China Achieves Breakthrough in Ultra-High-Capacity Optical Transmission

Building on previous technological accumulations in multi-core optical fibers and extended-band real-time optical transmission, the research team integrated multi-core fiber space-division multiplexing, ultra-broadband wavelength-division multiplexing and commercial high-speed optical module technologies. 

This integration enabled the verification of ultra-high-capacity real-time bidirectional transmission for practical engineering systems, laying a solid foundation for the application of the technology in real-world scenarios.

The core innovations and breakthroughs of this achievement fall into three key areas. 

First, it has realised a record-breaking Pb/s-level real-time bidirectional transmission capability. 

Over the 10.3-kilometre 24-core single-mode optical fiber, the team completed 2.5 Pb/s real-time bidirectional transmission covering the S+C+L three bands, with a total spectral bandwidth of 19.65 terahertz (THz). 

Through the combined multiplexing of 262 wavelength channels and 24 core channels, 6,288 parallel transmission channels were constructed, verifying the technical feasibility of ultra-large-scale space-wavelength joint expansion.

Second, a highly implementable commercial technology solution has been developed. The system adopts a self-developed commercial S+C+L band integrated 400G coherent optical module, achieving real-time transmission based on 64GBaud PDM-16QAM. 

This significantly enhances the engineering feasibility of full-band optical transmission and provides a reference technical pathway for future practical network deployment.

Third, an innovative multi-core fiber bidirectional transmission architecture has been created. By optimising the inter-core allocation mechanism, inter-core crosstalk is effectively suppressed, allowing the 24-core optical fiber to operate stably without the need for complex MIMO (Multiple-Input Multiple-Output) equalisation processing. 

This marked reduction in system complexity and deployment costs further facilitates the practical application of the technology.