Design of equally-spaced flat comb generator based on dual cascade mach-zehnder modulators

In this paper, simple technique of ultra-flattened optical comb generator based on a cascaded mode of two dual derive lithium Niobite Mach-Zehnder modulator (DD-LiNbO3-MZM) is proposed. More than 100 evenly spaced carriers were successfully generated by modulating a continuous laser source with a 114 GHz RF source using OptiSystem commercial software 7 software. Various parameters were adjusted to investigate their impact on the number of optical carriers and the average power fluctuations (the comb flatness). The results showed that defining the switching voltage and the RF switching voltages to 3 V and 10 V, respectively, has generated 0.1 nm evenly-spaced 101 ultra-flattened optical carriers with 10.3 nm total bandwidth. At this level, the overall modulator performance was also tested by calculating the average power fluctuations of the optical carriers which is mainly affected by the RF switching voltage. By adjusting a 10 V RFSV, a minimum average power fluctuation of 0.5 dB is achieved without any further enhancement.