The Mandelstam - Brillouin Backscatter Spectrum Profile Evaluation in Optical Fibers of Various Types

The research results of the frequency characteristics of the Mandelstam - Brillouin scattering in single-mode optical fibers are presented in this work. A method for obtaining the optical and acoustic modes distribution characteristics in single-mode optical fibers is considered. The procedure for determining the profile of the Mandelstam - Brillouin back scatter spectrum with known structure of single-mode optical fibers is shown. The examples are given of obtaining the characteristics of acoustic and optical modes for the dispersion-shifted optical fiber (Recommendation ITU- T G.653) based on the analysis of the acousto-optical interaction. Also the contribution of each acoustic mode to the final Mandelstam-Brillouin back scatter spectrum of the reflected in the backward direction light signal is determined. The profiles of the Mandelstam - Brillouin scatter spectrum of usual single-mode optical fiber (Recommendation ITU- T G.652) and dispersion-shifted optical fiber (G.653) obtained during experimental research with “ANDO AQ8603” BOTDR are presented.