Study of optico-mechanical properties of fibers under thermocycling conditions

The study describes the evolution of the stress strain state in an polarization-maintaining optical fiber of Panda-type in conditions of contact interaction between the fiber and the coil with a single-strand power winding and cyclic temperature change by means of mathematical modeling. The finite element method is used to construct a finite-dimensional discrete analog. Multivariant computational experiments were carried out in which the coil diameter and deviations of the cross-section geometry of the Panda-type fiber were varied. The dependences describing the evolution of the stress strain state in the fiber, the refraction index and birefringence in the light-conducting core were obtained. The influence of the geometry deviations of the cross section of the Panda-type fiber to optical characteristics were investigated. It was shown that the greater deviation of the geometry from the design values, leads the greater temperature change influence on its optical characteristic. It was found that the small diameter coils are characterized by nonlinear changes in the parameters under study at high temperatures, due to relaxation processes in the protective coating of the fiber.