Mode-multiplexed 16QAM transmission over 60-km coupled four-core fibres using real-time MIMO-DSP with high-accuracy frequency offset estimation

We demonstrated the first real-time mode-multiplexed 16QAM transmission. Two-stage frequency offset compensation with high frequency resolution followed by real-value 16×4 MIMO was implemented based on FPGA boards. The mode-division multiplexed WDM DP-16QAM signals were transmitted over a 60-km coupled four-core fibre.