A scheme to realize multicast/broadcast by superimposing DPSK signal onto Manchester/NRZ signal

A multicast scheme in Wavelength-Division-Multiplexing passive optical network (WDM-PON) is realized by superimposing multicast differential phase shift keying (DPSK) signal onto downstream point-to-point Manchester/NRZ signal. A commercial electrical logic XOR gate is used to produce Manchester signal. The proposed system is experimentally demonstrated with 5-Gb/s point-to-point Manchester/NRZ format signal and 1.25-Gb/s DPSK signal. At the receiver side, a Mach-Zehnder delay-interferometer (MZDI) and a low pass filter (LPF) are employed to retrieve the multicast DPSK signal.