Growth and photorefractive properties of near-stoichiometric In:Fe:Cu:LiNbO3 crystals

The near-stoichiometric LiNbO3 crystal co-doped with In2O3, Fe2O3, and CuO has been grown from a Li-rich melt (Li/Nb = 1.38, atomic ratio) by the Czochralski method in air atmosphere for the first time. The OH− absorption spectra were characterized to investigate the structure defects of the crystals. The appearance of the 3506 cm−1 absorption peak manifests that the composition of the grown crystal is close to the stoichiometric ratio. The photorefractive properties were also measured by the two-wave coupling experiments. The results show that the near-stoichiometric In:Fe:Cu:LiNbO3 crystal has a larger refractive index change, higher recording sensitivity and larger two-wave coupling gain coefficient than those obtained in the congruent In:Fe:Cu:LiNbO3 crystal under the same experimental conditions. The material of near-stoichiometric In:Fe:Cu:LiNbO3 crystal is a promising candidate for blue photorefractive holographic recording.