Experimental Investigations of Wavelength Spacing and Colorlessness of RSOA-Based ONUs in Real-Time Optical OFDMA PONs

End-to-end real-time optical orthogonal frequency-division multiple-access (OOFDMA) passive optical networks (PONs) with adaptive dynamic bandwidth allocation (DBA) and colorless optical network units (ONUs) are experimentally demonstrated, for the first time, at aggregated 10.375 Gb/s over 26.4 km standard single-mode fibers based on intensity modulation and direct detection. The colorless ONU operation for several representative wavelengths across the C-band is successfully achieved by utilizing cost-effective reflective semiconductor optical amplifier intensity modulators, whose narrow signal modulation bandwidths are fully exploited through adaptability of the OOFDM transceivers and adaptive DBA. Taking into account the optical beat interference effect, the impact of wavelength spacing between adjacent ONUs on the upstream OOFDMA PON performance is experimentally investigated, based on which the minimum achievable ONU wavelength spacing is identified.