In recent years the field of semiconductor optics has been pushed to several extremes. The size of semiconductor structures has shrunk to dimensions of a few nanometers, the semiconductor-light interaction is studied on timescales as fast as a few femtoseconds, and transport properties on a length scale far below the wavelength of light have been revealed. These advances were driven by rapid improvements  in both  semiconductor and optical technologies and  were further facilitated by  progress in the theoretical description of optical excitations in semiconductors. This...