Formation of copper nanoscale particles in implanted silica glass

Ion implantation into glass has potential in the fabrication of photonic or optoelectronic devices on planar glass substrates because it provides control of the dopant concentration and profile. We have measured the changes in optical and magnetic properties of silica glasses implanted with transition-metal ions and structural defects produced by the implantation. In previous papers two significant modifications of optical properties of copper-implanted silica glasses have been reported. The first is a large increase in the refractive index. The refractive index, measured at 632 nm (He-Ne laser) increases from 1.47 to 1.65 with doses increasing from 1 x 1016 to 6 x 1016 cm-2. A linear correlation was found between increments in the refractive index and the absorptivity of an induced optical band centred at 2.2eV. The second modification is a very large value (about 4 x 10-11 m2W-1 at a wavelength of 532 nm) of the non-linear refractive index. It was suggested that these two properties are due to the formation of copper colloids. In this letter we confirm the presence of Cu nanoscale particles in as-implanted silica glass. (author)