Enhanced photorefractive properties in Hf, Ce and Cu co-doped LiNbO₃ crystals for holographic application

Graphical abstract: Correlation spots of 200 holograms in a Hf, Ce and Cu co-doped LiNbO₃. - Highlights: • Several doped LiNbO₃ crystals with various level of Hf doping were grown by Cz method. • IR peak shift is attributed to the complex defect change at different level of Hf. • Enhanced photorefractive properties have been got with higher Hf-doping level. • Reduced defect and increased photoconductivity are responsible for optical properties. • 200 holograms' experiment is realized in a coherent volume 0.073 cm³. - Abstract: Hf, Ce and Cu co-doped LiNbO₃ crystals with various level of Hf doping were grown in air by a conventional Cz method. The infrared spectra were measured to discuss the defect structures and the mechanism of the absorption peak shift in these crystals. The light-induced scattering of the crystals was evaluated by the transmitted light method. The influence of the Hf-doping level on the photorefractive properties of Hf, Ce and Cu co-doped LiNbO₃ crystals was studied via two-beam coupling. It is found that proper doping Hf is an efficient method to enhance the comprehensive photorefractive properties of the LiNbO₃. Using one of these crystals as medium, 200 holograms storage and correlation experiments based on angle fractal multiplexing have been realized in a coherent volume 0.073 cm³. Moreover the diffraction efficiency is uniform and the storage density has reached 2.2 Gb/cm³