Optical Communication Record Renewed As 24‑Core Fiber Achieves 2.5 Pb/s, Nearing Practical Deployment

On March 24, China Information and Communication Technologies Group announced that its National Key Laboratory of Optical Communication Technology and Networks, in collaboration with Pengcheng Laboratory and FiberHome Fujikura Optical Fiber Technology Co., Ltd., achieved real‑time optical transmission of 2.5 Pb/s over a 24‑core fiber, establishing a new world record in optical communications.

The milestone reflects two fundamental transmission parameters: aggregate throughput and channel count. A throughput of 2.5 Pb/s corresponds to approximately 290,000 GB per second (1 Pb = 116,415 GB), a capacity sufficient to download more than 14,000 20 GB 4K films in a single second or to support instantaneous interaction with extremely large AI training datasets. The 24‑core configuration denotes a single cable containing 24 independent fiber cores, each functioning as a separate transmission channel; conceptually, this converts a single‑lane route into 24 parallel information highways. Unlike conventional systems that primarily employ the C and L bands, the experiment simultaneously utilized the S, C, and L bands, effectively adding multiple transmission layers to increase parallelism.

The experimental setup used an S/C/L integrated 400G optical module developed in‑house by China Information and Communication Technologies Group and demonstrated error‑free, real‑time transmission at capacities suitable for operational services. This advance positions the technology one step closer to deployment in scenarios such as data‑center interconnects, backbone optical transport networks, and ultra‑high‑speed optical infrastructures, providing a high‑capacity, stable foundation for the digital economy.

The success also indicates that manufacturing processes, connector standards, and testing methodologies for multi‑core fiber are maturing. Multi‑core fiber integrates multiple independent cores within a single cladding, enabling spatial division multiplexing when core spacing prevents inter‑core interference. This approach multiplies transmission capacity without proportionally increasing physical footprint or cost; for example, a four‑core fiber can deliver roughly four times the capacity of a single core without quadrupling expense.

Driven by the explosive growth of traffic from AI, large‑model computing, and hyperscale data centers, traditional single‑mode fiber systems are approaching capacity limits, creating an urgent need for new technical pathways. After nearly three decades of development, multi‑core fiber is transitioning from laboratory research toward industrialization.

At OFC 2026, held March 15–19 in Los Angeles, leading manufacturers including Corning and Yangtze Optical Fiber and Cable exhibited multi‑core fiber product portfolios. Corning showcased an integrated solution combining fiber, cable, and connectors that multiplies capacity while preserving coating radius and cross‑sectional area, reducing cable volume by up to 70%, connector counts by up to 75%, and installation time by up to 60% in practical deployments. Yangtze Optical Fiber presented an OIO solution based on high‑density interconnection, demonstrating precise coupling between multi‑core fiber and array light sources.

Separately, STL and Colt Technologies conducted a multi‑core fiber pilot within a London metropolitan network, linking two Colt points of presence over distances of 9 km and 63 km. STL’s leadership acknowledged that broad adoption will require time, but emphasized that industry progress has accelerated due to demand from hyperscale computing. STL’s telecom chief technology officer observed that while such transitions historically took a decade, 2026 may represent the year multi‑core fiber moves decisively into commercial use.