World first NTT space multiplexed link hits 455Tbit/s
NTT has shown the world’s first space division multiplexed long-distance terrestrial optical transmission with up to 455 Tbit/s
The long-distance transmission reached up to 1000 km using coupled-core used multicore fibre cable and saw the record field capacity of 455 terabits per second, more than 50 times that of the current system.
This was achieved by mounting and connecting 12-coupled-core multicore fibres with the same diameter as existing optical fibres, making it suitable for mass production to commercial high-density multicore cables, coupled with large-scale MIMO signal processing technology.
Commercial terrestrial networks contain many splices or connectors between repeaters. This time, Sumitomo Electric’s newly developed fibre fusion splicing technology for high-precision couple-core multicore fusion function and Chiba Institute of Technology’s connector technology for stable low-loss connection were used to provide a direct connection between multicore fibre in the field.
The optical loss of both types is as low as that of conventional single-mode fibre-to-fibre connections. In addition, the loss variation between spatial channels is small, contributing to stable transmission.
- NTT looks to 15Tbit/s optical chiplet interconnect
- Intel, NTT, sk Hynix in optical processing project
- Branched fibre boosts optical network rollout
The amplified transmission reached a capacity of 389 Tbit/s over 1,017 km, which can cover the distance between Tokyo and Osaka, the main artery of Japan’s optical backbone network. This is expected to be a fundamental technology for realizing future terrestrial optical transmission systems with transmission capacity more than 50 times that of conventional systems.
Space division multiplexing optical transmission using multicore fibres to increase the number of spatial channels by increasing the number of cores per fibre and transmitting optical signals in parallel. This is expected to be a fundamental technology for future high-capacity backbone optical networks that can expand transmission capacity.
The coupled-core multicore fibre intentionally allows crosstalk of optical signals between adjacent cores to enable high-capacity optical transmission because coupling between the signals can be undone by combining digital signal processing at the receiver after receiving the signal.
Compared with a conventional multimode fiber, which can also achieve a high spatial channel count, it has a higher degree of freedom in designing the propagation state of optical signals, and it can reduce propagation delay dispersion. This makes it possible to reduce the computational complexity of digital signal processing to follow fluctuations in the actual environment due to external disturbances such as wind and rain and is expected to enable optical transmission with reduced power consumption and cost.
Deploying this in a terrestrial transmission systems rather than undersea, meant ensuring stable high-capacity transmission in a field environment where the signal propagation environment inside the optical fibre cable changes dynamically.
The MIMO signal processing technology tolerates maintenance work in the installation environment and disturbances such as wind and rain, and demonstrated the feasibility of stable high-capacity transmission for the first time.
The MIMO signal processing technology used a polarization-multiplexed PCS-36QAM signal with a symbol rate of 140 gigabaud as a signal format that can use frequencies efficiently at high speeds.
By combining integrated circuit technology and digital signal processing technology developed by NTT, channel configuration of up to 15.0 terabits per second per wavelength channel was reached, with 12-core multiplexing and 31 wavelength division multiplexing over the 4.65 THz band over the entire C-band.
NTT plans to use this for high-capacity terrestrial infrastructure for its IOWN network for 5G and 6G in the 2030s.
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
