Two-color nonvolatile holographic recording in Bridgman-grown Ru:LiNbO3 crystals

Abstract

Abstract The Ru:LiNbO 3 crystal with the size of φ 25mm×70 mm was grown for the first time by the vertical Bridgman method from the congruent melt doped with a high concentration of 0.05 wt% RuO 2 . The as-grown crystal was dark brown in color without obvious color change along the growth direction. The optical properties of the crystal were studied along the growth axis ( Z ) by measuring the optical absorption spectra and OH − absorption peaks. The optical inhomogeneity was improved due to the effective suppression of RuO 2 evaporation during the Bridgman growth process. The X-cut sample annealed in air at 950 °C for 5 h exhibited considerable photochromic effect in a wide wavelength range from 360 to 680 nm after the UV illumination. Two-color nonvolatile holographic recording at 632.8 nm was realized in an X-cut as-grown Ru:LiNbO 3 crystal with the UV light of 300–400 nm for gating . A high diffraction efficiency of η =41.5% and nonvolatile readout with a fixing ratio of 57.8% were achieved. The crystal had a recording sensitivity of S =0.03 cm/J and a dynamic range of M /#=5.9/cm. The crystal also exhibited a fast erasability and free light-induced scattering at the recording power density of I 0 =0.23 W/cm 2 , which are favorable for holographic storage.