Study of linear and nonlinear optical properties of distorted Ti–O6 perovskite structure in BaxSr1−xTiO3 Original Research Article

We report the linear and nonlinear optical properties of sol–gel prepared BaxSr1−xTiO3 (BST) crystalline powders. The results from powder X-ray diffraction, birefringence, and second-order optical nonlinearity measurements indicate that the paraelectric–ferroelectric phase transition of Ba0.75Sr0.25TiO3 occurs near room temperature. The second-order optical nonlinearity of the ferroelectric BST is about 7.9 pm/V. The index of refraction, n=2.2, and birefringence, ΔnB∼0.05, are also appropriate for practical nonlinear optical applications.