20 Tbps Subsea Trial Reframes Asia-Pacific Network Upgrade Strategy

A trans-Pacific subsea trial suggests existing cables may scale further, shifting how Asia-Pacific operators plan upgrades

19 Dec 2025

A field trial on a trans-Pacific submarine cable has shown that existing systems may carry far more data than previously assumed, raising questions about how quickly new routes need to be built.

The test was carried out on the JUNO cable linking Japan and the US. Engineers transmitted 20 terabits per second on a single fibre pair over almost 10,000km under live traffic conditions. The result was achieved without altering the cable on the seabed, relying instead on upgraded equipment at either end.

Seren Juno, which operates the system, worked with Ribbon Communications to enhance terminal technology at the landing stations. By improving how optical signals are packed and processed, the companies were able to extract more capacity from the same physical infrastructure.

The experiment comes as data demand across Asia-Pacific continues to rise, driven by cloud computing, artificial intelligence workloads, video streaming and cross-border digital services. New submarine cables can take years to plan and deploy, often delayed by environmental approvals, manufacturing bottlenecks and geopolitical concerns.

Against that backdrop, terminal upgrades offer a faster and less capital-intensive option for meeting near-term demand, particularly on long-haul routes where new builds are expensive. The results are prompting operators and customers to reassess how much useful life remains in the cables already in service.

The trial also underlines the strategic value of modern, fibre-rich systems. While the announcement was not linked to any transactions, technical advances of this kind can influence how investors and partners assess subsea assets, especially as governments treat them as critical infrastructure.

There are limits to how widely the approach can be applied. Most details of the trial have come from company disclosures and industry reporting rather than independent analysis. Broader adoption will depend on commercial economics, resilience standards and regulatory scrutiny.

Even so, the demonstration suggests that future capacity gains in the Pacific may come as much from upgrading terminals as from laying new cables, at least in the near term.