A group of Japanese enterprises has demonstrated what they say is the world’s largest transmission capacity – 118.5 Tbits/s – using a multicore fibre with four optical paths (cores) in the same diameter – 125 µm – as currently used optical fibre. The partners believe the achievement proves the concept of multicore fibre-based long-haul and large capacity transmission system using multiple vendor technologies, and makes significant progress in the practical use of multicore fibre technology.
The background to the interest in multicore fibres is the explosive growth in capacity demand fuelled by services such as the Internet and smartphones. The Japanese companies reckon this trend could cause a capacity crunch in currently used optical fibre by the late 2020s. Moreover, they point out that the unchecked expansion of optical fibre counts and the convergence of optical wiring, particularly in data centres and/or central offices, could present serious problems in the future.
Multicore fibres have been the subject of worldwide investigation, and ultra large capacity transmission experiments have been undertaken with, for example, demonstrations of multicore fibres with 10 or more cores. However, these high count multicore fibres usually need a thicker glass diameter, require advances in fabrication processes, and necessitate further developments in sub-components. As a result, say the Japanese researchers, it is considered that it would take 10 years or so to make high count multicore fibres practical.
In order to accelerate the use of multicore fibre technology, NTT, KDDI Research, Sumitomo Electric, Fujikura, Furukawa, NEC and the Chiba Institute of Technology developed a multicore fibre with a conventional diameter in accordance with current International standards. This enables the use of existing optical fibre technology, even though it limits the number of cores to 4 or 5.
The group aims to introduce standard diameter multicore fibre by the early 2020s.