Limitation on gain of bidirectional amplifier in amplified WDM-PON using broadband light source seeded optical sources

We investigated the effect of in-band crosstalk on the bidirectional gain in amplified wavelength-division multiplexed passive optical networks (WDM-PONs). In a bidirectional transmission system over a single fiber, the system´s performance could be degraded by the in-band crosstalk generated with a double Rayleigh backscattering within a transmission fiber and a gain of bidirectional optical amplifier. Thus, the maximum gain of bidirectional optical amplifier in an amplified WDM-PON was evaluated with a broadband light source (BLS) seeded optical source. Using two simple bidirectional amplifiers without any optical components for the suppression of reflected signals, we found that the bidirectional gain could be increased to be 27 dB with a BLS seeded optical source.