Abstract
In the paper authors analyze the use of optical fiber to transmit data in telecommunication systems, the use of optical fiber in the rapidly growing field of fiber optic sensors based on the creation and functioning of the so-called Bragg gratings, describe the results of the experiment of measuring elongation and deformation when changing annealing parameters. The elongation of the sample was calculated using the finite (FEM) and boundary element method (BEM) in the mathematical model. The results of the experiment are shown - the effect of the increase in temperature at the Bragg grating on the wavelength, refractive index and spectral reflection characteristics.