Overlapped-subcarrier Multiplexing for Hybrid Tdm\wdm Passive Optical Networks

An innovative overlapped-subcarrier multiplexing (O-SCM) technique is proposed for wavelengthdivision multiplexed (WDM) passive optical networks (PONs).Allowing a certain amount of spectral overlap between the uplink and the downlink maximizes the spectrum usage of bandwidth-limited reflective semiconductor optical amplifier (RSOA)-based optical network units (ONUs), while reducing the effect of Rayleigh backscattering. In this paper, we report successful experimental demonstrations up to 2.5 Gb/s symmetrical bit rates over a 20 km bidirectional PON, using a 2 GHz bandwidth RSOA. In future we are going to develop hybrid TDM-WDM passive optical networks with dynamic wavelength allocation. These new scheme enable different ONUs to efficiently share (both in time and wavelength) the access network bandwidth to achieve better utilization. Keywords— Fiber-to-the-home (FTTH), passive optical networks (PONs), reflective semiconductor optical amplifiers (RSOAs), subcarrier multiplexing (SCM), wavelength-division multiplexing (WDM).