Analysis of residual stress in optical fiber

Residual stress in an optical fiber impacts several fiber properties, including reliability and geometry. The residual stress profile arises from a thermal expansion mismatch of the constituent materials, the tension applied during fiber forming, and the thermal profile experienced by the fiber during formation. The thermal profile of the fiber is determined by measuring the intensities of the two `defect' bands in the silica cladding of the fiber using Raman spectroscopy. Other studies have shown that the intensities of these bands increase with increasing fictive temperature and that these changes can be used to map changes in fictive temperatures across the fiber diameter. Optical birefringence is used to measure the residual stress profile of the fiber. The relationship between fictive temperature and fiber residual stress is explored for both straight fibers and fibers with a natural radius of curvature (curled fibers).