The effect of the thermal treatment of silica-based glasses and glass fibers on their Rayleigh scattering is investigated experimentally. The Rayleigh scattering coefficients of bulk glasses are found to be increased 5-10% by heating them to 1800C because the density fluctuation is in proportion to their fictive temperature. Based on these results, we propose a method for reducing the Rayleigh scattering losses of silica-based optical fibers by drawing them slowly at low temperatures. We used this method to obtain a GeO 2 doped silica core single-mode fiber with a minimum loss of 0.16 dB/km at 1.55 m. As a result, we confirmed that the reduction in the fictive temperature of silica-based glasses and glass fibers reduces their Rayleigh scattering.
Kyozo Tsujikawa, Katsusuke Tajima, and Masaharu Ohashi, "Rayleigh Scattering Reduction Method for Silica-Based Optical Fiber," J. Lightwave Technol. 18, 1528- (2000)