有机和金属有机非线性光学晶体材料

非线性光学材料是激光技术的重要物质基础之一,是高技术研究的一个组成部分。二十多年来,非线性光学材料的研究经历了无机晶体、有机材料的阶段,现在又开始了金属有机非线性光学材料的探索。本文拟综述有机和金属有机二阶非线性光学晶体材料的研究进展,而不讨论高分子材料以及三阶非线性光学效应。鉴于刊物读者的特     

硼原子的键合形式对硼酸盐晶体非线性光学行为的影响

在几种具有典型复杂结构的硼酸盐晶体中 ,从硼原子的键合形式出发讨论了不同键合情况下的B—O键对硼酸盐晶体的非线性光学行为的具体影响。结果表明 ,晶体中B—O键的键合形式是制约硼酸盐晶体非线性光学行为的重要因素。     

有机非线性光学晶体NPP的AFM研究

有机二阶非线性光学活性晶体的分子设计和晶体工程是复杂而又引人注目的课题．有机非线性光学晶体N一忡硝基苯基）－LWe脯氨醇（NPP）是一个极为成功的自］子山．由于在＊＊P分子中引入了含手性碳原子和可形成分子间氢键的电子给体脯氨醇，使得其分子跃迁偶极矩与单科P21晶体结构的二重轴之间的夹角为586”．接近于理论优化值（54．74”），因此，＊＊P具有很高的宏观二阶非线性光学活性，其粉末二次谐波强度为尿素的150倍．自1984年首次报导以来，对它的晶体生长门和物理性质已进行了广泛深入的研究．原子力显微镜（＊＊M）能够以极高…     

非线性光学有机晶体材料的研究进展

随着科技的进步和时代的发展,光电子技术将是21世纪的核心技术之一.对于光电子技术的发展,非线性光学材料,尤其是非线性光学晶体是不可缺少的关键材料.本文主要从分子设计方面概述了阴阳离子二元生色团体系、纯有机分子、纳米晶体和有机金属复合物等几种主要的非线性光学有机晶体材料的研究情况,并对其各自的特点做了简单的说明.     

化学键观点在寻找新型非线性光学晶体材料中的应用

从晶体组成化学键的角度出发 ,研究和探讨了化学键观点在寻找新型非线性光学晶体材料工作中的应用     

无机非线性光学材料的探索

我国在无机非线性光学晶体某些研究中处于国际领先水平。本文就非线性光学材料的发展，应用及前景作了综合的回顾。     

胶态晶体研究的新进展

胶态晶体作为胶体粒子的组装体在相变研究、光学器件，电子及信息存储材料等领域都有重要的应用，化学将在胶态晶体研究中发挥特殊作用。     

Mg：Fe：LiNbO3晶体光谱性能的研究

铌酸锂(LiNbO_3)晶体具有良好的电光与非线性光学性能,广泛应用于各种光学器件中。在较高功率密度激光的辐射下,LiNbO_3晶体易于产生光致折射率变化(光折变),光折变使激光束波前发生畸变,严重影响了基于LiNbO_3晶体的各种光学元件的性能。造成LiNbO_3晶体光折变的原因是由于存在Fe离子,高浓度掺杂镁(>4.6 mol％MgO)可大大增强LiNbO_3     

一种新型的硼酸盐晶体BiB_3O_6的二阶非线性光学行为的理论计算(英文)

利用化学键的观点 ,研究了一种新型硼酸盐晶体BiB3O6 的二阶非线性光学行为。计算结果表明 :该晶体确实具有很好的倍频性能。但是 ,它的性能还达不到目前实验报道的数值。从该晶体的结构特征出发 ,作者分析了所得出的结果 ,期待对该晶体性能做进一步测定。     

有机晶体材料DAST和DSTMS的电子结构与光学性质

采用基于赝势平面波基组的密度泛函理论(DFT)方法,研究了有机晶体材料4-(4-二甲氨基苯乙烯基)甲基吡啶对甲苯磺酸盐(DAST)和4-(4-二甲氨基苯乙烯基)甲基吡啶2,4,6-三甲基苯磺酸盐(DSTMS)的电子结构和光学性质.结果表明,两种化合物具有相似的能带结构,其中价带顶和导带底分别含有较多二甲氨基和甲基吡啶中N原子的2p轨道成分.在线性光学性质方面,两种化合物具有较高的双折射率(Δn>0.5),在中远红外区均具有较好的透过性能.在二阶非线性光学性质方面,该类晶体具有较强的二阶倍频(SHG)效应,静态倍频系数d11约为150 pm V-1.由能带结构分析结果可知,体系的SHG效应与推拉电子基团之间的电荷转移密切相关,同时乙烯桥键在该电子转移过程中也起着重要作用.     

Synthesis, Structure and Non-linear Optical Properties of Manganese Mercury Tetrathiocyanate

IntroductionRecently,ourresearchinterestshavefocusedonMHg(SCN).seriesofcrystallinecomplexesbecauseoftheirstrikingnonlinearopticalproperties.Inthepreviouspaper"',wehavereporedthesynthesis.structureandnonlinearoptical(NLO)propertiesofCdHg(SCN).andFeHg...     

金属硫氰酸根配合物FeHg(SCN)_4,MnHg(SCN)_4的合成、晶体结构与非线性光学性质的研究

合成了配合物晶体FeHg(SCN)_4和MnHg(SCN)_4用单晶X射线衍射方法测定了这两个晶体的结构.以尿素为标准样品用粉末晶体倍频1064nm的Nd:YAG激光,测得其倍频光强度分别为:FeHg(SCN)_4,0.6倍于尿素;MnHg(SCN)_4,50倍于尿素.后者显示了作为新的非线性光学材料的发展前景.     

Crystal growth of phase matchable new organic nonlinear optical material for UV laser generation

L-histidinium tetrafluorosuccinate (L-HFS), an organic nonlinear optical material has been synthesized and characterized by the elemental analysis, FT-IR, FT-NMR and X-ray diffraction studies. Solubility of L-HFS was found to be higher in water than ethanol. Single crystals with dimensions 10 mm x 6 mm x 3 mm were grown in an aqueous solution by the slow evaporation technique at 30 degrees C. The thermal stability of L-HFS has been analyzed by thermogravimetric and differential thermal analyses (TGA and DTA). The UV-vis spectral study reveals that the material has a wide optical transparency in the entire visible region with the lower cutoff wavelength at 235 nm. The phase matching condition was obtained by Kurtz powder second harmonic generation (SHG) efficiency test. The laser damage threshold of the grown crystal was measured using a Q-Switched Nd:YAG laser (1064 nm).     

1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基类复合物在不同波长下的三阶非线性光学性质

合成了两种新的金属双噻吩类复合物:(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基)-金(BTEAADT)和(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基)-镍(BTEANDT).采用Z扫描方法,在皮秒脉冲下,分别测试了两种材料的乙腈溶液在532和1064nm的三阶非线性光学特性.Z扫描的结果表明,BTEAADT的乙腈溶液在532nm具有反饱和吸收效应,在1064nm非线性吸收效应可以忽略且在两种波长都有自散焦效应,三阶非线性折射率为负值.BTEANDT的乙腈溶液在532nm非线性吸收效应可以忽略,在1064nm具有饱和吸收效应且在两种波长都有自聚焦效应,三阶非线性折射率为正值.分析了造成这种差异的原因.经过计算得到了两种材料在532和1064nm的三阶非线性折射率,三阶非线性吸收系数,三阶非线性极化率和超极化率.BETAADT的非线性折射率在532nm为-1.685×10-18m2·W-1,在1064nm为-1.459×10-18m2·W-1;BTEANDT的非线性折射率在532nm为1.452×10-18m2·W-1,在1064nm为7.311×10-18m2·W-1.两种材料的三阶非线性吸收系数,三阶非线性极化率和超极化率的数量级分别是10-11m·W-1,10-13esu和10-31esu.结果表明这两种材料在非线性光学领域有潜在的应用价值.     

金属硫氰酸根配合物FeHg(SCN)~4, MnHg(SCN)~4的合成、晶体结 构与非线性光 学性质的研究

合成了配合物晶体FeHg(SCN)~4和MnHg(SCN)~4。用单晶X射线衍射方法测定了这两个晶体的结构。以尿素为标准样品用粉末晶体倍频1064nm的Nd:YAG激光,测得其倍频光强度分别为:FeHg(SCN)~4,0.6倍于尿素;MnHg(SCN)~4,50倍于尿素,后者显示了作为新的非线性光学材料的发展前景。     

Single- and two-photon excited fluorescence in organic nonlinear optical single crystal 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole

Fluorescence of nonlinear optical organic single crystal of 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP) excited by a nonabsorbed light pulses from Q-switched Nd:YAG laser λ = 1064 nm as well as absorbed λ = 532 nm light is reported. Two mechanisms of two-photon excited fluorescence are considered: (i) direct two-photon excited fluorescence and (ii) single-photon excitation due to reabsorption of light generated in process of second harmonic generation (SHG) by the crystal due to its nonlinear optical properties. Strong anisotropy of fluorescence that has been observed is linked with uniaxial molecular alignment. Fluorescence decay profile shows two- exponential decay with lifetimes of emitting species of 3.7 and 5.6 ns at 293 K. The excitation and fluorescence spectra of the DCNP single crystal have been measured at 294 K and in function of temperature down to 77.4 K. The strong bathochromic shift of fluorescence spectrum in crystal with respect to fluorescence of DCNP molecule in solution is observed and interpreted with possible formation of molecular aggregates.     

Studies of Silver Nanoparticles by Laser Ablation Method

The laser ablation technique has been employed to study silver colloidal formation. Laser intensities, irradiation wavelengths (1064 nm and 532 nm), and solvents (water, methanol, and isopropanol) were all considered. Changes of the maximum UV-Visible absorbance of the solutions with laser intensities exhibited nonlinear behavior for 1064 nm and 532 nm and displayed better ablation efficiency at 532 nm. Larger mean sizes were observed at 532 nm or at higher pulse energy. For solvent effect, the bigger particle sizes were generated in H₂O. As to colloidal stability, isopropanol, which has a lower dielectric constant than water, was found to stabilize Ag nanoparticles without protecting reagents over six months. Preliminary results in 2-butanol suggested that the viscosity of solvent may need to be considered in addition to the dielectric constant.     

Two Pyrophosphates with Large Birefringences and Second‐Harmonic Responses as Ultraviolet Nonlinear Optical Materials

Two new pyrophosphates nonlinear optical (NLO) materials, Rb₃PbBi(P₂O₇)₂ ( I ) and Cs₃PbBi(P₂O₇)₂ ( II ), were successfully designed and synthesized. Both compounds exhibit large NLO effects and birefringences. Material I presents the scarce case of possessing the coexistence of large birefringence (0.031 at 1064 nm and 0.037 at 532 nm) and second harmonic generation (SHG) response (2.8× potassium dihydrogen phosphate (KDP)) in ultraviolet NLO phosphates and its SHG is the largest in the phase‐matching (PM) pyrophosphates. Both I and II have three‐dimensional (3D) crystal structures composed of corner‐shared RbO₁₂ (CsO₁₁), RbO₁₀ (CsO₁₀), BiO₆, PbO₇ (PbO₆) and P₂O₇ groups, in which P₂O₇ and PbO₇ (PbO₆) units form an alveolate [PbPO]_∞ skeleton frame. Theoretical calculations reveal that the P?O, Bi?O and Pb?O units are mainly responsible for the moderate birefringence and large SHG efficiency of I .     

NH4Be2BO3F2 and γ‐Be2BO3F: Overcoming the Layering Habit in KBe2BO3F2 for the Next‐Generation Deep‐Ultraviolet Nonlinear Optical Materials

KBe₂BO₃F₂ (KBBF) is still the only practically usable crystal that can generate deep‐ultraviolet (DUV) coherent light by direct second harmonic generation (SHG). However, applications are hindered by layering, leading to difficulty in the growth of thick crystals and compromised mechanical integrity. Despite efforts, it is still a great challenge to discover new nonlinear optical (NLO) materials that overcome the layering while keeping the DUV SHG available. Now, two new DUV NLO beryllium borates have been successfully designed and synthesized, NH₄Be₂BO₃F₂ (ABBF) and γ‐Be₂BO₃F (γ‐BBF), which not only overcome the layering but also can be used as next‐generation DUV NLO materials with the shortest type I phase‐matching second‐harmonic wavelength down to 173.9 nm and 146 nm, respectively. Significantly, γ‐BBF is superior to KBBF in all metrics and would be the most outstanding DUV NLO crystal.     

Experimental determination of laser induced breakdown thresholds of metals under nanosecond Q-switched laser operation

Laser-induced breakdown thresholds for several pure metals were determined using a nanosecond laser. A Q-switched pulsed Nd:YAG laser operating at infrared (1064 nm), visible (532 nm) and ultraviolet (266 nm) wavelengths has been used. The plasma was generated by focusing the Nd:YAG laser on the target in air at atmospheric pressure. The dispersed plasma light was detected using a two-dimensional intensified charge-coupled device (CCD) detector. The studied elements were chosen according to their different thermal and physical properties, particularly boiling point, melting point and thermal conductivity. The effect of wavelength on the plasma threshold has been discussed. Laser fluence thresholds in the ultraviolet were larger than those obtained using visible and infrared radiation, while the energy threshold is larger using infrared radiation. Correlations between the plasma threshold of metal targets and the melting point and boiling point at 266, 532 and 1064 nm have been established. The results indicate that thermal effects have an important influence on the ablation behavior of metals at the three wavelengths used.