A broad spectrum of experiments and applications takes place in the realm of intense but non-relativistic light-matter interaction. In particular for intensities close to the ionization threshold, the underlying dynamics proceeds far from equilibrium and is strongly coupled. So far, a rigorous classical description of such scenarios has been limited to small system sizes. In the framework of this thesis the novel microscopic particle-in-cell (MicPIC) model has been developed and applied to so far numerically inaccessible scenarios, ranging from nonlinear plasma wave dynamics to x-ray imaging.<eng>
