Spatiotemporal emission dynamics of a broad-area semiconductor laser in an external cavity: stabilization and feedback-induced instabilities

We present investigations of the influence of spatially filtered optical feedback on a broad-area semiconductor laser's spatiotemporal emission dynamics. Our measurements reveal the ambiguous effect of optical feedback on the emission behavior of the broad-area laser. The measurements confirm that optical feedback can have a stabilizing effect on the inherent spatiotemporal instabilities exhibited by solitary broad-area lasers. Moreover, at high feedback strengths, we observe feedback-induced instabilities instead of the inherent spatiotemporal instabilities, thus, a destabilizing effect of optical feedback. The results are complemented and extended by measurements of the optical spectrum, which demonstrate that stabilization of the emission dynamics by optical feedback is accompanied by a drastic reduction of the number of modes contributing to the emission.