50 Gbps PAM-4 Over Up to 80-km Transmission With C-Band DML Enabled by Post-Equalizer

Abstract

In this letter, transmission of directly-modulated PAM-4 in C-band is experimentally demonstrated. Instead of introducing any optical devices for dispersion management, we employ receiver-side equalization consisting of Volterra-based FFE and Volterra-based DFE, to mitigate the signal distortions induced by the frequency chirp effect and chromatic dispersion. Results indicate that, PAM-4 transmissions of 56 Gbps over 60-km and 60 Gbps over 80-km are achieved respectively under the HD-FEC limit ( $3.8\times 10^{-3}$ ) and SD-FEC limit ( $2.2\times 10^{-2}$ ).