Maxwell-Bloch equations for spatially inhomogeneous semiconductor lasers .2. Spatiotemporal dynamics

The spatiotemporal dynamics of broad-area lasers is analyzed on the basis of a space- and momentum-dependent density-matrix approach. To this means the space-dependent Maxwell-Bloch equations for the semiconductor laser (derived in our preceding paper I) are solved by direct numerical integration. The space and momentum resolved dynamics of the active semiconductor medium, described by microscopic charge-carrier distributions and nonlinear polarization functions, are treated self-consistently with the spatiotemporal dynamics of the light field. Carrier transport dynamics are approximated on the basis of an ambipolar diffusion approximation consistent wit the microscopic process. Boundary-influenced macroscopic waveguiding properties of typical conventional as well as tapered broad-area laser cavities are taken into account. The dynamics of the formation and longitudinal propagation of unstable transverse optical filamentary structures are analyzed. Simultaneous spectral and spatial hole burning with dynamical spatiospectral variations on ultrashort (ps and sub-ps) time scales are observed in the charge-carrier distributions, reflecting the interplay between stimulated emission and the relaxation dynamics of the carrier distributions as well as the polarization. The transverse hole burning leads to complex spatiotemporal patterns in the macroscopic intensity picture with different optical frequencies associated with various locations of the modelike near-field patterns.