Fabrication and properties of doped porous polysiloxane sol-gel layers on optical fibers

Polysiloxane porous layers doped with TiO- and phenyl-groups were fabricate d by the sol-gel method. Starting sols were prepared from alkoxides using c atalysis by HCl or HE Stable SiO-TiO-sols were obtained by using HE Porous gel layers with thicknesses of 0.3-1.1 mu m were coated on fiber surfaces o r silicon wafers. Layers with the refractive index of 1.38-1.48 were prepar ed. The fractional porosity of the layers was estimated to be 0.1-0.35. The interactions of the layers with vapor or liquid chlorinated hydrocarbons, alcohols or aromatic hydrocarbons have been studied in immersing experiment s by measuring the output light intensity from the fibers. The observed cha nges of the output intensity could be correlated to changes of the refracti ve index of the layer caused by the penetration of the tested chemicals int o the layer pores.