Researchers in China have set a world record for real-time optical data transmission, sending 3.2 petabits per second through a 24-core optical fibre cable. The milestone was achieved by combining multi-band light frequencies with spatial multiplexing on hardware built to commercial specifications.
Key points
- The transmission achieved 3.2 petabits per second across a single 24-core optical fibre in real time.
- Engineers combined spatial division multiplexing with transmission across the optical S, C and L frequency bands.
- The demonstration relied on commercially compliant hardware rather than offline signal processing.
- The speed surpasses the consortium’s earlier benchmark of 2.5 petabits per second established earlier this year.
How the 3.2 petabit transfer works
Four institutions collaborated on the project: Pengcheng Laboratory, Fiberhome Fujikura Fiber Optic Technology, the China Information and Communication Technologies Group, and the National Key Laboratory of Optical Communication Technology. Under ideal test conditions, the resulting link transferred data fast enough to download “more than 20,000 4K movies” in one second, according to statements on the Hubei provincial government website.
The test relied on two primary architectural methods: spatial division multiplexing and multi-band optical signalling. Spatial division multiplexing splits information across separate internal physical pathways, allowing 24 distinct streams of data to travel down individual cores within the same cable jacket without merging.
At the same time, the team widened the usable light spectrum by sending signals across the S, C and L bands simultaneously. Standard telecoms networks operate mostly within the conventional C band, leaving neighbouring frequencies unused. By opening the short-wavelength S band and long-wavelength L band alongside it, the researchers multiplied the available transmission lanes on every single core.
Real-time signals versus laboratory setups
The 3.2 petabit benchmark marks a step beyond the group’s previous record of 2.5 petabits per second, which used similar 24-core architecture earlier this year. More critically, the system processed and transmitted data continuously in real time.
Higher speeds have been recorded in academic environments. Research teams have documented optical speeds up to 5.29 petabits per second using 24-core fibre in laboratory trials. Those higher measurements, however, typically rely on post-processed signals, where data is recorded by instruments and decoded mathematically offline through computers.
The Chinese consortium stated that its transmission ran on physical equipment engineered to satisfy commercial requirements. Operating directly in real time means the transceivers and decoding chips handled the incoming stream on the fly, proving the underlying transmission physics work without artificial computation delays.
The engineering hurdles ahead
Running high volumes of traffic through packed multi-core cables presents acute physical obstacles. Packing 24 cores into a single strand creates cross-talk, where electromagnetic energy leaks between adjacent channels and degrades signal clarity. Managing interference across three separate wavelength bands simultaneously requires active equalisation, as light in the S band disperses differently from light travelling in the L band.
While the test proved the architecture can function under controlled settings, no rollout timetable or pricing details exist for telecom operators. Upgrading core transit routes requires substantial capital expenditure. Telecommunications providers continue to evaluate high-throughput terrestrial solutions alongside fringe proposals, such as whether orbital data centres could relieve bottlenecks, but ground-based glass remains the backbone of internet traffic.
The research consortium has not yet submitted the hardware to long-term operational stress tests outside the laboratory. Further trials will determine whether the multi-band 24-core format can withstand commercial deployment in field conditions over standard operating lifespans.
