Institute of Physics eBooks
Nonlinear light–matter interactions
Thomas Elsaesser, Klaus Reimann, Michael Woerner
Abstract
Theoretical concepts and framework for describing nonlinear light-matter interactions are the subject of this chapter. A density matrix approach is introduced for describing the nonlinear optical response of quantum systems to an electromagnetic field. Starting with the full description, different approximations are introduced and their limitations discussed from the viewpoint of physics. Basic concepts such as quantum coherences in multi-level systems, nonlinear currents, and nonperturbative light-matter interactions are explained and illustrated by model calculations.