Abstract

Present theories of phase conjugation by stimulated Brillouin scattering in waveguide geometry disagree on key results. Hellwarth¹ ignores incoherent scattering contributions to the nonconjugate fraction f₁ of the high gain mode and calculates a nonconjugate output f₁ that is independent of pump intensity. Zeldovich² introduces statistical quantities to account for the incoherent scattering and arrives at an intensity-dependent output f₁. We argue that these statistical quantities are not measurable under normal experimental circumstances and lead to conceptual problems. We show that both coherent and incoherent scattering contributions can be taken into account by deterministic methods. We focus attention on the spatial dependence of the gain coefficient. If its fluctuations can be ignored, f₁ can be derived as a sum of term. The largest term has the same form as that of Zeldovich’s result but involves only deterministic quantities. When incoherent contributions are neglected our solutions duplicate Hellwarth’s. We emphasize that the different results of the Hellwarth and Zeldovich theories are of physical origin and are not due to different field expansions.

© 1985 Optical Society of America