Silica-titania sol-gel planar waveguides were deposited on silica glass disks by spin coating. Fluorescence lifetimes as high as 375 μs were measured in neodymium-doped sol-gel planar waveguides and 1.78 ms for an erbium-doped film. Quenching was found to occur for the former at concentrations above 1 at. % of neodymium.
Abstract. Spin-coating is one of the possible methods for the fabrication of optical planar waveguides. These have several applications in integrated optical devices, provided that their optical losses are below ~1 dB/cm. The attenuation is caused in part by surface and bulk scattering. The latter depends on the microstructure of the films and, more particularly, the porosity, which is studied here. A series of SiO2-TiO2 films were prepared from solutions containing different concentrations of ethanol. The influence of the ethanol/(Si + Ti)alkoxides volume ratio on the porosity was investigated by Ellipsometry, Infrared Spectroscopy, and Scanning Electron Microscopy. The porosity volume fraction was found to reach a minimum when the ethanol volume ratio is near 4.
Abstract.A series of SiO2-TiO2 sol-gel films with and without heat treatment were analyzed by EXAFS and XANES spectroscopies. Both techniques indicate that essentially all Ti 4+ ions remain four-fold coordinated, with a Ti--O bond distance between 1.82-1.85/~. In the glassy films produced by heat treatment at 900~ a gradual phase separation may occur at the nanoscale, as the TiO2 concentration of the films increases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.