ABSTRACT
Maxwell's theory of electric and magnetic fields and his idea that light is an electromagnetic wave were two of the great milestones of scientific thought, and unified understanding of a large and diverse set of phenomena. The field of nonlinear optics is partially driven by anticipation of enormous technological dividends. The relatively long interaction lengths and small cross-sections available in waveguide and fiber materials means that low-energy optical pulses can achieve sufficiently high peak intensities to compensate for the intrinsically weak nonlinearities in many transparent optical materials. It is an ideal subject for the theoretician interested in nonlinear behavior and model building who is particularly well positioned to make major contributions to the development of the subject. The chapter looks at the question of defining a nonlinear system two ways, first by the mathematical character of the laws that describe its behavior and second by its actual function as an input-output device.
