EFFECT OF PREPARATION OF SOL-GEL COATINGS ON THE STRENGTH OF OPTICAL FIBERS

SiO2, TiO2, ZrO2, and TiO2-ZrO2 thin coatings were applied by sol-gel method on quartz fibres during the fibre drawing. Durable layers with the thicknesses up to 0.7 mu m were obtained. The layer smoothness and thickness were determined using electron microprobe analyzer and elec tron or optical microscopy. In order to investigate a decrease in the strength of sol-gel coated fibres a novel method employing silica capi llaries was developed. The fibre strength decrease was explained by th e influence of water penetrating as a result of the coating process in to the flaws on the fibre surface.