ABSTRACT
This chapter focuses on study of optical processes where the interaction of light with the medium is described as an inelastic scattering process. It examines processes where energy exchange with the medium produces a specific shift of the scattered photon energy. The scattering effects may involve atomic or molecular properties or an excited state of the system. The chapter considers the Raman effect where an optical field interacts with molecular vibrations and rotations. It also outlines a treatment of the related Brillouin effect, which couples optical fields to acoustic modes of the material. A key point of the Raman scattering: new frequencies are generated at the Stokes and anti-Stokes. It is possible to enhance the weak spontaneous Raman effect by introducing two laser beams: one at the pump and the other at the Stokes frequency. This type of arrangement is called the stimulated Raman scattering. The spontaneous Raman scattering contains both a Stokes and an anti-Stokes component.
