Third-order nonlinear optical studies of newly synthesized polyoxadiazoles containing 3,4-dialkoxythiophenes

The third-order nonlinear optical properties of newly synthesized soluble polyoxadiazoles containing 3,4-dialkoxythiophenes were investigated by using Z-scan and degenerate four-wave mixing (DFWM) techniques. The measurements were performed at 532 nm with 7 ns pulses from a Nd:YAG laser. We found a good agreement between the values of χ⁽³⁾ determined from both the experiments. Z-scan results indicate a negative nonlinear refractive index, n₂, whose magnitude is of the order of 10⁻¹⁰ esu for all the copolymers. The variation of nonlinear response among the copolymers clearly indicates the dependence of χ⁽³⁾ on donor and acceptor type of units present in these copolymers. The copolymers exhibit strong reverse saturable absorption and good optical limiting properties at 532 nm.     

Optical Nonlinearities of Phthalocyanines and Naphthalocyanines

The nonlinear absorption and refraction of soluble phthalocyanines and naphthalocyanines have been measured with z-scan technique using 8 ns, 532 nm laser pulses. The excited-state absorption cross-section and the excited-state refractive-index cross section have been estimated under the consideration of laser induced thermal effect. The excited state absorption induced n2 and Re χ⁽³⁾ values are in the range of 10^?12 esu. These observed data are enhanced by the concentrations of both metal substituted Pc's and Nc's, but this increment became very small for the metal free phthalocyanine. During the optical limiting experiments, a 25% linear transmitted solution of R₈PcH² can limit laser pulses to ≤ 120 μJ from incident energies as high as 2.0 mJ, and this limitation moved down to ≤ 50 μJ when replacing R₈PcCu from P₈PcH₂. A similar property has also been observed for the metal substituted naphthalocyanines. The results indicate that both the nonlinear refraction and optical limiting properties should be strongly affected by the metal induced triplet-state nonlinear absorption in both Pc's and Nc's. Moreover, the laser pulses created a self trapped filament inside the solution of this optical limiter, while emitting time-resolved, concentric rings on a projection screen, which could be induced by the thermal lensing effect. The various optical nonlinear properties observed from these materials should make them valuable as an optical limiter.     

有机金属酞菁类化合物及其非线性光限幅特性

随着激光技术的快速发展, 激光武器的性能也越来越优越, 所造成的危害也越来越大, 各国开始加大力度对激光防护材料进行研究. 酞菁化合物具有限幅窗口宽、限幅效果明显、响应迅速等特点, 是一类非常具有应用前景的光限幅材料. 当前, 制备出限幅性能好、稳定性强的酞菁光限幅材料成为激光防护材料领域中的研究热点. 本文评述和总结了近几年在酞菁光限幅材料方面开展的系统研究工作, 首先介绍了酞菁化合物实现光限幅效应的机制, 并在此基础上详细分析了影响光限幅效应的因素以及光限幅器件化过程对酞菁光物理和光限幅性能的影响机理. 根据分析结果提出了在基础和应用研究方面存在的科学问题, 指出了该类型光限幅材料面临的挑战和今后的重要发展方向.     

Second-harmonic properties of dendritic polymers skeleton-constructed with azobenzene moiety used for nonlinear optical materials

A series of dendrons and dendrimers skeleton-constructed with azobenzene moiety were synthesized and doped in a high T_g polycarbonate (PC) as a host for nonlinear optical (NLO) materials. The optimal loading density and poling conditions were investigated using UV-vis spectral and second-harmonic generation (SHG) measurements. The results showed that the dendrons and dendrimers have good solubility in PC host, which increased with the generation increased. Moreover, the SHG measurements indicated that the dendrons possess higher nonlinearity than the dendrimers. The chromophores of lower generation dendrons were easier to orient along the poling electric field and gave a cone shape with the azobenzene branching units, which coherently contributed to the molecular hyperpolarizability and resulted in the higher SHG intensity. The temporal stability of the dendrons with 15% loading density was also investigated, and showed that the decaying in nonlinearity was slower for higher generation dendrons.     

二甲基二氢芘类光致变色化合物及其光开关性质

介绍了二甲基二氢芘类化合物特殊的逆光致变色性质,讨论了内外取代基、间隔基以及稠合基团等因素对二甲基二氢芘光致变色性质的影响,综述了该类化合物在光学开关和信息的光化学读出等应用方面的研究状况,并展望了二氢芘类光致变色化合物的研究前景。     

聚酰亚胺多层膜的制备及其在非线性光学中的应用

报道了一种通过旋涂制备NLO聚合物多层膜的方法.紫外-可见吸收光谱及膜的厚度表征说明,在所得多层膜的结构中,聚合物单层膜的厚度可以较好地控制在100～200 nm之间,所得含有5个双层的NLO多层膜（厚度1.6 μm）具有良好的结构均一性,光学显微镜下没有观察到明显的结构缺陷.与单层具有较大厚度的NLO聚合物薄膜（如2～4 μm）相比,所得聚合物多层膜可以允许掺杂更多的发色团而不发生相分离.     

两种含偶氮苯共轭桥新型生色团分子的合成及性能

通过重氮化偶合反应和羟醛缩合反应合成了以偶氮苯为共轭桥、以2,2,3-三甲基-4-氰基-5-二氰基亚甲基-2,5-二氢呋喃为电子受体, 而给体分别为二甲氨基和二乙氨基的两种有机非线性光学生色团分子MFNC和EFNC. 利用IR、1H NMR和元素分析对分子的结构进行了表征. TGA和DSC测试发现, MFNC的热稳定性略好于EFNC, 其热分解温度最高达266 ℃. 通过测定两种材料在氯仿、丙酮和DMSO中的紫外-可见光谱, 用溶致变色法计算得到两种材料在激光波长为1064 nm处的二阶非线性品质系数μgβ, 对比发现EFNC的μgβ值高于MFNC, 其值达59706×10-48 esu(1 esu=3.34×10-10C).     

Organometallic Compounds for Nonlinear Optics—The Search for En-light-enment!

The importance of nonlinear optical phenomena has been known for some time, however, since the mid-1980s, there has been an explosion of interest in the search for and development of non-linear optical materials that possess commercial device applications. To date, the systems have been utilized in information processing, optical switching, optical frequency conversion, and telecommunications, and with the advancing development of optotechnology, burgeoning demands for suitable materials are becoming apparent. Of the many systems studied for example inorganic crystals and semiconductors, organic crystalline monomers, and long-chain polymers with delocalized π electrons, no one species has proved to be all-encompassing, with advantages for one application being negated by disadvantages for another. This is likely to remain the case for the foreseeable future with the criteria of the application governing the type of material used. However, chemists are gradually elucidating what actually governs second- and third-order nonlinear activity and thereby, tailoring species to show greater effects. In recent years, organometallic compounds, through their unique characteristics such as diversity of metals, oxidation states, ligands, and geometries, have found success and brought a new dimension to the area. This review attempts, with critical appraisal, to bring the discussion of organometallic nonlinear optical systems up to date, as well as giving a brief but general introduction to the field of nonlinear optics. For corrigendum see DOI: 10.1002/anie.199508261     

侧链含偶氮苯发色团的聚酰亚胺薄膜的制备及其三阶非线性光学和光存储性能的研究

将4,4'-二氨基三苯甲烷(DTM)单体与均苯四甲酸酐(PMDA)进行缩聚反应,再与对-硝基苯基重氮氟硼酸盐进行重氮偶合反应,然后经酰亚胺化合成了侧链含偶氮苯发色团的聚酰亚胺非线性光学材料(NLOPI).通过红外光谱对产物进行了结构表征.对产物的紫外-可见吸收光谱研究发现,在330和490nm处出现侧链偶氮苯发色团的特征吸收.通过简并四波混频方法(DFWM)测定侧链含偶氮苯发色团的聚酰亚胺薄膜的三阶非线性极化率χ⁽³⁾=4.58×10^-18m²/W.在DFWM中,前向泵浦光I_f和探测光I_p是主要的写入光,而后向泵浦光I_b是主要的读出光.证实了光致偶氮分子的顺反异构能够导致光信息存储的特性.     

Optically-induced second-order nonlinear optical effect in polyvinyl alcohol photopolymers

IR induced picosecond nonlinear optical effects in polyvinyl alcohol photopolymer is investigated. The second harmonic generation (SHG) is studied versus the pump power and delaying time between the pump and probing beam (λ=1.55 and 1.32 μm, respectively). The phenomena are explained within a framework of fifth-order nonlinear optical susceptibilities. An explanation of the observed dependences is given within a framework of photostimulated vibrations, which enhance acentric electron-phonon anharmonicity. Temperature dependences of the observed phenomena fully confirm the electron-phonon anharmonic origin of the observed effect.     

Organic Polymeric and Non-Polymeric Materials with Large Optical Nonlinearities

Nonlinear optical properties are a sensitive probe of the electronic and solid-state structure of organic compounds and as a consequence find various applications in many areas of optoelectronics including optical communications, laser scanning and control functions, and integrated optics technology. Because of their strongly delocalized π electronic systems, polymeric and non-polymeric aromatic compounds show highly nonlinear optical effects. Nowadays, polymer chemists are able to tailor specific materials properties for various applications. Some organic substances with π electronic systems exhibit the largest known nonlinear coefficients, often considerably larger than those of the more conventional inorganic dielectrics and semiconductors, and thus show promise for thin-film fabrication, allowing the enormous function and cost advantages of integrated electronic circuitry. The electronic origins of nonlinear optical effects in organic π electronic systems are reviewed, with special emphasis being given to second-order nonlinear optical effects. Methods for measuring nonlinear optical responses are outlined, and the critical relationships of the propagation characteristics of light to observed nonlinear optical effects and to solid-state structure are discussed. Finally, the synthesis and characterization of organic crystals and polymer films with large second-order optical nonlinearities are summarized.     

二腈基衍生物的合成及其光限幅性质

设计并合成了一系列含不同末端给电子基团及共轭链长度的1,1-二腈基-2,2-二苯基乙烯类化合物(D1-D7),用核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)和高分辨质谱(HRMS)对分子结构进行了表征.选用N,N-二甲基甲酰胺(DMF)为溶剂,测定了它们的线性光物理性质,用光漂白法研究了它们的光稳定性,用热失重法测试了它们的热稳定性.研究了这7个化合物针对800 nm脉冲激光(掺钛蓝宝石激光器,脉冲宽度~130 fs,重复频率1000 Hz)的光限幅性质.结果表明:以二烷基氨基为给电子基团的4个化合物(D4-D7)对800 nm的飞秒脉冲激光均具有显著的光限幅性能,限幅机制为双光子吸收(2PA),而端基给电子能力较弱、共轭链长较短的D1-D3光限幅效果并不明显.此外,D4-D7都具有较好的热稳定性和光稳定性.而且,该系列化合物的双光子吸收截面、光稳定性和热稳定性都具有随分子结构中给电子基团增强或共轭链增长而增大或提高的趋势.D7具有最好的综合性能,是一个有应用潜力的光限幅材料.     

Photoresponding ionic complex containing azobenzene chromophore for use in birefringent flm简

A novel photoresponding ionic complex （PANDAZO） was prepared by the ionic self-assembly （1SA） of sodium polyacrylate （PANa） and azobenzene chromophores （NDAZO）. The ionic complex forms an interdigitated lamellar structure with full overlap of the side chains. The optical anisotropy was investigated by using a polarization pulse laser （355 nm）. Furthermore, a high photoinduced birefringence （An = 0.365） was measured by using a continuous 488 nm laser as the pump light.     

含偶氮苯光学活性侧基聚合物研究进展

综述了含偶氮苯光学活性侧基聚合物近年来的发展概况,介绍了多种聚合体系的类型。由于偶氮苯光于活性侧基的存在,使得这些聚合物具有光致变色性、非线性光学活性、光学各向异性等光学性能,在光信息存储材料、非线性光学材料、液晶材料、光电子器件、生物分子活性光调控、纳米技术等诸多领域都有广泛的应用。     

Novel N-substituted-5-phenyl-1H-pyrazole-4-ethyl carboxylates as potential NLO materials

In the present investigation we have synthesized a novel series of N-substituted-5-phenyl-1H-pyrazole-4-ethyl carboxylates, which are characterized by ¹H NMR, UV–Vis and FT-IR spectroscopy methods. The optical nonlinearity of the compounds in chloroform solution has been studied at 532 nm using 5 ns laser pulses, employing the open-aperture z-scan technique. It is found that compound 3c having carboxylic acid group and ester substituent has maximum nonlinearity. From measurements we conclude that compounds 3c (4-[4-(ethoxycarbonyl)-5-phenyl-1H-pyrazol-1-yl]benzoic acid) and 3e (ethyl 1-(2-bromophenyl)-5-phenyl-1H-pyrazole-4-carboxylate) are potential candidates for optical limiting applications.     

偶氮苯侧链结构对聚丙烯酸酯三阶非线性光学性能影响

设计合成了一系列含偶氮苯非线性生色团的丙烯酸酯,并采用溶液聚合法合成了功能化的聚丙烯酸酯,利用FTIR、NMR、UV等对化合物的结构进行了表征,证实得到了指定结构的化合物.利用Z扫描技术对合成的聚丙烯酸酯的非线性光学性能进行了研究,通过对聚合物的非线性光学吸收拟合,计算得到非线性吸收系数β和三阶非线性系数χ(3),并探讨了取代基生色团分子结构与高分子三阶非线性光学性能的关系,结果显示增大侧链生色团π电子离域长度或强DπA(推拉基团)结构均可有效提高聚合物的三阶非线性光学性能.