Nonlinear Optics

Abstract

In the early 1960s the development of lasers provided light sources of sufficient power to produce nonlinear optical effects in solids. Nonlinear optics Not only has developed into a major field of research but also has found important applications in optical systems that require control and modulation of laser beams. Since lasers generally operate at a fixed wavelength or narrow range of wavelengths, one important application of nonlinear optics is to shift a laser wavelength to new wavelengths thus providing versatility necessary for many applications. This can be achieved by frequency mixing or parametric interactions. As an important example of this type of process the current chapter focuses on the nonlinear optical process of second‐harmonic generation (SHG). This example demonstrates the importance of crystal structure and symmetry in these types of processes. Much of what is discussed in this chapter depends on the concepts of light beam polarization and crystal birefringence discussed in Chap. 5. It is similar to the electrooptical effect discussed in Sect. 5.4 except that the electric field causing the effect is associated with a light wave instead of an external perturbation.