We propose a stable multi-longitudinal Brillouin/semiconductor fiber laser(BSFL) as the upstream source in a bidirectional single-fiber wavelength-division multiplexing-passive optical network(WDM-PON).The downstream wavelength serves as the pump of the BSFL.Brillouin-frequency-shifted(～10.8 GHz) upstream carrier is generated to suppress the Rayleigh backscattering and back reflection-induced crosstalk.The stable multi-longitudinal operation of the BSFL,attributed to the four-wave mixing(FWM) effect in the semiconductor optical amplifier(SOA) reduces the difficulty of generating a stable single-longitudinal fiber laser-based upstream carrier.Bidirectional symmetric transmission at 10 Gb/s over a 12.5-km single mode fiber with less than 2-dB power penalty is demonstrated.
