en.Wedoany.com Reported - On June 2, China Mobile announced that the world's first S+C+L three-band ultra-low loss multi-core optical cable line, independently designed in collaboration with its industry partners, has been officially completed and launched in Qingdao, Shandong, China. This line is designed to meet the demands of AI computing, T-bit-level high-speed transmission, and future metropolitan backbone network expansion, marking the entry of space-division multiplexing fiber and multi-band fusion technology into the commercial verification phase.
The core breakthrough of this new optical cable lies in simultaneously expanding two types of transmission resources: "space" and "spectrum." Traditional single-mode fibers primarily rely on a single core and limited bands to carry data. As traffic from artificial intelligence training, cloud computing, data center interconnection, high-definition video, and industrial internet continues to grow, simply increasing the number of fibers or repeatedly expanding pipelines faces constraints in construction, cost, routing resources, and operational complexity. China Mobile has adopted a four-core fiber structure, integrating four independent signal channels within a fiber as thin as a hair, and extending the ultra-low loss, large effective area characteristics from the C and L bands to the S band, enabling parallel transmission across the S+C+L three bands. According to publicly available information, this is equivalent to simultaneously increasing core channels and available spectral windows within the same fiber, boosting single-core bandwidth by nearly 50% and achieving a single-fiber capacity over five times that of traditional fibers, providing a higher-density underlying channel for high-capacity optical transmission.
Measured data also shows that the key indicators of this line have already met the engineering foundation for commercial network deployment. Publicly disclosed information indicates that the cable has a transmission loss of only 0.189 dB per kilometer, enabling longer signal transmission distances and higher stability; inter-core crosstalk is below -40 dB/100 km, resulting in low interference between different channels; and indicators such as dispersion and macro-bending loss all meet commercial standards. For multi-core fibers, low loss and low crosstalk are critical thresholds for entering existing networks. The former determines the signal attenuation level over long-distance transmission, while the latter affects the isolation capability during multi-channel parallel transmission. If crosstalk control between cores is insufficient, capacity gains will be offset by channel interference, making it difficult to support high-reliability service carriage.
The engineering deployment challenges are also concentrated in the precise alignment and splicing of multiple fiber cores. Unlike traditional single-core fibers, multi-core fibers require simultaneous high-precision alignment of multiple cores during on-site splicing. Environmental vibrations, terrain variations, splicing errors, and construction conditions can all affect the final transmission performance. China Mobile, in collaboration with its partners, has developed a multi-core splicing algorithm, achieving minute-level high-precision alignment splicing and completing line deployment under existing network conditions. This indicates that the technology is not just a laboratory sample but has been validated through real-world line environments, on-site construction, and network engineering processes.
For the information and communication industry, the significance of the three-band ultra-low loss multi-core optical cable extends beyond the capacity increase of a single line. Data exchange between AI computing centers, cross-regional scheduling of computing clusters, multi-availability zone interconnection for cloud service providers, and metropolitan backbone network expansion for operators all require an optical transmission foundation with higher capacity, lower loss, and greater reliability. As data centers evolve from single-point construction to regional clusters, optical networks will undertake more computing network connection tasks, and transmission systems need to release greater bandwidth within limited pipeline and fiber resources. The combination of S+C+L three bands with multi-core fibers provides operators with a new technical path to enhance network capacity without fully relying on new pipeline resources, and also leaves room for subsequent large-scale deployment of space-division multiplexing fibers, optical module adaptation, transmission equipment upgrades, and network operation and maintenance system adjustments.
Subsequent impacts will focus on the cost of large-scale deployment, maturity of the equipment ecosystem, and cross-vendor compatibility. For multi-core fiber lines to enter broader commercial use, supporting systems such as transmission equipment, optical amplifiers, optical modules, monitoring systems, construction tools, and operation and maintenance standards must be developed in tandem. The launch of the line in Qingdao, Shandong, provides an existing network sample. If it can be replicated in more metropolitan backbone, data center interconnection, and computing network scenarios in the future, it will drive China's optical communication infrastructure from single-band expansion and single-core expansion into a phase of multi-band, multi-core, and multi-dimensional parallel expansion.
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