Dependence of the quality of wavefront reversal by stimulated scattering in a fiber waveguide on the coupling-in conditions

An analysis is made of the possible causes of the deterioration of the quality of wavefront reversal by stimulated Brillouin scattering in fibers: inaccurate focusing of the beam being reversed on the end of the light-guiding core, escape from the scattered line profile of angular components inclined strongly relative to the fiber axis, frequency shift due to the stimulated scattering, and spatial depolarization of the pump radiation. It is shown that in the case of short fibers for which the depolarization length is greater than one-thirtieth part of the fiber length, the main source of reduction in the fraction of the wavefront reversed radiation of a narrow-band laser is the escape from the line amplified by the stimulated Brillouin scattering of the strongly inclined angular components of the Stokes wave.