Loss budget expansion technique using gain-saturated SOA in WDM single-fiber loopback access networks

This paper reduces the impact of backreflection in WDM single-fiber loopback access networks by using a gain-saturated semiconductor optical amplifier (SOA). The backreflection lights from two sources are taken into consideration, the continuous wave (CW) light at the central office (CO) (Reflection-I) and the modulated signal at the optical network unit (ONU) (Reflection-II). A SOA is placed at the ONU to reduce the intensity noise caused by Reflection-II. To investigate the effect by the proposed technique, an experiment creating multiple reflection points is conducted. The results show that a loss budget of 10 dB without SOA can be increased to 16 dB.