Influence of intensity pulsations on the stimulated emission spectrum of a semiconductor laser

A new multimode mechanism of the stimulated emission from a semiconductor laser is considered. The excitation of several axial modes in the presence of intensity pulsations is attributed to the compensating influence of the spontaneous emission on the effective gain of the secondary modes, which are neighbors of the dominant mode excited at the threshold. The intensities of these secondary modes increase when the depth of modulation of the output radiation is increased. This mechanism explains the multimode stimulated emission near the self-excitation threshold of semiconductor lasers.