Nonlinear Optical Properties of Porphyrins

Porphyrins and phthalocyanines have outstanding chemical and thermal stability. The macrocyclic structure and chemical reactivity of tetrapyrroles offers architectural flexibility and facilitates the tailoring of chemical, physical and optoelectronic parameters. The specific optical properties of the tetrapyrrole macrocycle combined with the synthetic methodologies now available and the already available theoretical and spectroscopic knowledge on their optical behavior make porphyrins a target of choice for this area. They are versatile organic nanomaterials with a rich photochemistry and their excited state properties are easily modulated through conformational design, molecular symmetry, metal complexation, orientation and strength of the molecular dipole moment, size and degree of conjugation of the π‐systems, and appropriate donor‐acceptor substituents. Here we review the structural chemistry and optical properties of recently synthesized porphyrin derivatives that offer potential for nonlinear optical (NLO) applications and complement existing studies on phthalocyanines. Classes of interest include the classic A₄ symmetric tetrapyrroles, while optimized systems include push‐pull porphyrins, oligomeric and supramolecular self‐assembled systems, films and nanoparticle systems, and highly conjugated porphyrin arrays.     

二氧化钛薄膜的三阶非线性光学特性

采用脉冲激光沉积技术在熔石英基片上制备了c轴取向的锐钛矿相TiO₂薄膜.通过X射线衍射和原子力显微镜对薄膜的结构、结晶性和表面特性进行了表征.通过透射光谱计算得到TiO₂薄膜折射率约为2.1,光学带隙约为3.18eV.结合飞秒激光和Z扫描方法测量了薄膜的超快非线性光学特性,结果表明：锐钛矿TiO₂薄膜具有负的非线性吸收系数和负的非线性折射率,其大小分别为-6.2×10^-11m/W和-6.32×10^-17m²/W,对应的三阶非线性极化率的实部和虚部分别为-7.1×10^-11esu和-4.42×10^-12esu.并计算薄膜的优值比T=βλ/n₂≈0.8,表明锐钛矿相的TiO₂在非线性光学器件方面具有潜在的应用前景.     

Nonlinear Optical Properties of Alternant Fullerene C48

Nonlinear optical properties of alternant carbon cluster C₄₈ are calculated and discussed. The dispersion of 2-nd hyperpolarizabilities for the 3-rd harmonic generation and 2-nd harmonic generation in presence of a static field is determined by two low lying poles connected with two two-photon allowed transitions in the absorbtion spectrum of C₄₈.     

可溶性聚噻吩甲烷的制备与光学性能

利用噻吩和对二甲氨基苯甲醛在酸性条件下共聚,制备了一种具有可溶性、分子链部分共轭的聚噻吩甲烷衍生物。采用傅里叶变换红外光谱、紫外-可见吸收光谱、荧光光谱、热重分析和X射线衍射谱对聚合物的分子结构、光学性能、热稳定性能及聚集态结构进行了表征和分析。由紫外-可见吸收光谱可得,该聚合物的光学禁带宽度为1.3 eV,属于窄带隙聚合物。荧光光谱显示,该聚合物溶液在480 nm可见光的激发下,出现约600 nm的发射光,说明该聚合物为橙黄色的荧光材料。X射线衍射谱中17.3°附近存在1个较为尖锐的衍射峰,表明该聚合物聚集态结构为部分结晶态。     

银复合的Ge-In-S-CsI硫系玻璃的非线性光学性能研究

通过真空熔融淬冷法制备了银复合的70GeS₂-20In₂S₃-10CsI硫系玻璃样品, 利用Z-扫描技术研究了玻璃样品在800 nm处三阶非线性光学性质, 发现引入Ag可提高其折射率n和非线性折射率γ, n从2.204增加至2.4087, γ从23.3×10^-18 m²/W增加到30.5×10^-18 m²/W, 此外非线性响应时间从70 fs增加到79 fs。热处理对玻璃的非线性光学性能的影响研究显示, 热处理后样品的γ增加至44.3×10^-18 m²/W, 是As₂Se₃玻璃的两倍多。发现析晶后带隙变小(吸收边红移)导致非线性吸收系数β减小, 使得样品的品质因子提高至3.3。Ag复合的硫系玻璃及玻璃陶瓷非线性折射率大、品质因子高、非线性响应快, 有望用于全关开关等各类非线性光学器件中。     

有机材料的二阶光学非线性特性研究

介绍了确定有机分子二阶非线性极化率的方法,如超瑞利散射技术、溶致变色法、电场诱导二次谐波(EFISHG),全光极化.在分子结构的角度上总结了共轭分子的链长、取代基的电子特性、共轭骨架与二阶非线性极化率的关系.共扼长度的增加和共扼体系的扩展有利于电子在更大范围内发生转移.给电子能力和受体的吸电子能力越强,越有利于体系形成电荷转移的共振态,扩大(π)电子的流动范围,使分子在外场中更易发生分子内电荷转移而有利于增强分子的微观倍频效应.     

含新型发色团的非线性光学聚合物体系的热性能研究

分别对掺杂了新型发色团分子的聚甲基丙烯酸甲酯(PMMA)和纯的PMMA进行了热重分析,得到了2种体系在不同质量损失下的温度并计算了积分程序分解温度(IPDT).结果表明,掺杂后聚合物体系的热稳定性好于纯的PMMA.采用Achar方法和Coats-Redfern方法对2种体系热降解的动力学过程进行了分析,得到了对应的非等温动力学方程.     

具有稳定的二阶非线性光学性能的互穿网络聚合物

报导了一类新型的含有４－硝基４’－胺基偶氮苯发色团的聚丙烯酸酯和环氧结脂的互穿网络型二阶非线性光极化聚合物的合成和极化工艺，电子显微镜显示该互穿网络聚合物有明显的微观相分离，ＤＳＣ曲线显示两个玻璃化转变温度。用可见光谱法测定了其极化膜发色团的取向度及取向的热稳定性，其二阶非线性光学极化系数ｘ达１０＾－７ｅｓｕ量级。该互穿网络聚合物极化膜有良好的光学性质，其序参数在１００℃可长期稳定。     

3种偶氮化合物的合成及三阶非线性光学性能

合成了3种1,3,4-噻二唑偶氮化合物,其中1种为新化合物,用IR、1H NMR和元素分析表征了其结构.采用飞秒激光,运用简并四波混频法,研究了化合物在非共振状态下的三阶非线性光学性能.它们的三阶非线性光学极化率X(3)为(3.84～3.95)×10-13esu,非线性折射率n2为(7.07～7.27)×10-12esu,分子二阶超极化率γ为(3.56～3.72)×1031esu,响应时间τ为101fs.探索了化合物的分子结构对三阶非线性光学性能的影响.引入离域能小的芳杂环,形成吸供构型,增大取代基的吸或供电子能力等有利于获得较大的三阶非线性光学性能.     

Nonlinear Optical Properties of Correlated Chromophores in Organic Mesoscopic Superstructures

A new design strategy for enhanced nonlinear optical properties, based on a simple vector model and situated at the mesoscopic level, between the microscopic molecular level and the macroscopic bulk, is explained and exemplified by a number of organic superstructures. The second-order nonlinear optical properties of the structures are analyzed in terms of the corresponding properties of the individual monomeric chromophores that constitute the structure. The chromophores can be considered as electronically independent with a high symmetry. A simple vector model can then account for the large secondorder nonlinear optical polarizability of the mesoscopic superstructure. Another important advantage that is clear from the vector analysis is the improved chromophore alignment, owing to the enlarged mesoscopic dipole moment.     

两种二阶非线性光学聚氨酯的合成及其性能

合成了一种含双偶氮发色团侧基的线型聚氨酯及一种由分菜红－１９与已二异氰酸酯反应生成的线型聚氨酯，玻璃化温度依次为１５４℃及１６３℃。前者的二阶非线性光学系数高达８×１０＾－７ｅｓｕ，室温放置３个月序参数仍保持初值的９８％；后者的极化膜较分散红－１９与甲苯二异氰酸酯反应得到的 取向稳定性好，１２０℃放置４００多小时序参数保持９５％以上。     

贵金属纳米粒子及其复合物的非线性光学性能和应用研究进展

具有非线性光学特性的贵金属纳米粒子受到广泛的关注,因为这类金属纳米粒子及其复合物不仅具有重要的理论研究意义而且在非线性光学器件方面具有重要的潜在应用价值.对这类金属纳米粒子的主要制备方法、光学特性以及在激光防护等非线性光学器件方面的应用研究进展进行了综述,并对未来的研究和尚存在的问题进行了分析和展望.     

Piezoelectric and Nonlinear Optical Properties of PbGe4O9 Crystals

The piezoelectric coefficients and second-order nonlinear optical responses of different PbGe₄O₉ polymorphs were measured as a function of temperature. The PbGe₄O₉ crystals were found to possess attractive piezoelectric and nonlinear optical properties. The room-temperature piezoelectric charge coefficient d ₁₁ of -PbGe₄O₉ crystals exceeds that of quartz by a factor of 8.6. -PbGe₄O₉ exhibits 90° phase matching for the fundamental frequency and second harmonic of Nd:YAG lasers.     

Dielectric and Nonlinear Optical Properties of SrTeO3-Based Solid Solutions

Sr_1–x Pb _x TeO₃ (0 < x < 0.2) and Sr_{1 – x} La_2x Te_{1 + 2x} O_{3 + 6x} (0 < x< 0.15) solid solutions are synthesized (the latter, for the first time), and their properties are studied. The results demonstrate that partial substitutions of Pb and La for Sr extend the temperature stability range of ferroelectric SrTeO₃.     

Unveiling the Superior Optical Properties of Novel Melamine-Based Nonlinear Optical Material with Strong Second-Harmonic Generation and Giant Optical Anisotropy

Two melamine-based metal halides, (C₃N₆H₇)(C₃N₆H₆)HgCl₃ (I) and (C₃N₆H₇)₃HgCl₅ (II), are synthesized by incorporating the heavy d¹⁰ cation, Hg²⁺, and the halide anion, Cl⁻. The noncentrosymmetric structure of I results from two unique attributes: large asymmetric secondary building units produced by direct covalent coordination of melamine to Hg²⁺ and a small dihedral angle between melamine molecules. The former makes inorganic modules locally acentric, while the latter prevents planar organic groups from forming deleterious antiparallel arrangement. The unique coordination in I results in an enlarged band gap of 4.40 eV. Due to the large polarizability of the heavy Hg²⁺ cation and the π-conjugated system of melamine, I exhibits a strong second-harmonic generation efficiency of 5 × KH₂PO₄, larger than any reported melamine-based nonlinear optical materials to date. Density functional theory calculations indicate that I possesses giant optical anisotropy, with a birefringence of 0.246@1064 nm.     

咔唑磺酸基铜酞菁的合成与其二阶非线性光学性能的研究

合成了具有潜在非线性光学性能的咔唑磺酸基铜酞菁,用红外光谱,元素分析进行了表征,采用溶剂化变色估算了其二阶非线性光学性能。结果表明,其二阶非线性光学系数与基态偶极距的复合量的值为37．1×10^-30esu．D。     

非线性光学聚合物薄膜DCDHF-2-V/PMMA的特性

将新型有机非线性光学分子DCDHF-2-V按一定比例掺入聚甲基丙烯酸甲酯(PMMA)中,采用旋涂方法制备聚合物薄膜。为了得到宏观二阶非线性光学特性,在90℃对薄膜进行电晕极化,形成各向异性。对极化前后的薄膜进行紫外/可见光吸收频谱分析和原子力显微镜分析。采用RHF方法在6-31G基组上对DCDHF-2-V/PMMA薄膜体系中的DCDHF-2-V分子和PMMA进行闭壳层Hartree-Fock理论计算,得到它们的一阶超极化率β分别为60.278755×10-30esu和10.902267×10-34esu。