UCL and Xtera smash transmission world record

UCL and Xtera , a provider of innovative subsea fibre optic technology, have broken current world records by transmitting 120 Terabit/s over a single fibre spanning 630 km. The capacity and span achieved today exceeds the previous record of 115 Terabit/s over 100 km by more than six times. The experiments, involving researchers from the UCL Optical Networks Group, used nine broadband amplifiers spaced at 70 km to transmit the signal. In the near future, these will be connected to form a loop to allow tests over much longer distances. Increasing the bandwidth is the best way to get more capacity from a given fibre and the combination of a C-band and an L-band amplifier has been used to get bandwidths of approximately 70 nm, but Raman amplification used by the team offers even greater bandwidth at 91 nm, while minimising noise. The experiment, used a hybrid distributed-Raman / EDFA amplifier which is an extension of the technology that Xtera currently deploys in subsea repeaters. This was combined with low-loss and large effective area fibre from Sumitomo, state-of-the-art modulators from Oclaro, and expertise in 256QAM generation, optical fibre transmission, digital signal processing, and adaptive forward error correction (FEC) from UCL.