Xihe Zhen

Structure and Photo-Damage Resistance of Li-Rich LiNbO3 Crystals Co-Doped with Zn2+/Er3+

The pure congruent LiNbO 3 , Er:LiNbO 3 and Zn,Er co-doped Li-rich LiNbO 3 crystals were grown by Czochralski method. The X-ray diffraction method and ultraviolet-visible absorption spectra of the crystals were used to analyze the structure of the crystals. The photo-damage ability resistance of the crystals was measured. The Zn,Er co-doped Li-rich LiNbO 3 crystals show a decrease in lattice constant values, a shift in absorption edge of ultraviolet-visible absorption spectra towards shorter wavelength, and three orders of magnitude increase in photo-damage resistance compared to congruent LiNbO 3 crystal. The intrinsic and extrinsic defects are discussed to explain the enhance of the photo-damage ability resistance.

Second Harmonic Generation in Zn-doped Li-rich LiNbO3 Crystals

6.0 mol. % ZnO doped LiNbO 3 crystals were grown by Czochralski technique. Various Li/Nb mole ratios of 0.942, 0.970, 1.000, and 1.020 were used to prepare the starting materials. Second harmonic generation (SHG) experimental results show that the phase matching temperature increases near linearly with the increasing of Li/Nb ratio, and the SHG efficiency is enhanced by the Zn doping and the increasing of Li/Nb ratio. The intrinsic and extrinsic defects are discussed in this paper to explain the SHG behavior and photo-damage resistance in the Zn doped Li-rich LiNbO 3 crystals.

Defect structure and optical damage resistance of Mg : Mn : Fe : LiNbO3 crystals

Mg?:?Mn?:?Fe?:?LiNbO3 crystals were prepared with fixed concentrations of Fe2O3 and MnCO3, and differing concentrations of MgO. Their ultraviolet?visible absorption spectra were measured in order to investigate their defect structures and their optical damage resistance was characterized by the transmitted beam pattern distortion method. The optical damage resistance of Mg?:?Mn?:?Fe?:?LiNbO3 crystals increases remarkably when the concentration of MgO exceeds a threshold concentration. The photoinduced birefringence change was measured by the S?narmont method. It decreased with increasing MgO concentration. The dependence of the optical damage resistance on the defect structure of Mg?:?Mn?:?Fe?:?LiNbO3 crystals is discussed.

Structure and optical damage resistance of Zn:Er:LiNbO3 waveguides

Abstract A series of Zn:Er:LiNbO 3 crystals were grown by Czochralski technique with 0.75 mol% of Er 2 O 3 and with 0, 3.0, 5.5, and 7.0 mol% of ZnO, respectively, and were made into waveguides. The optical damage resistance of the Zn:Er:LiNbO 3 waveguides was characterized by measurement of the holographic method. The optical damage resistance of Zn (7.0 mol%):Er:LiNbO 3 is much higher than that of other Zn:Er:LiNbO 3 . The ultraviolet–visible (UV) absorption spectra and the infrared (IR) transmission spectra of Zn:Er:LiNbO 3 crystals were measured and investigated. The structure defects were discussed in this paper to explain the improve of the optical damage resistance in the Zn:Er:LiNbO 3 crystals.

Effects of annealing processing on morphological, compositional and Schottky characterization of PtSi/Si diodes

The surface structure of PtSi/Si thin films by pulsed laser deposition (PLD) was studied using atomic force microscopy (AFM). The compositional structure of the PtSi as determined from X-ray photoelectron spectroscopy (XPS) is discussed. A possible growth model is presented on studying the variation of morphological features (i.e., roughness and size of crystallites) with annealing temperature and film thickness. By the AFM studies and Schottky characterization measurements of PtSi formation during various annealing processing, suitable preparation conditions are proposed to form the continuous and smooth PtSi thin film on Si substrate with the favorable Schottky property by PLD.

Study on photodamage of Mg:Ga:LiNbO3 crystal wave-guide substrate

Abstract MgO and Ga 2 O 3 were doped in LiNbO 3 (LN) to grow Mg:Ga:LN crystals. The OH − absorption spectra and photoredamage resistance threshold of Mg:Ga:LN were measured. The mechanism of the shift of OH − absorption peak was investigated. LN crystal was manufactured into proton transfer wave-guide substrate. By using the holograph method, the photodamage resistance ability of wave-guide substrate was measured. It was found that the photodamage resistance ability of Mg:Ga:LN wave-guide substrate was much higher than that of LN wave-guide substrate.

Study on holographic associate storage with self-pumping phase conjugate mirror

CuO and Co2O3 were doped in KNSBN and Czochralski method was used to grow Cu:Co:KNSBN crystal for the first time. ZnO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow Zn:Fe:LiNbO3 crystals. The diffraction efficiency and response time of the Zn:Fe:LiNbO3 crystals were measured. The response speed of the Zn:Fe:LiNbO3 crystal is four times higher than that of the Fe:LiNbO3 crystal. The self-pumping phase conjugate reflectivity and respond time of the Cu:Co:KNSBN crystal were measured. The result shows that the self-pumping phase conjugate reflectivity of the Cu:Co:KNSBN crystal is two time higher than that of KNSBN crystal. Zn:Fe:LiNbO3 and Cu:Co:KNSBN were used as storage element and self-pumping phase conjugate mirror, respectively, to make the holographic associative storage experiment. The excellent results were gained.

Study on growth and optical property of Nd:Zn:LiNbO3 crystal

Abstract Nd203(0.2 wt%) and ZnO(7.0 mol%) were doped in LiNbO3 crystal and Czochralski method was used to grow Nd:Zn:LiNbO3 crystals with optimized technological conditions. The stripe of growth and off-dissolution phenomena were eliminated. The ultraviolet-visible absorption spectra, infrared absorption spectra and photorefractive resistance threshold value were measured. The mechanism of optical property enhancement was studied. The second harmonic generation and self-second harmonic generation were experimentally investigated

Growth and structure determination of Tb:Fe:LiNbO3 with varying concentrations of K20 added to the melt

The Tb:Fe:LiNbO3 and LiNbO3 crystals with vary Li/Nb ratio in the melt were grown by the top-seed solution growth (TSSG) method and Czochralski technique, respectively. Their Li/Nb ratios were calculated by the lattice parameters. The defect structure of the Tb:Fe:LiNbO3 and LiNbO3 with vary Li/Nb ratio in the melt crystals was studied by X-ray analyses and UV spectra. The results show that an increase of Li/Nb ratio in the melts leads to a decrease of the lattice constants, which is accompanied by an improvement of the LiNbO3 lattice structure because of diminishing concentration of intrinsic nonstoichiometric defects.

Growth and holographic storage properties of stoichiometric Ce:LiNbO3 crystals

Nondoped and Ce2O3 doped near stoichiometric LiNbO3 (Ce:LiNbO3) single crystals were grown by the top-seeded solution method. The solution with [Li]/[Nb] ratio of 1 contained K2O component of 10.6 mol%(7.0 wt%). The ultraviolet-visible absoprtion spectra of the crystals were measured in order to analyze their structure. The photorefractive properties of stoichiometric LiNbO3 crystals were investigated and compared with congruent LiNbO3 crystal. Two-wave-coupling experiments shown that doped stoichiometric LiNbO3 crystals exhibited much larger photorefractive gain and faster response speed than congruent ones.