Research Note

Abstract

This year’s OFC was the most intriguing of recent years. The show posed many open questions with AI being at the forefront. What will be the impact of AI on data centers and the photonics industry? And is AI just the latest buzzword or will it change our industry?

Further impetus was added to the AI debate, if more was needed, given how OFC followed a week after Nvidia’s GTC AI conference. At GTC, Nvidia launched its DGX GB200 system, a cabinet crammed with Nvidia’s latest GPUs connected using NVlink over copper. Many of the questions at OFC revolved around the photonic options to connect AI systems including co-packaged optics (CPO), Linear Packaged Optics (LPO), ‘half-LPO’ or Linear Retimed Optics, also referred to as Linear Transmitter Optics (LRO/LTO), along with the continual progress of pluggable modules.

At the Optica Executive Forum which run alongside OFC, Google’s Hong Liu referred to CPO as “a technology that is always arriving in ‘N+2’ years, ‘N’ being the current year.”. LightCounting’s view is that this equation is finally about right. OFC 2024 saw many developments and announcements showing CPO’s progress. LPO, the topic of last year’s OFC, has also progressed with interop demos and a dozen-company-backed Multi-Source Agreement (MSA) announced. But questions remain as to whether hyperscalers will trust the technology at scale in their data centers. LPO suits 100-gigabit lanes but for 200-gigabit lanes it looks like LRO will be needed. Meanwhile, much progress was evident at 800G, 1.6T, and proposed 3.2T pluggable modules.

OFC remains a conference of multiple themes. For coherent optics, questions concerned the OIF’s latest ambitious 1.6-terabit 1600ZR and 1600ZR+ and how coherent modems supporting the OIF specifications will be achieved in a power-constrained pluggable. Another question is when the industry will turn to parallel multi-wavelength coherent modem designs because scaling the symbol rate no longer makes sense from a cost and power perspective. The expectation is that 240-280 gigabaud (GBaud) symbol rates that include the OIF’s 1600 ZR/ZR+ standards will be met in 3-4 years. The industry is confident that a further doubling to 400-500GBaud will be achieved in the next decade. All admit they don’t know how this will be done but they don’t see any reason why it won’t be achieved.

At OFC, coherent system issues were also prominent with discussions around expanding amplification beyond the C and L bands, and water-cooled coherent modules and optical transport systems from Fujitsu and Ciena. Longer term, the merits of hollow-core fiber were mentioned. Other developments reported at OFC include 200G VCSELs from Broadcom and Coherent, quantum dot lasers, passive optical networks, optical switching, and Google unveiled how AI can be used to develop novel optical componentry.

Some 12,500 people from 74 countries registered for this year’s OFC, while 630 companies exhibited, up a quarter from last year’s show.

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