Considering of PAM-4, DB, NRZ and RZ for Implementation in Next-Generation PONs

Abstract

The exponential traffic growth in access networks is driving demand for the increasing of the per-wavelength data rates in the next generation passive optical networks (NG-PONs) [1]. Hence, the utilization of the advanced modulation formats instead of the traditional non-return-to-zero (NRZ) has to be considered [2]. In this paper, we evaluate NRZ, return-to-zero (RZ), duobinary (DB) and four-level pulse amplitude modulation (PAM-4) for utilization in 8-channel wavelength-division-multiplexing (WDM) PON with per-channel data rates of 10 Gbit/s, 25 Gbit/s and 40 Gbit/s without applying any amplification, dispersion compensation or digital signal processing. We compare the performance of the investigated modulation formats in terms of bit error rate (BER), received optical power and receiver bandwidth.