High-speed oxide-VCSELS for optical data links in data center and cryogenic computing applications

In recent years, there is a growing demand for a high-speed and power-efficient data extraction from cryogenic environments, such as superconducting processors based on single flux quantum (SFQ) technology at 4 Kelvin (K). To achieve such data transfer from 4 K to room-temperature electronics, optical data links based on cryogenic VCSELs at 4 K or an intermediate temperature are promising solutions due to low signal loss and low heat leak in fibers. The main work demonstrated in this dissertation is the development of a record high-speed cryogenic VCSEL with optical data transmission over 50 Gb/s from liquid-nitrogen and liquid-helium temperature to room-temperature electronics. Furthermore, the bandwidth measurement, microwave modeling, and parameter extraction have indicated that the capability of the cryogenic VCSELs is far beyond 50 Gb/s data rate. The extracted intrinsic bandwidth of 88.7 GHz at liquid-nitrogen temperature projects to a 200 Gb/s, sub-100 fJ/bit single-VCSEL, single-fiber data link. Also reported is the first demonstration that superconducting circuits are used to modulate a fully packaged VCSEL for up to 20 Gb/s NRZ data transmission via a fiber link from 4 K all the way to room-temperature users. The data rate is limited by the superconducting processor available to use. The authors believe that this work paves the way for next-generation cryogenic computing technologies by solving one of the key issues: the need of a high-speed, efficient, and low-heat-leak data communication between cryogenic and room-temperature environments. To make a transition into the cryogenic VCSEL development chapter, room-temperature VCSEL development, which was partially contributed by the author, is presented first. For many years, room-temperature GaAs-based 850nm VCSELs have been deployed in data centers for short-reach optical data links. However, there is a constant need to increase the link speed to accommodate the ever-growing data traffic. The dissertation will discuss operation physics, emerging challenges, and solutions in the development of VCSELs for 50 Gb/s NRZ data link over 100 meters OM4 fiber and operation up to 115 °C.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Fu, Wenning

Contributors dc:contributor

• Feng, Milton
• Jin, Jianming
• Dragic, Peter D
• Lee, Minjoo Lawrence

• High-speed Communication
• Oxide Vcsels

Statement dc:rights

• Copyright 2023 Wenning Fu

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/120327

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F120327