Investigation of the Effects of Chirped RZ Signals in Reducing the Transmission Impairments in R-SOA-Based Bidirectional PONs

Distributed and concentrated reflections represent the two main limitations in reflective-semiconductor optical amplifier (R-SOA)-based passive optical networks (PONs). In this paper, we experimentally discuss how the use of chirped signals in centralized light seeding bidirectional PON can increase the resilience of the system against those two types of reflections. An experimental comparison of the performance of a highly chirped return to zero (RZ) modulation format and the nonreturn to zero is given. Error-free operation is achieved down to 10 dB of signal to crosstalk ratio in presence of distributed reflection, when the upstream signal is highly chirped RZ signal. The same chirped modulation leads to a tolerance of more than -25 dB network return loss due to concentrated reflections. Finally, we assess also the system feasibility of a R-SOA-based full-duplex PON where both the upstream and the downstream are modulated signals.