Detection of initial level of Brillouin frequency shift in optical fibres of different types

The paper presents results of researches of the hyper-acoustic wave velocity on characteristics of the optical fiber core. The values of Brillouin frequency shifts for various types of optical fibers at room temperature and without longitudinal tensile force are presented. Database of profiles of the Mandelstam - Brillouin backscattering spectrums for fibers of different kinds and manufacturers allows one to classify the optical fibers in the optical cables and detect "problem" sections of fiber optical communication line.