Comparison of return-to-zero phase shift keying and on-off keying in long haul dispersion managed transmissions

RZ-DPSK in DWDM dispersion managed transmission is studied experimentally and compared with OOK in a 10 Gb/s system. OOK out-performs PSK in a low spectral efficiency system. At 10 Gb/s transmission with 50 GHz channel separation, however, RZ-OOK and RZ-DPSK performances are comparable. RZ-PSK is advantageous in a high spectral efficiency system and results are shown of numerical studies of several PSK systems with high spectral efficiencies and long system reach.