LightTrends Newsletter

Co-packaged Optics Accelerate Innovation in Optical Components and Pluggable Transceivers

June 2021

Co-packaged Optics Accelerate Innovation in Optical Components and Pluggable Transceivers

LightCounting Discusses Highlights of OFC 2021

OFC 2021 was a fantastic event! It seems that the rate of innovation accelerated across a wide range of optical technologies. Virtual access, including replays of the talks, certainly helped to see a broader picture. We are looking forward to a live OFC in 2022, but the recordings should be part of all future events. It is a fantastic opportunity for all the attendees to catch up on the interesting presentations at a later date, while spending more time on live discussions at the event. 
Hong Liu’s (Google) presentation was the best of the show. She did a great job summarizing the history of optical deployments in mega datacenters (DCs), explained what is driving the demand, and presented Google’s plans for the next 10 years – all in just a dozen of slides over 15 minutes!
Google was the first Cloud company to deploy optics in its datacenters back in 2007. They are still ahead of all other mega DC operators in deploying the highest speed optics on the market: 2x400GbE this year. Google is also the only Cloud company that regularly shares actual data on traffic growth in its networks, shown in the figure below. Why is this important? It is the only “sanity check” for the industry (and market forecasters) to see that the demand for optics is real now and how it may change in the future.
OFC 2021
AI Clusters is where Google is seeing the highest growth, but most of the connections there are copper cables. How much optics these systems will need is a new research area for LightCounting. It is clear that Co-Packaged Optics (CPO) will have a role there, but these are longer term trends.

What matters the most for suppliers is what products Google will purchase in the next 3 years. Innolight reported first shipments of 800G PSM8 in the end of 2020, but other products (2x400G-FR4, 800G-CWDM8, 800-ZRlite and 800ZR) are still in various stages of development. 800G-ZRlite (10km reach, coherent module) is officially on Google’s roadmap now. It is also interesting to note the absence of VCSEL-based optics and MMF. Google questions the long-term reliability of 100G VCSELs, yet Broadcom announced this as a product at the show and guarantees the laser reliability. LightCounting includes 800G MMF transceivers in its market forecast, but it seems that Google is prioritizing SMF cabling. Probably getting ready for 1.6T and 3.2T pluggables.

Hong Liu has not shared much about Google’s plans for pluggables beyond 800G, apart from the fact that these plans exist and include 200G optics and SerDes. Hong is skeptical about co-packaged optics, but she does admit that the industry will need new solutions to support lane rates above 200Gbps. It you missed Hong Liu’s talk, a replay of the entire session is available here:

That session opens with a presentation by Andy Bechtolsheim of Arista, who also argues that pluggable optics are the best option for mega DCs over the current decade. He introduced a new OSFP-XD form factor for 1.6T and 3.2T pluggable transceivers. It is effectively a double density OSFP module, but using “DD” in the name would be a giveaway for Cisco. XD also sounds a lot more mysterious, but there is no mystery: it is 16X100G on the electrical side and 8x200G on the optical for direct detect and 2x800G for coherent modules. No specifications were released publicly, but at least one of the very large customers is drafting them.

A full version of the research note is available to LightCounting subscribers at:

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