衍射透镜的精确设计方法

根据光线在基板和衍射层中实际光路作者导出了衍射透镜的精确设计计算公式,基于这种公式设计出的微透镜的成象质量优于基于简化公式设计的衍射透镜.本文介绍这些严密的设计公式和设计过程,给出了工作波长λ=0.6328μm、直径2R=300μm、基板(折射率ns=1.51)厚1000μm、衍射层折射率nd=1.56的微透镜设计面形以及象点的能量分布.     

非线性包层光纤中TE0模的传播特性分析

本文对具有Kerr非线性包层和线性匀芯的光纤在不同光功率下的传播特性进行了理论分析和数值计算.结果表明,在适当光功率下,当模折射率N等于芯折射率n_f时,芯场变得相当均匀,而包层场迅速衰减.对于自聚焦包层,当从N<n_f逐渐变到N>n_f时,芯场剖面越过N=n_f从凸变凹.在拐点,芯场成为均匀的.论文给出了模场分布和光功率与模折射率的关系.指出纤芯出现匀场预期会在光纤器件、光电子器件、光子器件中得到应用.     

LiBX2 (B=Ga, In; X= S, Se, Te)光学性质与力学性质的第一性原理计算

采用基于第一性原理的赝势平面波方法系统地计算了LiBX₂ (B= Ga, In; X= S,Se,Te) 晶体的光学性质与力学性质. 由禁带宽度推断出晶体抗激光损伤阈值的大小顺序为LiGaS₂ > LiInS₂ > LiGaSe₂ > LiInSe₂ > LiGaTe₂ > LiInTe₂. 六种晶体在常压下均满足机械力学稳定性要求, 且铟化合物可塑性及延展性强于镓化合物. 这些晶体的静态电介电常数 ε₁(0)、静态折射率n(0)和双折射率Δn 理论计算值与实验值相符. LiGaS₂, LiInS₂, LiGaSe₂, LiInSe₂和LiGaTe₂五种化合物双折射率较高, 并且它们的吸收谱与反射谱在中远红外区是透过的, 因此可推断出这五种化合物可以成为优异的中远红外非线性光学材料.     

Z-切Ti:LiNbO3平面波导模式数量的色散特性

对于在流动干氩气中扩散而形成的Z-切Ti:LiNbO₃平面波导,用Fouchet等人提出的钛感应折射率增量在0.6～1.6μm波长范围内的色散关系,推得与扩散参数有显函数关系的模式数量的色散公式。在若干重要波长,用这些色散公式,画出模式数量和扩散参数的关系曲线,可用来控制相应波导和器件的模式数量。     

一维金属-介质周期结构的自准直特性和亚波长成像

计算了一维金属-介质周期结构(1DMD)的色散曲线，利用传输矩阵法模拟了该结构对入射高斯光束的自准直作用，着重讨论了金属层吸收的影响；对该结构在半波长厚度时近场成像特性进行了分析，单光源的成像分辨率为λ/8，达到亚波长分辨效果；分辨率随着光源逐渐远离近场范围而降低. 双狭缝的成像模拟进一步验证了1DMD结构的近场亚波长成像能力，分辨率达到λ/3.     

线性剖面克尔材料分层板波导中光波的传播

对三层板波导中光波传播问题进行了讨论.芯材料是克尔型介质,其折射率平方(n²)剖面分布随x作线性变化.此时芯区的亥姆霍兹方程约化为Painleve方程,利用Laurant级数可得到其近似解.     

Wn(n=3—27)原子团簇结构的第一性原理计算

使用密度泛函理论下的第一性原理方法，对W_n原子团簇(n=3—27)的结构特性进行了理论计算. 得到了W_n团簇(n=3—7)的最低能量结构和(n=8—27)的局域能量极小的典型结构. 使用凝胶模型，提出的电子组态1s²1p⁶1d¹⁰2s²1f¹⁴2p⁶3s     

同步测量大气湍流折射率结构常数和内尺度的光学方法

 基于不同波长的光闪烁,采用修正的大气湍流Hill谱模型,提出了一种同时反演大气湍流内尺度及折射率结构常数的方法。假定内尺度在某一个范围内取值,对于不同波长的闪烁指数,如果当内尺度取某一定值时,由光传输理论计算的C²_n(λ₁,…)和C²n (λ₂,…)相等,反演成功。根据此原理设计了三波长闪烁计并在某地进行了外场测量。近地面大气湍流的内尺度一般在2~10 mm之间,且随折射率结构常数（其量级为10^-16~10^-13）的变化而变化,两者之间存在一定的正相关;任意两波长组合进行反演得到的内尺度(或折射率结构常数)值具有自洽性,其相关系数的最小值为0.81,因此证明了该方法的可行性。     

光纤—光波导耦合膜层的研究

本文研究了铌酸锂单晶片与石英系光纤之间的耦合问题,以使集成光学器件逐步实用化。石英光纤的折射率在1.45左右,铌酸锂单晶折射率在2.2左右,为改善其间的耦合,我们采用电子迴旋共振微波等离子体化学气相沉积方法,在铌酸锂基片上制备出折射率n为1.78的氮氧化硅膜,并控制其厚度为λ_g/4(λ_g=1.52μm),已使反射率下降73%,可望进一步改善。     

Nd:LMA自锁模飞秒激光器腔结构最佳化设计

Nd:LMA晶体相对低的非线性折射率n₂,使得针对Ti:Sapphire自锁模激光器设计的腔,对Nd:LMA介质而言并没有提供足够的自幅度调制(SAM).为了在Nd:LMA激光器上实现自锁模,在腔内引入一个具有大的非线性系数n₂、快的响应时间的SF57介质,这样就使得激光腔的结构比较特殊.在这篇文章里利用ABCD传输矩阵对该激光器的结构从理论上进行了分析和计算,使腔结构达到了最佳化设计.     

石榴石外延膜色散关系的确定和膜厚的测量

本文提出了确定石榴石外延膜的色散关系和测量膜厚的一种方法。充分利用分光光度计获得的透射光谱,在波长大于2μm,因而膜和衬底的吸收及色散近于可忽略时,由透过率的极值计算得到相应波长下膜的折射率。按干涉条件计算并推定出所有干涉极值的干涉级数,进而算出各干涉极值波长下膜的折射率。最后用最小二乘法求得科希色散公式的系数,从而得到该膜的色散关系。利用此色散关系就可计算膜厚。 关键词：     

石英晶体的色散方程及折射率温度系数

研究了石英晶体在不同温度下折射率随波长的变化规律.通过对Sellmeier方程严格求解,得出了其系数表达式,计算出了不同波长对应的折射率,经验证与实验值符合得很好.通过曲线拟合求解出了折射率温度系数表达式,由此式可计算出不同波长折射率温度系数;进一步求解出了Sellmeier方程常量随温度变化地数值,得到求解不同温度任意波长的石英晶体主折射率的一种方法.     

光纤材料折射率的温度和非线性特性

用半经典理论研究了光纤材料的线性和非线性折射率,以及它们与温度的关系,并研究了零色散点与温度的关系,理论与实验相符。 关键词：     

Interferometric determination of the refractive indices and birefringence of some highly oriented fibres

Variable wavelength interferometric technique (VAWI) is a direct method for determining the refractive indices and birefringence of highly oriented fibres. This method uses the polarizing interference Pluta microscope with a monochromatic light from wedge interference filter that provides a continuously variable wavelength. The standard calibration process of the Pluta polarizing interference microscope is carried out and a calibration graph is obtained. The refractive indices and birefringence of PEN, CONEX and TECHNORA were measured over the visible range of the spectrum and the constants for the Cauchy's dispersion formula were determined. The oscillation and dispersion energies were calculated from the measurements of the refractive index.     

Evaluation of Influence of Multiple Scattering Effect in Light-Scattering-Based Applications

The extinction cross sections of a system containing two particles are calculated by the T-matrix method, and the results are compared with those of two single particles with single-scattering approximation. The necessity of the correction of the refractive indices of water and polystyrene for different incident wavelengths is particularly addressed in the calculation. By this means, the volume fractions allowed for certain accuracy requirements of single-scattering approximation in the light scattering experiment can be evaluated. The volume fractions calculated with corrected refractive indices are compared with those obtained with fixed refractive indices which have been rather commonly used, showing that fixed refractive indices may cause significant error in evaluating multiple scattering effect. The results also give a simple criterion for selecting the incident wavelength and particle size to avoid the ＇blind zone＇ in the turbidity measurement, where the turbidity change is insensitive to aggregation of two particles.     

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Optical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4′-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4′-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.     

Interferometric determination of refraction and dispersion of human blood-serum, saliva, sweat and urine

Multiple-beam interference fringes of equal chromatic order are produced in air and liquid sample interferometric gaps. The two gaps are of the same thickness and simultaneously enclosed in a wedge interferometer. A single shot interferogram containing fringes in the two gaps is sufficient to deduce the needed experimental data. Locations of the fringe maxima, in the two gaps, are introduced in a non-numerical procedure for determining the gap thickness and the liquid-phase refractive indices across the visible spectrum. The method has been used for measuring the phase refractive indices of human blood-serum, saliva, sweat, urine and water liquids. A third-order polynomial dispersion relation is applied for fitting the measured phase indices. Group refractive indices have been derived and fitted to the same dispersion formula.     

Accurate prediction of refractive index of inorganic oxides by chemical formula

A method is proposed for estimation of mean refractive index of a complex inorganic oxide whose chemical composition is known. This method is based on using mean refractive indices of simple oxides. Applicability of the method has been tested for a representative set of ∼120 known oxide crystals. It has been shown that mean refractive index can be predicted with possible error of 0-15% depending on the chemical nature of the compound. The majority of oxides show acceptable difference <5% between theoretical and experimental refractive index values and the mean error level for a set of 124 oxide crystals is as low as ∼5%. Refractive indices of a set of simple oxides are estimated by the Lorenz-Lorentz relation. Full table of refractive indices of simple oxides for all elements of Periodic Table is proposed.     

On the problem of calculating the optical film parameters from the measured transmission spectra

The procedure for calculating the dispersion of the refractive and absorption indices and thickness of an optical film, based on measurements of spectral dependence of the transmittance, is described. The film parameters are calculated using a solution of the approximation problem. The effect of the film model on the calculated values of the refractive and absorption indices is analyzed.