The Reuse of Downstream Carrier Data Erased by Self-Feedback SOA for Bidirectional DWDM-PON Transmission

To reuse the downstream carrier for upstream transmission, a data eraser is mandatory for bleaching the downstream data in the dense wavelength division multiplexing passive optical networks (DWDM-PONs). In this paper, a self-feedback semiconductor optical amplifier (SOA) fiber loop operated at power saturation condition is employed as a data-amplitude clipper, which helps to erase the downstream pseudorandom binary sequence (PRBS) data carried by the downstream channelized broadband light source. The self-feedback SOA fiber loop can adjust its feedback coupling ratio to offset the in-line amplified spontaneous emission power level; hence, the continuous-wave biased point of the input optical power can be adjusted prior to the input of the SOA. The self-feedback architecture efficiently clips the downstream data amplitude to significantly reduce the extinction ratio of data on carrier from 13 to 1.6 dB. Afterward, the data-erased downstream carrier is reused to successfully carry the upstream ON-OFF-keying PRBS data at 2.5 Gbit/s in a 200 GHz channelized bidirectional DWDM-PON. The downstream carrier reused for upstream transmission can provide a back-to-back receiving power sensitivity of -24 dBm at BER of 10^-9. The carrier reused upstream transmission induces a power penalty of -6 dB as compared to the downstream case. After transmission in a 25-km long single-mode fiber, the reused upstream transmission further degrades its receiving power sensitivity to -22 dBm with additional penalty of 2 dB.