China Achieves Record 51.3 Tb/s Transmission Over 128-Mile Hollow-Core Fiber Link

A consortium of Chinese telecom and fiber-optics firms completed what they describe as the world’s first field trial of a hollow-core fiber transmission system delivering 1.2 Tb/s per wavelength. The trial achieved a total capacity of 51.3 Tb/s across a 128-mile stretch of the longest commercial cross-border hollow-core fiber cable, operating without any signal repeaters.

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Unlike conventional fiber that guides light through solid glass, hollow-core fiber transports light through an air-filled core. This design reduces signal delay and boosts capacity, directly addressing key limitations of conventional fiber. Because of these advantages, hollow-core fiber is viewed as a promising option for backbone infrastructure and large-scale data-center interconnects. The trial was part of a national research initiative aimed at advancing optical-fiber technologies.

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The project brought together China Telecom, Yangtze Optical Fibre and Cable Joint Stock Limited Company, and the technology firm Dekoli. All three entities contributed to system design, deployment, and performance validation under real-world conditions.

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The team introduced an adaptive per-wavelength rate-control mechanism and flexible channel-power allocation, allowing each wavelength to operate at an optimized data rate while keeping balanced power across the spectrum. This enabled hybrid transmission across multiple data rates, channel spacings, and individually tuned power levels per wavelength. A new high-power amplifier, built on a cascaded dual-gain-unit architecture with multi-element doping, delivered strong gain flatness, preserving consistent signal strength across the bandwidth. Reported output power reached up to 33 dBm, while a separate measurement cited 5 dBm supporting robust transmission. The combined system sustained 51.3 Tb/s total capacity, equivalent to 1.2 Tb/s per wavelength, over the 128-mile link.

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To mitigate risks, the system incorporated optical-path power anomaly detection, automatic interlock shutdown functions, and alarm-linked response mechanisms. This layered safety approach provides continuous power monitoring, rapid shutdown on anomalies, and system-wide alerts, reducing equipment damage risk.

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Representatives of the consortium stated that the trial “solved the challenge of high-power signal transmission in a real-world hollow-core fiber network,” demonstrating stable high-speed performance outside laboratory settings. They added that the results “strengthen the case for hollow-core fiber as a novel communications technology” and emphasized that high-power transmission in an operational network had not been demonstrated previously. The findings were published in TrendForce.

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The source material provides two different power figures—“up to 33 dBm” and “5 dBm”—without clarification of their respective contexts, creating uncertainty about the amplifier’s peak output. Additionally, the exact number of wavelengths employed, the specific channel spacings used, and any measured latency reduction were not disclosed, limiting assessment of performance gains.

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