Large signal transient response of long-wavelength injection lasers

The large signal transient response of 1.3 μm InGaAsP Fabry-Perot type lasers is investigated by assuming that the injection current changes by steps. Single-mode and multimode operation are considered. For a one step current change the amplitude and frequency of the relaxation oscillations increase with the amplitude of the main pulse. Multimode operation shows the relative importance of the photon side modes during the transient. For a two steps current change a very important chirp reduction may be observed when the prepulse amplitude is smaller than the main pulse amplitude. By choosing the right prepulse amplitude and duration an absolute minimum for the chirp amplitude can be obtained. When the prepulse amplitude is larger than the main pulse amplitude there is no detectable change in the amplitude and frequency of the relaxation oscillations. By increasing the prepulse duration from zero up to its turn-on delay time, it is possible to vary the main pulse turn-on delay time between its maximum value and the prepulse turn-on delay time