Growth and photorefractive properties of near-stoichiometric Pr:Ce codoping lithium niobate crystals

The congruent Pr(0.1 wt%):Ce(0.1 wt%):LiNbO3 (PCLN) crystal and near-stoichiometric Pr(0.1 wt%):Ce(0.1 wt%):LiNbO3 (PCSLN) crystal have been grown by the Czochralski method from melts having compositions of 48.6 and 58 mol% Li2O, respectively. The Ultraviolet (UV)–Visible (Vis) absorption spectra and the OH− absorption spectra were investigated to characterize the structure defects of the crystals. The UV–Vis absorption edges shift to shorter wavelength and the OH− absorption peaks shift to longer wavelength as the [Li]/[Nb] ratio increases to stoichiometric. The photorefractive properties of the PCLN and PCSLN crystals were experimentally studied using the two-wave coupling method. The results show that as the [Li]/[Nb] ratio increases to stoichiometric, the holographic response time decreases; the diffraction efficiency, the photorefractive sensitivity and the dynamic range increase.