Simple model for a distributed feedback laser integrated with a Mach-Zehnder modulator

Presents a time-domain traveling-wave algorithm for the modeling of the large-signal dynamic response of a distributed feedback laser integrated with a Mach-Zehnder (MZ) modulator. The influence of residual optical feedback from the output of the modulator facet on the dynamic frequency chirp is studied. It is found that the difference in frequency chirp between the turn-on and -off states (i.e., adiabatic chirp) of a π/2-shifted 2 ×2 MZ modulator is minimal and is independent of-the residual optical feedback. In addition, it can be shown that the presence of chirped frequency spikes (i.e., transient chirp), due to the change in refractive index as a result of the rapid variation of the bias voltage, can broaden the linewidth and distort the spectrum of the modulated optical signal. Furthermore, the possibility of doubling the modulation frequency of MZ modulators using a dual-arm dual-signal modulation format is investigated.