{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/127487"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/127487","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Low-complexity coherent optical receivers","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01","abstract_has_math":false,"creators":["Abdelrahman, Ahmed"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Hanumolu, Pavan K","Hanumolu, Pavan Kumar","Shanbhag, Naresh R.","Rosenbaum, Elyse","Schutt-Aine, Jose E."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-12-04","date_published":"2024-12-04","updated_at":"2026-07-22T22:25:04Z","subjects":["Coherent Optical Receivers","Wireline","Serial Links","Transceivers","Serdes"],"languages":["en","eng"],"rights":["Copyright 2024 Ahmed Abdelrahman"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/127487","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hanumolu, Pavan K","Hanumolu, Pavan Kumar","Shanbhag, Naresh R.","Rosenbaum, Elyse","Schutt-Aine, Jose E."]},{"key":"dc:creator","label":"Author","values":["Abdelrahman, Ahmed"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-12-04","2024-12"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"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 at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Coherent Optical Receivers","Wireline","Serial Links","Transceivers","Serdes"]}]},{"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 2024 Ahmed Abdelrahman"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/127487"]}]},{"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 2026-12-01","The student, Ahmed Abdelrahman, accepted the attached license on 2024-12-03 at 11:15.","The student, Ahmed Abdelrahman, submitted this Dissertation for approval on 2024-12-03 at 11:26.","This Dissertation was approved for publication on 2024-12-04 at 17:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21473 on 2025-03-28 at 14:55:35","The rapid growth of data-intensive applications in data centers has driven the demand for high-speed, energy-efficient optical interconnects. Traditional intensity-modulation direct-detection (IM-DD) techniques face significant challenges in scaling data rates, making coherent detection a promising alternative for short-reach links. Coherent detection offers higher spectral efficiency by utilizing intensity, phase, and polarization but comes with increased power consumption due to the need for advanced digital signal processing (DSP) engines. This dissertation explores analog signal processing (ASP) techniques for designing low-complexity, power-efficient coherent optical receivers (RXs) tailored for short-reach data center interconnects (DCIs). By minimizing the reliance on power-hungry analog-to-digital converters (ADCs) and complex DSP algorithms, the proposed designs enable more energy-efficient operation. The first part of this work introduces a monolithically integrated, wide-bandwidth, analog carrier-phase recovery (CPR) loop for QPSK coherent RXs, that eliminates the need for external optical feedback loops, enhances phase tracking capabilities and reduces system complexity. Fabricated using a 28 nm CMOS process, the QPSK RX achieves error-free operation at 24 Gb/s, with 10–100 MHz CPR loop bandwidth and 600 MHz frequency tracking range, consuming only 3.2 pJ/bit. The second part extends the QPSK RX and CPR architectures to support 16-QAM formats, addressing the complexities of higher-order modulation. A novel phase detector (PD) design is proposed, leveraging both inner and outer symbols for improved phase tracking of 16-QAM constellations. The 16-QAM RX, also fabricated in a 28 nm CMOS, achieves a bit error ratio (BER) of 1E-10 at 64 Gb/s, with 20 MHz CPR loop bandwidth, while consuming just 1.54 pJ/bit. These innovations highlight the potential for scalable, low-power coherent optical RXs and pave the way for broader adoption of coherent technology in short-reach data center applications."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Low-complexity coherent optical receivers"]}]}],"canonical_facts":{"dc:contributor":["Hanumolu, Pavan K","Hanumolu, Pavan Kumar","Shanbhag, Naresh R.","Rosenbaum, Elyse","Schutt-Aine, Jose E."],"dc:creator":["Abdelrahman, Ahmed"],"dc:date":["2024-12-04","2024-12"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-12-01","The student, Ahmed Abdelrahman, accepted the attached license on 2024-12-03 at 11:15.","The student, Ahmed Abdelrahman, submitted this Dissertation for approval on 2024-12-03 at 11:26.","This Dissertation was approved for publication on 2024-12-04 at 17:24.","DSpace SAF Submission Ingestion Package generated from Vireo submission #21473 on 2025-03-28 at 14:55:35","The rapid growth of data-intensive applications in data centers has driven the demand for high-speed, energy-efficient optical interconnects. Traditional intensity-modulation direct-detection (IM-DD) techniques face significant challenges in scaling data rates, making coherent detection a promising alternative for short-reach links. Coherent detection offers higher spectral efficiency by utilizing intensity, phase, and polarization but comes with increased power consumption due to the need for advanced digital signal processing (DSP) engines. This dissertation explores analog signal processing (ASP) techniques for designing low-complexity, power-efficient coherent optical receivers (RXs) tailored for short-reach data center interconnects (DCIs). By minimizing the reliance on power-hungry analog-to-digital converters (ADCs) and complex DSP algorithms, the proposed designs enable more energy-efficient operation. The first part of this work introduces a monolithically integrated, wide-bandwidth, analog carrier-phase recovery (CPR) loop for QPSK coherent RXs, that eliminates the need for external optical feedback loops, enhances phase tracking capabilities and reduces system complexity. Fabricated using a 28 nm CMOS process, the QPSK RX achieves error-free operation at 24 Gb/s, with 10–100 MHz CPR loop bandwidth and 600 MHz frequency tracking range, consuming only 3.2 pJ/bit. The second part extends the QPSK RX and CPR architectures to support 16-QAM formats, addressing the complexities of higher-order modulation. A novel phase detector (PD) design is proposed, leveraging both inner and outer symbols for improved phase tracking of 16-QAM constellations. The 16-QAM RX, also fabricated in a 28 nm CMOS, achieves a bit error ratio (BER) of 1E-10 at 64 Gb/s, with 20 MHz CPR loop bandwidth, while consuming just 1.54 pJ/bit. These innovations highlight the potential for scalable, low-power coherent optical RXs and pave the way for broader adoption of coherent technology in short-reach data center applications."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/127487"],"dc:language":["en","eng"],"dc:rights":["Copyright 2024 Ahmed Abdelrahman"],"dc:subject":["Coherent Optical Receivers","Wireline","Serial Links","Transceivers","Serdes"],"dc:title":["Low-complexity coherent optical receivers"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:04Z"}