Behavior of MLSE-EDC With Self-Phase Modulation Limitations and Various Dispersion Levels in 10.7-Gb/s NRZ and Duobinary Signals

We investigate experimentally the effectiveness of maximum likelihood sequence estimation electronic dispersion compensation (MLSE-EDC) for signals limited by self-phase modulation (SPM) and with various dispersion levels. We study nonreturn-to-zero (NRZ) and duobinary signals modulated at 10.7Gb/s and find that the improvement obtained with an MLSE-EDC receiver depends strongly on the level of residual chromatic dispersion (after partial optical compensation) in both cases. In general, greater SPM tolerance to high channel powers is derived from the MLSE in the presence of larger residual dispersion values. An increase in the allowable channel launch power of more than 2 dB is observed for NRZ signals, whereas, the increase for duobinary may be almost 6 dB.