A downstream signal and continuous wave (CW) are supplied from optical line terminal (OLT) and they are distributed through AWG and redirected to certain ONU with RSOA installed.
75 % of optical power received in ONU is directed to RSOA and 25 % of it is directed to optical coupler receiver.
The problems related to performance of RSOA based WDM-PON system (later in this document the term "system" is used) includes many factors that affect system performance, i.e.
The influence of various reflecting points to downstream and upstream signals was evaluated by reflection tolerance depending on RSOA gain and reflection type , .
A reflection tolerance may be increased by optimising RSOA gain and/or coupler splitting ratio in ONU.
A fluctuation of amplitude is less when RSOA is in saturation condition.
RSOA bias dithering was proposed as a new method for using of amplitude-to-phase modulation in an active RSOA material ,  and phase modulation in laser .
The RSOA is highly cost-efficient in systems with orthogonal frequency division multiplexing (OFDM).
RSOA has a frequency chirp which results in optical signal power fading.
A theoretical wideband dynamic model was developed for numerical analysis of spatial and temporal distributions of photons and carriers in a bulk InP-InGaAsP RSOA. The influence of second order super-Gaussian optical filtering was estimated numerically for new generation 10 Gbps per channel DWDM system with RSOA, using NRZ signalling format with 25 GHz channel spacing.
A cost-effective solution was based on duobinary modulation  and the adjustments of the RSOA's electro-optical (E/O) response to a 2.5 GHz Bessel filter.