Nonvolatile two-step, two-color holography with continuous-wave lights for both congruent and near-stoichiometric LiNbO3:Fe

Abstract

We have studied theoretically the steady-state nonvolatile two-step, two-color holographic recording performance for both the congruent and the near-stoichiometric LiNbO3:Fe based on the two-center model (the deep-trap and the shallow-trap centers are Fe2+∕Fe3+ and NbLi4+∕NbLi5+, respectively). The results show that the direct electron exchange between the Fe2+∕Fe3+ centers and the NbLi4+∕NbLi5+ centers due to the tunneling effect dominates the charge-transfer process during the nonvolatile two-step, two-color holography and determines the two-step, two-color holography performance in LiNbO3:Fe. We have further studied the effects of the crystal stoichiometry on the performance of the two-step, two-color holography. It is shown that, as far as the total space-charge field is considered, the nonvolatile two-step, two-color holography performance in the near-stoichiometric LiNbO3:Fe is much better than that in the congruent LiNbO3:Fe within the intensity range reachable by the continuous-wave lights.