1. [Publications](/publications)
2. Beyond CPO: A Motivation and Approach for Bringing Optics onto the Silicon Interposer
 
 # Beyond CPO: A Motivation and Approach for Bringing Optics onto the Silicon Interposer

  ![Publication image](/sites/default/files/styles/wide/public/default_images/default.jpeg?itok=qUFsuJCP "Publication image")

 Co-packaged optics (CPO) technology is well positioned to break through the bottlenecks that impede efficient bandwidth scaling in key near-term commercial integrated circuits. In this paper, we begin by providing some historical context for this important sea change in the optical communications industry. Then, motivated by GPU-based accelerated computing requirements, we investigate the next pain points that are poised to constrain bandwidth and efficiency in future CPO-based systems. We identify 2.5D integrated optics (i.e., bringing optics onto the interposer) as a promising solution that can enable continued scaling for these systems due to the dense wiring available which facilitates more efficient slow-and-wide electrical interfaces. We explore the benefits, challenges, and requirements associated with such tight coupling of the processors and optical engines by considering high-level photonic link design, technology, and packaging. We demonstrate the viability of a control loop which can adequately regulate temperature within the aggressive thermal environment. Then, we introduce a custom simulation framework that allows quantified comparisons of detailed design decisions; the simulations validate the feasibility of the general approach while also providing key guidance to designers on best directions to pursue for efficient optimization.



 ## Authors



[Ben Lee](/person/ben-lee)

[Nikola Nedovic](/person/nikola-nedovic)

[Trey Greer](/person/trey-greer)

[Tom Gray](/person/tom-gray)

 

 

 ## Publication Date



Wednesday, February 15, 2023

 

 ## Published in



[Journal of Lightwave Technology](https://ieeexplore.ieee.org/document/9939069)

 

 ## Research Area



[Circuits and VLSI Design](/research-area/circuits)