  We present a time-domain model for the simulation of light-matter interaction
in semiconductors in arbitrary geometries and across a wide range of excitation
conditions. The electromagnetic field is treated classically using the
finite-difference time-domain method. The polarization and occupation numbers
of the semiconductor material are described using the semiconductor Bloch
equations including many-body effects in the screened Hartree-Fock
approximation. Spontaneous emission noise is introduced using stochastic
driving terms. As an application of the model, we present simulations of the
dynamics of a nanowire laser including optical pumping, seeding by spontaneous
emission and the selection of lasing modes.
