Japan-led group achieves optical transmission of ultrawide signal at 115.2 THz

05 Dec 2023

“World first” claimed by KDDI, Sumitomo Electric, Furukawa and OFS Labs; capability supports 6G developments.

Japan-based optical communications partners KDDI Corp. and KDDI Research, Sumitomo Electric Industries, Furukawa Electric, and US-based OFS Laboratories have conducted successful experiments on ultrawideband optical fiber transmission with a transmission bandwidth of 115.2 THz – the world’s largest transmission capacity: 484 Tbps – over a distance of 31 km using standard optical fiber diameter.

This result was achieved by combining uncoupled 12-core optical fiber with the independent cores densely arranged inside a 250 μm coating, the same size as a standard optical fiber, and a broadband O-band optical fiber amplifier.

In the 6G era, it is expected that far more and diverse data will transit networks than at present due to the proliferation of Internet of Things (IoT) devices and mobility services. KDDI and partners contend that it is essential to further expand the capacity of optical fiber communication to support evolving networks.

The 115 THz announcement states, “The success this time is in technology for supporting high-capacity, high-speed communication between data centers in the 6G era.

“Furthermore, the same transmission capacity can be secured with fewer fiber cores since the transmission capacity per optical fiber can be greatly expanded, and this technology is expected to enable the use of ordinary conduits and facilities with less space occupied.”

These results were first reported as a post-deadline paper at ECOC 2023 (European Conference on Optical Communications), held in Glasgow, UK, in October.

Dawning of the 6G era

The capacity of optical fiber communication needs to be further expanded to support networks in the 6G era. Transmission capacity per optical fiber can generally be increased by using wavelength division multiplexing, in which the wavelength of light is slightly changed for multiplexed transmission.

Until now, KDDI Research, Sumitomo Electric, and Furukawa Electric had been working toward practical application of multi-core optical fibers, which have multiple cores in a single optical fiber.

In March 2023, KDDI Research, Furukawa, and OFS conducted successful O-band (1260–1360 nm) coherent dense wavelength division multiplexing transmission experiments to utilize the O-band, which has approximately twice the transmission bandwidth of the C- and L-bands (1530–1565 nm, and 1565–1625 nm, respectively).

Furthermore, also in March 2023, Sumitomo Electric presented a high-density uncoupled 12-core optical fiber with a coating diameter of 250 μm, the same diameter as that of standard optical fibers, making it suitable for creating high-density optical cables.