An optical multicast overlay scheme using optical sub-carriers for WDM passive optical networks

We propose to make use of optical sub-carriers to realize optical multicast overlay on a WDM passive optical network. By employing optical carrier suppression technique at each downstream optical transmitter at the OLT, two coherent optical sub-carriers are generated to carry the 10-Gb/s downstream unicast DPSK signal and the 10-Gb/s downstream multicast ASK signal, separately without any additional light sources. At the ONU, the 10-Gb/s upstream data is superimposed on the received downstream unicast DPSK signal, to form the upstream ASK signal. System characterization is performed to optimize the performance. In addition, we further demonstrate simultaneous optical overlay of two streams of multicast data in the network.