Design Characteristics for a Full-Duplex IM/IM Bidirectional Transmission at 10 Gb/s Using Low Bandwidth RSOA

In this paper, the optimum design characteristics and the transmission performance limits of an intensity modulation full-duplex bidirectional transmission system at 10 Gb/s are experimentally studied and presented for application in next-generation-extended wavelength-division-multiplexed passive optical networks. A low-bandwidth (~1.2 GHz) reflective semiconductor optical amplifier (RSOA) is utilized at the optical network unit (ONU) site of the system. Its remodulation properties and performance are examined for both continuous wave and modulated downstream signal, stemming from the optical line terminal (OLT). The techniques adopted to optimize performance are: 1) the use of detuned optical filtering at the OLT receiver that takes advantage of the RSOA chirp and 2) the use of decision feedback equalization (DFE). The extinction ratio of the downstream signal and the driving operation point of the RSOA are examined experimentally in order to find the optimum conditions for the bidirectional transmission. Moreover, the impact of patterning effects in the performance of the system is evaluated. Finally, the additional performance improvement that is achieved with the use of DFE technique is shown.