The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

Abstract

Bismuth-doped lithium niobate (LN:Bi) crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi) reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm2). An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

The simultaneous enhancement of photorefraction and optical damage resistance in MgO and Bi2O3 co-doped LiNbO3 crystals

“…The micro-mechanism of this phenomenon was considered as that Mg 2+ dopants push Nb Li 5+ ions and photorefractive impurities from Li-sites to Nb-sites, which will cause these ions lose their function as photorefractive centers, therefore the optical damage resistance of LN:Mg is greatly improved. It was reported that the damage threshold of CLN and LN:Bi 1.0 is lower than 40 W/cm 2 and that of LN:Mg 5.0 is around 5 × 10 5 W/cm 2 under the same experimental conditions of this work 17 18 . Figure 2 shows that the optical damage threshold of LN:Bi,Mg 5.0 and LN:Bi,Mg 6.0 both reach 5.8 × 10 6 W/cm 2 .…”

“…The absorption spectrum of LN is sensitive to crystal composition and defects, and as we known that Bi dopants can introduced new absorption peaks into LN crystals 18 . The UV-visible transmission spectra of LN:Bi,Mg crystals are shown in Fig.…”

“…The electron lone-pair of Bi 3+ ion (6 s 2 ) always induces high polarizability in crystal lattice, which causes many interests in ferroelectrics, nonlinear optics and electro-optical properties. In a former work 18 , we reported the photorefractive characteristics of Bi doped LiNbO 3 crystals. It was shown that bismuth dopants may introduce new photorefractive centers to LN crystals.…”

Interaction between Mo and intrinsic or extrinsic defects of Mo doped LiNbO3 from first-principles calculations

“…[1][2][3] As we know, the photorefractive properties of LiNbO3 can be improved by doping with Fe 3+/2+ , Mn 3+∕2+ , Cu 2+∕+ , or Bi 3+∕2+ ions. [4][5][6][7][8][9] These materials are promising candidates for holographic storage applications. For example, bismuth (Bi) and magnesium (Mg) co-doped LiNbO3 (LN:Bi,Mg) crystals can be used in the dynamic holographic display.…”

“…For example, bismuth (Bi) and magnesium (Mg) co-doped LiNbO3 (LN:Bi,Mg) crystals can be used in the dynamic holographic display. 5,6 While, molybdenum-doped LiNbO3 (LN:Mo) is the only possible one for holographic storage from the ultraviolet to the visible with considerably shorter response time. 10,11 However, there are still not enough accurate and detailed knowledge about LN defects in experiments.…”