Colorless ONU With All-Optical Clock Recovery for Full-Duplex Dense WDM PONs

We propose a colorless optical network unit (ONU) comprised of a Fabry-Pérot filter (FPF) and a semiconductor optical amplifier (SOA) for all-optical clock recovery of the downstream signal, followed by a Mach-Zehnder modulator (MZM) as the upstream modulator. The all-optical clock recovery performs data erasure allowing for efficient wavelength reuse of the downstream signal for upstream remodulation. Operation at a full-duplex 10-Gb/s symmetrical data rate and 20-dB loss budget is demonstrated over fiber spans of 50 km.