Investigation on photorefractive properties of Hf:Fe:LiNbO_3 crystals

摘要

Photorefractive properties of congruent LiNbO_3 crystals codoped with HfO_2 and Fe_2O_3 have been investigated at 488 nm wavelength by holographic recording experiments. The results definitely show that when the HfO2 concentration is lower than its threshold concentration (4 mol.%), the photorefractive properties of Hf:Fe:LiNbO _3 crystals are reduced with the increase of the HfO_2 concentration. However, when the HfO_2 concentration exceeds its threshold concentration, the photorefractive properties of the crystal return to enhance. This unusual behavior with various HfO_2 concentrations is explained. Fe~(2+) ions are suggested to be the main contributor to the photoconductivity of the crystal and subsequently to induce the dissimilar photorefractive properties.