Generation of a phase-conjugate wave by degenerate four-wave mixing in an erythrosin-B-doped planar waveguide

A phase-conjugate wave (PCW) generated by degenerate four-wave mixing (DFWM) in a nonlinear-optical waveguide excited by a cw Ar-ion laser was observed. The planar waveguide consisted of a transparent polyvinyl alcohol layer partly doped with erythrosin-B. The DFWM excitation was performed as follows: Two pump waves impinged in the interaction region of the waveguide from the outside, and a probe wave was introduced into the guiding layer by a prism coupler. A PCW reflectivity of 6.3 x 10(-5) outside the prism coupler was obtained at a pump intensity of 1.2 W/cm(2).