This is a course designed for advanced undergraduate and graduate students having some previous exposure to the field of optics. After discussing the basic principles of light-matter interaction and the wavelength- and energy-regimes that lead to a great deal of different effects, selected modern experiments and applications will be presented, including experimental techniques for the investigation of fundamental processes and the demonstrations of new phenomena with potential for the development of future devices.

The basics will include resonant and non-resonant, high-intensity and low-intensity excitations, local fields, and the origin, symmetry, and sometimes confusing definitions of the nonlinear optical susceptibilities. Experiments and applications will be selected from among the following topics: Measurement of nonlinear optical properties and the pitfalls of inconsistent definitions found in the literature; Molecular hyperpolarizabilities and macroscopic nonlinearities; Second and third order effects; Wave interaction in anisotropic crystals and atomic gases; Frequency conversion; Optical Kerr effect; Optical switching; Nonlinear time-resolved spectroscopy; Four-wave mixing; Rabi oscillations; Electromagnetically induced transparency; Pulse propagation, “slow” light, “fast” light, superluminal and negative pulse velocities. Some recent publications in the field will be examined.