Researches on the Growth Habit and Optical Properties of Fe^(3+) Ion Doped KDP Crystal

During the process of KDP crystal growth, metal ions strongly affect the growth habit and optical properties of KDP single crystal. In this paper, KDP crystals were grown from an aqueous solution doped with different concentration of Fe^3＋ dopant by traditional temperaturereduction method and ＂point-seed＂ rapid growth method. Furthermore, we examined the light scatter and measured the transmission of these KDP crystals. It is found that the dopant of Fe^3＋ ion can improve the stability of the KDP growth solution when its concentration is less than 30 ppm. The effects of Fe^3＋ ion on the growth habit and optical properties of KDP crystal are also obvious.

Thermal and Mechanical Properties of a Complex Nonlinear Optical Material:Cadmium Mercury Thiocyanate Crystal

Institute of Crystal Materials and State Key Laboratory of Crystal Materials,Shandong University,Ji'nan 250100(Received 18 March 2000)The data of the thermal expansion and specific heat of cadmium mercury thiocyanate crystal have been obtained.The specific heat is 0.7588J/g℃at room temperature.The thermal expansion occurs in the direction parallel to the c-axis,and the thermal contraction occurs in the direction parallel to the a-axis.The thermal expansion is the same as the thermal contraction at 353 K.The relationship between thermal properties and crystal structure is discussed.

Nonlinear Optical Properties of Perfectly Polarized KIO_(3) Single Crystal

The nonlinear optical properties of a perfectly polarized KIO^single crystal were investigated.The principal refractive indices and nonlinear optical coefficients have been measured.The results are as follows:n1=1.6967,n2=1-8329,n3=1.8358 for 0.5893μm;d_(31)=1.2|d_(31)(LiIO_(3))|,d_(32)=1.8|d_(31)(LiIO_(3))|.The in tensity of the frequency-doubled light of the KIO_(3 )single crystal with 2.96 mm thickness is 1.2 times as large as that of the KTP single crystal with the same thickness.

Rapid epitaxy of 2-inch and high-quality α-Ga_(2)O_(3) films by mist-CVD method

High thickness uniformity and large-scale films of α-Ga_(2)O_(3) are crucial factors for the development of power devices.In this work, a high-quality 2-inch α-Ga_(2)O_(3) epitaxial film on c-plane sapphire substrates was prepared by the mist-CVD method.The growth rate and phase control mechanisms were systematically investigated. The growth rate of the α-Ga_(2)O_(3) films was limited by the evaporation of the microdroplets containing gallium acetylacetonate. By adjusting the substrate position(z) from 80 to 50 mm, the growth rate was increased from 307 nm/h to 1.45 μm/h when the growth temperature was fixed at 520 °C.When the growth temperature exceeded 560 °C, ε-Ga_(2)O_(3) was observed to form at the edges of 2-inch sapphire substrate.Phase control was achieved by adjusting the growth temperature. When the growth temperature was 540 °C and the substrate position was 50 mm, the full-width at half maximum(FWHM) of the rocking curves for the(0006) and(10-14) planes were 0.023° and 1.17°. The screw and edge dislocations were 2.3 × 10~6 and 3.9 × 10~(10)cm~(-2), respectively. Furthermore, the bandgaps and optical transmittance of α-Ga_(2)O_(3) films grown under different conditions were characterized utilizing UV-visible and near-IR scanning spectra.

First-principles study of structure and nonlinear optical properties of CdHg(SCN)_4 crystal

The geometric structure,electronic structure,and optical properties of CdHg（SCN）4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approximation.The band gap of CdHg（SCN）4 crystal is calculated to be 3.198 eV,which is in good agreement with the experimental value 3.265 eV.The calculated second-order nonlinear optical coefficients are d14 = 1.2906 pm/V and d15 = 5.0928 pm/V,which are in agreement with the experimental results（d14=（1.4 ±0.6） pm/V and d15=（6.0 ±0.9） pm/V）.Moreover,it is found that the contribution to the valence band mainly comes from Cd-4d,Hg-5d states,and the contributions to the valence band top and the conduction band bottom predominantly come from C-2p,N-2p,and S-3p states.The second-order nonlinear optical effect of CdHg（SCN）_4 crystal results mainly from the internal electronic transition of（SCN）^-.

Fabrication of Two-Dimensional Photonic Crystals with Controlled Defects by Combination of Holographic Lithography and Two-Photon Polymerization

一个新第三的相片聚合物系统在由单个光子、二光子的相片聚合的联合与控制缺点制作 photonic 晶体(PhCs ) 被使用。以前的过程能在一步舞记录与生产 PhCs 一低力量(十 mW ) 在 532 nm 的连续波浪的激光，当后者能创造需要的缺点时。材料，光安装和初步的试验性的结果的准备被给。与另外的方法相比，这条途径为可见的光的使用更可存取、方便并且有快速并且经济地在大规模做 PhCs 并且确切介绍任何缺点的优点，特别为三维的结构。

Growth,Defects and Non-critical Phase Matching of Nb Doped KTP Crystals

A series of Nb doped KTP crystals are grown with seed Aux method and Hux pulling method.The results of our investigation on growth,morphology defects of the crystals are reported in this paper.We obtained the relationship between Nb contents and second-harmonic generation angles of the crystals.Noncritical phase matching has been realized by 4%Nb doped KTP crystal for Nd:YAG laser 1.06μm output.

Effects of Lu^(3+ )Doping on Optical Properties and Laser Performances of NYAB Crystal

Volume compensation(VC)achieved in(Lu,Nd):YAl_(3)(BO_(3))_(4)(YAB)crystal codoped with Lu^(3+)and Nd^(3+)ions is described.The lattice parameters,spectral properties and laser performances of the VC(Lu,Nd):YAB and single-doped Nd:YAB(NYAB)crystals are measured and compared.The results indicate that the laser performances of NYAB crystal can be greatly improved by the VC doping.

Effect of Solvents on the Absorption Properties of GaP Nanocrystals

GaP nanocrystals were synthesized by both the organic solvent reflux and high temperature high pressure benzene thermal synthesis methods.The effect of organic solvent on the optical absorption properties of GaP nanocrystals were studied.The results show that crystal grains of the sample synthesized by the latter method have better quality and uniformity.The solvents which consist of polar molecules and form strong chemical bonds with Ga atoms cause obvious redshift of the absorption spectra of GaP nanocrystals.The absorption spectra redshift much more if the solvent molecules have π electrons which involved in the formation of complex bond between Ga atoms and solvent molecules.

CRYSTAL GROWTH AND FUNDAMENTAL PROPERTIES OF Cd_(x)(Sr_(0.61)Ba_(0.39))_(1-x)Nb_(2)O_(6)

Cd_(x)(Sr_(0.61)Ba_(0.39))_(1-x)Nb_(2)O_(6)(CdSBN)crystals have been grown successfully by Czochralski technique.The difficulty in crystal growth increased with the increase of the crystal diameter.Macroscopic defects,such as striations and crackings were observed in some crystals.Temperature dependence of dielectric constant ε′γ3 and pyroelectric coefficient P were studied.The relationship between grown behavior and melt compositions was also discussed.

LOW TEMPERATURE PROPERTIES OF Tb-DOPED Sr_(1-x)Ba_(x)Nb_(2)O_(6)(SBN)CRYSTALS

Tb-doped SBN crystals were prepared by the Czochralski technique.Their dielectric,ferroelectric,and pyroelectric properties were studied.A low temperature phase transition between two polar phases was revealed by the anomalies of the dielectric and pyroelectric properties;the polar axis changes its direction during this transition.The point group of the low temperature phase may be mm2,m or 1.

Growth and Properties of Tungsten Bronze-Type Second Harmonic Generation Crystal LiBa_(2)Nb_(5)O_(15)

Striation-free LiBa_(2)Nb_(5)O_(15)(LBN)single crystal of good optical quality has been grown by Czochralski method.The crystal growth and dielectric,structural,spectral properties of LBN were measured.Experimental results show that LBN single crystal belongs to tetragonal tungsten bronze structure at room temperature.Experiments carried out with LBN powder samples have shown that this crystal has good second harmonic generation effect.At room temperature,the dielectric constant ε_(33) is about 87 and Curie temperature T_(c),is about 586℃.A very ideal uniaxial conoscope image can be observed in LBN single crystal under polarizing microscope.In the range of 600 to 2600nm,the transmission of single crystal is about 75%.

Growth and High Reflectivity Self-Pumped Phase Conjugate of Cu-Doped KNSBN Crystal

The Cu-doped'KNSBN crystals have been grown.The self-pumped phase conjugate mirrors of Cu-doped KNSBN crystals have been demonstrated.The phase conjugate reflectivity reaches as high as 68% for the crystal with 0.04 wt.%Cu-doped.The phase conjugate reflectivity and its response time were also measured as a function of the argon-ion laser wavelengths.

Observation of Self-pumped Phase Conjugation for Two Mutually Coherent Input Beams in a KNSBN Crystal

Two coherent or incoherent stable self-pumped phase conjugations have been obtained simultaneously in a Ce-doped(K_(0.5)Na_(0.5))_(2y)(Sr_(0.61)Ba_(0.39))_(1-y) Nb_(2)O_(6)(KNSBN)crystal by using two mutually coherent input beams from a He-Ne laser,and energy translation from one beam to another induces self-pumped phase conjugative reflectivity of one beam above 100%.

Sduties on Modification of Pb_(1-x)BaxNb_(2)O_(6) Crystals

This paper reports the growth of pqre and Na,K modified lead barium niobate crystals and the measurement of their dielectric and structure properties.Exprimental results show that both pure and Na,K modified lead barium niobate crystals have growth striations.All the crystals belong to 4mm point group of tetragonal system at room temperature.Their Curie temperature are 379℃,389℃ and 473℃,respectively.

Formation of the Bicrystal Structure of KTiOPO_(4) Crystals

In this paper,by comparing the three possible combinations of the basic structure unit TiO_(6) octahedra,a simple model is proposed to explain the cause of the formation of the bicrystal structure in KTiOPO_(4)(KTP)crystals.The theoretical morphology of KTP crystal is studied and the rate of the appearance possibilities of different faces are obtained.The relationships between bicrystal structure and crystal properties are discussed.

EXCITED EMISSION AND SELF-FREQUENCY-DOUBLING EFFECT OF Nd_(x)Y_(1-x)Al_(3)(BO_(3))_(4) CRYSTAL

Using dye laser as pumping light source,we have first realized on NYAB crystal the laser self-frequency doubling run from 1.06μm to 0.53μm.The threshold energy is less than 4mJ;conversion efficiency is 6.2%,and the self-frequency-doubling green light output energy is 2.5mJ.

Flux Growth and Properties of KNPBN Crystal

Potasium sodium lead barium niobate KNPBN crystals have been grown successfully by flux method.The dielectric constant along the polar axis was measured at 50 kHz as a function of temperature in the range of 0 to 400℃.The flux system,diffuse phase transition and optical absorption were also discussed.

Field and Temperature Dependence of Susceptibility of Single Crystal Bi_(2)Sr_(2)CaCu_(2)O_(8)

Susceptibility measurements on Bi_(2)Sr_(2)CaCu_(2)O_(8) single crystals do reveal field-induced-suppression of sharp phase transition.No apparent anisotropy of the susceptibility was observed when magnetic field was applied along the three main directions a,b and c.The three dimensional isotropic fluctuation diamagnetism theory is proposed to explain our experimental finding of isotropic susceptibility.In a wide range of magnetic field,the temperature dependence of susceptibility does not show any obvious change in its character when the sample enters into expected vortex-lattice state from vortex-liquid state.

Low Temperature Phase Transition of a Crystal in the Potassium Lithium Niobate System

A potassium lithium niobate crystal with tetragonal tungsten bronze structure was prepared by the Czochralski technique.The dielectric and pyroelectric properties were investigated in the temperature range of 300 to 10 K.A broadened ferroelectric-ferroelectric transition between phases with space group 4mm and space group m was found at about 80K.