An Introduction to the Nonlinear Optical Properties of2DMaterials

In this chapter, we summarize the latest development in the field of two-dimensional (2D) materials for nonlinear optics. We first briefly describe the fundamental of nonlinear optics, mainly including second- and third-order nonlinearity. We then introduce the associated measuring methodologies, including harmonic generation, Z-scan techniques, pump–probe techniques, and nonlinear optical imaging. Thereafter, the applications of 2D materials in various fields, such as optical limiting, mode-locking, optical switch, and nonlinear frequency conversion, are numerated in detail. We also provide our insight on the challenges and future development of nonlinear optics of 2D materials.