A novel technique for doping silicate glasses with transition metals and rare-earth for waveguides applications

Field-Assisted Solid-State Ion-Exchange (FASSIE) technique for doping silicate glasses with either transition metals or rare earths has been attracting much attention for its potential application in light waveguides, luminescent materials and for the possibility to realize systems in which formation of metal nanoclusters is controlled by suitable post-exchange techniques. In this framework, metallic films of either silver or gold are deposited onto soda-lime and borosilicate glasses by the rf-sputtering technique. Owing to an external electric field, metal ions diffuse into the glass replacing its alkali content at different values of processing temperature and electric field. The nanocomposites are then characterized by secondary ion mass and m-line spectrometries, optical absorption and transmission electron microscopy, indicating that the migration not only depends on the experimental conditions but also on the matrix and the chemical phenomena occurring at the metal/glass interface. For both transition metals, dark m-lines detection suggests that the samples may actually support guided modes, although the quality of the surface creates some problems for the prism coupling used in the measurements. In particular, the yet broaden lines seem to indicate two modes in the visible and one in the IR.