Anomalies of Doped-LiNbO₃ Crystal in Photorefractive Phase Conjugation with Relation to Structural Phase Transformation

We investigate the photorefractive phase conjugation in a Ce:Fe:LiNbO₃ crystal as a function of temperature (293-393 K) and find the phase conjugate reflectivity increases sharply in the vicinity of 55, 70 and 110°C. The anomalous phenomenon is possibly concerned with the structural phase transformation of a crystal, which induces an extra internal electric field to influence the phase conjugation. The value of the field is estimated at the order of 10⁵ V/m, in agreement with the published data.