Nonlinear Optics probes in great depth quadratic and cubic nonlinearities, photorefractive nonlinear optics, the nonlinear optical properties of nematic liquid crystals, and photonic bandgap structures. This reference places core physical principles and theoretical concepts in dialogue with contemporary applications and research and presents the essential physics behind the products and promise of this very fertile field. It presents new developments in the dispersion management in nonlinear optical fibers and the combined effects of quadratic and cubic nonlinearities on harmonic generation. Coverage includes a review of linear wave propagation and the origins of optical nonlinearity.