Abstract

Besides their technological importance Broad area semiconductor lasers are interesting devices to study complex spatio-temporal dynamics with one transverse degree of freedom. They can be characterized by their lateral width of the active area which has been enlarged as compared to single stripe lasers from typically w ~ 1μm to 50μm ≤ w ≤ 200μm. Model calculations based on the semiconductor Maxwell Bloch equations predict the onset of spatio-temporal instabilities, resulting in spatially and temporally irregular pulsing of the emitted light intensity in the nearfield of such lasers on a sub-ns time scale [1,2]. We present single-shot measurements of the spatio-temporal intensity dynamics in the nearfield of a broad area laser with w = 100μm obtained with a streak camera system. We focus on the dynamical behavior of this laser in the first 10 ns after switching the injection current to typically twice the threshold current. The laser starts by emitting relaxation oscillations which break up spatially resulting in the onset of spatio-temporal behavior with irregular pulsing and migrating optical filaments. This is in close correspondence to the numerically obtained behavior. Characterization of the behavior can be achieved by the calculation of spatio-temporal cross-correlation functions.

© 1996 IEEE