福建物构所等深紫外非线性光学晶体研究取得新进展

<正>非线性光学(NLO)晶体可以有效扩展现有商用激光的波长范围,因而在现代激光科学与技术领域起着重要作用,其中的深紫外非线性光学晶体由于其在深紫外波段的重要应用是目前急需发展的一类非线性光学晶体材料。中国科学院福建物质结构研究所中科院光电材料化学与物理重点实验室罗军华课题组在国家自然科学优秀青年基金和副研究员赵三根主持的海西研究院"春苗"人才专项等项目资助下,对已知的磷酸盐深紫外     

氟化钙晶体的生长和应用研究

CaF2晶体作为一种传统晶体材料,应用十分广泛。文中综合介绍了CaF2晶体在深紫外光刻机的光学元件、激光晶体和被动Q开关三个领域的应用现状及趋势,归总了CaF2晶体具有的优异性能,阐述了CaF2晶体与深紫外准分子激光之间的作用,晶体结构对激光性能的影响,晶体生长和加工等诸多方面的研究进展。     

硼酸盐化合物的研究进展

硼酸盐化合物因其结构类型的可设计性强,物理化学性能稳定,因而具有很强的工业化应用价值,硼酸盐晶体化合物作为非线性光学晶体材料的应用是目前的研究热点。对硼酸盐化合物的研究进展进行了介绍,总结了硼硅酸盐和硼硫酸盐结构与性能之间的关系。     

中远红外及太赫兹波段非线性晶体硒化镓

中远红外及太赫兹波段激光在国防和民用领域都有非常突出和迫切的需求,硒化镓(GaSe)晶体是一综合性能优异的红外非线性光学材料,通过差频产生和光学参量振荡可实现这两个波段的可调谐激光输出。综述了GaSe晶体及掺杂晶体在合成、生长、掺杂性能及差频产生中远红外及太赫兹辐射方面的最新研究成果,重点介绍了GaSe晶体及掺杂晶体的光学、力学性能,非线性性能及它们在频率转换方面的应用性能。通过全面的分析找出综合性能最优的掺杂晶体种类。     

KDP和ADP晶体的生长以及紫外透过性能研究

作为非线性光学晶体材料,由于晶胞参数的不同,KDP、ADP在生长方面以及性质上都存在着差异。本文采用"点籽晶"快速生长法对KDP和ADP晶体的生长进行了研究。同时测量了快速生长法生长的KDP和ADP晶体在紫外波段的透射光谱性能,实验证明ADP晶体的紫外透过率要优于KDP晶体。     

四氮唑-L-樟脑磺酸盐的合成

有机非线性晶体材料由于其非线性活性大、组装形式多样等特点,在非线性光学领域有着巨大的应用价值,目前正引起普遍重视和研究。设计合成了两种新结构四氮唑-L-樟脑磺酸盐,2-对碘苯基-3-对硝基苯基-5-苯基四氮唑-L-樟脑磺酸盐和3-（4,5-二甲基-2-噻唑）-2,5-二苯基四氮唑-L-樟脑磺酸盐,其结构经IR、^1H～NMR确证。该类化合物有可能成为新的有机二阶非线性晶体材料。     

硫脲掺杂马尿酸晶体的结构及性质研究

以丙酮/水(体积比为30∶20)为溶剂,采用溶剂挥发法合成了马尿酸单晶以及硫脲掺杂的马尿酸单晶,对未掺杂和硫脲掺杂的马尿酸单晶进行了晶相、光学透过性以及热性质研究。通过元素分析(EA)和粉末X射线衍射(XRD)证实硫脲已掺入到马尿酸晶格中;根据热重分析(TGA)、紫外反射光谱(UV-Vis)和吸湿性实验发现,掺杂后晶体的热降解点变低、熔程变宽、透光性加强、吸湿量减小。实验证明,2种晶体都是综合性能优异的有机非线性光学材料。     

稀土掺杂纳米氧化锌的制备及光学性能研究

低温水热法合成了直径分别为11~48和9~15 nm的棒状氧化锌和稀土La~(3+)掺杂氧化锌微粒。通过X-射线粉末衍射(XRD)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-vis DRS)和荧光光谱(PL)等对氧化锌结构进行了表征以及光学性能测试。结果表明,本研究制备的纳米Zn O是结晶良好的棒状晶体,La~(3+)的掺入使氧化锌晶体发生了晶胞膨胀,紫外吸收增强,带隙向紫外区偏移,随La~(3+)掺杂浓度的增大,荧光强度增加。     

光折变材料BaTiO3单晶生长及品质鉴定

四方相BaTiO_3单晶是一种新型非线性光学晶体,由于其强的非线性而在光学应用方面具有许多潜在的用途。 本文报道了以两种合成的BaTiO_3为原料,采用顶部籽晶熔盐生长技术进行块状BaTiO_3单晶生长研究。对生长出的晶体进行了结构和成份分析以及结晶学表征,并测量了Curie温度和透光率,从而获得了生长BaTiO_3单晶的较佳工艺条件     

D-π-A 星型分子的合成及非线性光学性质

以苯基为中心, 通过 Suzuki 偶联反应引入两个电子给体(D)单元三苯胺和电子受体(A)单元菲并咪唑, 合成了新的 D-π-A 星型分子(Y), 其结构通过NMR、ESI-MS 及元素分析进行了表征;通过紫外可见吸收光谱、荧光光谱、荧光量子产率、理论计算以及 Z 扫描测试技术对该分子的三阶非线性光学性质进行了研究。结果表明, 分子Y的荧光量子产率 (ϕ) 可达 0.77, 双光子吸收截面 (σ₂) 为120GM, 三阶非线性折射率(n₂)为9.0×10^-7cm²/GW, 可见该化合物具有较好的非线性光学性质, 为非线性光学材料的分子设计提供了一定的思路。     

Conformational polymorphism on styrl quinolinium salts of 2-[(E)-2-(4-hydroxy-3-methoxystyrl)-1-methyl]-quinolinium 4-chlorobenzenesulfonate (HMQ-CBS): Potential nonlinear optical crystals for terahertz application

Polymorphism is an important phenomenon to investigate the relationship between the chemical structures and properties of functional materials. Here, we demonstrate the existence of conformational polymorphism in the terahertz (THz) compounds of 2-[(E)-2-(4-hydroxy-3-methoxystyrl)-1-methyl]-quinolinium 4-chlorobenzenesulfonate (abbreviated as HMQ-CBS). There are two different crystalline phases (I and II, respectively). X-ray structural analyses reveal that HMQ-CBS crystallizes in the monoclinic crystallographic system with the non-centrosymmetric space group P_c for phase-I, and centrosymmetric space group of P2₁/n for phase-II. These two different crystalline phases exhibit the distinct anionic orientations and crystal packings, leading to significantly different nonlinear optical (NLO) properties. Second harmonic generation (SHG) measurements reveal that crystals in phase-I possess the SHG efficiency of about 0.5 times that of N, N-dimethylamino-N-methylstilbazolium p-toluenesulphonate (DAST), which indicates that HMQ-CBS in phase-I might be a potential NLO crystal for THz application. In contrast, crystals in the phase-II show no SHG responses. Comparison of their crystal structures and NLO properties enables us to understand the correlation between molecular conformational changes and bulk NLO properties, and sheds light on the design of organic THz materials.     

Physicochemical Analysis of Tetrakis (Thiourea) Palladium Chloride: A Prospective Non Linear Optical Crystal

The solubility test and nucleation kinetics studies of Tetrakis (thiourea) palladium chloride (TTPC) have been carried out and optical quality crystals of TTPC have been harvested by means of slow evaporation method. The single crystal X-ray diffraction studies revealed the orthorhombic structure and Pna2₁ space group of the crystals. To ascertain the stoichiometry and the purity of the crystals, elemental analysis has been performed. The etching studies of the crystal suggested the dimensional nucleation mechanism. Fourier Transform Infrared spectral studies have been employed in order to establish the metal—sulphur coordination prevailing in the crystal. The Ultra Violet transmittance study has been conducted to calculate the transmittance, band gap energy, Urbach’s energy, nature of electronic transitions, reflectance, refractive index, optical and electrical conductivities, extinction coefficient and electrical susceptibility. The mechanical stability of the TTPC crystals has been examined by Vicker’s hardness test in terms of hardness number, elastic stiffness constant, Meyer’s Index, minimum level of indentation load, load dependent constant, brittleness index and corrected hardness. Kurtz method has been adopted which showed the phase matching nature of TTPC and concluded that TTPC showed 1.15 times second harmonic generation efficiency as that of KDP. By using the dielectric and ac conductivity study, the activation energy values of the electrical process have been measured. Using theoretical approach, important solid state parameters such as valence electron plasma energy, Penn gap, Fermi energy and polarisability have been derived. The photoconductivity studies revealed the negative conductivity of the title crystal.     

镁铟共掺杂铌酸锂晶体的生长及光学性能

在同成分铌酸锂(LiNbO3,LN)体中掺入3%(摩尔分数,下同)MgO,并分别掺入0.5%,1%,1.5%In2O3,用提拉法生长了一系列Mg:In:LN晶体.通过紫外坷见吸收光谱测试确定了晶体样品的组成和缺陷结构.通过透射光斑畸变法检测Mg:In:LN晶体抗光损伤能力.结果表明:Mg:In:LN晶体抗光损伤能力比纯LN晶体提高2个数量级.以波长为1 064nm的Nd:YAG激光为基频光源,对Mg:In:LN晶体的倍频性能进行了测试.结果表明:Mg:In:LN晶体的相位匹配温度在室温附近,Mg:In:LN晶体的倍频效率要高于In:LN晶体和Mg:LN晶体.     

Intrinsic second-order nonlinearity in chalcogenide glasses containing HgI2

Frequency conversion using nonlinear optical (NLO) crystals is widely used in advanced photonic technologies to produce coherent light in the spectral regions where the available laser sources are missing. Isotropic glasses usually do not show second order nonlinear processes like second harmonic or difference frequency generation (SHG, DFG) except for temporarily induced anisotropy under external stimuli. Here, we show that a HgI₂–Ga₂S₃–GeS₂ homogeneous glass exhibits a strong intrinsic SHG response comparable with that of the well-known NLO single crystal LiNbO₃. The origin of this extremely rare phenomenon seems to be noncentrosymmetric bent HgI₂ molecules embedded in a sulfide glassy host. Taking into account the unique properties of chalcogenide glasses (wide IR transmission, low phonon density, unlimited ability to be modified changing the appropriate glass properties, fiber drawing and thin layer design), the observed phenomenon opens up the possibility of creating fundamentally new devices for mid-IR photonics.     

An investigation into the morphology and electro‐optical properties of 2‐hydroxy ethyl methacrylate polymer dispersed liquid crystals

Polymer dispersed liquid crystal (PDLC) films are fabricated using E7 liquid crystals, tetraethylene glycol diacrylate (TeGDA) crosslinking agent, and 0–66.49 mol % 2‐hydroxy ethyl methacrylate (HEMA). The effects of different levels of HEMA addition on the microstructure and electro‐optical properties of the PDLC samples are examined using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV‐Vis spectroscopy, respectively. The results show that the refractive index of the PDLC films is insensitive to the level of HEMA addition. However, an increasing HEMA content improves the degree of phase separation during the polymerization process and increases the size and uniformity of the liquid crystal domain. As a result, the electro‐optical properties of the PDLC films are significantly improved as the level of HEMA addition is increased. Overall, the results show that a PDLC comprising 40 wt % E7 liquid crystals, 33.51 mol % TeGDA and 66.49 mol % HEMA has a high contrast ratio (13 : 1) and a low driving voltage (10 V) and is therefore an ideal candidate for a wide variety of intelligent photoelectric applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

不同晶体形貌NH2-MIL-125(Ti)制备及光催化性能

采用溶剂热法合成了NH2-MIL-125(Ti)晶体，通过调变N,N-二甲基甲酰胺（DMF）和无水甲醇（MeOH）两种溶剂比例，NH2-MIL-125(Ti)晶体呈现出圆形片、十面体和八面体形貌。采用XRD、SEM、FT-IR和BET等表征手段对不同形貌的NH2-MIL-125(Ti)晶体进行物性分析，并将其用于可见光光催化环己烷氧化反应，探究了催化性能与晶面之间的构效关系。分析得出， 环己烷选择性氧化生成环己醇和环己酮目标产物主要反应发生在NH2-MIL-125(Ti)晶体的{110}晶面族，而{101}晶面族主要是进一步氧化环己醇和环己酮产生COx。     

近化学计量比Fe:Mg:LiNbO_3晶体生长与其存储性能

在LiNbO3(LN)中分别掺入0.5%(摩尔分数,下同),1%和2% MgO,0.03%(质量分数)Fe2O3,配料中n(Li)/n(Nb)=1.38,采用顶部籽晶溶液生长法生长近化学计量比Fe:Mg:LiNbO3(near-stoichiometric Fe:Mg:LiNbO3,Fe:Mg:SLN)晶体。测试了晶体的红外光谱、抗光损伤能力和存储性能。结果表明:Fe:2%Mg:LN晶体的OH-吸收峰移到3535cm-1,抗光损伤能力比Fe:LN提高3个数量级。Fe:0.5%Mg:LN晶体的灵敏度、动态范围和抗光损伤能力比Fe:LN晶体分别高2.5倍,2倍和1个数量级。以Fe:2%Mg:LN晶体和Fe:LN晶体分别作为存储介质,进行大容量存储实验。在一个公共体积内实现1200幅体全息图的存储。Fe:2%Mg:LN晶体的存储质量优于Fe:LN晶体。     

Patterning of Non-Linear Optical Crystals in Glass by Laser-Induced Crystallization

This paper reports recent progress in the patterning of non-linear optical crystals on the glass surface by laser irradiation. Two techniques for the writing of crystal lines have been developed, i.e., rare-earth (samarium) atom heat processing and transition metal atom heat processing, in which a continuous wave Nd:YAG laser (wavelength: λ=1064 nm) is irradiated to the glasses containing rare-earth (RE: Sm³⁺, Dy³⁺) ions or transition metal (TM: Ni²⁺, Fe²⁺, V⁴⁺) ions. The writing of crystal lines such as β-BaB₂O₄, Sm _x Bi_{1− x} BO₃, and Ba₂TiGe₂O₈ showing second harmonic generations has been successful. It is clarified from the azimuthal dependence of second harmonic intensity and polarized micro-Raman scattering spectra that crystal lines consist of highly oriented crystals along the crystal line growth direction. It is also possible to write two-dimensional crystal bending or curved lines by just changing the laser scanning direction. The mechanism of the laser-induced crystallization has been proposed.