Observation of 180-deg domain structure of MgO:LiNbO3 by SHG interference microscope

The SHG interference microscope was applied to the observation of the ferroelectric 180 degree(s) domain structure along the axial direction in a y-cut MgO:LiNbO3. Using four different SHG interference images with phase difference of 0, (pi) , +(pi) /2, and -(pi) /2, the special functions of the SHG intensities were calculated in the so- called (eta) -plane, from which the 3D domain structure was successfully obtained.