{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/8808"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/8808","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"The effect of proton bombardment on semiconductor saturable absorber structure","abstract":"Carrier lifetime reduction resulting from proton bombardment of InGaAs/InP-based semiconductor saturable absorbers was studied experimentally, using a standard degenerate, cross-polarized pump-probe technique. Proton bombardment reduced carrier lifetimes by as much as a factor of 40 at low optical excitation densities. For high fluences, significant induced absorption was observed. The recovery of this excited state absorption did not show as significant a dependence on the level of proton bombardment. It is possible that the cause of this induced absorption - carriers outside the InGaAs quantum wells, highly excited carriers, or those trapped in satellite valleys - is not sensitive to the effects of bombardment. Also, the bombardment-created defects may saturate at such high fluences. The detrimental side-effects of proton bombardment - reduced modulation depth and increased non-saturable loss - have been shown to be mitigated with a short post-growth anneal. Finally, modelocking was demonstrated with the proton-bombarded samples in an erbium fiber laser.","abstract_html":"Carrier lifetime reduction resulting from proton bombardment of InGaAs/InP-based semiconductor saturable absorbers was studied experimentally, using a standard degenerate, cross-polarized pump-probe technique. Proton bombardment reduced carrier lifetimes by as much as a factor of 40 at low optical excitation densities. For high fluences, significant induced absorption was observed. The recovery of this excited state absorption did not show as significant a dependence on the level of proton bombardment. It is possible that the cause of this induced absorption - carriers outside the InGaAs quantum wells, highly excited carriers, or those trapped in satellite valleys - is not sensitive to the effects of bombardment. Also, the bombardment-created defects may saturate at such high fluences. The detrimental side-effects of proton bombardment - reduced modulation depth and increased non-saturable loss - have been shown to be mitigated with a short post-growth anneal. Finally, modelocking was demonstrated with the proton-bombarded samples in an erbium fiber laser.","abstract_has_math":false,"creators":["Gopinath, Juliet Tara, 1976-"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.","school":null,"contributors":[],"advisors":["Erich Ippen."],"committee_chairs":[],"committee_members":[],"year":2000,"date_issued":"2000","date_published":"2000","updated_at":"2026-07-22T22:22:11Z","subjects":["Electrical Engineering and Computer Science."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. 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For high fluences, significant induced absorption was observed. The recovery of this excited state absorption did not show as significant a dependence on the level of proton bombardment. It is possible that the cause of this induced absorption - carriers outside the InGaAs quantum wells, highly excited carriers, or those trapped in satellite valleys - is not sensitive to the effects of bombardment. Also, the bombardment-created defects may saturate at such high fluences. The detrimental side-effects of proton bombardment - reduced modulation depth and increased non-saturable loss - have been shown to be mitigated with a short post-growth anneal. Finally, modelocking was demonstrated with the proton-bombarded samples in an erbium fiber laser."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effect of proton bombardment on semiconductor saturable absorber structure"]}]}],"canonical_facts":{"dc:contributor.advisor":["Erich Ippen."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."],"dc:contributor.other":["Massachusetts Institute of Technology. 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It is possible that the cause of this induced absorption - carriers outside the InGaAs quantum wells, highly excited carriers, or those trapped in satellite valleys - is not sensitive to the effects of bombardment. Also, the bombardment-created defects may saturate at such high fluences. The detrimental side-effects of proton bombardment - reduced modulation depth and increased non-saturable loss - have been shown to be mitigated with a short post-growth anneal. Finally, modelocking was demonstrated with the proton-bombarded samples in an erbium fiber laser."],"dc:description.degree":["S.M."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/1721.1/8808"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Electrical Engineering and Computer Science."],"dc:title":["The effect of proton bombardment on semiconductor saturable absorber structure"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:22:11Z"}