A comprehensive nonlinear filter scheme for 50Gb/s PAM4-PON Systems

A comprehensive nonlinear filter scheme for 50Gb/s PAM4-PON systems is proposed in this paper. In our scheme, both the forward symbols and the backward symbols of the Volterra filter are considered and the decision term is added after the Volterra filter to better eliminate the inter-symbol interference (ISI). An experiment of 50Gb/s PAM4 transmission is demonstrated over 20 km SSMF. Results show that a link power gain of 1.3 dB can be obtained at the HD-FEC threshold (3.8×10
⁻³
) compared to the Volterra filter.