Mathematical model of radiation scattering on a quasi – periodic structure in an optical fiber

Abstract

The paper considers a quasi – periodic microheterogeneity structure formed under the effect of optical fiber melting, which can be used as a sensitive element for an optical sensor based on a Fabry – Perot interferometer or an optical radiation scatterer with improved flexibility and strength parameters. Mathematical modeling of the process of transmission and reflection of radiation on the microcavities of the intrafiber structure will make it possible to predict the characteristics of the developed sensors. The simulation was carried out in the COMSOL Multyphysics simulation package. A section of a single – mode SMF-28e fiber with microinhomogeneities located in the core, the dimensions of which were measured in the course of an empirical study, is considered. To solve the problem, a system of equations was compiled that describes the propagation of a plane electromagnetic wave in matter. The results obtained showed that the calculated reflection spectrum qualitatively coincides with the measured value, but does not describe it with high accuracy. This may be due to the fact that the model does not take into account intermode interference in the fiber, and does not have an introduced melt zone around microcavities, since such a melt zone has a complex refractive index distribution and composition