Old Fiber, New Record: 450 Tbps Over London Streets

Japan's NICT pushed 450 Tbps through a live London metro fiber link, no new cable required

17 Jun 2026

Japan's National Institute of Information and Communications Technology has set a new global record for optical data transmission, pushing 450 terabits per second through a 39-kilometre fibre link in London without replacing a single cable. The result, presented at the OFC2026 postdeadline session on 19 March 2026, surpasses the previous benchmark of 430 Tbps, which had been achieved only under controlled laboratory conditions.

Led by Dr Ruben S. Luis at NICT's Photonic Network Laboratory, the team used multi-band wavelength-division multiplexing across five spectral bands: O-, E-, S-, C- and L-, covering a combined 42.4 terahertz of total bandwidth. The transmission ran over standard single-mode fibre already in the ground, connecting University College London to the Telehouse North data centre. NICT President OHNO Hideo confirmed it was the first time such a rate had been achieved over legacy urban infrastructure.

The commercial implications are direct. Upgrading capacity on metropolitan fibre networks has historically required expensive underground cable replacement, a process that disrupts city operations and strains operator budgets. Demonstrating that existing cable can carry 450 Tbps changes that calculation entirely, opening a path to significant bandwidth growth through hardware and software upgrades alone.

Cloud computing providers, AI workload operators, and real-time data platforms stand to benefit most. Metropolitan fibre networks carry the bulk of digital commerce, and higher throughput at lower upgrade cost tends to compress prices for enterprises and end users alike.

Supported by infrastructure from the UK National Dark Fibre Facility, the London link replicates the field conditions operators face in most major cities. That choice was deliberate. Results from a working urban network carry more immediate weight than laboratory simulations, and the approach is replicable elsewhere without novel cable deployment.