral","degree_discipline":"Optical Science and Engineering","degree_department":null,"school":null,"contributors":["Shiek-Bahae, Mansoor","Malloy, Kevin","Hayat, Majeed","Jeffrey, Cederberg"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-06-09T07:00:00Z","date_published":"2016-06-09T07:00:00Z","updated_at":"2026-07-24T05:26:35Z","subjects":[],"languages":["English"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalrepository.unm.edu/ose_etds/16"],"render_values":[{"text":"https://digitalrepository.unm.edu/ose_etds/16","href":"https://digitalrepository.unm.edu/ose_etds/16","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1928/32316","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Shiek-Bahae, Mansoor","Malloy, Kevin","Hayat, Majeed","Jeffrey, Cederberg"]},{"key":"dc:creator","label":"Author","values":["Li, Chia-Yeh"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Optical Science and Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral","Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Optical Science and Engineering"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/1928/32316","https://digitalrepository.unm.edu/ose_etds/16"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This dissertation centers on broadband terahertz spectroscopy and is arranged in four main sections. In the first section, we describe terahertz generation from a two-color laser air breakdown plasma. This is modeled with a plasma current that includes plasma density and dispersion in propagation. The terahertz spatial profile has a ring-like structure with a frequency dependent radius. Parameters for optimal terahertz generation are also presented. The next two sections discuss broadband terahertz detection techniques: optically biased coherent detection and electro-absorption in a semiconductor. The subject of the fourth section is terahertz imaging with electroabsorption. Optically biased coherent detection is distinguished from air-breakdown coherent detection by replacing the electrical bias for an optical field. The importance of phase control in this technique is demonstrated. In addition, we found the terahertz-induced second harmonic to be spectrally delay-dependent. This is due to the phase matching condition and is discussed in detail. Terahertz-induced electro-absorption is performed in GaAs/AlGaAs multiple double quantum wells and an AlGaAs bulk semiconductor. To the best of the author's knowledge, this is the first demonstration of large modulation induced by a single cycle terahertz pulse in such structures. The underlying mechanism is identified as the Franz-Keldysh effect that has been successfully modeled in both the temporal and spectral regimes. Terahertz imaging of the plasma profile is accomplished with electro-absorption in these structures. The observed ring pattern is reproduced with the model described in the first section of this dissertation. Terahertz raster scan imaging of a large object is also presented."]},{"key":"dc:title","label":"Title","values":["Ultrafast Broadband Terahertz Spectroscopy"]}]}],"canonical_facts":{"dc:contributor":["Shiek-Bahae, Mansoor","Malloy, Kevin","Hayat, Majeed","Jeffrey, Cederberg"],"dc:creator":["Li, Chia-Yeh"],"dc:description.abstract":["This dissertation centers on broadband terahertz spectroscopy and is arranged in four main sections. In the first section, we describe terahertz generation from a two-color laser air breakdown plasma. This is modeled with a plasma current that includes plasma density and dispersion in propagation. The terahertz spatial profile has a ring-like structure with a frequency dependent radius. Parameters for optimal terahertz generation are also presented. The next two sections discuss broadband terahertz detection techniques: optically biased coherent detection and electro-absorption in a semiconductor. The subject of the fourth section is terahertz imaging with electroabsorption. Optically biased coherent detection is distinguished from air-breakdown coherent detection by replacing the electrical bias for an optical field. The importance of phase control in this technique is demonstrated. In addition, we found the terahertz-induced second harmonic to be spectrally delay-dependent. This is due to the phase matching condition and is discussed in detail. Terahertz-induced electro-absorption is performed in GaAs/AlGaAs multiple double quantum wells and an AlGaAs bulk semiconductor. To the best of the author's knowledge, this is the first demonstration of large modulation induced by a single cycle terahertz pulse in such structures. The underlying mechanism is identified as the Franz-Keldysh effect that has been successfully modeled in both the temporal and spectral regimes. Terahertz imaging of the plasma profile is accomplished with electro-absorption in these structures. The observed ring pattern is reproduced with the model described in the first section of this dissertation. Terahertz raster scan imaging of a large object is also presented."],"dc:identifier":["http://hdl.handle.net/1928/32316","https://digitalrepository.unm.edu/ose_etds/16"],"dc:language":["English"],"dc:title":["Ultrafast Broadband Terahertz Spectroscopy"],"thesis:degree_discipline":["Optical Science and Engineering"],"thesis:degree_level":["Doctoral","Dissertation"],"thesis:degree_name":["Optical Science and Engineering"]},"updated_at":"2026-07-24T05:26:35Z"}