Chapter 2 Polarization techniques for surface nonlinear optics

Publisher Summary This chapter provides an overview of second-order nonlinear optical polarization techniques as applied to the study of surfaces and thin films and emphasizes the common underlying principles of the techniques, their practical implementation, and their most important applications. Explicit discussions based on second-harmonic generation (SHG) are provided. However, cases with one and two input beams are treated at the fundamental frequency. It is evident that the basic principles are also applicable to sum-frequency generation (SFG) and difference-frequency generation (DFG). The number of independent components of the various susceptibility tensors can be very large for samples of low symmetry. Although the basic physical principles remain unchanged in such cases, they give rise to very long mathematical expressions that are difficult to decipher. Two important applications of polarization techniques in surface and thin-film nonlinear optics are presented. The first application is to the study of chiral thin films and the second application is the use of polarization techniques to distinguish between the surface and bulk contributions of isotropic materials. The theoretical treatment is expanded to include the linear optical properties of the samples and the implications for thick samples and for ultrathin samples is discussed. Finally, the conclusions and an outlook for nonlinear optical polarization studies are presented in the chapter.