Abstract
We derive an exact solution including pump depletion of collinear four-wave mixing in a birefringent Kerr medium. We find mirrorless optical multistability for a linearly polarized backscattered signal with orthogonal pumps at cw power levels using a few meters of polarization-maintaining silica fiber. An expression for the nonlinear phase distortion of ideal phase conjugation is obtained, showing a fundamental limitation to generating time-reversed wave fronts using Kerr nonlinearity.