Relaxation of Rayleigh scattering in silica core optical fiber by heat treatment

This report describes the possibility of reducing Rayleigh scattering loss in a silica core optical fiber, which is believed to have realized its ultimate optical loss. The Rayleigh scattering measured for small fiber segments after heat treatment shows a clear reduction, and the time‐dependent change in the scattering due to the heat treatment can be represented by a linear relaxation function. An examination of the relation between the relaxation time and the viscosity of the fiber indicates that the reduction due to the heat treatment is attributable to viscous relaxation in the glass structure of the fiber. Based on these results, an evaluation of the viscous relaxation by an in‐line heat treatment during fiber drawing suggests that the Rayleigh scattering loss can be reduced by approximately 15%. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(12): 35–41, 2000