The structure of defects and its link with photorefractive properties in doped LiNbO3

Abstract

We present a new method to determine the photorefraction (PR) efficiency in doped and undoped LiNbO3 (LN) crystals. For this we study the activation of forbidden Raman lines by the nonlinear optical polarization associated with the photorefraction (PR) as a function of the wavelength of the exciting laser line. Results are plotted for various LN crystals within the same scale. The change of the PR efficiency can be related to the variations of the optical absorption and conductivity. In Hf-doped LN crystals the dependence of the PR process vs Hf content can be linked to the change in site occupation of Hf ions in the lattice.