Dyriv M. Optical Raman amplification at the Stokes noise background in silica fibers.

The thesis is devoted to complex research of physical processes of nonlinear photon-phonon interaction in light scattering by optical phonons, to the leakage o coherent optical waveguides processes and Raman amplification of light in single-mode fibers at optical Stokes stochastic noise background. The technique of the approximation of experimental Raman gain efficiency profiles in typical single-mode fibers SMF, DCF and TrueWaveRSTM with using the spectral decomposition method and basic standard functions of line shape is improved. Given simple analytical expressions for the approximation of Raman gain efficiency profile are applicable to further numerical modeling and optimization of net gain and to maximally exact calculation of the behavior of optical waves along the fiber at multichannel fiber Raman amplifiers (FRA) synthesis. The Raman gain efficiency profile is firstly modeled in dispersion compensating fiber on the basis of just seven-component superposition of Gauss functions. It is shown that optimal number of spectral components is ten and mean-square errors of the approximation reduce to 2?10-3 (in fiber DCF) and 2.9?10-3 (in fiber TrueWaveRSTM). Such spectral model is also suitable to Raman gain efficiency profile in SMF, despite its complex shape. These results are consistent with calculations of Raman gain efficiency profile using the temporal response function.