Theoretical Models for Describing an Enhancement in Nanoscale Optical Nonlinearities for Applications Design

This chapter focuses on the description of the theoretical models that occasionally change or improve the response of the optical nonlinearities for the design of photonic applications at the nanoscale. Thus, the theoretical and important procedures related to classical and quantum states that describe the changes in the optical response of nanostructured systems are highlighted. Thus, through this analysis, it is possible to understand the optical parameters dependent on various effects, and other factors such as size, geometric structure, and support material of nanostructured optical systems. Among the mechanisms analyzed are physical mechanisms, quantum confinement, thermal and plasmonic effects, as well as Fano resonances and the Purcell effect. So, this chapter establishes the theoretical foundations related to external effects on the transmission of light waves through nonlinear optical media.