Coherent on Scaling AI Beyond the Cluster

AI workloads are outgrowing single data centers. Frontier model providers are pushing training runs across multiple facilities because no single facility has enough power to process the workload, a shift the industry now calls scale-across.

At the Six Five Summit: AI Unleashed 2026, Matt Kimball is joined by Sanjai Parthasarathi, Chief Marketing Officer at Coherent, to walk through what that shift requires. Parthasarathi points to data center interconnect transceivers and optical transport equipment as the two components that matter most, with bandwidth and energy efficiency topping customer priorities. He uses Coherent's multi-rail platform, which delivers 4X the capacity in the same physical footprint, as proof that energy pressure is real, and closes by looking ahead to data centers in space, where Coherent's satellite optics experience already applies.

Key Insights:

🔹 Scale-across is driven by power limits. Parthasarathi says AI training runs are spanning multiple data centers because no single facility has enough power to process the workload, which is driving demand for high-bandwidth interconnects between sites.

🔹 Two functional blocks define scale-across networking: data center interconnect transceivers at the edge of each facility, and optical transport equipment that amplifies and monitors the signal across distance. Bandwidth and energy efficiency are the top performance priorities customers ask about.

🔹 Coherent's multi-rail platform lets customers hit four times the capacity inside the same physical enclosure. Power needs scale sub-linearly as capacity grows, solving a real constraint for transport equipment housed in fixed-size huts along highways and in residential areas.

🔹 Coherent's differentiation runs from raw materials to finished systems. Parthasarathi points to roughly 50 years of engineering history, more than 50 global manufacturing sites (20+ in the US), and expanding Indium Phosphide production to meet AI-driven demand.

🔹 Data centers in space face a different set of optical challenges. Parthasarathi says components need to survive launch, radiation, and vibration, and maintain line-of-sight connections between objects moving at roughly 4,000 kilometers per hour, work Coherent already does for the satellite communications market.

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Matt Kimball:
Hi, everyone, and welcome to the Six Five Summit AI Unleashed 2026. My name is Matt Kimball with More Insights and Strategy. And for this Connected Intelligent Edge Networks and Agents Spotlight, we're going to be exploring how AI infrastructure is evolving beyond the boundaries of any single cluster and why networking is becoming one of the defining challenges of the AI era. Joining us is Sanjay Parthasarathy, Chief Marketing Officer at Coherent. Sanjay, thanks for joining me on this 6.5 Summit. It's going to be a fun conversation.

Sanjai Parthasarathi: 

Thanks, Matt. It's great to talk to you again and really great to be here.

Matt Kimball: 

Hey, so let's jump right in, all right? Because there's a lot to cover. Of course, networking has become the bottleneck that everybody has been pointing to. And in that kind of world of networking, everyone's gotten really comfortable with this concept of scale up and scale out, right? Terms that nobody talked about three years ago, everybody is talking about today. And now we're hearing about scale across. And I think a lot of folks I speak with out in the marketplace, When I say that, there's a little bit of like, what do you mean by that? So when we talk about scale across, what exactly are we talking about? And why is this all of a sudden showing up everywhere in AI infrastructure conversations?

Sanjai Parthasarathi: 

Yeah. At its core, Matt, it's all about optical communications. I've been in the optical communications, optical networking industry for almost 30 years. And I can tell you, this is perhaps the most exciting time in photonics and optical networking. And now, coming back to optical communications, people have been, communicating with light is not new. The Phoenicians were signaling with light thousands of years ago, right? So it's not something new. Jokes apart, modern communications began with the telegraph, and that connectivity was all electrical. But when you need to go longer distances, or you want to go at higher speeds, or a combination of higher speeds and longer distances, the only way to do it is optical. I mean, the physics demands that you drive towards optical. So today, most of the world's communications networks are all on an optical network. the optical of the communications networks. Let me give you an example. You pick up your phone, and let's say you're sending a photo or you're talking to your friend in Singapore. The first talk between your phone and the RF tower is RF signals. But at the base of every one of those RF towers these days is an optical transceiver. So that takes electrical signals, converts them to optical signals, and pushes it through the fiber network. And from that point on, your data, your voice, is in the optical domain. It goes through the access networks, the metro networks, the long-haul networks. And at some point of time, because the signal needs to go to Singapore, you enter a submarine cable landing station. You know, there is one a hundred miles from where we are right now, where I am right now, there is a, there is a cable, the submarine cable, that goes for all the way to Singapore. So your signals go through the submarine cable. Then when it comes to Singapore, then you have the same oil distribution, and then it comes into the RF tower and back to the phone. And so all of that is optical. And by the way, Coherent, we are one of the broadest and deepest portfolios in the optical industry, and we have the photonic components and modules that enable you to do all of that. All of those components that you need from this one end of cell tower to the other cell tower, we are able to provide. Now, let me come back to scale across, right? So you started by asking scale across, so what scale across? So data centers are power constrained. That's the single, any discussion on the data center, it starts with energy; it's about energy efficiency, et cetera. So when you have large AI workloads, now these workloads are being forced to be spread across multiple data centers because there's just not enough power in one data center to process these large workloads. So that, in turn, drives a demand for these very high-bandwidth connections between the data centers. And that's what we call the industry has started to refer to that at a scale across networks.

Matt Kimball:

So when you talk about that, right, so we have a, you know, we have multiple data centers, and I'm doing a, I'm a, I'm a frontier model provider, I'm doing a training run that, you know, spans multiple data centers, that networking problem is different than obviously connecting from one rack to another. You know, in that kind of equation, what optical technology becomes, like, non-negotiable at this point? And by the way, if I'm the person that has to design that network, what are the specs I should be paying attention?

Sanjai Parthasarathi:

Sorry, I forgot to turn off the phone. You're OK. So I just turned it off. Maybe we should start the second question again.

Matt Kimball:

Yep, that's perfect. Thank you for doing that.

Sanjai Parthasarathi:

Yeah, go ahead.

Matt Kimball:

Okay, so this is really interesting, right? This concept of scale across. So let's put this kind of in the real world, okay? I'm a frontier model provider. I've got a training run that's spanning across multiple data centers. When that happens, that networking problem is entirely different than plugging cables from one rack to another, right? So in that equation, what optical technology becomes non-negotiable for me? And part two to that is, if I'm the person that's designing that network, what are the things I should be focusing on most closely? Like what are those specs I should be really paying attention to as I design that network out?

Sanjai Parthasarathi:

Okay, so let me unpack all of that. So let me just start by saying optical networks have been becoming increasingly desegregated over the years. So large monolithic systems have been sort of giving way to smaller, easy-to-deploy functional elements or functional blocks. And there are two important functional blocks for scale across. One is data center interconnect transceivers or DCI. I mean, just by the definition, these are transceivers that sit at the edge of a data center. They're high-bandwidth, high-capacity transceivers that take electrical signals, convert them to optical signals, and then shoot it across to the next data center. But equally important is another class of equipment that's called optical transport equipment. And that equipment sits in between the two data centers. And again, as the name implies, optical transport equipment helps transport the optical signal. And you say, what does that mean? Well, when you launch an optical signal into a fiber, after the signal goes for a certain distance, it starts to die down; it attenuates. So you need amplifiers to boost the signal again. You need signal conditioning. You need to monitor the strength of the signal, the health of the signal. You need to monitor the health of the fiber infrastructure. all of that, all of those functions are being done by this transport equipment. So it's a pretty important class of equipment. So, two main functional blocks: data center interconnect transceivers and transport equipment. I have a question on what is it? What are the performance metrics, right? What is it that customers care about? Again, for the past 30 years, the longest time I've been in this market, it always starts with bandwidth, bandwidth, bandwidth, bandwidth. And then energy efficiency. That's been the mantra for quite some time. Other things like reliability, they're a given. They're like table stakes. But in the AI data center context, it's a really big focus on energy. So customers are looking at how we can improve every little bit of energy efficiency within this equipment.

Matt Kimball:

Makes sense. That makes total sense. So I've been hearing more and more about the multirail system from Coherent, the multirail platform, I'm sorry. And so for folks that are watching at home, who have no idea what this actually is, can you walk us through this a little bit? And maybe even more importantly, can you talk about, like, the customer problem that made you kind of think about this platform and build it in the first place?

Sanjai Parthasarathi:

Yeah, so I mentioned transport equipment, right? So multiradio is a part of the transport equipment. So it performs important functions like amplification, signal conditioning, monitoring, and others. So the transport equipment typically does not sit in the data center. It sits in separate enclosures that are in between the data centers. So these could be, these enclosures could be by a highway. You would have probably seen them. Yeah.

Matt Kimball:

We had a little disruption there in the quality. One of us froze; I'm not sure. So I'm going to restart that question for you. I apologize.

Sanjai Parthasarathi:

Yeah, and Matt, I thought you were going to ask the why coherent question.

Matt Kimball:

I was going to add that in after.

Sanjai Parthasarathi:

Oh, OK.

Matt Kimball:

Do you want me to lead with that before I go to the multi-rail?

Sanjai Parthasarathi:

Yeah, because I was going to show multi-rail as an example.

Matt Kimball:

OK, perfect. Got it.

Sanjai Parthasarathi:

Thank you.

Matt Kimball:

Yeah, no worries. All right. Ready?

Sanjai Parthasarathi:

Yeah.

Matt Kimball:

Okay. Okay. So Sanjay, this is interesting. And I have to say, you know, as an analyst in the industry, and I think even casual observers who are playing out in the market, you know, we keep hearing more and more about optical networking and more and more players entering the space, right? You mentioned Coherent has a very solid position in a really robust portfolio. But within that context, tell me what makes Coherent unique? What separates Coherent from everybody else in this space?

Sanjai Parthasarathi:

OK. Coherent, we have one of the broadest and deepest portfolios in the industry. So it's not just the breadth of the portfolio. We have a deep, vertically integrated technology stack. Technology stack map goes all the way down to the materials. And we are a company of innovation, right? We have about 50 years of innovation, a long track record of bringing industry-first advances to the industry. You know, many cases where we have our products have actually created a new market segment for the industry. And AI is just challenging the industry to innovate at all levels of the value chain. So that's a big differentiator for us because we have all the platforms within the company, and we're deeply vertically integrated. So when we develop our solutions, they're kind of tailor-made, with innovation all the way down to the materials level and up to the systems level. You know, a great example of a recent example of our innovation is our multi-rail platform. You know, I mentioned earlier that hyperscalers and data center operators are driving big reductions in energy, right? They want to be most energy efficient. And multi-rail is just, it's really groundbreaking innovation. Unprecedented levels of energy efficiency that platform brings to the market. So that's just an example. But, you know, our differentiation is not just about the innovation and the technology. It's our ability to manufacture at scale. And these days we've started using the word manufacturing at AI scale, at a scale that the industry has never seen before, right? If you take Indium Phosphide, a platform that is critical for AI connectivity. Indium Phosphide is a platform on which detectors, lasers, plane of light wave circuits for scale up, scale out, scale across, scale in, everything, right? That's where it's built on. Wte are doubling production, and we are doubling production again, and more than doubling production. So manufacturing and for Coherent, we were founded as a manufacturing company in Saxonburg, Pennsylvania, which is still our global headquarters today, right? We have over 50 and we have a diversified global manufacturing footprint. We have over 50 sites worldwide, but more than 20 are in the US. So we're super proud about that as well.

Matt Kimball:

That's fantastic. It's interesting you mentioned, you know, manufacturing at scale. It's a, you know, it seems that every time there's, you know, you find a, you know, a, a kind of constraint in the supply chain and you get through that, there's another constraint. It's interesting that Coherent is staying ahead of the demand by, you know, by increasing manufacturing so significantly to meet those needs, and networking is without a doubt perhaps the largest bottleneck that we see in the AI equation.

Sanjai Parthasarathi:

Matt, that's a great point, because that's one of the big advantages that we bring, because we make pretty much everything that goes into our products on the optical component side, and that's a giant advantage. I mean, all of our product lines are ramping up in this area, so it's a pretty exciting time.

Matt Kimball:

That's fantastic. Hey, I want to loop back to something that you mentioned. We heard multi-role platform in there. And I think, you know, folks that might be new to coherent and certainly new to optical networking, if they hear that term cold, they're probably thinking, well, what the heck is that? Right. So walk me through that a little bit. And maybe even more importantly, as you walk me through it and walk the listener through it, the viewer through it, Talk to the customer problem that makes you kind of think about building this platform in the first place.

Sanjai Parthasarathi:

Okay. So yeah. So, you know, I mentioned transport equipment, right? So multi-rail is basically transport equipment. This is equipment that does not sit in the data center. Sometimes it does, but most of the time these are, this equipment is in between the data centers. And transport equipment, I mean, just to, you know, I mentioned it earlier, but they perform a lot of important functions. They help amplify the optical signals, they help condition the optical signals, they monitor the health of the signals, monitor the health of the fiber infrastructure- just a whole host of important functions that this equipment performs. The equipment is often housed in what we call amplifier huts or fiber huts. What the heck is that? Well, they look like huts. These are enclosures, and they could be anywhere. I mean, you've probably seen them when you're driving on the highway. Some are in residential neighborhoods. These are enclosures that obviously have power going into it. They have equipment sitting there. And in many cases, they're controlled. They're environmentally controlled, temperature-controlled. And so now with the AI networks growing and the demands on scale across networks, our customers want five, four times a multifold increase in capacity. And when they're driving those kinds of demands, just imagine the situation here. So you've got this enclosure, but today's technology, if you want to, let's say, increase capacity by a factor of four, you need four times more space and four times more power. And imagine what the, I mean, this enclosure that's sitting by the street here, imagine the challenges you're gonna go through if you wanna make it four times larger, all the regulatory environments and all the power issues. They just, even if you could get the power, there may not be any power available in that location, right? I mean, it's a serious problem. And that's really where our multi-rail platform comes in. Basically multi-rail in this particular case, if you take the Forex case, you're able to essentially process four times increased capacity by a factor of four within the same volumetric envelope. So the hut can be the same size. So imagine now we are able to do four times more traffic. Yes, you need a little more power, but it's significant savings in the power requirements. The platform sub-linearly scales with power. So It is a groundbreaking innovation, a lot of excitement from our hyperscale customers and our OEM customers.

Matt Kimball:

That's fantastic. Hey, we're talking about some pretty interesting stuff here. I want to end on a science fiction note, if you will. Everyone has heard about data centers in space. My gosh, my dad calls me and talks about data centers in space. You know, it's at the mainstream when George Kimball is calling me. Um, so in your opinion, maybe your opinion, certainly the coherent position. Yeah. How, how real is this, and how far out are we talking about if, if in fact, you know, there's, this is grounded in reality, a couple, couple of elements to set the first question. Second is, you know, what are the optical problems that exist, you know, kind of trying to transmit from space versus kind of ground to ground and. I know that Coherent's done some work or has given some thought around this. So I'd love to get your viewpoint on this.

Sanjai Parthasarathi:

Yeah. Believe it or not, my dad asked me about it. My dad and I had a conversation about this center in space three weeks ago. So it is in the mainstream media, if you will, I guess. But today, we serve the SAPCOM market. In fact, we have one of the industry's broadest portfolio for free space optical communications, which is really space communications. And if you look at what are the components there, everything that you need- all the photonic components that you need for terrestrial transmission-- you need for space-based transmission. So in the SAPCOM market that we service today, you've got all the same components. But here's the twist. These components need to, there's a whole host of additional requirements on these components. They need to survive radiation; they need to survive launch; they need to survive the shock and the vibration or they need to be able to operate reliability in a harsh environment of space. And then, by the way, you're talking about a line-of-sight connection between two objects that are moving at 4,000 kilometers an hour. So there is a whole host of other optical components that you need: telescopes and gimbal mirrors. And so there's a lot of specialized optics, and a lot of which we make at Coherent. And to the extent there are data centers in space, it's great for optical connectivity, and it's great for Coherent. I'm sure, as my colleague often says, I'm sure in the future data centers will be deployed in ways that we have not imagined today. You know, unconceivable ways. So I guess wherever humanity takes the data center, Corinth will be there to provide the connectivity, both within the data center and between the data centers.

Matt Kimball:

That's a fantastic close. I love that. Yeah, it's a, I wholeheartedly agree with you. The one thing we, I think, all can agree on is, you know, the feature data center, is going to look a lot different than the data center of today, and it's going to live in places we never thought imaginable. Sanjay, thank you so much for taking the time on this. This is our Connected Intelligent Edge Spotlight. This has been a really fun conversation, and I hope we can continue this at another time.

Sanjai Parthasarathi:

Yeah, thank you, Matt. I enjoyed it. Thanks for having me.

Matt Kimball:

Of course, yeah. And to our viewers, don't forget to hit subscribe, follow us on social media, and check out all of our Six Five Summit content at sixfivemedia.com slash summit. And we will see you next time.