OFC 2025 industry reflections - Part 2
Sunday, May 4, 2025 at 2:26PM Gazettabyte is asking industry figures for their thoughts after attending the 50th-anniversary OFC show in San Francisco. In Part 2, the contributions are from BT's Professor Andrew Lord, Chris Cole, Coherent's Vipul Bhatt, and Juniper Network's Dirk van den Borne.
Exhibition floor. Source: OFC
OFC was a highly successful and lively show this year, reflecting a sense of optimism in the optical comms industry. The conference was dominated by the need for optics in data centres to handle the large AI-driven demands. And it was exciting to see the conference at an all-time attendance peak.
From a carrier perspective, I continued to appreciate the maturing of 800-gigabit plugs for core networks and 100GZR plugs (including bidirectional operation for single-fibre working) for the metro-access side.
Hollow-core fibre continues to progress with multiple companies developing products, and evidence for longer lengths of fibre in manufacturing. Though dominated by data centres and low-latency applications such as financial trading, use cases are expected to spread into diverse areas such as subsea cables and 6G xHaul.
There was also a much-increased interest in fibre sensing as an additional revenue generator for telecom operators, although compelling use cases will require more cost-effective technology.
Lastly, there has been another significant increase in quantum technology at OFC. There was an ever-increasing number of Quantum Key Distribution (QKD) protocols on display but with a current focus on Continuous—Variable QKD (CV-QKD), which might be more readily manufacturable and easier to integrate.
Chris Cole, Optical Communications Advisor
For the premier optics conference, the amount of time and floor space devoted to electrical interfaces was astounding.
Even more amazing is that while copper's death at the merciless hands of optics continues to be reported, the percentage of time devoted to electrical work at OFC is going up. Multiple speakers commented on this throughout the week.
One reason is that as rates increase, the electrical links connecting optical links to ASICs are becoming disproportionately challenging. The traditional Ethernet model of electrical adding a small penalty to the overall link is becoming less valid.
Another reason is the introduction of power-saving interfaces, such as linear and half-retimed, which tightly couple the optical and electrical budgets.
Optics engineers now have to worry about S-parameters and cross-talk of electrical connectors, vias, package balls, copper traces and others.
The biggest buzz in datacom was around co-packaged optics, helped by Nvidia's switch announcements at GTC in March.
Established companies and start-ups were outbidding each other with claims of the highest bandwidth in the smallest space; typically the more eye-popping the claims, the less actual hard engineering data to back them up. This is for a market that is still approximately zero and faces its toughest hurdles of yield and manufacturability ahead.
To their credit, some companies are playing the long game and doing the slow, hard work to advance the field. For example, I continue to cite Broadcom for publishing extensive characterisation of their co-packaged optics and establishing the bar for what is minimally acceptable for others if they want to claim to be real.
The irony is that, in the meantime, pluggable modules are booming, and it was exciting to see so many suppliers thriving in this space, as demonstrated by the products and traffic in their booths.
The best news for pluggable module suppliers is that if co-packaged optics takes off, it will create more bandwidth demand in the data centre, driving up the need for pluggables.
I may have missed it, but no coherent ZR or other long-range co-packaged optics were announced.
A continued amazement at each OFC is the undying interest and effort in various incarnations of general optical computing.
Despite having no merit as easily shown on first principles, the number of companies and researchers in the field is growing. This is also despite the market holding steady at zero.
The superficiality of the field is best illustrated by a slogan gaining popularity and heard at OFC: computing at the speed of light. This is despite the speed of propagation being similar in copper and optical waveguides. The reported optical computing devices are hundreds of thousands or millions of times larger than equivalent CMOS circuits, resulting in the distance, not the speed, determining the compute time.
Practical optical computing precision is limited to about four bits, unverfied claims of higher precision not withstanding, making it useless in datacenter applications.
Vipul Bhatt, Vice President, Corporate Strategic Marketing at Coherent.
Three things stood out at OFC:
- The emergence of transceivers based on 200-gigabit VCSELs
- A rising entrepreneurial interest in optical circuit switching
- And an accelerated momentum towards 1.6-terabit (8x200-gigabit transceivers) alongside the push for 400-gigabit lanes due to AI-driven bandwidth expansion.
The conversations about co-packaged optics showed increasing maturity, shifting from ‘pluggable versus co-packaged optics’ to their co-existence. The consensus is now more nuanced: co-packaged optics may find its place, especially if it is socketed, while front-panel pluggables will continue to thrive.
Strikingly, talk of optical interconnects beyond 400-gigabit lanes was almost nonexistent. Even as we develop 400 gigabit-per-lane products, we should be planning the next step: either another speed leap (this industry has never disappointed) or, more likely, a shift to 'fast-and-wide', blurring the boundary between scale-out and scale-up by using a high radix.
Considering the fast cadence of bandwidth upgrades, the absence of such a pivotal discussion was unexpected.
Dirk van den Borne, director of system engineering at Juniper Networks
The technology singularity is defined as the merger of man and machine. However, after a week at OFC, I will venture a different definition where we call the “AI singularity” the point when we only talk about AI every waking hour and nothing else. The industry seemed close to this point at OFC 2025.
My primary interest at the show was the industry’s progress around 1.6-terabit optics, from scale-up inside the rack to data centre interconnect and long-haul using ZR/ZR+ optics. The industry here is changing and innovating at an incredible pace, driven by the vast opportunity that AI unlocks for companies across the optics ecosystem.
A highlight was the first demos of 1.6-terabit optics using a 3nm CMOS process DSP, which have started to tape out and bring the power consumption down from a scary 30W to a high but workable 25W. Well beyond the power-saving alone, this difference matters a lot in the design of high-density switches and routers.
It’s equally encouraging to see the first module demos with 200 gigabit-per-lane VCSELs and half-retimed linear-retimed optical (LRO) pluggables. Both approaches can potentially reduce the optics power consumption to 20W and below.
The 1.6-terabit ecosystem is rapidly taking shape and will be ready for prime time once 1.6-terabit switch ASICs arrive in the marketplace. There’s still a lot of buzz around linear pluggable optics (LPO) and co-packaged optics, but both don’t seem ready yet. LPO mostly appears to be a case of too little, too late. It wasn’t mature enough to be useful at 800 gigabits, and the technology will be highly challenging for 1.6 terabits.
The dream of co-packaged optics will likely have to wait for two more years, though it does seem inevitable. But with 1.6 terabit pluggable optics maturing quickly, I don’t see it having much impact in this generation.
The ZR/ZR+ coherent optics are also progressing rapidly. Here, 800-gigabit is ready, with proven interoperability between modules and DSPs using the OpenROADM probabilistic constellation shaping standard, a critical piece for interoperability in more demanding applications.
The road to 1600ZR coherent optics for data centre interconnect (DCI) is now better understood, and power consumption projections seem reasonable for 2nm DSP designs.
Unfortunately, the 1600ZR+ is more of a question mark to me, as ongoing standardisation is taking this in a different direction and, hence, a different DSP design from 1600ZR. The most exciting discussions are around “scale-up” and how optics can replace copper for intra-rack connectivity.
This is an area of great debate and speculation, with wildly differing technologies being proposed. However, the goal of around 10 petabit-per-second (Pbps) in cross-sectional bandwidth in a single rack is a terrific industry challenge, one that can spur the development of technologies that might open up new markets for optics well beyond the initial AI cluster application.
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