纳米PIC-I分子聚集体的超辐射和Z-扫描研究

分子聚集体在非线性光学和集成光学等领域有潜在的应用前景。纳米结构一维染料分子J—聚集体有许多既不同于单个分子又不同于体材料的奇异性质，即超辐射和巨光学非线性。这种超辐射是由于在几个本征态内振于强度结合在一起，得到一巨跃迁偶极于，因而是超辐射的。跃迁速率与耦合分子个数N成正比。分子聚集体的J—吸收和超辐射发射是共振的。利用Z—扫描技术测量PIC在不同配比下的非线性折射率、非线性吸收系数和非线性极化率。观测到随着链长变短，样品的三阶非线性极化率增大。对这种非线性增强的机制进行了分析和讨论。     

厚高阶光学非线性介质Z扫描的变分法分析

利用变分法对具有五阶光学非线性介质的Z扫描特性进行了研究。通过比较，发现当介质在具有较大的五阶非线性系数或较大光强的情况下，五阶非线性项的作用是不可忽略的。这对光限制器的设计和Z扫描实验都具有一定的指导意义。     

Determination of optical nonlinearities in Cu(mpo)2 by Z-scan technique

The optical nonlinearities of Cu(mpo)₂ [formula = C₁₀H₈N₂CuO₂S₂] complex have firstly been investigated by using the Z-scan technique with a nanosecond-pulsed Nd:YAG laser at its second harmonic (532 nm) radiation. The nonlinear optical absorption and refraction coefficients of Cu(mpo)₂ have been measured with the different on-axial peak irradiances I ₀ at the waist ranging from 0.48 to 5.66 GW/cm². The nonlinear transmittance characteristics exhibit the near resonant two-photon absorption (TPA) at 532 nm and are explained by a population redistribution model. The nonlinear absorption originates from the near resonant TPA while the mechanism of the nonlinear refraction is the near resonant TPA transition enhancement. The linear increasing dependences of the optical nonlinearities on the incident irradiance arise from the population redistribution due to the near resonant TPA.     

大非线性相移下光学非线性Z扫描特性的研究

采用高斯分解法(GD)对大非线性相移下的Z扫描特性进行了分析，通过对数值算法的优化，将GD推广到对脉冲入射激光下大非线性相移下的Z扫描理论分析.对不同条件下大非线性相移Z扫描曲线峰谷结构的比较，发现在大非线性相移的情况下，Z扫描曲线的峰和谷随透过光阑或入射光强变化表现出某些新的特性.随着透过光阑孔径的增加，Z扫描曲线峰的变化要明显快于谷的变化，而且在谷明显存在的情况下，峰很快消失.采用皮秒脉冲激光下的纯二硫化碳实验对理论结果加以验证，实验结果和理论分析相一致.我们的分析结果对大非线性相移下Z扫描测量有一定的指导性意义，避免在大非线性相移下对Z扫描结果产生错误的分析. 关键词： 大非线性相移 高斯分解法 Z扫描     

Mo(W)-Cu(Ag)-S簇合物的非线性光学性能研究

本文介绍了非线性光学性测试中的Ｚ－扫描方法。总结了Ｍｏ（Ｗ）－Ｃｕ（Ａｇ）－Ｓ簇合物的光限制效应、非线性吸收和非线性折射等光学性质。讨论了簇合物结构与光学性能的关系。     

Amino acids (l-arginine and l-alanine) passivated CdS nanoparticles: Synthesis of spherical hierarchical structure and nonlinear optical properties

CdS nanoparticles (NPs) passivated with amino acids (l-alanine and l-arginine) having spherical hierarchical morphology were synthesized by room temperature wet chemical method. Synthesized NPs were characterized by ultraviolet–visible (UV–vis) spectroscopy to study the variation of band gaps with concentration of surface modifying agents. Increase in band gap has been observed with the increase in concentration of surface modifying agents and was found more prominent for CdS NPs passivated with l-alanine. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were carried out for the study of crystal structure and morphology of CdS NPs. The average particle size of CdS NPs calculated from Debye-Scherer formula was found to less than 5 nm and agrees well with those determined from UV–vis spectra and TEM data. Fourier transform infrared (FT-IR) spectroscopy was performed to know the functional groups of the grown NPs. Peaks in FT-IR spectra indicate the formation of CdS NPs and capping with l-alanine and l-arginine. Photoluminescence spectra of these NPs were also studied. Finally, colloidal solution of CdS-PVAc was subjected to Z-scan experiment under low power cw laser illumination to characterize them for third order nonlinear optical properties. CdS-PVAc colloidal solution shows enhanced nonlinear absorption due to RSA and weak FCA on account of two photon absorption processes triggered by thermal effect.     

3-溴-4-丁氧基-4'-硝基偶氮苯三阶非线性光学性能的研究

采用Z扫描技术对一种新的偶氮苯类化合物的三阶非线性光学系数进行了测量.实验结果的分析表明,该化合物具有较大的三阶非线性极化率;其三阶非线性主要来源于强的π电子离域性.     

DFT structural and optical nonlinear investigations of a synthesized new azo β-diketone dye

A new azo β-diketone (NA1) compound is synthesized by coupling reaction of 4-aminoantipyrine with acetylacetone. The NA1 compound is characterized via FTIR, Mass, ¹H NMR and ¹³C NMR spectroscopies. The keto-enol tautomers of the compound electronic structures and energies are investigated using density functional theory (DFT) via B3LYP method/6-311G (d,p) level. The NA1 compound nonlinear optical (NLO) properties are studied via the diffraction patterns (DPs) and the Z-scan where the compound nonlinear index of refraction (NIR), the optical limiting (OLg) property using 473 nm visible, low power, continuous (cw) laser beam are used while the all-optical switching (AOS) property is studied using two laser beams of wavelengths 473 nm and 532 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.