Principles of Nonlinear Optical Response

Abstract

This chapter describes the nature and origins of nonlinear optical response in materials. It aims to provide a general background to materials behavior for optoelectronics and nonlinear optics, except that the important topic of electromagnetic wave propagation in nonlinear materials is not covered. More specific accounts dealing with particular phenomena, materials, and devices are given in other chapters. The following section gives a general phenomenological description of nonlinear response, considering aspects of frequency dependence and symmetry. Next second-harmonic generation and the Pockels effect are treated briefly as examples in order to illustrate how the general description applies to specific cases each with its own specialized notation. After that, the microscopic origins of nonlinear optical response are considered. By understanding these origins, one can begin to design new materials. This is a particularly attractive possibility in molecular materials, as discussed in the final section.