Enhanced self-mode-locking in broad area semiconductor lasers by pulse injection

In this paper we give evidence that in free-running broad area semiconductor lasers (BALs) weak self-mode-locking of longitudinal modes already exists, leading to a fast regular intensity modulation of the output at the cavity round trip time. This fast dynamics deteriorates the output in terms of spectral width and temporal stability on the one hand, but on the other hand it could also offer an interesting possibility for optical pulse generation in these semiconductor laser devices. In fact, a significant improvement of the pulsed output has been achieved by additional injection of a picosecond pulse into the device.