Ultrafast optical processes in nitrides

We discuss here so-called 'propagation phenomena' in nitrides, i.e. the phe nomena of light-matter coupling at the femtosecond and picosecond timescale s. Specifics of nitrides, namely, giant oscillator strengths of A and B exc itons and extremely important potential disorder in GaN and related structu res makes the elastic scattering of light by excitons a dominant process th at has a huge influence on all kinds of coherent optical spectrum. We show how to extract the oscillator strength and inhomogeneous broadening from th e reflection and resonant Rayleigh scattering spectra of GaN-based QWs. Fin ally, we discuss the stability of excitonic complexes like charged trions i n nitrides and the effect of the free electron-hole plasma on their optical properties.