We report here an anomaly that the photorefractive phase conjugate ref
lectivity increases sharply near 55, 70, and 110 degrees C in three di
fferent doped-LiNbO3 crystals. The anomalous phenomenon is possibly co
ncerned with the structural phase transformation of the crystal, which
induces an extra internal electric field and enhances the reflectivit
y. (C) 1995 American Institute of Physics.