Consequences of TiO2 doping on the optical properties of porous silica layers coated on silica optical fibers

Abstract The paper deals with the investigation of optical properties of porous silica and TiOTi chains – doped porous silica layers coated on silica optical fibers. The porous layers composed of dried gels have been prepared by the sol–gel method from alkoxides. The refractive indices and optical attenuation of the layers have been determined from the measured angular distributions of the output optical power. For this purpose, a model based on geometrical optics has been developed. The interaction of the porous layers with benzene, toluene, xylene and hexane has been investigated by measuring the changes of the output optical power induced by the effect of vapors of the hydrocarbons in air. On the basis of these measurements, the porosity of the layer, partition coefficients and equilibrium adsorption constants of the hydrocarbons have been estimated. The measured decrease of the optical power for the aromatic hydrocarbons and the increase of the output power for the aliphatic hydrocarbon have been explained on the basis of the developed model.