Measurement of stress profiles in the preform of a polarization-holding fiber with stress-applying parts

Stress difference distribution, principal stress trajectories, and surface stress profiles are measured for the preform of a polarization-holding fiber with stress-applying parts. Experimentally evaluated stresses are compared with stresses computed by a finite element method. Experimental results are well explained by the calculated ones. Contour maps for stress difference and principal stress are presented. Surface stress is found to be compressive for the entire boundary of the fiber. Tensile test is carried out for the fiber drawn from the same preform rod. The result reveals that the strength of the polarization-holding fiber is comparable with that of a usual fiber without a stress-producing structure.