| Light-matter interaction is a historically ancient topic, yet it is still under intense research, owing to the invention of novel optical techniques and the growth of unprecedented materials. The first goal of the work presented in this thesis is to understand the fundamental origin of various nonlinear optical phenomena. Susceptibilities are physical quantities describing the way that a material system responds to an optical field. We present in Chapter 3 the derivations of susceptibilities based on quantum mechanical statistics, revealing the electronic origin of optical nonlinearities.;Different theoretical tools have been applied to the interaction between light and a material system. Among them, the Jaynes-Cumming model is of importance in that it describes the interplay between a quantized light field and a two-level system. In Chapter 4, we will theoretically discuss the application of the Jaynes-Cumming model to the Faraday/Kerr rotation experiments on a single electron spin. As a magneto-optic effect, Faraday/Kerr rotation is one example of various nonlinear optical processes that are studied in detail in Chapter 3.;The second part of this thesis is dedicated to experimental demonstration of applications by exploiting different nonlinear mechanisms. One example is the mode-locked ultrafast laser discussed in Chapter 5. Another is the generation and detection of THz radiation in oxide nanostrucutures, which is covered in both Chapter 6 and Chapter 7. |
