Grating curvature and/or varying spacing in barium titanate during self-pumped phase conjugation

Abstract

We present experimental observations of gratings formed in barium titanate during self-pumped phase conjugation. Coplanar beams from an argon-ion laser were applied simultaneously to the face of a poled BaTiO3 crystal in a typical self-pumped configuration.1 Phase conjugate beams appeared simultaneously on all input beams.2 A He-Ne laser beam was applied normal to the plane of incidence of the input beams and was spatially scanned to probe the interaction region in the crystal. The observed diffraction patterns of the probe beam were curved lines which disappeared when the corresponding conjugate beam gratings were erased. For a second crystal of barium titanate not exhibiting self-pumped conjugation (i.e., unpoled), the beam diffraction pattern showed beam spots due to the interference gratings of pairs of beams. Our results suggest that gratings of varying spacing, possibly curved, are formed for self-pumped phase conjugate beams in barium titanate.