稀土材料的超快共振非线性光学特性研究

用抽运-探测技术测量光学响应材料非线性极化率的方法，研究了稀土材料非线性折射率的共振增强和超快响应的非线性动力学过程。测得钕玻璃的三阶非线性折射 率强度系数为10^-14cm^2/W，比其基质的非线性折射率强度系数提高了2个量级。用该方法研究了Nd:YVO4、Er:YAG等晶体的超快非线性响应过程。实验结果与理论分析表明，抽支-探测技术是测量非线性极化率的简单而又灵敏的方法。这一测量技术对研究与开发超高速光响应器件具有重要的实用价值。     

测量慢弛豫介质的非线性折射率Z扫描方法

对非线性折射率慢弛豫介质的Z扫描理论进行了详细推导,得到了透射光场的表达式.分析表明:对于慢弛豫介质,其Z扫描过程也是非线性折射的累积过程.实验结果与理论分析一致. 关键词：     

相位物体Z-扫描研究金属簇合物[Tp*W(μ3-S)3Cu3Py3(μ3-Br)](PF6)/DMF溶液的瞬态热致非线性折射

在纳秒时域,采用相位物体(PO)Z-扫描技术研究了一种新型金属簇合物溶液的瞬态热致非线性效应.该方法的最大优点是很容易区分瞬态热致非线性折射和三阶非线性折射.本文利用PO Z-扫描和传统Z-扫描研究了在8 ns脉宽、不同能量激光脉冲作用下[Tp*W(μ3-S)3Cu3Py3(μ3-Br)](PF6)/DMF溶液的光学非线性.从声波方程和热传导方程出发,对实验结果进行了理论分析和数值模拟,理论值和实验结果很好的吻合.研究结果表明,样品溶液的非线性折射主要来源于瞬态热致非线性效应.     

利用单光束测量掺有叶绿素-α的有机聚合材料的光学非线性折射率

本文研究了利用单光束纵向扫描法测量介质的光学非线性折射率n_2中,介质的线性吸收对测量结果的影响,指出样品的吸收使得纵向扫描方法的测量范围减小,测量精度降低,在实验上,利用纵向扫描法测量了一种掺有叶绿素-α的有机聚合材料的非线性折射率,获得的n_2为3.4×10~(-9)esu,对实验结果的分析表明,材料的非线性折射来源于有机材料的共轭π电子效应.     

Fe2O3纳米微粒溶胶非线性光学特性的Z-扫描研究

利用Z扫描技术在透明区域研究了Fe₂O₃纳米微粒水溶胶和表面包覆有机溶胶的非线性光学特性，给出了非线性折射率γ、双光子吸收系数β、自由载流子折射系数σ_r和自由载流子吸收截面σ_ab等重要物理参数，讨论了自由载流子效应对Fe₂O₃纳米微粒非线性特性的影响 关键词：     

透明和吸收介质非线性参数n2,X^（3）及其时间响应特性研究

对透明和吸收介质的简并四波混频理论作了处理,实验上给出了掺半导体玻璃,无机和有机材料的三阶非线性极化率x~(3)和非线性折射率n_2的值,而且确定了非线性参数x~(3)的时间响应特性,实验装置的时间分辨率为5ps.     

3～5μm角度调谐LiNbO3晶体光参量振荡器的技术研究

用LiNbO₃作参量晶体、调QNd:YAG(1.064μm)激光器做泵源,通过求出相位匹配点对有效非线性系数进行数值计算,找出有效非线性系数的最大值,从而求出该点对应的相位角和方位角,确定出进行角度调谐LiNbO₃晶体的切割角在理论计算过程中,用计算机模拟,得出了OPO的角度调谐曲线、有效非线性系数曲线和参量增益曲线实验研究中实现了369μm单点参量光输出,实验结果与理论计算结果相吻合.     

LN晶体自散焦到自聚焦转换的耦合理论分析

对铌酸锂晶体进行了三阶非线性折射系数测量的Z扫描实验和光折变非线性系数测量的时间扫描实验。为了分析时间分辨扫描曲线的特点，基于非线性介质中光折变非线性与三阶非线性光学效应的耦合作用，引入非线性折射率随时间变化的表达式，分析了空间亮孤子的形成过程，进而揭示了其在一定条件下从自散焦到自聚焦转换的动态行为的物理机制,得到了与实验现象相一致的结论，并说明了自聚焦光折变晶体中可能存在稳定的暗空间孤子。     

透明和吸收介质非线性参数n2,χ(3)及其时间响应特性研究

对透明和吸收介质的简并四波混频理论作了处理,实验上给出了掺半导体玻璃,无机和有机材料的三阶非线性极化率χ(3)和非线性折射率n2的值,而且确定了非线性参数χ(3)的时间响应特性,实验装置的时间分辨率为5 ps.     

用Z-scan法研究非线性介质中的热效应

从热传导方程出发,研究了脉冲激光作用下因样品线性和非线性吸收引起热效应而产生的折射率变化.从理论分析得出,当仅存在线性吸收时,非线性折射率的概念在通常情况下并不适合于由热效应产生的非线性,但在所用的激光脉冲很短的情况下,类似于其它非线性的各种效应,对热效应也可定义时间平均非线性折射率,并可用Z-scan法对这两类吸收感生的不同非线性折射率进行测量.所得结论符合实验结果.     

Determinations of the transient thermal lensing effect in metal cluster Polymer {WS4Cu4I2(bpe)3}n solution by the use of the Z-scan

The nonlinear optical (NLO) properties of a novel cluster Polymer {WS₄Cu₄I₂(bpe)₃}_n solution are studied by using Z-scan technique with laser pulses of 4.5 ns pulse-width at a wavelength of 532 nm. The results show that the cluster solution possesses strong nonlinear absorption and refraction. Nonlinear refraction of the cluster is composed of third-order nonlinear refraction and transient thermal effect. The thermal effect is mainly due to the strong nonlinear absorption. Numerical simulations obtained by solving simultaneously photo-acoustic and electromagnetic wave equations, agrees basically with experimental results.     

Nonlinear optical response of inorganic metal cluster MoCu3Se4(PPh3)3Cl solution

The pump-probe response of the metal cluster MoCu₃Se₄(PPh₃)₃/CH₂Cl₂ solution is similar to that of CBS, which implies a nonlinear scattering origin of its nonlinearity. To testify how much the nonlinear scattering contributes to the optical limiting process, we employ a method by inserting a light collection lens in a standard OL experimental setup. Results from such an experiment show that nonlinear scattering is important when the concentration is low. For a high-concentration sample, the nonlinear energy loss is mainly related to thermal induced nonlinear absorption.     

高掺镁LiNbO3晶体折射率温度系数的表示式

推导了掺５ｍｏｌ％ＭｇＯ的ＬｉＮｂＯ３晶体折射率温度系数的表示式。利用这些表示式可以计算２９３～４２８Ｋ温度和０．５３９８μｍ～１．３４１４μｍ波长范围内的折射率温度系度，结果表明：计算值和实验值的最大相对偏差是１２％，用具有最大相对偏差的折射率温度系数的计算值，计算１．０７９５μｍ波长的非临界相位匹配温度，其值为３８２．４Ｋ，它与实验值仅差６Ｋ。因此，本文得到的表示式，对于采用这种晶体，设计在上     

K2O-ZnO-Al2O3-B2O3-SiO2系掺Cr3+透明莫来石微晶玻璃的研究

采用了X射线衍射、透射电镜和吸收光谱及荧光光谱技术研究了K2O－ZnO-Al2O3-B2O3－SiO2系掺Cr^3 玻璃的析晶性能和光谱。研究结果表明：在K2O－Al2O3-B2O3-SiO2系掺Cr^3 玻璃的基础上引入ZnO后，析晶性能明显改善；析晶温度降低，析出的纳米莫来石微晶均匀、规则；微晶玻璃的发光强度明显增强。     

Diffusion Dynamics of Cux Cluster on Cu(111) Surface

利用分子动力学与修正分析型嵌入原子模型研究了从200K至800 K范围内,Cux (1·x·8)小团簇在(111)面的自扩散动力学行为,计算了Cu小团簇的扩散系数与激活能. 计算结果表明,密排的Cu7团簇的激活能最高,其扩散前因子比单个吸附原子的高3个数量级,这与其他类似金属的实验结果一致. 另外,还定量讨论了薄膜生长与团簇扩散的关系.     

Band structure and cluster model calculations of LaNiO3 compared to photoemission,O 1s X-ray absorption,and optical absorption spectra

We studied the electronic structure of LaNiO₃ using band structure and cluster model calculations. This compound is a paramagnetic metal with a R3?c rhombohedral structure. The band structure was calculated using the generalized gradient approximation (GGA). The cluster model was solved using the configuration interactions (CI) many-body method. We present results for the density of states (DOS), the spectral weight, and the dielectric function ${\epsilon }_2$. The calculations are compared to previous photoemission (PES), O 1s X-ray absorption (XAS), as well as optical absorption spectra. Both band structure and cluster model results are in good agreement with the experimental data. We point out that this concordance is very rare and far from trivial; we argue that this may be due to the unusual characteristics of the ground state of LaNiO₃.     

Photoluminescence in γ-irradiated α-quartz investigated by synchrotron radiation

We report an experimental investigation of the photoluminescence, under excitation by synchrotron radiation within the absorption band at 7.6 eV, induced in γ-irradiated α-quartz. Two emissions centered at 4.9 and 2.7 eV are observed at low temperature: the former decreases above 40 K, whereas the second band exhibits an initial slight increase and its quenching is effective above 100 K. Furthermore, the decay kinetics of both emissions occur in a time scale of nanoseconds: at T=17.5 K we measured a lifetime τ1.0 ns for the photoluminescence at 4.9 eV and τ3.6 ns for that at 2.7 eV. These results give new insight on the optical properties associated with defects peculiar of crystalline matrix, also on the basis of their comparison with previous studies on silica.     

Electron paramagnetic resonance of Gd3+ in PbTe

X-band EPR measurements have been made on single crystals of lead telluride doped with gadolinium in nominal concentrations of 0.04, 0.1, 0.5, and 1.0 atomic %. Fully resolved fine structure appropriate to Gd³⁺ ions in sites of cubic symmetry was observed in the temperature range from 4.2 K to 300 K. The parameters of the spin Hamiltonian were determined from the spectra by diagonalization of the Hamiltonian matrix and the use of a nonlinear least-squares program. The three parameters are independent of concentration and at 4.2 K have the values g=1.9908 ± 0.0002, b₄= ?110.16 ± 0.08 MHz and b₆ = +2.40 ± 0.02 MHz respectively. The parameter b₄ is temperature dependent; the other parameters are not, to within experimental accuracy. An additional resonance line, possibly analogous to the “cluster” line observed in metallic systems, was seen near g=2.     

适用于全光开关的[(C3H7)4N][Au(C3S5)2]三阶非线性光学性质研究

合成了一种金属有机配合物[(C3H7)4N][Au(C3S5)2].配制了浓度为1×10－3 mol/L的[(C3H7)4N][Au(C3S5)2]/乙腈溶液,并用旋涂法制备了掺杂浓度质量比为1%的[(C3H7)4N][Au(C3S5)2]/PMMA复合薄膜.运用Z扫描方法,分别研究了样品溶液和薄膜在波长为1 064 nm,脉宽为20 ps条件下的三阶非线性光学性质.研究发现薄膜的三阶非线性极化率χ(3)比溶液高出三个数量级.其中,薄膜的非线性折射率n2为－1.76×10－15 m2/W、三阶非线性极化率χ(3)为9.37×10－10 esu.结果表明,该材料在全光开关方面具有潜在的应用价值.