Nonlinear optics is the study of the interaction between light and matter under intense electromagnetic fields that deviate from linear response theories. In this field, the behavior of light is described by nonlinear equations and phenomena that occur when light interacts with materials in a non-linear way, leading to effects such as frequency conversion, self-focusing, and solitons. Nonlinear optics has a wide range of applications in various fields including telecommunications, laser technology, and biophotonics.