Spatial noise reduction in broad area semiconductors

One of the most inconvenient of Broad Area Semiconductor Lasers is the large amount of spatial modes involved in the output beam and the possible temporal unstabilization due to their interaction. This introduces strong difficulties in the output beam focalization in order to be coupled to fibers or other devices. One possibility to increase the output beam quality of these devices is a spatial modulation of the Gain/Loss and refraction index in the amplifying material that can improve the signal/noise ratio during beam propagation. We consider a static model that can be linearized for low intensities allowing an analytic treatment of the problem. An interesting and technologically useful effect is the simultaneous spatial filtering and focalization behind the material.