Complexity-reduced Equalization for 200Gbps PON Downstream Systems based on SSB Modulation and Direct Detection

Abstract: The 200 Gbit/s passive optical network (PON) is most likely to be the next-generation scheme following 50G PON. The cost- effective direct detection (DD) system is the economical choice. However, larger-capacity DD systems will face much more serious power fading caused by chromatic dispersion (CD) combined with square-law DD and thereby significantly increases the complexity of equaliza⁃ tion algorithms. In this paper, a 200 Gbit/s Nyquist 4-level pulse amplitude modulation (PAM4) single side-band (SSB) modulation-DD downlink scheme is designed, and a low complexity quadratic-nonlinear equalizer is proposed for this system. The computational complex⁃ ity of the quadratic nonlinear equalizer is about 28% of that of the conventional Volterra nonlinear equalizer, while still exhibiting excel⁃ lent nonlinear equalization ability. Simulation results for the 200 Gbit/s system with 20 km fiber transmission show that it can achieve a power budget of 29 dB, while a 30.4 dB power budget is obtained in the 50 Gbit/s experimental transmission.

Keywords: 200 Gbit/s passive optical network; single side band modulation; direct detection; equalization