- CableLabs recently demo’d coherent PON that can reach 50,000 Gbps over a single fiber strand
- CEO Phil McKinney thinks the tech will use far less power than XGS-PON to reach longer distances
- But broader coherent PON deployments are a long way away
When you think of coherent optics, typically long-haul backbone and subsea cables come to mind, but CableLabs wants to see the technology more broadly adopted in the access network.
At this week’s SCTE Tech Expo, CableLabs CEO Phil McKinney highlighted a lab demo of coherent PON that reached a whopping 50,000 Gbps over a single strand of fiber. That’s just scratching the surface of the benefits operators can gain, he told Fierce in an interview.
He estimated coherent PON will use “60-70% less power than XGS-PON because of the way it does the splits,” referring to how coherent optical line terminal (OLT) ports can divide their network capacity among a much greater concentration of end users compared to traditional PON technology.
“It requires less front-end gear to reach more homes,” McKinney said. “You can do remote towns over very long distances that a traditional XGS-PON would never be able to do.”
Coherent PON aims to deliver 100 Gbps over a single wavelength and also extend the reach of PON over fiber up to 80 kilometers. Ciena has said the technology can support up to 512 end users on a single OLT port, whereas standard PON typically supports 32 or 64 users per port.
Coherent optics potential for rural broadband
Widescale commercial coherent PON deployments are still far off. CableLabs has been working on coherent PON specifications over the last couple of years and expects to publicly issue a full list of specs by the end of 2025.
But coherent optics are picking up steam for fiber-to-the-premises rollouts. Comcast, for instance, announced this week it’s using Ciena’s coherent access platform to expand current fiber deployments by more than 100 kilometers, targeting more rural areas.
In McKinney’s view, if coherent PON were fully developed today, it could have offered a more cost-effective approach for fiber under the Broadband Equity, Access and Deployment (BEAD) program. His comments come after NTIA chief Arielle Roth confirmed it’s asking states to lower costs for certain BEAD projects.
“I kind of wish we had coherent PON going into BEAD, because it would have radically reduced the cost for these remote towns when you’re trying to push fiber deep and into underserved communities,” he said. “But we have what we have, the technology we have today.”
50,000-gig and what’s next
Regarding the 50,000-gig stat, McKinney emphasized “there’s nothing special about the fiber material” that was used to achieve those speeds. He did note the fiber CableLabs uses for its testing “is all Corning,” which is producing fiber for the likes of Lumen and Microsoft to boost network capacity for AI. But he said operators can get up to 50,000 gigs with any of the commercial fiber that’s currently on the market.
Asked what services networks could enable with 50,000 Gbps, McKinney said it’s hard to say when most consumers probably don’t even need 2-gig in their homes. It’s all about thinking of what technology comes next, even if it doesn’t exist yet.
“There isn’t an obvious ‘Oh my God, that’s the thing we’re building to.’ Because if we waited to do that, the network would always be behind what the market needs,” he said. “You’re betting along the way that innovators are coming behind, they’re going to create that next service that then is going to take advantage of those [capabilities].”