Comparison of Two-wave Mixing–Self-focusing inDiffusion- and Drift-type Photorefractive Materials

Self-focusing and -defocusing of light in two-wave mixing is investigatedexperimentally for BaTiO3 and BSO. Amplification and self-focusing of a probe beamare measured as functions of the frequency shift between probe and pump beam. The self-focusingin two-wave mixing in BSO is anisotropic, whereas it is isotropic in BaTiO3.Consequences of gain saturation for the measurement of self-focusing in BaTiO3 arediscussed.