Light-induced charge transport in LiNbO3 crystals

We develop a concept of charge transport for congruent and stoichiometric LiNbO3 crystals, both doped and nominally pure. The concept is based on well-established experimental facts. It incorporates fragments of the known one-center and two-center models and other important elements including electronic transitions and transport channels. The model explains qualitatively the main features of the optical damage for the congruent and stoichiometric compositions within the low-to-high intensity range.