China completes 1,000-km hollow-core fiber transmission verification

China has completed a 1,000-kilometer hollow-core fiber transmission verification, marking a new breakthrough in key technologies for next-generation communication networks.

The verification, jointly conducted by China Telecom, Yangtze Optical Fibre and Cable (YOFC), and ZTE over a 1,007.48-kilometer fiber link, achieved simultaneous bidirectional signal transmission at 64 Tb per second in each direction, equivalent to supporting the upload and download of 160 films in 4K resolution per second, according to China Telecom on November 4.

The vast majority of optical fibers in widespread use are solid-core fibers, in which signals travel through a quartz glass core at 200,000 kilometers per second, whereas hollow-core fibers carry signals mainly through air channels at close to 300,000 kilometers per second.

This shortens transmission time and lowers latency. A signal takes just 3.43 milliseconds to travel one way across the 1,000-kilometer link, according to test technicians.

The technology doubles transmission capacity and extends transmission distance by 60 percent compared with the best-performing solid-core fibers currently available, according to the technicians.

The experiment confirmed that hollow-core fiber can deliver long-distance, large-capacity and low-latency transmission using existing transmission equipment, providing a key technological reserve for computing power networks, said Huo Xiaoli, chief expert for next-generation information and communications at China Telecom.

The use of hollow-core fibers can improve computing efficiency and reduce investment costs for GPUs or memory chips in AI data centers, which require low-latency, high-speed optical connections and transmission.

Such technology will also boost data transmission speed and bandwidth between data centers, helping AI training and inference.

It is reported that this hollow-core fiber technology has been applied in a commercial line connecting Shenzhen and Hong Kong in south China.

More than ten commercial and pilot hollow-core fiber projects have also been implemented in Asia, Europe and other regions.