Influence of output intensity pulsations on the emission spectrum of an injection laser

An investigation was made of the influence of spiking on the spectral characteristics of injection-laser diodes. The investigation was carried out on single and double GaAs diodes operating at 90°K. It was found that the emission spectrum obtained in the non-spiking case consisted of one or two longitudinal modes. Spiking characterized by a modulation depth of about 50% increased the number of modes to three or four. The appearance of spikes with a greater modulation depth gave rise to five to eight axial modes. This behavior of the emission spectrum of semiconductor lasers was attributed to the excitation of axial modes by spikes.