"The optimization of the nonlinear (NL) optical response in NL materials is a key element in the development of future photonic and biophotonic applications. Nevertheless, the characteristics of the materials utilized so far do not meet all the stringent requirements imposed for their implementation into real systems. To understand better the NL optical behavior of new materials or to improve previous compounds, it is necessary to develop different studies of structure–property for several systems. The main objective of this dissertation is to study the second and third–order NL optical properties in nonresonant and resonant regime of novel organic and inorganic materials, and to correlate the magnitude of such nonlinearities with the materials structure. A nonresonant electronic optical nonlinearity, by its nature, would have the fastest response time, limited only by the width of the driving laser pulse. In contrast, resonant optical nonlinearities have response times limited by the lifetime of the excitation and they also exhibit beam depletion due to absorption and thermal damage."