Raman investigation of optical fibers under high tensile stress

Raman spectra have been obtained from fused silica optical fibers under tensile stresses from 0 to 3.3 GPa (33 kbars). Reversible intensity increases, relative to the principal Raman maximum at 440 cm−1, were observed for the defect peak at 490 cm−1 and for shoulders near 350–375 and 115 cm−1. Application of tensile stress to fused silica appears to produce changes in the stretched Si—O defect sites, as well as changes in the main network structure.