Intra-Cavity Chromatic Dispersion Impacts on 10-Gb/s Optical OFDM Transmissions Over 25-km Dual-RSOA-Based Self-Seeded PON Systems

Owing to the lack of strong physical mechanisms capable of elaborately balancing a large number of longitudinal modes created in a self-seeded passive optical network (PON), the resulting coherent-like optical signals are vulnerable to frequency-dependent optical phenomena such as chromatic dispersion (CD). In this paper, based on our recently reported real-time dual-reflective semiconductor optical amplifier (RSOA)based self-seeded adaptive optical orthogonal frequency-division multiplexing (OOFDM) transmitters, detailed experimental explorations are undertaken, for the first time, of the impacts of intra-cavity CD on 10-Gb/s OOFDM transmissions over 25-km self-seeded PON systems. The cavity length-dependent intra-cavity CD effect is identified to be one of the most prominent physical mechanisms determining the practically achievable performance of such PON systems. In comparison with a 10-m-long dual-RSOA self-seeded fiber cavity, the accumulated intra-cavity CD effect associated with a 1-km-long dual-RSOA self-seeded fiber cavity not only considerably broadens the optical spectral width of the self-seeding-created coherent-like optical signal but increases the signal relative intensity noise (RIN) by 4.8 dB (at a 2-GHz signal spectral region) as well. In addition, a further 1.1-dB signal RIN growth is also measured after the 25-km single-mode fiber (SMF) PON system transmissions. As a direct result, the dual-RSOA self-seeded PON with a 1-km-long fiber cavity suffers from a 2.2-dB power penalty degradation for 10 Gb/s over 25-km SMF intensity modulation and direct detection OOFDM transmissions.