Laser-induced damage threshold of ZrO2 thin films prepared at different oxygen partial pressures by electron-beam evaporation

ZrO2, films were deposited by electron-beam evaporation with the oxygen partial pressure varying from 3 X 10(-3) Pa to I I X 10(-3) Pa. The phase structure of the samples was characterized by x-ray diffraction (XRD). The thermal absorption of the films was measured by the surface thermal lensing technique. A spectrophotometer was employed to measure the refractive indices of the samples. The laser-induced damage threshold (LIDT) was assessed using a 1064, nm Nd: yttritium-aluminium-garnet pulsed laser at pulse width of 12 ns. The influence of oxygen partial pressure on the microstructure and LIDT of ZrO2 films was investigated. XRD data revealed that the films changed from polycrystalline to amorphous as the oxygen partial pressure increased. The variation of refractive index at 550 nm wavelength indicated that the packing density of the films decreased gradually with increasing oxygen partial pressure. The absorptance of the samples decreased monotonically from 125.2 to 84.5 ppm with increasing oxygen partial pressure. The damage threshold, values increased from 18.5 to 26.7 J/cm(2) for oxygen partial pressures varying from 3 X 10(-3) Pa to 9 X 10(-3) Pa, but decreased to 17.3 J/cm(2) in the case of I I X 10(-3) Pa. (C) 2005 American Vacuum Society.

The study on the interface adhesion comparison of the MgF2, Al2O3, SiO2 and Ag thin films

Adhesion between the interface of pure silver thin film and three kinds of low refractive index coatings MgF2, Al2O3, SiO2 were compared in this article. The results indicated that the adhesion of Al2O3 and Ag was evidently superior to that of MgF2 and Ag, and the adhesion of MgF2 and Ag was evidently superior to that Of SiO2 and Ag. Reasons were analyzed accordingly. On the other hand, we compared the effect on the optical characteristic of Ag film when these three kinds of films were used as protective coatings and enhanced coatings. Considering the difference of the adhesion between Ag and MgF2, Al2O3, SiO2, suited uses are given for each other. © 2004 Elsevier B.V. All rights reserved.

Extended bidirectional reflectance distribution function for polarized light scattering from subsurface defects under a smooth surface

By introducing the scattering probability of a subsurface defect (SSD) and statistical distribution functions of SSD radius, refractive index, and position, we derive an extended bidirectional reflectance distribution function (BRDF) from the Jones scattering matrix. This function is applicable to the calculation for comparison with measurement of polarized light-scattering resulting from a SSD. A numerical calculation of the extended BRDF for the case of p-polarized incident light was performed by means of the Monte Carlo method. Our numerical results indicate that the extended BRDF strongly depends on the light incidence angle, the light scattering angle, and the out-of-plane azimuth angle. We observe a 180 degrees symmetry with respect to the azimuth angle. We further investigate the influence of the SSD density, the substrate refractive index, and the statistical distributions of the SSD radius and refractive index on the extended BRDF. For transparent substrates, we also find the dependence of the extended BRDF on the SSD positions. (c) 2006 Optical Society of America.

沉积参量及时效时间对SiO2薄膜残余应力的影响

SiO2薄膜由电子束蒸发方法沉积而成。用GPI数字波面光学干涉仪测量了不同沉积条件下玻璃基底镀膜前后曲率半径的变化，并确定了SiO2薄膜中的残余应力。在其他条件相同的情况下，当沉积温度由190℃升高到350℃时，SiO2薄膜中的压应力由一156MPa增大为-289MPa。氧分压由3．0×10^-3Pa升高到13．0×10^-3Pa时，SiO2薄膜中的应力由-223．5MPa变为20．4MPa。通过对薄膜折射率的测量，发现薄膜的堆积密度随沉积条件的改变也发生了规律性的变化。应力的变化主要是由于沉积时蒸发粒子

Laser-induced damage threshold of ZrO2 thin films prepared at different oxygen partial pressures by electron-beam evaporation

ZrO2, films were deposited by electron-beam evaporation with the oxygen partial pressure varying from 3 X 10(-3) Pa to I I X 10(-3) Pa. The phase structure of the samples was characterized by x-ray diffraction (XRD). The thermal absorption of the films was measured by the surface thermal lensing technique. A spectrophotometer was employed to measure the refractive indices of the samples. The laser-induced damage threshold (LIDT) was assessed using a 1064, nm Nd: yttritium-aluminium-garnet pulsed laser at pulse width of 12 ns. The influence of oxygen partial pressure on the microstructure and LIDT of ZrO2 films was investigated. XRD data revealed that the films changed from polycrystalline to amorphous as the oxygen partial pressure increased. The variation of refractive index at 550 nm wavelength indicated that the packing density of the films decreased gradually with increasing oxygen partial pressure. The absorptance of the samples decreased monotonically from 125.2 to 84.5 ppm with increasing oxygen partial pressure. The damage threshold, values increased from 18.5 to 26.7 J/cm(2) for oxygen partial pressures varying from 3 X 10(-3) Pa to 9 X 10(-3) Pa, but decreased to 17.3 J/cm(2) in the case of I I X 10(-3) Pa. (C) 2005 American Vacuum Society.

基底微缺陷对介质薄膜光学性能影响的理论研究

基于非均匀膜理论提出一种存在微缺陷的介质基底的折射率分层模型，将基底依次分为表面层、亚表面层和体材料层，其中表面层和亚面层分别等效为折射率服从统计分布的非均匀膜，将它们分别再次细分为N1和N2个子层，每一子层均视为均匀介质膜．应用光学薄膜特征矩阵法对其进行理论分析，并对单层介质膜的光学性能进行数值计算．研究结果表明：基底的表面和亚表面微缺陷改变了薄膜和基底的等效折射率，导致了准Brewster角和组合反射率与理想情形的偏离．同时这些微缺陷也改变了光在薄膜和基底中的传播特性，因此反射相移和相位差均偏离理想情

氧分压对电子束蒸发SiO2薄膜机械性质和光学性质的影响

采用ZYGO MarkⅢ-GPI数字波面干涉仪、NamoScopeⅢa型原子力显微镜对不同氧分压下电子束蒸发方法制备的SiO2薄膜中的残余应力及表面形貌进行了研究，结果发现：随着氧分压的增大，薄膜中的压应力值逐渐减小，最后变为张应力状态；同时薄膜的表面粗糙度也随着氧分压的增大而逐渐增大，另外，折射率对氧分压也非常敏感，随着氧分压的增大呈现出了减小的趋势，这些现象主要是由于氧分压的改变使得SiO2薄膜结构发生了变化引起的。

Modelling analysis of influence of substrate surface defect on optical characteristics of single-layer coating

A simple and practical model is used to analyse the influence of substrate surface defect on the optical characteristics of a single-layer coating. A single-layer coating is prepared and its optical properties are fitted. Some explanations for the origin of the transition layer are presented. It is concluded that there is a transition layer forming between the substrate and coating, which is attributed to substrate surface defects, and its refractive index change is nearly of linearity.

共蒸法制备非均匀膜的速率控制分析

渐变折射率薄膜，又称为非均匀膜。利用德鲁德理论分析了混合介质膜的介电常量与各个膜料的介电常量之间的关系，介绍了共蒸法制备非均匀膜的制备机理。对混合膜的沉积速率为两种膜料的沉积速率之和的情况，分别从两种膜料的单分子体积是否相等和总的沉积速率是否为常数两个方面，探讨了双源共蒸法制备的非均匀膜的折射率分布规律与膜料的沉积速率之间的关系，并给出了几种常见的折射率分布如线性变化、正弦变化、指数变化和双曲变化规律的膜料沉积速率表达式。最后以混合介质膜的总沉积速率为常数、折射率按照线性变化为例进行了说明。

线性共蒸法制备渐变折射率薄膜的光学特性分析

利用德鲁德理论和洛伦兹一洛伦茨理论，从介电常数分析人手，探讨了混合介质膜的折射率表达式，给出利用双源共蒸法镀制的渐变折射率薄膜在混合介质膜的总沉积速率恒定、两种膜料的单分子大小近似相等和沉积速率均为线性变化时的折射率表达式；从正变和负变、单周期和多周期、不同的周期数和不同的单周期厚度几个方面对渐变折射率薄膜的光学特性进行了模拟分析和讨论；对渐变折射率薄膜的实现、应用以及实验制备中有待进一步解决和处理的问题进行了讨论。

倾斜角沉积技术制备ZnS双折射雕塑薄膜

使用倾斜角沉积（GLAD）的电子束蒸发技术，制备了倾斜角度在60°～85°之间的ZnS双折射雕塑薄膜（STF）。使用X射线衍射（XRD）和扫描电镜（SEM）检测了ZnS薄膜的结晶状态和断面形貌，使用Lamda-900分光光度计测量了薄膜在不同的偏振光入射时的透过率。研究发现，室温下倾斜沉积ZnS薄膜断面为倾斜柱状结构，且薄膜的结晶程度不高。在相同的监控厚度时，随倾斜角度增大，沉积到基片上的薄膜厚度逐渐变小，但仍然大于余弦曲线显示的理论厚度。根据偏振光垂直入射时薄膜的透过光谱计算了不同角度沉积的薄膜的折射率

Influence of LiB3O5 structure on microstructure and optical properties of ZrO2, thin films prepared by electron beam evaporation

ZrO2 thin films were deposited bill using an electron beam evaporation technique on three kinds of lithium triborate (LiB3O5 or LBO) substrates with the surfaces at specified crystalline orientations. The influences of the LBO structure on the structural and optical properties of ZrO2 thin films are studied by spectrophotometer and x-ray diffraction. The results indicate that the substrate structure has obvious effects on the structural end optical properties of the film: namely. the ZrO2 thin film deposited on the X-LBO, Y-LBO and Z-LBO orients to m(-212), m(021) and o(130) directions. It is also found that the ZrO2 thin film with m(021) has the highest refractive index and the least lattice misfit.

利用分光光度计测量光学晶体的折射率

晶体折射率的准确测定是晶体上薄膜器件设计的基础。介绍了利用分光光度计测量晶体折射率的方法，通过背面影响系数法、背面镀增透膜和将两者结合起来的方法消除晶体反射率测量时背面反射带来的影响，给出了具体的步骤并对测量误差进行了分析。由于晶体的光学各向异性，采用起偏器扫描的方法测量晶体光学性质随方向的变化。通过对LiB3P5晶体的折射率的测量，证实了该方法的可行性并可用于其他光学晶体折射率的测量。

Optimization of near-field optical field of multi-layer dielectric gratings for pulse compressor

Multi-layer dielectric (MLD) gratings for pulse compressors in high-energy laser systems should provide high diffraction efficiency as well as high laser induced damage thresholds (LIDT). Nonuniform optical near-field distribution is one of the important factors to limit their damage resistant capabilities. Electric field distributions in the gratings and multi-layer film region are analyzed by using Fourier modal method. Optimization of peak electric field in the gratings ridge is performed with a merit function, including both diffraction efficiency and electric field enhancement when the top layer material is HfO2 and SiO2, respectively. A set of optimized gratings parameters is obtained for each structure, which reduce the peak electric field within the gratings ridge to being respective 1.39 and 1.84 times the value of incident light respectively. Finally, we also discuss the effects of gratings refractive index, gratings sidewall angle and incident angle on peak electric field in the gratings ridge. (c) 2006 Elsevier B.V. All rights reserved.

Antireflective characteristics of triangular shaped gratings

The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function of grating period, filling factor, and groove depth, and the antireflective characteristics are also studied when visible-infrared light is incident upon them. Numerical examples are given for gratings on glass substrate with refractive index of 1.5. The results show that this kind of grating is capable of reducing reflections, and could achieve very low reflectivity over a wide field of view and a wide waveband by choosing appropriate parameters.