Abstract :
It has been found that the light transmission characteristics of certain hot-pressed ferroelectric ceramics depends on the magnitude and direction of the ferroelectric polarization. Although scattering and optical depolarizing effects are present, transmittances as high as 0.9 have been measured. Two distinct types of optical properties have been observed and characterized in thin polished plates of rhombohedral lead zirconate-lead titanate ceramics. Coarse-grained materials, i.e., with nominal gain diameters (G) of two microns or more, almost completely depolarize the light by scattering. Fine-grained materials (G less and two microns) depolarize transmitted light by 5 to 20%, but otherwise behave the same as birefringent crystals (chromatic retarders). In optically uniaxial crystals, i.e., barium titanate and lead zirconate-lead titanate solid solutions, retardation depends upon the electrical polar axis orientation or ferroelectric polarization. Similar dependence has been observed in the fine-grained ceramics. The effects of various ferroelectric polarization states on light transmission in both coarse-grained and fine-grained materials are described in this paper.
