Active optical properties of Er-containing crystallites in sol-gel derived glass films

Thin films of controlled refractive index are prepared by sol-gel processing and thick multilayer deposits are used as planar waveguides for integrated optics (IO). By doping these layers with rare-earth ions such as Nd3+ or Er3+, IO devices such as lasers or amplifiers can be fabricated; the incorporation of these active elements into crystallites offers possibilities for increased dopant concentration without quenching, improved spectroscopic performance and high gain. The controlled growth of crystallites such as Er2Ti2O7 or ErPO4 in SiO2-TiO2 based sol-gel films through suitable heat treatments is described. The growth of crystallites was measured by grazing incidence X-ray diffraction. Doping of the glass matrix with Er-containing crystallites improved the Er fluorescence lifetime of the 1.55-mu m transition, in some cases by more than 200%. (C) 1998 Elsevier Science B.V. All rights reserved.