{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/130152"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/130152","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"High-speed oxide-VCSELs for cryogenic computing applications","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-08-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-08-01","abstract_has_math":false,"creators":["Wu, Haonan"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Feng, Milton","Dallesasse, John","Jin, Jianming","Dragic, Peter"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-07-18","date_published":"2025-07-18","updated_at":"2026-07-22T22:25:06Z","subjects":["Cryogenic Photonic Interconnect","Vertical-cavity-surface-emitting-laser (vcsel)","Cryogenic Physics","Opto-electronic Packaging","Artificial Intelligence"],"languages":["en","eng"],"rights":["Copyright 2025 Haonan Wu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/130152","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Feng, Milton","Dallesasse, John","Jin, Jianming","Dragic, Peter"]},{"key":"dc:creator","label":"Author","values":["Wu, Haonan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-07-18","2025-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Cryogenic Photonic Interconnect","Vertical-cavity-surface-emitting-laser (vcsel)","Cryogenic Physics","Opto-electronic Packaging","Artificial Intelligence"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Haonan Wu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/130152"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-08-01","The student, Haonan Wu, accepted the attached license on 2025-07-14 at 17:40.","The student, Haonan Wu, submitted this Dissertation for approval on 2025-07-14 at 20:13.","This Dissertation was approved for publication on 2025-07-18 at 13:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22446 on 2025-10-25 at 15:53:18","The rapid growth of artificial-intelligence workloads and the emergence of superconducting and quantum processors are pushing data-movement requirements far beyond what conventional electrical links can sustain—especially inside cryogenic environments, where thermal budgets are exceptionally tight. This dissertation advances vertical-cavity-surface-emitting-laser (VCSEL) technology from its traditional role in room-temperature data centers to a new generation of energy-efficient optical transmitters capable of operating at temperatures down to 2.6 K. After reviewing VCSEL lasing physics and oxide-aperture design trade-offs, the work introduces a custom epitaxial platform and fabrication flow that enable reliable cryogenic operation. A fully packaged 4 K optical link directly driven by a superconducting single-flux-quantum circuit is demonstrated, followed by a record-setting 128 Gb/s PAM-4 link at 2.8 K—the fastest cryogenic optical transmission reported to date. To further reduce heat dissipation, a sub-micron-aperture architecture is developed. Shrinking the oxide aperture to 0.9 µm yields an unprecedented threshold current of 50 µA at 3 K and an energy cost of only 45.5 fJ bit⁻¹ while sustaining 112 Gb/s modulation, establishing a new benchmark for cryogenic optical interconnects. Because even microwatt-scale self-heating can degrade performance at deep-cryogenic temperatures, this dissertation also presents a novel experiment–simulation co-design framework that combines Cryo-VCSEL wavelength-shift thermometry with nonlinear three-dimensional finite-element Cryo-VCSEL thermal modeling. The model captures temperature-dependent thermal behavior of the Cryo-VCSELs from 2.6 K to 130 K, accurately predicting cavity temperatures and guiding design rules to mitigate thermal rollover. Collectively, these results show that oxide-confined VCSELs can deliver terabit-per-second-class bandwidth with femtojoule-level energy efficiency at cryogenic temperatures, paving the way for scalable optical I/O in superconducting and quantum computing systems. The thesis concludes with a roadmap for high-power single-mode cryogenic VCSELs, large-scale VCSEL arrays, and integrated electro-optic–thermal design tools that will further unlock the potential of cryogenic photonic interconnects."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["High-speed oxide-VCSELs for cryogenic computing applications"]}]}],"canonical_facts":{"dc:contributor":["Feng, Milton","Dallesasse, John","Jin, Jianming","Dragic, Peter"],"dc:creator":["Wu, Haonan"],"dc:date":["2025-07-18","2025-08"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-08-01","The student, Haonan Wu, accepted the attached license on 2025-07-14 at 17:40.","The student, Haonan Wu, submitted this Dissertation for approval on 2025-07-14 at 20:13.","This Dissertation was approved for publication on 2025-07-18 at 13:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22446 on 2025-10-25 at 15:53:18","The rapid growth of artificial-intelligence workloads and the emergence of superconducting and quantum processors are pushing data-movement requirements far beyond what conventional electrical links can sustain—especially inside cryogenic environments, where thermal budgets are exceptionally tight. This dissertation advances vertical-cavity-surface-emitting-laser (VCSEL) technology from its traditional role in room-temperature data centers to a new generation of energy-efficient optical transmitters capable of operating at temperatures down to 2.6 K. After reviewing VCSEL lasing physics and oxide-aperture design trade-offs, the work introduces a custom epitaxial platform and fabrication flow that enable reliable cryogenic operation. A fully packaged 4 K optical link directly driven by a superconducting single-flux-quantum circuit is demonstrated, followed by a record-setting 128 Gb/s PAM-4 link at 2.8 K—the fastest cryogenic optical transmission reported to date. To further reduce heat dissipation, a sub-micron-aperture architecture is developed. Shrinking the oxide aperture to 0.9 µm yields an unprecedented threshold current of 50 µA at 3 K and an energy cost of only 45.5 fJ bit⁻¹ while sustaining 112 Gb/s modulation, establishing a new benchmark for cryogenic optical interconnects. Because even microwatt-scale self-heating can degrade performance at deep-cryogenic temperatures, this dissertation also presents a novel experiment–simulation co-design framework that combines Cryo-VCSEL wavelength-shift thermometry with nonlinear three-dimensional finite-element Cryo-VCSEL thermal modeling. The model captures temperature-dependent thermal behavior of the Cryo-VCSELs from 2.6 K to 130 K, accurately predicting cavity temperatures and guiding design rules to mitigate thermal rollover. Collectively, these results show that oxide-confined VCSELs can deliver terabit-per-second-class bandwidth with femtojoule-level energy efficiency at cryogenic temperatures, paving the way for scalable optical I/O in superconducting and quantum computing systems. The thesis concludes with a roadmap for high-power single-mode cryogenic VCSELs, large-scale VCSEL arrays, and integrated electro-optic–thermal design tools that will further unlock the potential of cryogenic photonic interconnects."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/130152"],"dc:language":["en","eng"],"dc:rights":["Copyright 2025 Haonan Wu"],"dc:subject":["Cryogenic Photonic Interconnect","Vertical-cavity-surface-emitting-laser (vcsel)","Cryogenic Physics","Opto-electronic Packaging","Artificial Intelligence"],"dc:title":["High-speed oxide-VCSELs for cryogenic computing applications"],"dc:type":["text"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:06Z"}