This article presents the RSOA-based re-modulation schemes for practical application to the WDM-PON link. Emphasis is put on the three methods for reducing the residual downstream signal in the upstream transmission; the simplest one is to use the RSOA gain-saturation property, the second uses selective filtering of the adiabatic-chirped DFB-LD output spectrum, and the last uses a dynamic RSOA gain control by varying its driving current according to the incident binary signal. The reflection sensitivity in the proposed re-modulation link is also qualitatively presented in the cases of using two different types of seed light: coherent light from DFB-LD array and spectrum-sliced incoherent ASE light. We show experimental results of an error-free bidirectional gigabit transmission over 20 km at -30 dB reflection with the spectrum-sliced ASE seed light.