文摘
We experimentally demonstrate a 16QAM DFT-spread OFDM system based on DML and direct detection. A series of DSP algorithms including ISFA(intra-symbol frequency averaging ), DD-LMS (decision-directed least mean square) and NLE (nonlinear equalization) are implemented to improve the system performance. For 20-Gbaud 16QAM-OFDM signal, with the aid of NLE, we respectively provide 6.2-dB and 5.2-dB receiver sensitivity improvement under HD-FEC threshold of 3.8×10-3 for the back-to-back case and transmission over 10-km SSMF case, related to only adopt post-equalization scheme. To our knowledge, this is the first time to use dynamic nonlinear equalizer based on the summation of the square of the difference between samples in IM/DD OFDM system with DML to mitigate nonlinear distortion.