9. Nonlinear Metamaterials and Metadevices

Metamaterials have brought unique functionalities by allowing the engineering of the material parameters at the level of their elementary units (meta-atoms) to creating functional metadevices. One of the important developments in this field is the demonstration of many of the nonlinear effects known in nonlinear physics and nonlinear optics such as nonlinear self-action, parametric interactions, and frequency conversion, which will boost the development of various methods for achieving tunable, switchable, nonlinear, and sensing functionalities of metamaterials. The study of nonlinear effects in artificial media and engineering the nonlinear response of such media are crucially important for this progress. In the context of photonic integration, for instance, metamaterials promise pathways for light that are impossible in normal materials and offer new freedom in exploiting nonlinear processes. By incorporating nonlinear and tunable metamaterials, it will be possible to create functional metamaterials that display sensitive tuning and novel or enhanced nonlinear behavior. These materials will ultimately provide the basis of a revolutionary platform for optical processing. This chapter will give a brief review on the update progress of nonlinear metamaterials and inspired functional metadevices.