Performance analysis of advanced optical modulation formats for GPON and XG-PON passive optical networks: WDM extension, dispersion compensation, FWM analysis and LDPC-FEC

Ten optical modulation formats are compared for Gigabit-capable passive optical network (GPON, 2.5 Gbps) and 10-Gigabit-capable PON (XG-PON, 10 Gbps) links in OptiSystem v17.0, with a 622 Mbps broadband PON (BPON) baseline. Dispersion, chirp, split-ratio loss, four-wave mixing (FWM) and low-density parity-check (LDPC) coding, a type of forward error correction (FEC), are modelled. At 622 Mbps, alternately chirped non-return-to-zero (ACNRZ) gives the highest Q -factor (31.86 at 10 km), whereas carrier-suppressed return-to-zero (CSRZ) leads beyond 45 km ( Q = 5.85 at 50 km). At 10 Gbps, differential quadrature phase-shift keying (DQPSK) is best ( Q = 12.60 at 10 km; 5.40 at 50 km). Dispersion-compensating fibre (DCF) raises Q by 2.52–3.71 dB and beats a fibre Bragg grating for seven of the 10 formats. In a four-channel wavelength-division-multiplexed PON (WDM-PON), DQPSK gives the lowest FWM power (−36.2 dBm) and Q -penalty (0.79 dB). Rate-6/7 LDPC brings CSRZ, ACNRZ, differential phase-shift keying (DPSK) and DQPSK into compliance with the G.975 FEC threshold at 50 km on XG-PON.