World’s First S+C+L Multi-Core Fibre Cable Opens in Qingdao, China

The world’s first ultra-low-loss multi-core fibre (MCF) cable operating across the S, C and L bands has been completed and put into service in Qingdao, Shandong Province. Designed independently by China Mobile in collaboration with industry partners, the new cable marks a commercial milestone for China’s space-division multiplexing (SDM) and multi-band integration technologies.

Breaking the capacity limits of conventional single-mode fibres, the deployment delivers a new technical blueprint for interconnection and ultra-high-bandwidth transmission in the intelligent era.

The design adopts a four-core structure, integrating four independent signal channels within a single hair-thin fibre. Ultra-low loss and large effective area characteristics, previously available only on the C and L bands, have now been extended to the S band, enabling simultaneous transmission across all three bands.

This upgrade is analogous to expanding a data highway from dual carriageway to three-lane, boosting per-core bandwidth by nearly 50% and delivering over five times the capacity of traditional fibres. The specification aligns with requirements for AI computing clusters and terabit-per-second transmission networks.

Precision alignment and splicing of multiple cores represented the most significant engineering challenge. Faced with environmental vibration, complex terrain and stringent accuracy demands, the joint team developed dedicated MCF splicing algorithms to achieve high-precision alignment within minutes, supporting stable, high-quality deployment across the route.

Independent testing confirms performance exceeds current commercial network standards. Attenuation is measured at 0.189 dB per kilometre, supporting longer and more stable transmission. Inter-core crosstalk is kept below −40 dB/100 km, ensuring negligible interference between channels. Dispersion and macro-bend loss parameters fully meet commercial specifications.

End-to-end real-time transmission tests across the full S+C+L spectrum have been successfully completed, demonstrating error-free, low-jitter operation. The outcome represents a critical transition of the technology from laboratory validation to live-network deployment.

Following the opening of the Qingdao route, further trials are scheduled to evaluate the performance of multi-core and multi-band technologies in diverse network scenarios. The results will inform the design of future high-capacity backbone and data centre interconnection systems, supporting the scalable development of digital infrastructure.