Duobinary transmitter with low intersymbol interference

A duobinary transmitter employing two-level electrical drive signals for the modulator, exhibits negligible penalties for transmitting 2/sup 7/-1 as well as 2/sup 31/-1 pseudorandom bit sequences (PRBS's). Previous implementations of duobinary transmitters have relied on driving the modulator with three-level electrical signals, which are very susceptible to distortion in saturated amplifiers. The logic operation necessary for generating an optical duobinary signal is carried out in the dual-drive Mach-Zehnder modulator.