Researchers from ZTE have demonstrated what they claim is a record-breaking long-haul transmission of single-carrier 800G – using a 120Gbaud carrier with polarisation-multiplexed 16QAM encoding – over 1,200km of terrestrial optical fibre.
This experiment uses the highest symbol rate reported so far for electrical time division multiplexing (ETDM)-based 16QAM signals, according to the company. This achievement sets a new benchmark for the global optical networking industry, and paves the way towards terabit transmission.
In the experiment, researchers generated single-carrier 120-Gbaud polarisation-multiplexing (PM) 16QAM optical signals to achieve a data rate of 960Gb/s – a 800Gb/s payload with 20 per cent overhead for forward error correction (FEC).
Both transmitter-side, optical pre-emphasis and receiver-side maximum likelihood sequence estimation (MLSE) were used to mitigate the narrow filtering effect caused by bandwidth limitation of the optoelectronic components at such high speeds.
They then combined twelve WDM channels on a 150-GHz grid, each loaded over a 1,200-km link made up of 100-km spans of TeraWave optical fibre. Terawave fibre from OFS is a large-effective area fibre that has been designed to support coherent transmission systems at 100Gb/s and beyond.
The achieved data rate interface provided spectral efficiency of 5.33b/s/Hz.
Dr Jianjun Yu, chief scientist at ZTE US Optical Lab and Fellow at The Optical Society (OSA), said: “Thanks to the high-baud-rate signal generation, transport interfaces with bit-rates of up to 1Tb/s will be achieved in the near future. ZTE has been relentless in pushing forward-looking research and development on single-carrier 400G transmissions and beyond, and we have key technologies for future terabit solutions.’
The experiment follows one carried out last year also in cooperation with OFS, in which ZTE US Optical Lab successfully transmitted 400Gb/s single-carrier PDM-QPSK signals over a distance of 10,000km.
Earlier this year, ZTE collaborated with T-Mobile Austria on a field trial to show transmission of hybrid 10G/100G/400G optical signals over existing networks, indicating that 400G optical transport networks are ready for complex, long-haul applications.