Interaction and dispersion of waveguide modes in an optical fiber with microirregularities of the core surface

Abstract

A self-consistent linear model is proposed for the transformation of the average intensity of the mode spectrum I(z) of the waveguide field in a multimode optical fiber with a stepped refractive index profile and the core having a rough surface. The model is based on the concept of the intermodal dispersion matrix of an elementary segment of the fiber, ∆, whose elements characterize the mutual transfer of energy between the waveguide modes, as well as their conversion to radiation modes on the specified interval. On this basis, the features of the transformation of the mode spectrum I(z) in a multimode optical fiber with a stepped refractive index profile are considered that is due to the effects of multiple dispersion of the signal by the stochastic irregularities of the duct. The effect of self-filtering of I(z) is described that results in the formation of a stable (normalized) distribution I*. The features of the normalization of the radiative damping of a group of modes I i (z) in an optical fiber are considered.