Recently, the China Telecom Research Institute and YOFC, as co-builders of a national key laboratory, together with ZTE Corporation, jointly completed the world's first bidirectional real-time transmission verification over a 1,000-km hollow-core fiber link: on a 1007.48-km hollow-core fiber link, they achieved extended C+L-band single-wavelength 800 Gb/s (PCS-16QAM modulation) bidirectional single-fiber transmission, with a total capacity of 128 Tb/s (terabits per second), pushing the record for real-time hollow-core fiber transmission distance to a new height and marking another milestone breakthrough by China in key core technologies for next-generation optical communications.
It is understood that this trial was based on the innovation platform of the national key laboratory for "Advanced Manufacturing and Application Technology of Optical Fiber and Cable" and the "China Telecom Cloud-Network Convergence Technology Pilot Verification Platform," with coordinated efforts advancing across three levels: fiber, equipment, and system. At the fiber level, through optimization of the fiber fabrication process, the core technical challenge of GLA degrading transmission performance was overcome; at the equipment level, by combining the loss characteristics of hollow-core fiber with the operating characteristics of amplifiers, high-power amplifiers were abandoned in favor of commercial amplifiers with conventional output power, achieving optimal system performance for single-wavelength 800G full-wavelength transmission; at the system level, a lightweight transmitter-side pre-equalization scheme was adopted to ensure stable and balanced channel performance across the extended C+L full band, an end-to-end reflection and inter-modal interference impact assessment model was established, and verification of extreme operations and maintenance scenarios such as band dropping was completed, confirming that the system showed no performance degradation in such scenarios.
According to the introduction, the success of this trial provides a practical and feasible technical basis for building large-bandwidth, long-distance, low-latency backbone networks using hollow-core fiber based on high-order modulation format systems. It is an important achievement of China's independent innovation in key core technologies for next-generation optical communications and further consolidates China's leading position in the global hollow-core fiber technology and industry.