Influence of higher Stokes components on lasing under conditions of stimulated Brillouin scattering in loop systems

A four-wave interaction is analyzed in a loop system based on stimulated Brillouin scattering with an amplifier in the feedback loop. It is shown that at inadequate input intensities, the appearance of higher Stokes components in the reflected wave spectrum reduces the reflection coefficient of the system and also the efficiency of energy coupling-out from the amplifier. Radiation having an intensity comparable to the threshold intensity of a phase-conjugation device with a double-pass amplifier must be coupled into the system to achieve good parameters.