Optimized Volterra filter equalizer based on weighted principal component analysis for IM-DD transmission.

Volterra filter equalizer (VFE) is a commonly-used nonlinear equalizer (NLE) to effectively mitigate both linear and nonlinear impairments arising in intensity-modulation direct-detection (IM-DD) transmission. However, the high calculation complexity of VFE becomes the bottleneck for the high-speed long-reach IM-DD transceiver. To achieve the hardware-efficient NLE, we propose an optimized VFE based on the weighted principal component analysis (WPCA), which uses both supervised weights and unsupervised PCA to extract principal components, so that the number of VFE taps can be significantly reduced without transmission penalty. It is experimentally verified that the proposed method can reduce 40% and 60% taps of traditional VFE, respectively, for C-band 80 Gb/s four-level pulse amplitude modulation (PAM-4) transmission over 20 km chromatic dispersion (CD)-uncompensated standard single-mode fiber (SSMF) and 56 Gb/s PAM-4 transmission over 100 km CD-managed SSMF.