Elements of the Theory of Nonlinear Optics
Optics is an important part of everyday life. Light seems to flow or propagate through empty space, as well as through material objects, and provides us with visual information about our world. The familiar effects of reflection, refraction, diffraction, absorption, and scattering explain a wide variety of visual experiences common to us, from the focusing of light by a simple lens to the colors seen in a rainbow. Remarkably, these can be explained by assigning a small set of optical parameters to materials. Under the ordinary experiences of everyday life, these parameters are constant, independent of the intensity of light that permits observation of the optical phenomena. This is the realm of what is called linear optics.