Influence of asymmetric nonlinear gain on the transient intensities of longitudinal modes in long wavelength Fabry-Perot laser diodes

The intensity transients of the longitudinal modes in a modulated 1.3-/spl mu/m Fabry-Perot laser diode are analyzed theoretically and experimentally. A simulation of the transient spectra, based on a 21-mode rate-equation model, shows that nonlinear gain strongly affects the intensities of longitudinal modes during transients. The simulation results are confirmed by time-resolved spectrum measurements. From a comparison of measurements and the simulations, the self- and cross-saturation coefficients are estimated. Our simulations also show that the transient spectrum strongly depends on the bit interval during digital modulation.