III-nitride nanowire lasers have drawn significant attention as potential compact coherent light sources for a wide range of applications such as on-chip communication, optical sensing, and solid-state lighting. For practical applications, control over the lasing properties is needed. For example, a single mode lasing is beneficial for reducing the pulse broadening and the signal errors during the optical communications. An annular-shaped beam could be potentially used for the atom trapping or the stimulated emission depletion spectroscopy. The polarization-sensitive on-chip optical components also require linear polarization. However, due to the compact size of nanowire lasers and the cross-sectional symmetry of the traditional nanowire lasers, controlling the lasing properties still remains challenging. A top-down two-step etch process developed for vertical GaN nanowires offers the ability to precisely control the cross-section of the nanowire lasers. Consequently, the lasing properties can potentially be tailored by controlling the cross-section. In this dissertation, annular-shaped emission was demonstrated from GaN nanotube lasers with optical pumping at room temperature, consistent with finite-difference time-domain simulation results. Linearly polarized lasing emission was also realized from rectangular cross-sectioned GaN nanowire lasers. When the shorter y-dimension is ~120 nm, the rectangular cross-section creates a large contrast of the effective index of refraction, resulting in higher transverse confinement factors for the y-polarized modes than for the x-polarized modes. In order to pursue electrically injected single III-nitride nanowire lasers, non-polar InGaN/GaN multi-quantum-wells core-shell nanowires were fabricated by a combination of the top-down two-step etch process and a regrowth process. Lasing was observed from the core-shell nanowires by optical pumping at room temperature. A Hakki-Paoli measurement shows high modal gains of the non-polar core-shell nanowire lasers and the non-uniform gains resulting from the inhomogeneous regrowth. As a step towards electrical pumping, a Ti ohmic like' contact to the n-GaN core was fabricated. However, because of the lack of the ohmic contact to the p-GaN shell, the injection efficiency was extremely limited. As a result, instead of electrically-driven lasing, only weak spontaneous emission was observed in the electroluminescence measurement.'
","abstract_html":"<p>III-nitride nanowire lasers have drawn significant attention as potential compact coherent light sources for a wide range of applications such as on-chip communication, optical sensing, and solid-state lighting. For practical applications, control over the lasing properties is needed. For example, a single mode lasing is beneficial for reducing the pulse broadening and the signal errors during the optical communications. An annular-shaped beam could be potentially used for the atom trapping or the stimulated emission depletion spectroscopy. The polarization-sensitive on-chip optical components also require linear polarization. However, due to the compact size of nanowire lasers and the cross-sectional symmetry of the traditional nanowire lasers, controlling the lasing properties still remains challenging. A top-down two-step etch process developed for vertical GaN nanowires offers the ability to precisely control the cross-section of the nanowire lasers. Consequently, the lasing properties can potentially be tailored by controlling the cross-section. In this dissertation, annular-shaped emission was demonstrated from GaN nanotube lasers with optical pumping at room temperature, consistent with finite-difference time-domain simulation results. Linearly polarized lasing emission was also realized from rectangular cross-sectioned GaN nanowire lasers. When the shorter y-dimension is ~120 nm, the rectangular cross-section creates a large contrast of the effective index of refraction, resulting in higher transverse confinement factors for the y-polarized modes than for the x-polarized modes. In order to pursue electrically injected single III-nitride nanowire lasers, non-polar InGaN/GaN multi-quantum-wells core-shell nanowires were fabricated by a combination of the top-down two-step etch process and a regrowth process. Lasing was observed from the core-shell nanowires by optical pumping at room temperature. A Hakki-Paoli measurement shows high modal gains of the non-polar core-shell nanowire lasers and the non-uniform gains resulting from the inhomogeneous regrowth. As a step towards electrical pumping, a Ti ohmic like' contact to the n-GaN core was fabricated. However, because of the lack of the ohmic contact to the p-GaN shell, the injection efficiency was extremely limited. As a result, instead of electrically-driven lasing, only weak spontaneous emission was observed in the electroluminescence measurement.'</p>","abstract_has_math":false,"creators":["Li, Changyi"],"institution":null,"degree_name":"Optical Science and Engineering","degree_level":"Doctoral","degree_discipline":"Optical Science and Engineering","degree_department":null,"school":null,"contributors":["Brueck, Steven","Wang, George","Feezell, Daniel","Dawson, Ralph"],"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":["Other Engineering"],"languages":["English"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalrepository.unm.edu/ose_etds/15"],"render_values":[{"text":"https://digitalrepository.unm.edu/ose_etds/15","href":"https://digitalrepository.unm.edu/ose_etds/15","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1928/32315","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brueck, Steven","Wang, George","Feezell, Daniel","Dawson, Ralph"]},{"key":"dc:creator","label":"Author","values":["Li, Changyi"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2018-05-16T07:00:00Z"]},{"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":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Other 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/1928/32315","https://digitalrepository.unm.edu/ose_etds/15"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["III-nitride nanowire lasers have drawn significant attention as potential compact coherent light sources for a wide range of applications such as on-chip communication, optical sensing, and solid-state lighting. For practical applications, control over the lasing properties is needed. For example, a single mode lasing is beneficial for reducing the pulse broadening and the signal errors during the optical communications. An annular-shaped beam could be potentially used for the atom trapping or the stimulated emission depletion spectroscopy. The polarization-sensitive on-chip optical components also require linear polarization. However, due to the compact size of nanowire lasers and the cross-sectional symmetry of the traditional nanowire lasers, controlling the lasing properties still remains challenging. A top-down two-step etch process developed for vertical GaN nanowires offers the ability to precisely control the cross-section of the nanowire lasers. Consequently, the lasing properties can potentially be tailored by controlling the cross-section. In this dissertation, annular-shaped emission was demonstrated from GaN nanotube lasers with optical pumping at room temperature, consistent with finite-difference time-domain simulation results. Linearly polarized lasing emission was also realized from rectangular cross-sectioned GaN nanowire lasers. When the shorter y-dimension is ~120 nm, the rectangular cross-section creates a large contrast of the effective index of refraction, resulting in higher transverse confinement factors for the y-polarized modes than for the x-polarized modes. In order to pursue electrically injected single III-nitride nanowire lasers, non-polar InGaN/GaN multi-quantum-wells core-shell nanowires were fabricated by a combination of the top-down two-step etch process and a regrowth process. Lasing was observed from the core-shell nanowires by optical pumping at room temperature. A Hakki-Paoli measurement shows high modal gains of the non-polar core-shell nanowire lasers and the non-uniform gains resulting from the inhomogeneous regrowth. As a step towards electrical pumping, a Ti ohmic like' contact to the n-GaN core was fabricated. However, because of the lack of the ohmic contact to the p-GaN shell, the injection efficiency was extremely limited. As a result, instead of electrically-driven lasing, only weak spontaneous emission was observed in the electroluminescence measurement.'
"]},{"key":"dc:title","label":"Title","values":["Top-down Cross-Section Controlled III-Nitride Nanowire Lasers"]}]}],"canonical_facts":{"dc:contributor":["Brueck, Steven","Wang, George","Feezell, Daniel","Dawson, Ralph"],"dc:creator":["Li, Changyi"],"dc:date.available":["2018-05-16T07:00:00Z"],"dc:description.abstract":["III-nitride nanowire lasers have drawn significant attention as potential compact coherent light sources for a wide range of applications such as on-chip communication, optical sensing, and solid-state lighting. For practical applications, control over the lasing properties is needed. For example, a single mode lasing is beneficial for reducing the pulse broadening and the signal errors during the optical communications. An annular-shaped beam could be potentially used for the atom trapping or the stimulated emission depletion spectroscopy. The polarization-sensitive on-chip optical components also require linear polarization. However, due to the compact size of nanowire lasers and the cross-sectional symmetry of the traditional nanowire lasers, controlling the lasing properties still remains challenging. A top-down two-step etch process developed for vertical GaN nanowires offers the ability to precisely control the cross-section of the nanowire lasers. Consequently, the lasing properties can potentially be tailored by controlling the cross-section. In this dissertation, annular-shaped emission was demonstrated from GaN nanotube lasers with optical pumping at room temperature, consistent with finite-difference time-domain simulation results. Linearly polarized lasing emission was also realized from rectangular cross-sectioned GaN nanowire lasers. When the shorter y-dimension is ~120 nm, the rectangular cross-section creates a large contrast of the effective index of refraction, resulting in higher transverse confinement factors for the y-polarized modes than for the x-polarized modes. In order to pursue electrically injected single III-nitride nanowire lasers, non-polar InGaN/GaN multi-quantum-wells core-shell nanowires were fabricated by a combination of the top-down two-step etch process and a regrowth process. Lasing was observed from the core-shell nanowires by optical pumping at room temperature. A Hakki-Paoli measurement shows high modal gains of the non-polar core-shell nanowire lasers and the non-uniform gains resulting from the inhomogeneous regrowth. As a step towards electrical pumping, a Ti ohmic like' contact to the n-GaN core was fabricated. However, because of the lack of the ohmic contact to the p-GaN shell, the injection efficiency was extremely limited. As a result, instead of electrically-driven lasing, only weak spontaneous emission was observed in the electroluminescence measurement.'
"],"dc:identifier":["http://hdl.handle.net/1928/32315","https://digitalrepository.unm.edu/ose_etds/15"],"dc:language":["English"],"dc:subject":["Other Engineering"],"dc:title":["Top-down Cross-Section Controlled III-Nitride Nanowire Lasers"],"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"}