Mitigation of optical multipath interference algorithms in IM-DD transmission system

This paper aimed to propose two algorithms, DA-M and RF-M, of reducing the impact of multipath interference (MPI) on intensity modulation direct detection (IM-DD) systems, particularly for four-level pulse amplitude modulation (PAM4) systems. DA-M reduced the fluctuation by averaging the signal in blocks, RF-M estimated MPI by subtracting the decision value of the corresponding block from the mean value of a signal block, and then generated interference-reduced samples by subtracting the interference signal from the product of the corresponding MPI estimate and then weighting factor. This paper firstly proposed to separate the signal before decision — making into multiple blocks, which significantly reduced the complexity of DA-M and RF-M. Simulation results showed that the MPI noise of 28 GBaud IM-DD system under the linewidths of 1e5 Hz, 1e6 Hz and 10e6 Hz can be effectively alleviated.