OFC 2025 industry reflections - Part 3
Gazettabyte is asking industry figures for their thoughts after attending the OFC show in San Francisco. In the penultimate part, the contributions are from Cisco’s Bill Gartner, Lumentum’s Matt Sysak, Ramya Barna of Mixx Technologies, and Ericsson’s Antonio Tartaglia.
Bill Gartner, Senior Vice President and General Manager, Optical Systems and Optics, Cisco
There was certainly much buzz around co-packaged optics at Nvidia’s GTC event, and that carried over into OFC.
The prevailing thinking seems to be that large-scale co-packaged optics deployment is years away. While co-packaged optics has many benefits, there are challenges that need to be overcome before that happens.
Existing solutions, such as linear pluggable optics (LPO), continue to be discussed as interim solutions that could achieve close to the power savings of co-packaged optics and preserve a multi-vendor pluggable market. That development in the industry will be an intermediate solution before co-packaged optics is required.
By all accounts, IP-over-DWDM, or Routed Optical Networking as Cisco calls it, is now mainstream, enabling network operators to take advantage of the cost, space, and power savings in almost every part of the network.
Through the Openzr+ and Openroadm models, coherent pluggable usage has expanded beyond data centre interconnect (DCI) and metro applications. The subject was covered in many presentations and announcements, including several trials by Arelion and Internet2 of the new 800-gigabit ZR+ and 400-gigabit ultra-long-haul coherent pluggable. ZR and ZR+ pluggable optics now account for more than half of the coherent ports industry-wide.
I also saw some coherent-lite demonstrations, and while the ecosystem is expanding, it appears this will be a corner case for the near future.
Lastly, power reduction was another strong theme, which is where co-packaged optics, LPO, and linear retimed optics (LRO) originated. As optics, switches, routers, and GPU (graphics processor unit) servers become faster and denser, data centres cannot support the insatiable need for more power. Network operators and equipment manufacturers are seeking alternative ways to lower power, such as liquid cooling and liquid immersion.
What did I learn at OFC? Pradeep Sindhu, Technical Fellow and Corporate Vice President of Silicon with Microsoft, gave one of the plenary talks. He believes we should stop racing to higher lane speeds because it will compromise scale. He believes 200 gigabits per second (Gbps) is a technology sweet spot.
As for show surprises, the investor presence was markedly larger than usual, a positive for the industry. With almost 17,000 people attending OFC this year and AI driving incremental bandwidth that optics will serve, you could feel the excitement on the show floor.
We’re looking forward to seeing what technologies will prevail in 2026.
Matt Sysak, CTO, Cloud and Networking Platform at Lumentum.
The industry spotlight at OFC was on next-generation data centre interconnects and growing AI-driven bandwidth demands.
Several suppliers demonstrated 400 gigabit-per-lane optics, with Lumentum showcasing both 450 gigabit-per-second (Gbps) indium phosphide Mach-Zehnder and 448 gigabit-per-lane externally modulated laser (EML) technologies.
In long-haul networking, the continued expansion of data centre traffic across longer fibre spans drives demand for high-capacity solutions such as 800G ZR C+L band transceivers. I learned at the show that the focus has shifted from incremental upgrades to building fundamentally new network layers capable of supporting AI workloads at scale. Conversations around innovations such as 400-gigabit DFB Mach-Zehnder lasers and advancements in optical circuit switches made it clear that the industry is driving innovation across every network layer.
One of the biggest surprises was the surge in optical circuit switch players. The core technology has expanded beyond traditional micro-electro-mechanical systems (MEMS) to include liquid crystal and silicon photonics approaches. There is clearly growing demand for high-radix, low-power optical interconnects to address rising data centre power consumption.
With our proven expertise in MEMS and the ability to scale port counts with low insertion loss, we believe Lumentum’s optical circuit switch offers clear advantages over competing technologies.
Ramya Barna, Head of Marketing and Key Partnerships, Mixx Technologies.
It was evident at OFC 2025 that the industry is entering a new phase, not just of optical adoption but also of architectural introspection.
Co-packaged optics was the dominant theme on the show floor, with vendors aligning around tighter electrical-optical integration at the switch level. However, discussions with hyperscalers were more layered and revealing.
Meta spoke about the need for full-stack co-optimisation: treating photonics not just as a peripheral, but as part of the compute fabric.
AWS emphasised co-designing power and photonics—optics and electricity as first-class citizens in infrastructure planning.
Microsoft, meanwhile, challenged the community on reliability and manufacturability at the DRAM scale, demanding optics that can be trusted, such as memory.
These inputs reinforce a core truth: the AI bottleneck is not compute capacity, but bandwidth, latency, and power at scale.
The current wave of co-packaged optics implementations is a step forward, but it remains constrained by legacy system boundaries where retimers, linear interfaces, and electrical serdes bottlenecks still dominate.
At Mixx, we’ve long viewed this not as an integration problem but an architectural one. AI infrastructure requires a redesign in which photonics is not bolted on but directly integrated into compute—native optical paths between ASICs. That is our thesis with optical input-output (I/O).
OFC 2025 reinforced that the industry is converging on the same realisation: optical interfaces must move deeper into the package, closer to the logic. We’re aligned on timelines, and most importantly, on the problem definition.
Looking forward to OFC 2026, where system-level transformation takes over.
Antonio Tartaglia, System Manager and Expert in Photonics at Radio and Transport Engineering, Transport Systems at Ericsson.
The effort invested in traditional telecom connectivity is decreasing, and more attention is being paid to solutions that have the potential to unlock new revenue streams for communications service providers (CSP).
A good example is distributed fibre sensing, which involves reusing deployed telecom-grade fibre plants. Optical connectivity for satellite communications was also a trending topic, with much excitement about low-Earth orbit (LEO) satellites as a complement to radio access networks (RAN).
OFC 2025 highlighted that the telecom industry must continue to reuse wisely and adapt optical technologies developed for datacom, which is acting as the innovation powerhouse for the whole industry.
The only way to reuse the solutions developed for data centres is, well … to build a data centre. Still, the same basic technologies can often be reused and adapted to telecom use cases with reasonable development effort.
I believe industry-wide initiatives (MSAs, alliances, consortia) pursuing this objective will become even more critical for telecom.
Speaking of the segment close to my heart – optical connectivity for RAN – the adaptation of datacom technologies works fine for short reach (<2km) optical interconnects, where we reuse one optical lane of data centres’ multi-lane optical interfaces.
After OFC 2025, I believe the relentless optimisation of coherent technology towards shorter and shorter reaches, and the concurrent rise of packet fronthaul in RAN, could pave the way for a new breed of ‘coherent-lite’ optical solutions for radio transport networks.
It was awe-inspiring to hear talks on scaling AI compute clusters, which are now aiming at the ‘psychological’ threshold of AI models with 100 trillion parameters—the estimated compute power of a human brain.
This journey will require clusters of millions of interconnected GPUs resulting in 2 megawatt data centres, with electric power availability limiting the choice of locations. An emerging research area to reduce power is integrated optics “optical co-processors” for GPUs, performing energy-efficient vector-to-matrix multiplications in the optical domain. Although technology readiness is low, start-ups are already working on this challenge.
The most obvious solution to the power conundrum seems to be dividing these GPU mega-clusters across smaller sites. This approach will increase the demand on data centre interconnects (DCI), requiring them to function as long-haul RDMA (remote direct memory access) interconnects.
These interconnects will need ultra-low latency and precise time synchronisation, which could be very attractive for future RAN transport needs.
The future of optical I/O is more parallel links
Chris Cole has a lofty vantage point regarding how optical interfaces will likely evolve.
As well as being an adviser to the firm II-VI, Cole is Chair of the Continuous Wave-Wavelength Division Multiplexing (CW-WDM) multi-source agreement (MSA).
The CW-WDM MSA recently published its first specification document defining the wavelength grids for emerging applications that require eight, 16 or even 32 optical channels.
And if that wasn’t enough, Cole is also the Co-Chair of the OSFP MSA, which will standardise the OSFP-XD (XD standing for extra dense) 1.6-terabit pluggable form factor that will initially use 16, 100 gigabits-per-second (Gbps) electrical lanes. And when 200Gbps electrical input-output (I/O) technology is developed, OSFP-XD will become a 3.2-terabit module.
Directly interfacing with 100Gbps ASIC serialiser/ deserialiser (serdes) lanes means the 1.6-terabit module can support 51.2-terabit single rack unit (1RU) Ethernet switches without needing 200Gbps ASIC serdes required by eight-lane modules like the OSFP.
“You might argue that it [the OSFP-XD] is just postponing what the CW-WDM MSA is doing,” says Cole. “But I’d argue the opposite: if you fundamentally want to solve problems, you have to go parallel.”
CW-WDM specification
The CW-WDM MSA is tasked with specifying laser sources and the wavelength grids for use by higher wavelength count optical interfaces.
The lasers will operate in a subset of the O-band (1280nm-1320nm) building on work already done by the ITU-T and IEEE standards bodies for datacom optics.
In just over a year since its launch, the MSA has published Revision 1.0 of its technical specification document that defines the eight, 16 and 32 channels.
The importance of specifying the wavelengths is that lasers are the longest lead items, says Cole: “You have to qualify them, and it is expensive to develop more colors.”
In the last year, the MSA has confirmed there is indeed industry consensus regarding the wavelength grids chosen. The MSA has 11 promoter members that helped write the specification document and 35 observer status members.
“The aim was to get as many people on board as possible to make sure we are not doing something stupid,” says Cole.
As well as the wavelengths, the document addresses such issues as total power and wavelength accuracy.
Another issue raised is four-wavelength mixing. As the channel count increases, the wavelengths are spaced closer together. Four-wavelength mixing refers to an undesirable effect that impacts the link’s optical performance. It is a well-known effect in dense WDM transport systems where wavelengths are closely spaced but is less commonly encountered in datacom.
“The first standard is not a link budget specification, which would have included how much penalty you need to allocate, but we did flag the issue,” says Cole. “If we ever publish a link specification, it will include four-wavelength mixing penalty; it is one of those things that must be done correctly.”
Innovation
The MSA’s specification work is incomplete, and this is deliberate, says Cole.
“We are at the beginning of the technology, there are a lot of great ideas, but we are going to resist the temptation to write a complete standard,” he says.
Instead, the MSA will wait to see how the industry develops the technology and how the specification is used. Once there is greater clarity, more specification work will follow.
“It is a tricky balance,” says Cole. “If you don’t do enough, what is the value of it? But if you do too much, you inhibit innovation.”
“The key aspect of the MSA is to help drive compliance in an emerging market,” says Matt Sysak of Ayar Labs and editor of the MSA’s technical specification. “This is not yet standardised, so it is important to have a standard for any new technology, even if it is a loose one.”
The MSA wants to see what people build. “See which one of the grids gain traction,” says Sysak.
Ayar Labs’ SuperNova remote light source for co-packaged optics is one of the first products that is compliant with the CW-WDM MSA.
Sysak notes that at recent conferences co-packaged optics is a hot topic but what is evident is that it is more of a debate.
“The fact that the debate doesn’t seem to coagulate around particular specification definitions and industry standards is indicative of the fact that the entire industry is struggling here,” says Sysak.
This is why the CW-WDM MSA is important, to help promote economies of scale that will advance co-packaged optics.
Applications
Cole notes that, if anything, the industry has become more entrenched in the last year.
The Ethernet community is fixed on four-wavelength module designs. To be able to support such designs as module speeds increase, higher-order modulation schemes and more complex digital signal processors (DSPs) are needed.
“The problem right now is that all the money is going into signal processing: the analogue-to-digital converters and more powerful DSPs,” says Cole.
His belief is that parallelism is the right way to go, both in terms of more wavelengths and more fibers (physical channels).
“This won’t come from Ethernet but emerging applications like machine learning that are not tied to backward compatibility issues,” says Cole. “It is emerging applications that will drive innovation here.”
Cole adds that there is hyperscaler interest in optical channel parallelism. “There is absolutely a groundswell interest here,” says Cole. “This is not their main business right now, but they are looking at their long-term strategy.”
The likelihood is that laser companies will step in to develop the laser sources and then other companies will develop the communications gear.
“It will be driven by requirements of emerging applications,” says Cole. “This is where you will see the first deployments.”
CW-WDM MSA charts a parallel path for optics
Artificial intelligence (AI) and machine learning have become an integral part of the businesses of the webscale players.
The mega data centre players apply machine learning to the treasure trove of data collected from users to improve services and target advertising.
Chris Cole
They can also use their data centres to offer cloud-based AI services.
Training neural networks with data sets is so intensive that it is driving new processor and networking requirements.
It is also impacting optics. Optical interfaces will need to become faster to cope with the amount of data, and that means interfaces with more parallel channels.
Anticipating these trends, a group of companies has formed the Continuous-Wave Wavelength Division Multiplexing (CW-WDM) multi-source agreement (MSA).
The CW-WDM MSA will specify lasers sources and the wavelength grids they use. The lasers will operate in the O-band (1260nm-1360nm) used for datacom optics.
The MSA is defining eight, 16 and 32 channels and will build on work done by the ITU-T and the IEEE.
This is good news for the laser manufacturers, says Chris Cole, Chair of CW-WDM MSA (pictured), given they have already shipped millions of lasers for datacom.
“In general, lasers are typically the hardest thing,” he says.
Wavelength count
The majority of datacom pluggable modules deployed today use either one or four optical channels. “When I started in optics 20 years ago it was all about single wavelengths,” says Cole.
Four channels were first used successfully for 40-gigabit interfaces. “That is when we introduced coarse wavelength-division multiplexing (CWDM),” says Cole.
Four wavelengths are the standard approach for 100, 200 and 400-gigabit optical modules. Spreading data across four channels simplifies the design of the electrical and optical interfaces.
“But we are ready to move on because the ability to increase parallel channels - be it parallel fibres or wavelengths - is much greater than the ability to push speed,” says Cole. “If all we do is rely on a four-wavelength paradigm and we keep pushing speed, we will run into a brick wall.”
Integration
Adopting more parallel channels will have two consequences on the optics, says Cole.
One is that photonic integration will become the only practical way to build multi-channel designs. Eight-channel designs are possible using discrete components but it won’t be cost-competitive for designs of 16 or more channels.
“It has to be photonic integration because as you get to eight and later, 16 and 32 wavelengths, it is not supportable in a small size with conventional approaches,” says Cole.
The MSA favours silicon photonics integration but indium phosphide or polymer integration platforms could be used.
The MSA will also cause wavelengths to be packed far more closely than the 20nm used for CWDM. Techniques now exist that enable tighter wavelength spacings without needing dedicated cooling.
One approach is separating the laser from the silicon chip - a switch chip or processor - that generates a lot of heat. Here, light from the source is fed to the optics over a fibre such that temperature control is more straightforward because the laser and chip are separated.
Cole also highlights the athermal silicon photonics of Juniper Networks that controls wavelength drift on the grid without requiring a thermo-electric cooler. Juniper gained the technology with its Aurrion acquisition in 2016.
Specification work
“Using the O-band has a lot of advantages,” says Cole. “That is where all the datacom optics are.”
The optical loss in the O-band may be double that of the C-band but this is not an issue for datacom’s short spans.
The MSA is to define a technology roadmap rather than a specific product, says Cole. First-generation products will use eight wavelengths followed by 16- and then 32-wavelength designs. Sixty-four and even 128 channel counts will be specified once the technology is established.
“Initially we did [specify 64 and 128 channels] but we took it out,” says Cole. “We’ll know a lot more if we are successful over three generations; we’ll figure out what we need to do when we get to that point.”
The MSA is proposing two bands, one 18nm wide (1291nm-1309nm) and the other 36nm wide (1282nm-1318nm). Eight, 16 and 32 wavelengths are assigned across both bands.
“It’s smack in the middle of the CWDM4 grid which is the largest shipping laser grid ever, and it is smack on top of the LWDM4 grid [used by -LR4 modules] which is the next highest grid to ship in volume,” says Cole.
The MSA will also specify continuous-wave laser parameters such as the output power, spectral width, variation in power between the wavelengths, and allowable wavelength shift.
Members
Cole started work on the CW-WDM MSA in collaboration with Ayar Labs while he was still at II-IV. Now at Luminous Computing, Cole, along with MSA editor Matt Sysak of Ayar Labs, and associate editor Dave Lewis of Lumentum, are preparing the first MSA draft and have solicited comments from members as to what to include in the specifications.
The MSA has 11 promoter members: Arista, Ayar Labs, CST Global, imec, Intel, Lumentum, Luminous Computing, MACOM, Quintessent, Sumitomo Electric, and II-VI.
The MSA has created a new observer member status to get input from companies that otherwise would be put off joining an MSA due to the associated legal requirements.
“So we have an observer category that if someone is serious and they want to see a subset of the material the MSA is working on and provide feedback, we welcome that,” says Cole.
The observer members are AMF, Axalume, Broadcom, Coherent Solutions, Furukawa Electric, GlobalFoundries, Keysight Technologies, NeoPhotonics, NVIDIA, Samtec, Scintil Photonics, and Tektronix.
“This MSA is meant to be inclusive, and it is meant to foster innovation and foster as broad an industry contribution as possible,” concludes Cole.
Further information
The CW-WDM MSA has several documents and technical papers on its website. The first document is the CW-WDM MSA grid proposal while the rest are technical papers addressing developments and applications driving the need for high-channel-count optical interfaces.