Evaluation of the Channel Spacing and Transceiver Bandwidth for PAM-4 Modulated WDM-PON

Considering the exponential traffic growth in access networks, this paper focuses on the four-level pulse amplitude (PAM-4) modulated wavelength-division multiplexing passive optical network (WDM-PON), that is promising solution for the increase of per-wavelength data rate of the PON. The paper evaluates the utilization of different bandwidths of the transmitter (12, 20, 30 GHz) and receiver (10, 20, 30 GHz) as well as channel spacing (50 GHz and 100 GHz) in eight-channel WDM-PON transmission system with per-wavelength data rates of 25 and 40 Gbit/s. The paper focuses on the adjustment of the electrical filter of the receiver for ensuring smaller transmitter and receiver bandwidth, higher receiver performance and longer transmission distance for given data rate and channel spacing. Based on the obtained results paper determines the most appropriate PAM-4 modulated WDM-PON transmission system configuration for the investigated channel spacing up to 100 GHz and bitrates up to 40 Gbit/s.