The growth striations have been intentionally produced in Y-doped LiNbO3 crystals during Czoohralski growth. The LiNbO3 crystals with periodic change of refractive index have been prepared. Birefractive index and Bragg diffraction have been oboserved and measured in the crystals. Experimental results show that the correspondence relation between period of refractive index and period of growth layers has been demonstrated.