SYMMETRY REQUIREMENTS FOR 10-GB S OPTICAL DUOBINARY TRANSMITTERS/

We report design guidelines for external modulator transmitter paramet ers such as modulator offset, modulation amplitude, chirp, and nonidea l driver electronics, Binary and duobinary transmitters are found to h ave large differences in design tolerances. The dispersion tolerance i n the optical duobinary system rely on the symmetry in signal and modu lator, causing a reduced tolerance on parameters breaking this symmetr y, In particular, differences in the frequency response in the two arm s of the modulator are found to be much more critical in duobinary sys tems as compared to binary systems.