Chinese telecom and fiber-optics companies have achieved a major milestone in next-gen communications, successfully demonstrating what is described as the world’s first field trial of a hollow-core fiber transmission system capable of delivering 1.2Tb/s per wavelength. 

The project brought together China Telecom, Yangtze Optical Fibre and Cable Joint Stock Limited Company, and Dekoli under a national research initiative focused on advanced optical fiber technologies.

The test was carried out on the world’s longest commercial cross-border hollow-core fiber cable. Using an optimized transmission system, the team reached a total capacity of 51.3Tb/s over a distance of roughly 128 miles without signal repeaters, setting a new benchmark for long-distance high-capacity data transmission.

Reducing latency and boosting network capacity

Unlike traditional fiber-optic cables that transmit light through solid glass, hollow-core fiber guides light through air. This fundamentally different design helps reduce signal delay and boosts transmission capacity, addressing key limitations of conventional fiber. Because of these advantages, hollow-core fiber is increasingly seen as a promising technology for next-gen optical networks, especially for backbone infrastructure and large-scale data centers.

Now, the project team managed to solve the challenge of high-power signal transmission in a real-world hollow-core fiber network, something that had not been achieved before. By validating stable high-speed performance outside laboratory conditions, the test strengthened the case for hollow-core fiber as a novel communications technology.

The team improved overall transmission performance by introducing an adaptive per-wavelength rate control mechanism, combined with flexible channel power allocation across the system. Instead of relying on fixed parameters, the approach dynamically adjusted how each wavelength carried data, allowing the system to operate under more optimized and variable conditions.

This design enabled hybrid transmission across multiple data rates, different channel spacings, and individually tuned power levels per wavelength. As a result, the system could better balance performance across the full spectrum of channels rather than treating them uniformly.

New amplifier architecture enables higher power and stability in transmission

The team introduced a new high-power amplification design based on a cascaded dual-gain-unit architecture combined with a multi-element doping approach. This configuration was developed to improve both efficiency and stability in optical signal amplification under high-power conditions.

As a result, the researchers were able to build an optical amplifier with strong gain flatness, ensuring more consistent signal performance across operating ranges. The system also achieved a maximum output power of up to 33.5 dBm, supporting more robust transmission performance in the overall fiber-optic setup.

Furthermore, the system was equipped with additional safety measures designed to reduce risks associated with optical link failures. These included optical-path power anomaly detection to continuously monitor signal stability, automatic interlock shutdown functions to stop operation when unsafe conditions are detected, and alarm-linked response mechanisms that trigger alerts across the system.

Together, such safeguards enable rapid identification of abnormal operating conditions and provide multiple layers of protection. By responding quickly to faults or irregular power levels, the system helps prevent equipment damage and improves overall operational safety and reliability in high-power optical transmission environments.

The test findings were published in TrendForce.

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