Zhehua Yan

OH− absorption and holographic storage properties of Sc(0, 1, 2, 3):Ru:Fe:LiNbO3 crystals

A series of Sc:Ru:Fe:LiNbO3 crystals with various levels of Sc2O3(0, 1, 2, and 3 mol%) doping were grown from congruent melts in air by using the Czochralski technique. The defect structures and photorefractive properties of the Sc:Ru:Fe:LiNbO3 crystals were investigated by acquiring infrared spectra of the crystals and performing two-wavelength nonvolatile experiments, respectively. Our results showed the holographic storage properties of Ru:Fe:LiNbO3 crystals to be enhanced by doping them with a high concentration of Sc2O3, and indicated Sc:Ru:Fe:LiNbO3 crystals to constitute a promising medium for holographic storage.

Effect of dopant concentration on the spectroscopic properties in an In3+ doped (0, 1, 2 and 4 mol%) Yb:Tm:LiNbO3 crystal

A series of Yb:Tm:LiNbO3 crystals with x mol% In3+ ions (x = 0, 1, 2 and 4 mol%) were grown by a conventional Czochralski technique for the first time. The In, Yb and Tm contents in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES). The results revealed that the segregation coefficients of Yb3+ and Tm3+ ions decreased with increase of the In3+ doping concentration. Also the segregation coefficient of In3+ ions increases with the increasing In3+ doping concentration in the melts, and it is close to one. The IR transmission spectra and UV-vis spectra were measured to analyze the defect structure of the crystals.

Effect of dopant concentration on the spectra characteristic in Zr4+ doped Yb:Nd:LiNbO3 crystals

Abstract A series of Yb:Nd:LiNbO 3 crystals tridoped with various concentrations of Zr 4+ (1 mol.%, 2 mol.% and 4 mol.%) were grown by the Czochralski technique from the congruent melt. The X-ray powder diffraction, UV-Vis-NIR absorption spectra and IR transmittance spectra were measured to analyze the crystal composition and defect structure. The Zr 4+ , Yb 3+ and Nd 3+ ions in LiNbO 3 crystal had two effects: volume compensation effect and ion valence state compensation effect. The ZrO 2 doping threshold concentration was nearly 2.0 mol.%. The fluorescence emissions of Nd 3+ ions and Yb 3+ ions were observed under 808 nm excitation. The intensity of fluorescence emissions enhanced with the increasing of the Zr 4+ doping concentrations. The Zr:Yb:Nd:LiNbO 3 crystals with 4 mol.% doping concentration of Zr 4+ ion revealed strong emission around 1 μm, which is of great significance for laser materials.

Influence of magnesium concentration on the optical properties of ytterbium and holmium co-doped lithium niobate crystal

In this paper, a series of Yb (0.5mol.%):Ho (0.5mol.%):LiNbO3 crystals doped with various concentration of Mg2+ (1, 3, 5 and 7mol.%) were grown by the Czochralski technique. The ability of optical damage resistance of Mg:Yb:Ho:LiNbO3 crystals increases with increasing the Mg2+ doping concentration. The optical homogeneity of Mg:Yb:Ho:LiNbO3 crystals doped with different concentration of Mg2+ was detected using the birefringence gradient method. The results demonstrated that the optical homogeneity is getting better with the increase of the Mg2+ doping concentration. The studies on the infrared transmission spectra indicated that Mg2+ ions first replaces anti-site NbLi4+ in the form of MgLi+ defect, once the concentration of Mg2+ reaches or exceeds the threshold concentration, it begins to substitute Li-site and Nb-site of normal lattice and form defect of MgNb3−−3MgLi+. Therefore, the change of Mg2+ doping concentration is the fundamental reason leading to a violet shift of the OH− absorption peak.

Dopant occupancy and UV-VIS-NIR spectroscopy of Mg (0, 4, 5 and 6 mol.%):Dy:LiNbO3 crystal

A series of Dy:LiNbO3 crystals with x mol.% Mg2+ ions (x =0, 4, 5 and 6 mol.%) were grown by the Czochralski method. The effective segregation coefficient of Mg2+ and Dy3+ ions was studied by the inductively coupled plasma-atomic emission spectrometry (ICP-AES). UV-VIS-NIR absorption spectra and Judd–Ofelt theory were used to investigate their spectroscopic properties. J–O intensity parameters (Ω2 = 7.53 × 10−20cm2, Ω4 = 6.98 × 10−20cm2, and Ω6 = 3.09 × 10−20cm2) and larger spectroscopic quality factor (X = 2.26) for Mg:(6 mol.%)Dy:LiNbO3 crystals were obtained.