The second- and third-order harmonic distortion in distributed feedbac
k (DFB) lasers is simulated using a time domain large signal dynamic m
odel, The effects of the longitudinal spatial hot burning, nonlinear g
ain, spontaneous emission, and current leakage are included in the mod
el, Composite second-order (CSO) and composite triple beat (CTB) are c
alculated for an 80 channel 60-540 MHz system with 3% modulation depth
in each channel, The simulation results are compared with the experim
ental harmonic distortion measurements.