Resonant nonlinear interactions of light with matter

This text uses a unified approach based on the concept of a generalized two-level system to discuss most of the effects related to resonant nonlinear optics: single- and multiphonon absorption, Raman scattering, parametric interactions self-action of light in resonant media, etc. The techniques developed here are applied to a study of polarization effects and the influence of phase locking and parametric self-induced transparency on the efficiency of frequency conversion and other resonant wave processes. A unified analytic theory of the dynamics of two-level systems under the action of quasi-resonant fields with arbitrary modulated frequency and amplitude is given. Various self-action effects based on a resonant nonlinear refractive index are discussed. They include self-focussing, self-bending (or self-deflection), the recently discovered effect of the switching of light reflection at nonlinear interfaces and optical bistability based on mututal self-focussing of counterpropagating laser beams.