Kinetics of the emission spectrum of an injection laser and collapse of single-mode emission

An experimental investigation was made of the kinetics of the emission spectra of aluminum-gallium arsenide stripe heterojunction lasers. The investigation was carried out at 300°K for time resolutions down to 3·10^–11 sec. A composite tunable resonator was used to ensure reliable single-mode emission. An analysis of the streak spectrograms indicated that the single-mode emission could be a steady-state process, whereas the multimode emission was only a transient process that appeared, for example, in the presence of regular pulsations or spikes and it lasted only for short intervals (10^–10–10^–9 sec). Occasional collapse of the laser action was observed at conditions intermediate between single-mode and multimode emission and in most cases such collapse was accompanied by fluctuations of the output frequency, amounting to several tens of gigahertz. In the presence of growing shallow pulsations the fluctuations of the output frequency were synchronous with the intensity pulsations and shifted with respect to the latter by a quarter of the pulsation period.