Improved Performance of high-order QAM OFDM Based on Probabilistically Shaping in the Datacom

We experimentally demonstrated a PS-256-QAM OFDM fiber transmission in a low-cost IM-DD system. Compared with uniform 128-QAM, the proposed PS-256-QAM obtains the same entropy of 7 bits/QAM symbol, but higher achievable-information-rate performance and stronger nonlinearity robustness.