Our research field is optical spectroscopy on semiconductor quantum structures at low temperatures and in high magnetic fields. Specifically, we are focussing on the spin properties of free carriers - electrons or holes. The semiconductor quantum structures are, e.g., GaAs-AlGaAs heterostructures, which host high-mobility two-dimensional electron systems (2DES) or two-dimensional hole systems (2DHS). Furthermore, we are interested in novel magnetic semiconductor heterostructures, consisting, e.g., of a combination of magnetic (GaMnAs) and nonmagnetic (e.g., InGaAs-GaAs) layered semiconductors. Those systems are prototyps of spin-injection structures for a possible future semiconductor spintronics. For the investigation of the spin dynamics of free carriers we are employing ultrafast experiments - e.g., time-resolved Faraday rotation, time-resolved Kerr rotation or time-resolved photoluminescence. By means of Raman spectroscopy (inelastic light scattering) we are studying the elementary excitations of the crystal lattices (phonons) or of the charge carrier systems (plasmons, spin-density waves, spinflip excitations) in the nanostructures. Here, we are planning to do time-resolved Raman experiments to explore the dynamics of the excitations. Recently we have extended the range of investigated materials to graphene (single layer of graphite) and to one-dimensional nanostructures, like Carbon nanotubes or GaAs nanorods.