Nonlinear light propagation and self-inscription processes in a photopolymer doped with Ag nanoparticles

Abstract

<p>The resonance of surface plasmons on metal nanoparticles can be excited at visible wavelengths. The extraordinary enhancement of a variety of optical phenomena in the vicinity of metal nanoparticles has been attributed to the strong fields generated under resonance conditions. As a result, extensive research has been carried out to incorporate the extraordinary optical properties of metal nanoparticles into optical devices and applications, ranging from spectroscopy (e.g, surface enhanced Raman, IR and Fluorescence), optical sensing and imaging, to photovoltaic cells, photonic crystals and optical switches. Particular effort has been directed towards producing stable dispersion of metal nanoparticles within soft dielectric matrices and their subsequent construction into different device geometries.</p> <p>This thesis describes a method to photolytically generate Ag nanoparticles within organosiloxane sols, which can subsequently be photopolymerized in the presence of photoinitiators and therefore, be patterned through a variety of photo-inscription processes. The mechanism of Ag nanoparticle growth and evolution is described in detail followed by the fabrication of periodic metallodielectric gratings through photomask and laser interference lithography. Studies also showed that three different forms of nonlinear light propagation, optical self-trapping, modulation instability and spatial self-phase modulation could be elicited in the Ag nanoparticle-doped systems. Detailed experimental examination of these phenomena elucidated significant differences in their dynamics in the metallodielectric systems compared to non-doped samples. These included variations in the dynamics of self-trapped beams such as the excitation of optical modes, critical thresholds for modulation instability and self-phase modulation. The potential of these nonlinear processes for the self-inscription of 3-D metallodielectric structures including cylindrical multimode waveguides and waveguide lattices has also been studied.</p>