Experimental study of quantum dot and dash lasers

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dc.check.embargoformatNot applicableen
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dc.contributor.advisorOsborne, Simonen
dc.contributor.advisorO'Reilly, Eoin P.en
dc.contributor.authorHeck, Susannah C.
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderEuropean Commissionen
dc.date.accessioned2013-04-09T09:17:53Z
dc.date.available2013-04-09T09:17:53Z
dc.date.issued2009
dc.date.submitted2009
dc.description.abstractQuantum dashes are elongated quantum dots. Polarized edge-photovoltage and spontaneous emission spectroscopy are used to study the anisotropy of optical properties in 1.5μm InGaAsP and AlGaInAs-based quantum dash lasers. Strain, which causes TM-polarized transitions to be suppressed at the band edge, coupled with carrier confinement and dash shape leads to an enhancement of the optical properties for light polarized along the dash long axis, in excellent agreement with theoretical results. An analysis of the integrated facet and spontaneous emission rate with total current and temperature reveals that, in both undoped and p-doped InGaAsP-based quantum dash lasers at room temperature, the threshold current and its temperature dependence remain dominated by Auger recombination. We also identify two processes which can limit the output power and propose that the effects of the dopant in p-doped InGaAsP-based lasers dominate at low temperature but decrease with increasing temperature. A high threshold current density in undoped AlGaInAs-based quantum dash laser samples studied, which degrade rapidly at low temperature, is not due to intrinsic carrier recombination processes. 1.3μm GaAs-based quantum dots lasers have been widely studied, but there remains issues as to the nature of the electronic structure. Polarized edge-photovoltage spectroscopy is used to investigate the energy distribution and nature of the energy states in InAs/GaAs quantum dot material. A non-negligible TM-polarized transition, which is often neglected in calculations and analyses, is measured close to the main TE-polarized ground state transition. Theory is in very good agreement with the experimental results and indicates that the measured low-energy TM-polarized transition is due to the strong spatial overlap between the ground state electron and the light-hole component of a low-lying excited hole state. Further calculations suggest that the TM-polarized transition reduces at the band edge as the quantum dot aspect ratio decreases.en
dc.description.sponsorshipEuropean Commission (FP6-NMP 017140 ZODIAC (Zero Order Dimension based Industrial components Applied to teleCommunications) )en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationHeck, S. C. 2009. Experimental study of quantum dot and dash lasers. PhD Thesis, University College Cork.en
dc.identifier.urihttps://hdl.handle.net/10468/1036
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.urihttp://library.ucc.ie/record=b1894212
dc.rights© 2009, Susannah C. Hecken
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectDiode Laseren
dc.subjectQuantum dashesen
dc.subjectSpontaneous emission spectroscopyen
dc.subjectTM-polarized transitionsen
dc.subjectInGaAsPen
dc.subjectAlGaInAsen
dc.subjectAuger recombinationen
dc.subjectGaAsen
dc.subjectPolarized edge-photovoltage spectroscopyen
dc.subjectTE-polarized ground state transitionen
dc.subjectQuantum doten
dc.subject.lcshQuantum dotsen
dc.subject.lcshLasersen
dc.thesis.opt-outfalse*
dc.titleExperimental study of quantum dot and dash lasersen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisoralancollins@ucc.ie*
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