Light–Matter Interaction

Abstract

The investigation of condensed matter systems using light as a probe is a versatile and powerfull concept, which provides various kinds of information not only about the structure but also of the electronic and lattice excitations and their dynamics. Besides linear optical processes, like absorption and emission (including photoemission), light-scattering, two- (or three-)photon absorption, photo-luminescence and high-excitation spectroscopy also belong to the methods to gain information about the single-particle and collective excitations of a solid. In semiconductor samples with a proper design, coherent light emission is possible and used in solid-state lasers. These methods, which allow studies in the frequency or time domain, are all based on the interaction of light with matter. In Sect. 3.5 we have already treated the optical excitation of lattice vibrations as an example. In this chapter, we shall present a systematic the- oretical description of light–matter interaction, which can be found in one or the other representation in standard textbooks [7, 14, 89, 95, 282, 283].