Sol-gel fabrication of rare-earth doped photonic components

The use of sol-gel to fabricate silica-on-silicon waveguides, and particula rly erbium-doped waveguide amplifiers, is reviewed. In particular, efforts to use sol-gel to improve molecular homogeneity in heavily Er-doped silica- based films is discussed. A variety of material studies carried out to inve stigate the gain limitations found in these materials is then presented. Th ese include x-ray diffraction, ellipsometry and Rutherford backscattering. Excess heat treatment is used to force crystallisation of the films, and an alysis of the resulting structure is used to infer properties of the glass before the additional heating. The use of erbium alkoxide precursors is sho wn to alter the erbium environment in the final glass, in comparison to the use of inorganic erbium salts.