NTT hits 455 Tbps using multicore fibre

Using multicore fibre cables and massive MIMO signal processing, it has achieved stable signal transmission at rates of up to 455 Tbps in a field test that simulated environmental effects such as wind, rain and civil works – all of which can affect signal propagation.

NTT explained that in traditional optical network architecture, data flows down a single core, but efforts are underway to see how multiple cores can be used to transmit signals in parallel, increasing the number of channels and by extension, capacity – all the while maintaining the same 0.125 mm diameter as existing optical fibre.

NTT says it was able to couple 12 fibre cores, employing digital signal processing at the receiver end to overcome the issue of interference from adjacent cores.

In terms of distances, NTT reached 455 Tbps over 53.5 kilometres, while a still-impressive 389 Tbps was reached at a distance of 1,017 km. NTT said this is the equivalent length of Japan's main fibre backbone linking Tokyo, Nagoya and Osaka, and therefore its demo has implications for this technology's future uses.

NTT claims that multicore fibre has the potential to become "a fundamental technology for realising future terrestrial optical transmission systems with a transmission capacity more than 50 times that of conventional systems."

"With the spread of high-capacity mobile networks and the increase in communications between data centres that support the ever-developing AI technology, the amount of data travelling around the world continues to increase exponentially," said NTT. "This trend is expected to continue, and terrestrial backbone optical networks need to continuously increase their capacity to support demand."

Indeed, and in fact, optical transmission records are regularly toppled.

In September alone, Nokia and Greek telco OTE managed to achieve a speed of 800 Gbps on a single channel over 2,580 km, and 900 Gbps over 1,290 km, which they claim is a new record.

Days later, Australian incumbent Telstra claimed a milestone of its own, reaching 1.6 Tbps over a 700 km route between Melbourne and Canberra.

Last month, US telco Verizon and Ciena managed to record a speed of 1.6 Tbps on a single carrier wavelength over a distance of 118 km over a Boston metro route.

All these speeds seem positively lackadaisical compared to what NTT's just managed, albeit with multiple fibre cores working in tandem.

The big question regarding all this is when this technology could find its way into commercial service. NTT isn't offering specifics, but is working towards commercialisation with existing supplier Fujitsu.

"Going forward, by collaborating with related technology fields and further advancing research and development of this technology, Fujitsu Laboratories aims to commercialise high-capacity terrestrial networks that will contribute to the realisation of a high-capacity optical transmission infrastructure for the IOWN (Innovative Optical and Wireless Network) concept in the 2030s and the Beyond 5G/6G era," said NTT.

So not any time soon then.