NTT and vendors demo multi-core fiber with standard diameter glass

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NTT and six partners – KDDI Research, Sumitomo Electric Industries, Fujikura, Furukawa Electric, NEC and Chiba Institute of Technology – say they have demonstrated the world’s largest transmission capacity of 118.5 Tbps using a multi-core fiber with four optical paths in the same diameter of existing optical fiber.

The companies said in a joint statement the achievement proves the concept of a multi-core fiber-based long-haul and large capacity transmission system consisting of multiple vendor technologies, and marks significant progress in the practical use of the multi-core fiber technology.

With data growth generating increasing demand for transmission capacity, especially in and between data centers, researchers have been investigating the possibility of developing a fiber with multiple optical paths (or cores) to overcome the future capacity crunch and to enable high density in optical facilities (or to save space).

Up to now, ultra large capacity transmission experiments using a multi-core fiber with ten cores or more have been demonstrated, but these required a thicker glass diameter, as well as an extreme advance in the fabrication process and further development on sub-components. Consequently, it was believed that it would take ten years or more for high-core-count fiber to become practical.

In order to accelerate that timetable, NTT, KDDI Research, Sumitomo Electric, Fujikura, Furukawa, NEC, and CIT developed a multi-core fiber with a conventional diameter in accordance with the current International standard (125 micrometers) that enables the use of existing optical fiber technology, although this limits the number of cores to four or five.

Experiments conducted by the companies demonstrated that four to five cores can be arranged within a 125-micrometer glass diameter while maintaining the same transmission quality as current optical fiber. The 118.5 Tbps transmission speed was achieved using a 316 km multi-core transmission line (composed of optical fibers from multiple vendors) with a 0.21 dB/km average loss, multi-core optical amplifiers and existing optical connectors.

The companies said they plan to introduce standard diameter multi-core fiber by the early 2020s.

The work was partially based on work commissioned by the National Institute of Information and Communications Technology (NICT).

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