In situ video observation of 180° domain switching in LiTaO₃ by electro-optic imaging microscopy

We report video observation of 180° domain switching in congruent LiTaO₃ under an external electric field by electro-optic imaging microscopy. The sideways wall velocity of independently growing 180° domains in the Z plane of the crystal was measured to be 0.1-0.2 mm/s at a constant field of 21.2 kV/mm. The merging of independently growing domains results in a serrated domain front which displays an order of magnitude increase in the wall velocity to ∼2.3 mm/s. We show that this is directly related to ledge formation upon domain merging where preferential nucleation takes place. These velocities are also an order of magnitude higher than those reported earlier for equivalent switching times that were measured by pulsed voltage application followed by ex situ optical observation.