Abstract

It is well known that pump beams $E_1{e}^{{\text{iK}}_2\text{R}}$ and $E_1{e}^{{\text{iK}}_2\text{R}}$ which interact through any scheme of double-conjugation^1-6 in photorefractive crystals with diffusion gratings and very slow nonlinear response δω₁₂τ >>> 1, should not, nevertheless, be mutually coherent. This out-of-the-way effect results from the generation of the waves $a_1{e}^{-{\text{iK}}_2\text{R}}$ and $a_2{e}^{-{\text{iK}}_2\text{R}}$, which are phase-conjugate replicas for the pump waves $a_1~E_1^{*}$, $a_2~E_2^{*}$. In these schemes it is not necessary to fix moving interference patterns created by the superposition of pump beams with one another.

© 1991 Optical Society of America