Effect of line codes and WDM wavelengths on the performance of transmission systems based on the Mach-Zehnder modulator

Simulation studies on the effects of the modulation line codes and WDM wavelengths of the dual-drive Mach-Zehnder modulator are presented. The two coding formats considered are non-return-to-zero (NRZ) and return-to-zero (RZ) operating at 10 and 40 Gbit/s within a wavelength range of 1548-1553 nm. The transmission performance of the compensated system has been evaluated. The results of Q-factor and bit-error-rate (BER) diagrams have shown that NRZ codes are much less affected by the detuning of the WDM wavelengths than the RZ format.