Classical Nonlinear Optics

Abstract

Many problems of interest in optics and virtually all of those in this book involve nonlinear interactions that occur when the electromagnetic interaction becomes too large for the medium to continue to respond linearly. We have already seen how a nonlinearity plays an essential role in the free electron laser pendulum equation (1.131). In another example that we discuss in detail in Chap. 6, the output intensity of a laser oscillator builds up until saturation reduces the laser gain to the point where it equals the cavity losses. In situations such as second harmonic generation, one uses the fact that nonlinearities can couple electromagnetic field modes, transferring energy from one to another. Such processes can be used both to measure properties of the nonlinear medium and to produce useful applications such as tunable light sources.