China Telecom Research Institute, YOFC, and ZTE have successfully completed the world's first real-time transmission test over a 1007.48-kilometer hollow-core fiber link. The system achieved a total capacity of 128Tb/s using C+L band expansion and single-wavelength 800Gb/s transmission with PCS-16QAM modulation.
This project set a new global record for the longest point-to-point non-loopback real-time transmission in hollow-core fiber. The team maintained a loss margin of at least 3dB per span and an OSNR maintenance margin of at least 3dB. This is the first successful demonstration of long-distance bidirectional real-time transmission at the 1000-kilometer scale.
The researchers eliminated gas line absorption (GLA) within the C+L band by optimizing fiber manufacturing processes. On the equipment side, the team utilized standard commercial amplifiers instead of high-power alternatives, while the system design incorporated lightweight pre-equalization to ensure stable channel performance across the entire band.
The test included validation of extreme maintenance scenarios, such as wavelength drops, confirming no performance degradation. The results provide a technical foundation for building high-bandwidth, long-distance, and low-latency backbone networks using hollow-core fiber technology.
