IN Brief:
- Lightera is expanding submarine optical fibre manufacturing at Brøndby in Denmark and Norcross in the United States.
- Manufacturing capacity is planned to nearly triple by 2029 as hyperscale, cloud, AI, and global-network investment increase demand.
- The investment also prepares production for initial multicore submarine fibre deployments expected around 2029 to 2030.
Lightera will nearly triple its submarine optical fibre manufacturing capacity by 2029 through investment in Denmark and the United States, expanding current production while preparing its manufacturing base for emerging multicore subsea networks.
The programme covers Lightera’s Brøndby operation in Denmark and its Norcross facility in Georgia, both of which manufacture optical fibre for submarine systems. The company has not disclosed the value of the investment but says the additional capacity will support existing customer commitments and future cable programmes.
Timing matters in the submarine market because fibre is purchased well before a completed cable enters service. Lightera says optical fibre is typically ordered about a year ahead of cable deployment, giving fibre producers early visibility of demand coming from cable manufacturers and hyperscale network operators.
The expansion is being driven by continued investment in AI infrastructure, hyperscale datacentres, cloud computing, and wider global-network capacity. Submarine cable projects increasingly sit underneath those digital services, carrying traffic between regions where terrestrial networks cannot provide an alternative route.
Lightera is also preparing for multicore fibre as part of the capacity programme. The company expects initial submarine deployments around 2029 to 2030, introducing several optical cores within a single strand rather than relying only on additional conventional fibres to increase spatial capacity.
That manufacturing transition is more demanding than simply drawing extra cores into the glass. Core geometry has to remain tightly controlled across very long production runs, while cable manufacturing, jointing, testing, and system design have to preserve the performance of each optical path through infrastructure intended to operate for decades.
Submarine networks place unusually severe requirements on reliability. Once a cable is laid, faults can require specialist vessels and lengthy repair operations, making manufacturing consistency and qualification more important than in short terrestrial links where physical access is easier.
Multicore fibre offers a route to increase spatial capacity without expanding fibre count in direct proportion to transmission demand. That can reduce pressure on cable diameter and internal space, although the complete system still has to deal with additional optical channels through repeaters, amplifiers, splices, landing equipment, and monitoring systems.
Lightera is developing some of the supporting technology in parallel. Its current four-core fibre work includes multi-vendor interoperability over 500m and 50km links, while its FITEL splicing operation is developing rotational alignment techniques for connecting multicore strands accurately. Those terrestrial demonstrations operate over far shorter distances than a submarine system but address practical handling problems that become critical once multiple cores have to be joined.
The company has also announced broader fibre and cable manufacturing expansion during 2026, but the submarine investment is more specialised. Undersea fibre production has to match the specifications of cable makers and system suppliers working to long project timelines and stringent reliability requirements.
Increasing capacity ahead of expected multicore deployment reduces one industrial risk: reaching technical qualification without enough manufacturing output to serve large cable programmes. The opposite risk remains that manufacturing investment arrives before the new fibre architecture is widely adopted, leaving conventional submarine demand to justify much of the additional capacity in the meantime.
That demand currently appears substantial enough for Lightera to proceed. Its direct relationships with submarine cable manufacturers and hyperscale customers give the company visibility into programmes before the cables are deployed, while the 2029 expansion date aligns with the period in which it expects multicore systems to begin entering the market.
The next milestones will be qualification with cable manufacturers, repeatable multicore production, and proof that the wider connection and test ecosystem can achieve submarine-grade reliability. Nearly tripling manufacturing capacity provides the industrial base; the harder task is ensuring new fibre structures can use that capacity without compromising the service life expected on the seabed.
