AMO-OFDM Signal Delivery of 20 Gbit/S throughput in 20-Km Single Loopback Fiber Link Employing Baseband I/Q Separation - Adaptive Optical OFDM Modulation and Separate I/Q Baseband Signal Transmission with Remotely-fed RSOAs for Colorless ONU in Next-generation WDM Access

Abstract: We demonstrated a novel scheme to transmit 20-Gb/s adaptively modulated optical orthogonal frequency division multiplexed (AMO OFDM) signal employing separate in-phase (I) and quadrature (Q) channel baseband delivery in a 20-km single loopback fiber link based on 1-GHz reflective semiconductor optical amplifiers (RSOAs) for a colorless optical network unit (ONU). Adaptive loading process was applied to the OFDM signals to overcome the bandwidth limitation of RSOAs. The I and Q channel data streams in the OFDM signals were separately carried on individual optical carriers with different wavelengths without Hermitian Symmetry for baseband transmission. Our proposed scheme was experimentally demonstrated using a periodic property of free spectral range (FSR) in a wavelength multiplexer. The separated optical “dual” carriers were provided by the same port of a wavelength multiplexer to reduce the number of used WDM channels for a upstream.