Light scattering induced by opposite microdomains in LiNbO3:Fe:Hf crystals.

We report on the light scattering phenomenon in annealed multidomain LiNbO3:Fe:Hf crystals. The scattering sources are found to be some fog-like "defects", which cause the polarization-dependent scattering of the light, and can be removed completely by the illumination of visible light. Based on these results and the etch patterns, these "defects" are suggested to be refractive index fluctuations induced by the space charges accumulated at the boundary of opposite microdomains. The influence of quick heating-up on the "defects" is also studied and the results firmly support our suggestion about the nature of the "defects". At last, the temporal curves of the transmitted intensity during the light scattering are explained. The mechanism for the opposite microdomain formation is also explained from the view of crystal growth.