The internal electric field and backswitching in congruent lithium niobate

We present experimental results showing the correlation between the internal electric field and the baekswitching phenomenon in congruent lithium niobate. The large internal electric field, responsible for the offset of the hysteresis loop, is shown to have reoriented parallel to the new spontaneous polarization after two months at room temperature and is shown not to be the cause of backswitching. The reduction and recovery of the poling field after a backswitching event are presented, showing that the coercive field for the domains that were involved in the backswitching is significantly reduced, recovering to its nominal value after approximately 200 ms. These results indicate the presence of a fast component to the internal electric field which decays with a time constant of 50 ms. The dependence of backs witching on the impedance of the poling circuit is also shown.