Dual-Operability and Bandwidth Partitioning Enabled by an ONU With Tandem-Modulator

An upgrade at the physical layer regarding unbundling and dynamic bandwidth provisioning of a wavelength division multiplexed access network is presented. The capability of a reflective modulator to act as a photodetector is exploited and allows a tandem configuration to be used at the optical network unit (ONU) for flexible switching of the detection and modulation branch. Consequently, a mechanism for service operator selection and for dynamic bandwidth partitioning up to twice the nominal data rate is provided. The scheme is experimentally evaluated for different kinds of modulators and shows, together with a full-duplex transmission at 10 Gb/s, additional operation modes, featuring unidirectional downstream and upstream burst-mode transmission with up to 20 Gb/s for ONUs based on a combination of a semiconductor optical amplifier and a reflective electro-absorption modulator.