Change in Refractive Index of a Borosilicate Glass Fiber Annealed below the Glass Transformation Temperature


Glass fibers pulled from multihole bushings can have a slight difference in thermal history that causes a distribution in the refractive index that can be narrowed by annealing the fibers. The kinetics for the initial stage change in refractive index for fiber annealed between 300° and 500°C are best described by a second-order reaction with an activation energy of 120 ± 17 kJ/mol. The improved uniformity in refractive index for annealed fibers is indicated by a decrease in the half-height width of the optical transmission versus temperature curve for glass fiber immersed in a liquid. The standard deviation in the refractive index of glass fibers with a bimodal distribution in diameter decreases from 8 x 10-4 ± 0.0002 to 4 x 10-4 ± 0.0002 after the fibers are annealed at 400°C for 1 h.


Materials Science and Engineering

Keywords and Phrases

Activation energy; Annealing; Borosilicate glass; Glass transition; Light transmission; Reaction kinetics; Refractive index; Thermal effects; Bimodal distribution; Multihole bushings; Temperature curve; Glass fibers

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version


File Type





© 1996 Wiley-Blackwell, All rights reserved.

Publication Date

01 Oct 1996