This year marked a special milestone for the Optical Fiber Communication Conference (OFC). It was the 50th edition of OFC, an event that dives deep into the world of optical networking and communications. Held in San Francisco, California, this year’s OFC attracted 16,700 attendees from 83 countries.

DCD was among those that flocked to the Moscone Center for the event, and found that AI seemed to pin together all the key themes, as the optical communication industry gathered to discuss the opportunities that the technology presents, and how the sector can build it into the networks of the future.

A key focus was on how AI will influence the demands on data center infrastructure as hyperscalers push to adapt and build future-proof networking.

Developments around hollow core fiber (HCF), subsea connectivity, pluggables, and Generative AI were all discussed, plus silicon photonics and much more.

This feature first appeared in issue 57 of DCD Magazine. Read it free of charge by registering here.

High scores for HCF

It was evident from the get-go that HCF was going to be a key theme at OCF, given the number of keynotes dedicated to the topic. HCF features a hollow space in the middle through which light is transmitted, rather than the glass core found in traditional fiber.

This could offer considerable speed benefits, but is the industry ready for it, and what sectors will it serve?

“We don’t change our fiber very often,” Andrew Lord, optics and quantum R&D lead, BT, noted in a keynote, where seating was at a premium.

BT began deploying fiber back in 1982. Some of that fiber was recently tested by the telco, explains Lord, who stated that it is still performing as well as it did 40 years ago.

“The fiber still works, it hasn’t changed,” he said. “Fiber is really good. I mean, the fiber guys here [referring to an image from the 1980s] have done a good job, maybe too good. But maybe since 1982, it’s time to start to refresh that infrastructure,” he adds.

Lord told DCD earlier this year that HCF won’t replace the fiber that is being used to roll out networks across the world at present, as telcos pivot away from legacy copper infrastructure. He reiterated this point during OFC, explaining that it’s too expensive to install at that sort of scale. The use cases HCF has been earmarked for include high-frequency financial trading.

“Does anybody here think that the use case here is a complete wholesale swap out of existing fiber for a new hollow core fiber? I don’t think so,” said Lord.

Instead, he envisions that HCF could play a role in the future in the development of the Radio Access Network (RAN), ultimately helping to reduce latency. He suggested that HCF could go that bit further, to areas standard fiber can’t reach.

“It’s a niche, but that’s what we want,” said Lord. “We want examples where it’s not a wholesale replacement, but where it steps in to help in situations where standard fiber doesn’t do the job.”

Lord added that HCF could be utilized for resiliency, and possibly even for quantum networks, and could play a role in the future of subsea cables.

A rare opportunity for fiber

The discussion around HCF and its potential is only likely to grow, according to Jason Eichenholz, co-founder, Relativity Networks. The company specializes in providing fiber, including hollow-core fiber, for its clients.

“If somebody is not talking about it now [HCF] they’re asleep at the switch,” Eichenholz told DCD.

“The challenge is that in the market there’s an insatiable demand for hollow core fiber. You can’t go through a technical session at this conference talking about the future without bumping into hollow core.

“Quantum is another hot topic, but that’s a bit further out. Hollow core has real-world applications today, especially in the data center space. We have an opportunity that doesn’t happen very often. Every 50 years or so, you get a big paradigm shift. We’re changing latency and we’re changing the speed of light and fiber.”

Much like Lord, Eichenholz doesn’t see a need for HCF to go directly to the home, but does think there are opportunities around the passive optical network (PON). PON is where a single fiber optic cable is used to deliver data to multiple users, usually for services such as broadband.

“I don’t think it’s a world where, in the next 20 years, you’ll see hollow core fiber going to the home. That being said, if you look at PON networks, I absolutely think there are proven opportunities for hollow core fiber, because of the power-handling capability in that network. It won’t be that last mile to the home, but getting that PON signal down to the splitters? Absolutely.”

Network vendor Nokia also outlined opportunities around HCF. During a media briefing, Edward Englehart, VP of engineering and head of subsystems at Nokia Optical Networks, stated that HCF can drive the open line system (OLS), which is a modular architecture for optical networks.

“Hollow core can really bring some key application advantages and some really interesting technology advantages that will drive the OLS and where we’re going with the OLS,” says Englehart.

“So first of all, with hollow core, there’s significant latency improvements. Second, there is much higher power you can transmit over this, which gives you some better reach, and more importantly, there is significantly lower electro-optics or impairments based on the fiber, which again gives you better performance.”

The subsea opportunities of the future

Relativity Networks’ Eichenholz noted that the potential of HCF was also touched upon in other keynotes covering areas beyond telecoms and data center opportunities.

One such market that noted opportunities in this field was the subsea cable industry. More than 370 cable routes are active across the globe. During a keynote on the future these systems, Alexis Carbo Meseguer, system design, Alcatel Submarine Networks (ASN), explained that HCF could be a potential alternative for future submarine cables.

“Under power constraints, it could be interesting, but also the fact that this fiber has no linearities, so it can help to adopt multi-band systems,” said Meseguer. But, he warned, “it’s not a mature technology at all.”

Discussing potential trends around subsea cable demand in the future, Pascal Pecci, submarine cable systems engineer at Meta, noted that AI is the “driver for the need for additional capacity.”

He said that the current technology maximum of 24 fiber pairs is nowhere near enough to meet the capacity demands. On this basis, only half a Petabit of capacity is possible.

“For transporting distance at a capacity of half petabits, we are using the maximum number of fiber pairs that subsea cables can manage, which is 24 fiber pairs,” said Pecci.

He explains that 1Pb repeatered cable builds will launch soon, possibly within the next two to three years. “We believe that in the coming years a 1Pb cable will be built, because we all know that for subsea, if we include unlimited distance on repeated cable, one petabit is already reached,” says Pecci.

However, he doesn’t stop there, noting the next step will be for 2Pb, though this will come somewhere between five and 10 years down the line.

Nvidia’s CPO push

Another hot topic on the menu at this year’s show was co-packaged optics (CPO), which is the integration of optical and electrical components into a switch ASIC package, rather than using separate pluggable modules.

CPOs have been identified as an important way of addressing the growing bandwidth and power challenges in data centers.

Just weeks before OFC, Jensen Huang, founder and CEO of Nvidia, showcased a strong appetite for silicon photonics during Nvidia’s GTC event.

The chipset giant unveiled its silicon photonics networking switches, which the company claims can lower power consumption and improve deployment speeds. Compared to undisclosed ‘traditional methods,’ the company promises 3.5x more power efficiency, 63x greater signal integrity, 10x better network resiliency ‘at scale,’ and 1.3x faster deployment.

A key area of photonics technology is CPO, and this is something that Nvidia is putting a lot of effort into, explained Craig Thompson, VP LinkX products, networking group, Nvidia.

“We made an announcement at GTC around our CPO investment. This is a major initiative inside the company, and we’re putting a lot of attention and resources behind it,” Thompson told a media briefing at OFC, which delved into the need to scale networks to support the next generation of AI workloads.

“We’ve put our weight behind CPO for a number of reasons, but I would say the two most pressing are power and reliability, or cluster uptime.”

He added that CPO is a way for Nvidia to “simplify the high-speed interfaces from the core switches to the optical interface.”

Best of the rest – Gen AI, chatbots, Infinera, and the road to 1.6Tb

It wasn’t just data center folk at OFC, the big US network carriers were also present. Unsurprisingly, the topic centered around everyone’s favorite buzzword, AI.

Generative AI’s role for telcos was touched upon during the event. Larry Zhou, lead member of technical staff, AT&T, highlighted some of the earlier generative AI use cases being adopted by carriers, and unsurprisingly, it featured use cases such as chatbots for customer service support.

“We believe agentic AI workflow is going to rewrite the whole industry,” explains Zhou, who says this will go beyond chatbots and is pivotal towards creating truly autonomous systems.

Zhou also added that it aims to use generative AI to “predict problems before they escalate.”

Meanwhile, network vendor Nokia had a big presence at this year’s event, pushing its data center ambitions.

This included the company showcasing its recent $2.3 billion acquisition of Infinera, notably through advertising across the showfloor.

It was also difficult to ignore the 1.6Tb hype on show in North California. As networks move away from 200G to 400G and 800G, the industry is already pushing the idea of 1.6Tb optical speeds.

This, of course, matters because the demands of AI mean that the computing power needed is greater than ever, and will only continue to grow. There were many 1.6Tb optical modules on show at OFC. Even if these modules are some way off deployment, it shows that the industry is already looking in the future, being proactive, not reactive.

Thompson added that he expects the bandwidth required for the optical networks, to continue growing.

“GPU bandwidth is doubling every two years,” he noted. “We’ve seen bandwidth across a single lane double in roughly the same period for the last few generations, and I don’t really see it slowing down yet.”

Thompson expects this to continue in the coming years. Although 1.6Tb is yet to hit deployment, it probably won’t be too long before 3.2Tb is plastered around the OFC showfloor. “

The ride will continue for at least the next few years, and it will be a really exciting time,” he says.

“We need the ecosystem to come along with us. We need innovation, startups, and investment. We need bigger networks.”