Single channel 224 Gbit/s (56‐GBaud) PAM‐16 transmission using linear digital pre‐distortion

With linear digital pre‐distortion (DPD) and 8‐bit digital to analogue converter (DAC), a single channel 224 Gbit/s (56‐GBaud) 16‐level pulse amplitude modulation (PAM‐16) signal is experimentally transmitted over a 100 m standard single‐mode fibre (SSMF) for the first time using intensity modulation and direct detection (IM/DD). The 3 dB bandwidth of the whole system is around 22 GHz, which is far below the bandwidth of the 56‐GBuad PAM‐16 signal. The strong inter‐symbol interference caused by the limited system bandwidth is pre‐compensated by the proposed linear DPD technique. The experimental results indicate that the linear DPD process can effectively avoid the noise enhancement by the aggressive feed‐forward equalisation at the receiver, and also improves the system performance at the cost of additional finite impulse response filter at the transmitter.