Diode pumped Nd: YVO_4 laser at 671 nm with a type-Ⅱ noncritical phase-matched LBO

A diode pumped intracavity frequency-doubled Nd: YVO4 laser emitting at 671 nm with a type- n noncritical phase-matched LBO crystal is reported. A maximum output power at 671 nm of 404 mW was obtained under an incident pump power of 5.16 W, with an optical-to-optical conversion efficiency up to 7.8%. The output power fluctuates less than 5% while the temperature change of the LBO crystal is maintained at ±0.5℃ at the phase-matched temperature.     

LD端面泵浦Nd∶YAG/LBO蓝光激光器热效应分析

采用平凹腔,实现LD端面泵浦Nd∶YAG/LBO全固态蓝光激光器.在泵光功率为7.33W时,得到最大蓝光输出87.6mW,倍频光转换效率为1.2%,斜效率为2.6%.通过求解Possion热传导方程,得出了Nd∶YAG内部温度场分布.     

1319nm与660nm双波长Nd:YAG激光器的研究

为研究获得高功率红光的有效方法,研制了一种准连续输出1319nm与660nm双波长Nd:YAG激光器.文中分析了波长1319nm激光的辐射跃迁能级,论述了抑制1064nm激光的生成从而提高1319nm激光输出等关键技术,研究了光学镜片的镀膜参数与腔型结构,实现1319nm激光连续输出最高功率43W,以1319nm激光为基频,置入KTP晶体内腔倍频,并设置声光Q开关,获得660nm红光准连续输出2W,实现1319nm与660nm双波长输出.     

Yb3+-doped large-mode-area photonic crystal fiber laser with 210 W continuous-wave output power

An Yb^3＋-doped double-clad large-mode-area photonic crystal fiber （LMA PCF） laser with up to 210 W of continuous-wave output power centered at 1.05 lira is demonstrated. The length of the fiber used is 2 m and the produced laser power per meter can attain 105 W. The PCF is pumped by two diode lasers with central wavelength of 976 nm. The slope efficiency is 76%, and the beam quality factor M^2 at x and y axes are measured to be 1.06 and 1.08, respectively. No thermo-optical problems and other roll-over even are observed at the highest output power.     

基于Nd:YAG/V:YAG键合晶体的1338 nm微片激光器研究

基于Nd:YAG/V:YAG键合晶体,在连续和准连续LD端面泵浦条件下,研究了输出波长1 338 nm的被动调Q微片激光器的输出特性。在连续泵浦条件下,最大的输出功率为0.73 W,此时得到稳定的调Q脉冲输出,脉冲宽度为139 ns。在准连续泵浦下,获得了被动锁模调Q激光输出,输出的最大功率为1.01 W,对应的脉冲宽度为80 ns,其中的锁模系列单脉冲宽度约为70 ps。实验结果表明,Nd:YAG/V:YAG键合晶体有利于获得高功率紧凑的1 338 nm脉冲激光输出,同时准连续泵浦能有效地降低激光晶体的热效应从而获得更高功率的激光输出。     

大功率LD脉冲泵浦Nd:YAG蓝光激光器研究

采用大功率LD脉冲运转泵浦Nd：YAG,以消除连续运转时产生的热效应的影响,采用LBO腔内倍频获得高效蓝光输出。实验比较了不同脉冲占空比及不同脉宽时激光的输出特性,对脉冲泵浦减小热效应进行了研究。在未采取特殊致冷,泵光与腔模不匹配的情况下,在占空比为1：3,泵浦功率为7．2W时,获得239mW的473nm蓝光输出,光-光转换效率达到3.3％。     

Growth of AgGaS2 single crystal by descending crucible with rotation method and observation of properties

This note reports a new procedure of polycrystalline synthesis and a new technique of single crystal growth on AgGaS₂, i.e. two-zone temperature oscillation vapor transporting and descending crucible with rotation. A single phase dense AgGaS₂ polycrystalline ingot was synthesized, and a crack-free AgGaS₂ single crystal with 15 mm in diameter and 30 mm in length was grown by the techniques mentioned above. Structure integrity of the crystal was studied by the X-ray diffraction technique. Six order X-ray spectra from the 011 face of the crystal were obtained, and an anomalous phenomenon was observed for the first time that intensity of the higher order diffraction peak is much stronger than that of the lower order diffraction peak. Etch-pits of the crystal were observed by the scanning electron microscopy (SEM).     

二极管泵浦Nd:YVO4/KTP/BBO准连续紫外激光器

报道了一种声光调Q二极管泵浦Nd:YVO4晶体腔外四倍频266 nm紫外激光器。实验采用简单的直腔结构,分别利用KTP和BBO晶体产生532 nm倍频绿光、266 nm四倍频紫外激光,实现了从Nd:YVO4近红外激光到266 nm紫外激光的频率变换。在10.3 W泵浦功率下,获得平均输出功率59 mW、脉宽约8 ns,峰值功率370 W的266 nm紫外激光输出。     

Hydrothermal synthesis, characterization and nonlinear optical effect of orthorhombic phase Ca2B6O11 · H2O

Hydrothermal treatment of calcium oxide and boric acid mixtures at temperatures between 234 °C and 300 °C has produced a colorless, transparent, orthorhombic compound Ca₂B₆O₁₁ · H₂O. Of the seven known members of the series of hydrated dicalcium hexaborate containing boron-oxygen six-membered ring anionic group (B₃O₈)^-7, only the title compound has been found to have the nonlinear optical effect. The second harmanic generation (SHG) effect of its crystal is larger than that of KH₂PO₄ (KDP). The reflection spectrum has shown that this compound has no absorption in the experimental wavelength range (800–240 nm). Its crystal structure is favorable for generating the nonlinear optical effect.     

Harmonic mixing of Bi2Sr2CaCu2O8+x intrinsic junction at millimeter waveband

Using intrinsic Josephson junctions in Ba₂Sr₂CaCu₂O_8+x single crystal, harmonic frequency mixing at 8 and 3 mm wavebands was successfully demonstrated at liquid nitrogen temperatures with harmonic numbers up to 68 and 50 respectively. The dependences of intermediate frequency output on the local oscillator power and dc bias were carefully studied.     

Two-dimensional crystallization and preliminary electron crystallographic result of partially purified F<Subscript>0</Subscript> from porcine mitochondria

After removal of cytoplasmic sector F₁ from submitochondrial particles of F₀F₁-ATP synthase complex with guanidine hydrochloride, the transmembrane sector F₀ was specifically extracted from the stripped membranes in the presence of detergent CHAPS and partially purified. Two-dimensional crystals were produced by the reconstitution of the partially purified F₀ into asolectin and microdialysis. The obtained crystals are able to diffract to 2 nm. The projection map of the negatively stained crystal shows that the crystal has p42₁2 symmetry, lattice constant, a=b=14.4 nm. A unit cell contains four F₀ molecules.     

Photocatalytic property of TiO2 sensitized by different crystal phase CdS

TiO2 samples sensitized by different crystal phase CdS(CT) are synthesized by hydrothermal process at different reaction temperature. The samples are characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), and UV-Vis diffuse reflectance(UV-Vis). The XRD result reveals that the crystal phase of CdS is transformed from cubic phase to hexagonal phase with the increase of hydrothermal reaction temperature(120-160 ℃). The absorption edge of CT is extended from 498 nm to 546 nm. The photocatalytic degradation of rhodamin B(RhB) in aqueous solution is used to evaluate the photocatalytic activity of CT. With the increase of the preparation temperature, the photocatalytic activity of CT becomes stronger. The degradation rate of RhB by CdS/TiO2 at 160 ℃(CT-160 ℃)reaches 78%.     

Non-catalytic nucleation coating for undercooled Cu50Ni50 melt

A non-catalytic nucleation coating (B-F3) was prepared by the high temperature curing process of the sol-gel glass film based on the viscous flow mechanism of the coating. X-ray diffraction technology was adopted to study the crystallization behavior of the coating as a function of treating temperature. It was evident that no crystallization phenomenon happened on the coating which kept stable after the heat treatment of 60 min at 1773 K. The purified melt of Cu₅₀Ni₅₀ was selected to evaluate the effectiveness of undercooling heredity of the coating in the undercooling experiments. The maximum undercooling of the melt solidified in the coated mold could reach 236 K. Based on the solidified microstructural evolution at different undercoolings, a single crystal of the alloy Cu₅₀Ni₅₀ was achieved with no aid of the selection process of the crystal in the mold with the B-F3 coating by means of undercooling technology.     

［Ni(phen) 3］2［Ni(PO4)2(H2PO4)6(OH)6(MoO2)12］的合成和晶体结构

利用中温水热技术合成一种新型还原型钼磷酸盐： ［Ni(phen) ₃］₂［Ni(PO₄)₂(H₂PO₄)6(OH)₆(MoO₂)₁₂］(phen: 邻菲啰啉), 并通过单晶X射线衍射技术测定了该化合物的晶体结构.该化合物属于三斜晶系, P1空间群, 晶胞参数: a=1.404 2(3) nm, b=1.405 0(3) nm, c=1.408 2(3) nm, α=74.53(3)°, β=74.72(3)°,γ=74.81(3)°, V=2.527 6(9) nm3, Z=1, R1=0.076 2, wR2=0.168 6.     

β-Ｄ-吡喃葡萄糖叠氮化物的合成及晶体结构

合成了β-Ｄ-O四乙酰基糖基叠氮化合物， 并得到单晶， 经X射线衍射方法解析， 其晶系属于单斜晶系，P2₁空间群， 其中a=0.759　6(6) nm,b=1.518　4(13) nm，c=1.641　2(14) nm，V=1.893　0(3) nm³，α=90.00°，β=90.045(1)°，γ=90.00° ，Z=2. 在晶体结构中， 六元糖环采取经典⁴C₁椅式构象， 糖环上所有 的取代基均以平伏键存在， 其中叠氮基不是以直线型结构存在， 呈现一定的弯曲现象.     

Flux-Bridgman growth and characterization of Mn-doped ZnO single crystals

Mn-doped ZnO single crystals have been grown by the flux-Bridgman method from a high temperature solution of 24% ZnO-76%PbF_2(molar fraction).A fast nucleation was induced by the gas-cooling system at the bottom of the Pt crucible.A red Mn.ZnO crystal up to 13 mm×15 mm×(3-4) mm was obtained.Powder XRD patterns showed that the as-grown crystals were in wurtzite structure.Electron Probe Microanalyser(EPMA) revealed that some PbF_2 inclusions formed due to fast nucleation.The additional Raman mode at 524 cm ' ...     

α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的合成和晶体结构

 在酸性介质中,3,4-二乙酰基-2,5-己二酮与萘胺作用,合成得到了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘,用IR,1H-NMR,MS,HRMS对其进行了表征,并用X射线衍射测定了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的晶体结构.该晶体属三斜晶系,P1空间群,晶体学数据为:a是0.8045(1)nm,b是1.0018(1)nm,c是2.0757(2)nm,α是80.09(1)°,β是82.66(1)°,γ是83.81(1)°,V是1.6281(3)nm³,Z是4,M_r是305.36,D_c是1.246×10³kg/m³,μ(M_oK_α)是0.080mm^-1,F(000)是648,在I>2σ(I)的独立可观测衍射点为3669个,最终偏差因子R是0.0406,W_R是0.0962.     

High pulse energy femtosecond large-mode-area photonic crystal fiber laser

A high pulse energy femtosecond fiber laser based on a large-mode-area photonic crystal fiber is demonstrated. A segment of Yb-doped single-polarization large-mode-area photonic crystal fiber with extremely low nonlinearity is explored as gain media of this fiber laser, resulting in intrinsically envi- ronmentally stability. The fiber laser is based on a linear cavity with dispersion compensation free con- figuration, and the stable mode-locking is obtained by a semiconductor saturable absorber mirror （SESAM）. The fiber laser directly generates 2.5 W of average power at a repetition rate of 51.4 MHz, corresponding to a single pulse energy of 50 nJ. The output pulse duration is 4.2 ps, which is dechirped to 410 fs after extracavity dispersion compensation. The nonlinear absorption of SESAM determines the pulse shaping at low output power, while the mode-locking mechanism is under the balance between spectrum broadening from self-phase-modulation and gain filtering at the high output power.     

激光二极管端面泵浦Er,Yb:YAB微片激光器的热效应研究

文章利用激光二极管泵浦Er,Yb:YAB晶体,实验获得290 mW的连续单横模1.5μm激光输出,激光转换的斜效率为8.5％.在此基础上,利用刀片法实验测量了Er,Yb:YAB晶体的热焦距随泵浦功率的变化关系,泵浦功率5W时,晶体的热焦距仅为10 mm,实验结果与理论预测基本相吻合.     

Photoluminescence from Ge-SiO2 thin films and its mechanism

Ge-SiO₂ thin films were deposited on p-type Si substrates using the radio frequency (rf) magnetron sputtering technique with a Ge-SiO₂ composite target. Films were annealed in N₂ ambience for 30 min at 300℃—1000℃ with an interval of 100℃. Through the X-ray diffraction, the average size of Ge nanocrystals (nc-Ge) was determined. They increased from 3.9 to 6.1 nm with increasing annealing temperature in the range of 600℃—1000℃. Under ultraviolet excitation, all samples emit a strong violet band centered at 396 nm. With the formation of nc-Ge, the samples exhibit another emission of orange band with the peak at 580 nm and its intensity increases with the increasing size of nc-Ge. The peak positions of two bands do not shift obviously. Experimental data indicate that the violet band comes from GeO defect and the orange band originates mainly from the luminescence centers at the interface between the nc-Ge and SiO₂ matrix.