ABSTRACT
If a high-intensity beam of light illuminates a specimen, the specimen will behave in a nonlinear manner and higher optical harmonics will be generated in addition to the linear optical response (see Chapter 2). As demonstrated in section 2.6, this nonlinear harmonic generation will be a function of the atomic and molecular structure of the specimen. All materials possess odd order nonlinear optical susceptibility; however, even-order nonlinear susceptibility terms exist only in crystals that have non-centrosymmetric atomic geometry [Blombergen (1965); Boyd (1992); Shen (2003)].
