六棱柱型金属团簇化合物Mo2Ag4S8(dppy)4的合成与非线性光学性质

新合成了一种六棱柱型金属团簇化合物Mo2Ag4S8(dppy)4, 并用X射线单晶衍射结构分析方法测定了其晶体结构. 应用Z-scan技术研究了该金属团簇化合物在波长为532 nm的纳秒激光脉冲作用下的三阶非线性光学特性. 为了研究Mo2Ag4S8(dppy)4的非线性起源, 应用泵浦探测技术研究了该金属团簇化合物在波长为532 nm的皮秒激光脉冲作用下的光学非线性响应. 实验结果表明金属团簇化合物Mo2Ag4S8(dppy)4具有自聚焦特性和非线性吸收特性; 非线性折射率n2, 非线性吸收系数β和非线性极化率χ(3)分别为1.45×10－10 esu, 6.2×10－10 m/W及2.1×10－11 esu. 实验结果表明金属团簇化合物Mo2Ag4S8(dppy)4的光学非线性响应是非线性吸收和非线性散射共同作用的结果.     

四磺化酞菁氧钒自组装膜的三阶非线性光学性能研究

为提高金属酞菁膜的三阶非线性光学性质,采用静电自组装技术制备出了包含阴离子四磺化酞菁氧钒（VOTsPc）和阳离子聚乙烯亚胺（PEI）交替层的复合薄膜.通过紫外-可见光谱仪表征了VOTsPc/PEI交替多层组装体的组装过程,结果表明组装过程为有规律的连续吸收过程.利用原子力显微镜技术研究了VOTsPc/PEI薄膜的表面形貌,结果表明膜表面是光滑的、均匀的;膜表面紧密堆积了纳米级颗粒,平均粒径为75 nm,平均表面粗糙度为4.406 nm.使用调 Q 倍频ns/ps Nd∶YAG脉冲激光系统,在输出激光波长为532 nm,脉冲宽度为4 ns条件下,通过Z-扫描测试研究了组装膜的三阶非线性光学性质.通过对实验数据的模拟和计算,30-双层VOTsPc/PEI膜的非线性极化率n2和非线性吸收系数β值分别为4.87×10-6 esu和1.2×10-5 m/W,三阶非线性极化率χ(3) 值为1.57×10-6 esu.VOTsPc/PEI膜显示出较强的非线性反饱和吸收性能,具有广阔的应用前景.     

水溶性CdTe:Mn量子点的双光子吸收

采用激发波长800 nm、脉宽50 fs、重复频率1 kHz的Ti:sapphire放大飞秒激光器作为激发光源,利用开孔Z扫描技术研究了不同粒径的CdTe:Mn量子点的非线性吸收性质。理论计算结果表明,同一生长时间CdTe:Mn量子点的双光子吸收系数是CdTe量子点的1.1倍,其双光子吸收系数随量子点尺寸的减小而增大,这是由于CdTe:Mn量子点非线性吸收属于反饱和吸收,掺杂了Mn元素,减小了表面缺陷浓度,表明掺杂量子点具有很好的双光子吸收现象。     

Large nonlinear optical properties of Fe2O3 nanoparticles

Nonlinear optical properties of Fe₂O₃ nanoparticles were investigated by the signal-beam Z-scan technique with Ar⁺ and Ne–He lasers. The largest reported effective nonlinear coefficient, n₂=−8.07×10⁻⁷ cm²/W, was obtained. It is demonstrated that the nonlinear optical response originals from quantum confinement effect.     

Study of Nonlinear Optical Properties of Organic Material Utilizing Two－color Z－scan

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Investigation of optical nonlinearities in Pd(po)2 by Z-scan technique

With nanosecond scale at a 532 nm wavelength, we firstly measured the nonlinear optical absorption and refraction coefficients of Pd(po)₂ complex by using Z-scan technique, here Hpo=1-hydioxy-2-pyridone. We describe an empirical expression for the case when nonlinear refraction is accompanied by nonlinear absorption to separately evaluate the nonlinear refraction and the nonlinear absorption by performing straightforward measurements with the aperture removed. The nonlinear optical response of Pd(po)₂ was determined by the linear decreasing irradiance-dependence. The nonlinear absorption originates from the near resonant two-photon absorption while the mechanism of the nonlinear refraction is the near resonant two-photon absorption transition enhancement. The linear increasing dependences of the optical nonlinearities on the incident irradiance arise from the population redistribution due to the near resonant two-photon absorption.     

Orientational order parameter and rotational viscosity in C60 doped E7 nematic liquid crystal

The reorientational order parameter dependent complex linear susceptibilities are derived based on the angular averaged linear response theory of the molecular polarizability, which includes the Vuks type equations of anisotropic refractive indices and absorbances. The polar angular absorbance at 633 nm wavelength is measured as a function of the concentration of fullerene C₆₀ in E7 nematic liquid crystals (NLCs), from which the order parameter is deduced. It is shown that the order parameter has a linear dependence of dopant concentration. We also present a simple optical transmission method by adopting the closed-aperture Z-scan geometry under the influence of switching on and off the dc electric field to determine the optical relaxation time and the rotational viscosity coefficient of C₆₀ doped E7 NLC. The experimental results are pretty well explained by using the Osipov-Terentjev theory of the rotational viscosity with the measured order parameter.     

Sensitivity of Z-scan using diffraction efficiency

We report Z-scan and eclipsing Z-scan experimental traces measuring diffraction efficiency in the image plane of the 4f system. Using nonlinearly diffracted energy, the sensitivity of both techniques is compared in order to increase the signal-to-noise ratio. The optimization of the optical signal for nonlinear characterization is proposed. A simple linear relation is provided in order to characterize nonlinear refraction from diffraction efficiency measurements. The influence of the nonlinear absorption is discussed.     

Measurement of nonlinear refractive index of pure and doped KTP crystals by Z-scan technique using cw He–Ne Laser

Single crystals of pure, Mo and W doped KTP crystals were grown by flux technique. The grown crystals were subjected to various characterization studies such as EDX, powder XRD, FTIR and UV analysis. The SHG efficiencies of the pure and doped KTP crystals were measured by Kurtz–Perry technique and it was found that the doped KTP crystals exhibit higher values of SHG. Nonlinear refractive indexes were measured on different growth planes of pure and doped crystals by Z-scan method using a cw (continuous wave) He–Ne laser at 632.8 nm. The measured values of nonlinear refraction of different planes were in the order of 10⁻¹² cm²/W.