On the dynamics of periodically-poled lithium niobate formation by off-center Czochralski technique

The formation mechanisms which might be responsible for the domain structures observed in periodic-poled lithium niobate crystals grown by the off-center Czochralski technique were investigated varying the process parameters. We show that the periodic inverted domains structure does not maintain the polarization over the whole crystal, as commonly accepted. In particular, a ‘‘separation plane’’ parallel to the growth axis exists and divides the crystal in two halves, each with periodic structure but with opposite domain sequences. A possible explanation of the phenomenon is presented invoking both the thermoelectric effect fluctuation experienced by the growing crystal.