China activates first commercial three-band optical fibre system

The project, completed in Qingdao, Shandong province, is a collaboration between state-owned telecommunications giant China Mobile and its industry partners, including Hengtong Optic-Electric. The 35-kilometer (21.7-mile) link serves as a commercial test bed for next-generation optical networking technologies, connecting major computing facilities within the city.

This new system utilizes three transmission windows—the S-band, C-band, and L-band—simultaneously within a standard optical fibre. This approach, likened to expanding a two-lane motorway into a three-lane highway, enables substantially more data to travel through existing infrastructure. While most long-haul fibre systems primarily use the C-band and L-band, technical hurdles in signal amplification, noise control, and stability had previously limited the commercial use of other spectrum parts, particularly the S-band.

The system's functionality is based on two key advancements: extending ultra-low-loss transmission capabilities into the S-band, which was previously too unstable for commercial use, and integrating this with multi-core fibre technology.