Dependence of In-Band Incoherent Crosstalk-Induced Penalty on Seed Source in RSOA-Based WDM-PONs

We have investigated the dependence of in-band incoherent crosstalk-induced power penalties on seed source in reflective semiconductor optical amplifier (RSOA)-based wavelength-division-multiplexed passive optical networks (WDM-PONs). The in-band crosstalk penalties in an RSOA-based WDM-PON were measured with two different seed sources; a broadband light source (BLS) and a distributed feedback laser diode (DFB-LD). The 1-dB power penalties with a BLS seeded and a DFB-LD seeded RSOA source were observed when the crosstalk-to-signal ratios were ~ -14 and -16 dB, respectively. From the results, we found that the directly-modulated RSOA sources with a BLS or a DFB-LD seed source were more tolerant to the in-band crosstalk than an externally-modulated DFB-LD source. In addition, we confirmed that the in-band crosstalk-induced power penalty in the RSOA-based WDM-PONs could be calculated with a proper estimation of an equivalent optical source bandwidth.