Analysis of domain structure in BaTiO/sub 3/ by second-harmonic generation

Summary form only given. Photorefractive holograms can be fixed in ferroelectric crystals by a structure of 180/spl deg/ ferroelectric domains, which electrically compensate the photorefractive space charge (domain fixing). Exactly how and where the domains are formed or distorted such that the photorefractive space-charge is compensated is not known well, and may be different for different kinds of crystals. Furthermore, the coarseness of the domain structure must have a strong effect on the resolution, efficiency, and stability of the fixed holograms, so that knowledge of the domain structure is required. We study the domain structure of barium titanate through second-harmonic scattering. A pulsed /spl lambda/=1.064 /spl mu/m is sent through a barium titanate crystal with 180/spl deg/ domains, producing a scattered second-harmonic wave (/spl lambda/=532 nm), which is recorded by a CCD camera. In the far field, the intensity of the scattered light is proportional to the square of the Fourier transform of the domain structure. By measuring the angular variation of the intensity of the second harmonic we determine the statistical distribution of the location and size of 180/spl deg/ domains in the crystal. This experiment is performed at different degrees of crystal depolarization, which is accomplished by applying an electric field against the c-axis. The degree of polarization reversal is determined by integrating the switching current.