Microstructure and Third Order Optical Nonlinearities of Ion-Implanted and Thermally Annealed Cu-SiO₂ Thin Films

The crystal structure and optical properties of copper nanoparticles, prepared in fused silica by ion-implantation and subsequent heat-treatment, were characterized by X-ray, TEM, linear absorption, and degenerate four-wave mixing (DFWM) technique. The X-ray data show fee lattice structure of the nanocrystals and their size was measured as 8-20 nanometer by high resolution TEM. Using DFWM, the third-order nonlinear optical coefficient of the Cu-SiO₂ thin films was measured as 0.4-1.1×10^-s esu the surface plasmon resonance absorption region (540-570 nm).