Nonlinear Optics of Structured Nanoparticle Materials and Attenuated Total Reflection Devices.

This thesis consists of two parts: modeling and measurements of structured nanoparticle composite materials; and the attenuated total reflection (ATR) device configuration for linear and nonlinear optical measurements. In part I, we have developed the models for multilayered structured nanoparticle composite materials. Formulae for the multi-shell concentric nanoparticle model has been derived. Local electrical field enhancement, equivalent absorption coefficients and the enhanced effective third order optical nonlinearity are calculated. The device figure of merit for these composites have been calculated. Optical bistability of various composite materials has also been derived and the switching thresholds have been calculated. Although the effects of quantum confinement have not been explicitly calculated, these models should also form a basis for multiple layer quantum dots. Experimental work has been done on a series of polychromatic samples, in which, we believe, metal coated nano-particles are embedded. The measured absorption spectrum is in good agreement with the model calculation. The nonlinearity enhancement observed in DFWM experiments is well correlated to the absorption in each sample. On the other hand, the results of spectrum hole burning experiments seem to favor an asymmetric model rather than our symmetric concentric model. In part II, we have modeled and experimentally investigated several ATR (attenuated total reflection) optical device configurations. Some configurations are specifically applicable to thin films of nanodot composites. The ATR configurations include coupling to the Fabry Perot mode feature, to the critical angle feature, to the surface plasmon mode feature and to the waveguide mode feature. These ATR techniques are shown to be useful for optical thin film characterization and for the nonlinear optical measurements.