Eu3+- and Er3+-doped SiO2-TiO2 sol-gel films for active planar waveguides

Sol-gel films of SiO2-TiO2-doped with Eu3+ or Er3+ ions were prepared by spin coating with a variety of molar concentration ratios of tetraetoxysilane (TEOS) and titanium isopropoxide (TPOT). The ratios of SiO2-TiO2 were 90/10, 85/15, 80/20, 75/25 and the concentrations of Eu and Er ions varied from 10-3 to 5·10-2 mol%. Silica-titania films annealed from 150 up to 900oC decreased their thickness from 300 to 150 nm and increased the refractive index from 1.49 to 1.62. The multilayer (6-8 layers) silica-titania thin films with thickness of about 1.2-1.6 μm have been developed in order to make highly doped with Eu3+ or Er3+ planar waveguides on silicon substrates. Luminescence spectra, lifetimes as well as FTIR and micro-Raman spectra have been measured. Influence of active ion concentrations and annealing temperature on the luminescence properties and the structure of thin films were investigated. (author)