50～11O nm波段高反射率多层膜的设计与制备

阐述了50～110 nm强吸收波段亚四分之一波长多层膜的设计方法.这种膜系是由强吸收材料叠加而成,每层膜光学厚度小于四分之一个波长.与常规周期多层膜相比,这种膜系更适用于提高强吸收波段的反射率.利用该方法设计了50 nm处高反射多层膜,并以此为初始条件通过Levenberg-Marquart优化方法完成了50～110 nm强吸收波段宽带高反射率Si/W/Co多层膜的设计,其平均反射率达到45%.采用直流磁控溅射方法制备了Si/W/Co多层膜,用X射线衍射仪(XRD)对膜层结构进行了测试,测试结果表明制作出的多层膜结构与设计结构基本相符.     

50~110 nm波段高反射率多层膜的设计与制备

阐述了50~110 nm强吸收波段亚四分之一波长多层膜的设计方法.这种膜系是由强吸收材料叠加而成，每层膜光学厚度小于四分之一个波长.与常规周期多层膜相比，这种膜系更适用于提高强吸收波段的反射率.利用该方法设计了50 nm处高反射多层膜，并以此为初始条件通过Levenberg-Marquart优化方法完成了50~110 nm强吸收波段宽带高反射率Si/W/Co多层膜的设计，其平均反射率达到45%.采用直流磁控溅射方法制备了Si/W/Co多层膜,用X射线衍射仪(XRD)对膜层结构进行了测试，测试结果表明制作出的多层膜结构与设计结构基本相符.     

基于电阻膜与分形频率选择表面的超薄宽频带超材料吸波体的设计

设计了一种基于一阶Minkowski分形双方环(Minkowski fractal double square loop, MFDSL)电谐振器结构与电阻膜复合的超薄、 宽频带、极化不敏感和宽入射角的超材料吸波体. 该吸波体的基本结构单元由MFDSL电谐振器结构、方块电阻膜、电介质基板和金属背板组成. 采用时域有限差分算法对这种复合结构吸波体的电磁波吸收特性进行数值模拟分析. 模拟得到的反射率和吸收率表明: 该吸波体在7.5-42 GHz之间对入射电磁波具有大于90%以上的强吸收特性. 模拟得到的不同极化角和不同入射角下的吸收率表明: 该吸波体具有极化不敏感和宽入射角特性. 进一步的数值模拟结果表明, 该复合结构吸波体对电磁波的吸收主要是基于电磁谐振和电路谐振机制, 通过方块电阻的设计可以实现工作频率范围的调节. 关键词： 电阻膜 分形频率选择表面 宽频带吸收     

一类Cantor分形吸收薄膜系的反射率

讨论了一类含有吸收介质的Cantor分形薄膜系，计算了该膜系的反射率，并讨论了膜系反射谱的性质．与不含吸收介质的情形不同，该膜系的全部反射谱并不呈现自相似性，但此反射谱高于一定频率的部分在一定条件下却仍是近似自相似的 关键词：     

一类多标度分形介质膜系的反射率

应用鲁阳德（Ｒｏｕａｒｄ）递推方法计算光在垂直入射时二标度和三标度分形介质膜系的反射率。结果表明,多标分形介质膜系的反射率具有分形的自相似特征。     

宽截止窄带高反射滤光膜设计

窄带高反射滤光膜在光通讯、光学探测仪器等领域有着重要应用.探讨了"基片|H(LH)m1aL(HL)m2βCr,M|空气"膜系结构的窄带高反射滤光膜系,讨论了金属Cr层厚度,以及两种不同的匹配膜系对滤光膜特性的影响,计算了Cr层内部的电场分布.结果表明,较厚的金属层可实现更宽的截止带宽,匹配层的加入有效地实现了宽截止带的深截止,使中心波长处导纳为较大值的匹配膜系可以更好地实现滤光膜宽截止、窄带高反射特性;匹配膜层使中心波长处Cr层内部的电场强度趋于零,有效地降低了整个膜系的吸收,提高了反射率.     

帽层对极紫外多层膜反射特性影响分析

介绍了在极紫外波段，利用帽层材料来减少多层膜反射镜因外部环境干扰而造成的反射率降低，使多层膜光学元件能够长时间稳定工作.计算了在139nm波长处Mo/Si极紫外多层膜反射镜在表面镀制不同帽层材料时的理论最大反射率，利用单纯形调优法，对帽层和多层膜的周期厚度进行优化，同时把分层理论用于多层膜帽层优化,可使多层膜的反射率得到进一步提高.分析了在加入帽层前后多层膜外层电场强度的分布变化情况. 关键词： 多层膜 反射率 帽层 极紫外     

254 nm低通滤光片的研制

根据紫外光学系统的设计要求,在K9基底上研制了254 nm高反射率、可见光谱区高透过率的低通滤光片.根据膜系设计理论,通过针法优化,获得了干涉型低通滤光片的膜系;对电子束蒸镀HfO_2和MgF_2材料进行了研究,解决了材料喷溅的问题,减少了薄膜的吸收;采用考夫曼离子源,通过优化工艺参数,提高膜层致密性,解决了光谱曲线漂移的问题,改善了成膜质量.     

遗传算法设计多层微波吸收材料的结构

本文用遗传算法优化设计多层结构的电磁波吸收材料,通过优化设计和数值计算给出了材料的结构参数,并对优化结果的多种约束条件（总厚度、吸收带宽、反射率大小）进行了加权评估,从而得到了多种介质材料匹配后具有优良吸波特性的吸波材料．     

多层介质光学膜系的计算机模拟误差分析

用计算机数值计算方法模拟多层介质光学膜系的实际镀膜工艺过程，分析膜厚误差对λ0／4高反射膜系透射率和反射率的影响，讨论在一定技射率要求条件下不同层数膜系的允许厚度误差。发现当膜层偏离λ膜厚时，光学厚度控制工艺能通过自动调整其后膜层的厚度有效地降低厚误差对膜系透射率和反射率的影响。对于镀制高反射率膜而言，膜厚允许误差仍可有较大的范围。     

透射式GaAs光电阴极抗光反射膜的研究

本文计算了在透射式GaAs光电阴极的窗玻璃和GaAlAs缓冲层之间引入Si₃N₄或SiO₂膜使光电阴极的入射光反射率所产生的变化,并测量了Si₃N₄膜、SiO₂膜和SiO₂/Si₃N₄复合膜对阴极反射率的影响。理论计算和测量表明,Si₃N₄膜和SiO₂/Si₃N₄复合膜可有效地降低光电阴极对入射光的反射率。当Si₃N₄膜的厚度约为100nm时,可使光电阴极的反射率降低近60%。本文结果为科学地选择透射式GaAs光电阴极所需的的抗光反射膜提供了依据。     

ZnO thin film characterization by X-ray reflectivity optimization using genetic algorithm and Fourier transformation

Zinc oxide (ZnO) thin film was fabricated by sol-gel spin coating method on glass substrate. X-ray reflectivity (XRR) and its optimization have been used for characterization and extracting physical parameters of the film. Genetic algorithm (GA) has been applied for this optimization process. The model independent information was needed to establish data analyzing process for X-ray reflectivity before optimization process. Independent information was exploited from Fourier transform of Fresnel reflectivity normalized X-ray reflectivity. This Fourier transformation (Auto Correlation Function) yields thickness of each coated layer on substrate. This information is a keynote for constructing optimization process. Specular X-ray reflectivity optimization yields structural parameters such as thickness, roughness of surface and interface and electron density profile of the film. Acceptable agreement exists between results obtained from Fourier transformation and X-ray reflectivity fitting.     

软X射线多层膜单色器能量分辨研究

从理论上分析了影响软X射线多层膜单色器能量分辨率的机制，给出了一种既能提高多层膜能量分辨率又不影响其反射率的膜材选择规则．并给出近年来在北京同步辐射装置上开展多层膜单色器应用研究的结果 关键词：     

Structure and morphology of Cu/Ni film grown by electrodeposition method: A study of neutron reflectivity and AFM

We present detailed study of structure and interface morphology of an electrodeposited Cu/Ni film using X-ray diffraction, X-ray reflectivity, neutron reflectivity and atomic force microscopy (AFM) techniques. The crystalline structure of the film has been determined by X-ray diffraction, which suggest polycrystalline growth of the film. The depth profile of density in the sample has been obtained from specular X-ray and neutron reflectivity measurements. AFM image of the air-film interface shows that the surface is covered by globular islands of different sizes. The AFM height distribution of the surface clearly shows two peaks and the relief structure (islands) on the surface in the film, which can be treated as a quasi-two-level random rough surface structure. We have demonstrated that the detailed morphology of air-film interfaces, the quasi-two-level surface structure as well as morphology of the buried interfaces can be obtained from off-specular neutron reflectivity data. AFM and off-specular neutron reflectivity measurements also show that the morphologies of electrodeposited surface is distinctively different as compared to that of sputter-deposited surfaces in the sample.     

Laser diagnostics of nanoscale dielectric films on transparent substrate by integrating differential reflectivity and ellipsometry

The effect of nanometer dielectric films on the differential reflection characteristics of linearly polarized light from non-absorbing materials is investigated in the long-wavelength approximation. The second-order formulas for changes in the reflectance of s- and p-polarized light caused by ultrathin layer are obtained. A detailed analysis of the influence of ultrathin film to the reflectivity of p-polarized light in the vicinity of the Brewster angle is carried out. The novel methods are developed for determining the thickness and refractive index of uniform (or the average values of refractive index of nonuniform) nanometer-scale films by differential reflectivity and ellipsometric measurements.     

新型AgInSbTe相变薄膜的光学及记录性能

利用直流磁控溅射法制备了一种新型AgInSbTe相变薄膜。示差扫描量热(DSC)实验测定的结晶峰温度为193．92℃。X射线衍射(XRD)表明未经热处理的沉积态薄膜是非晶态,而经过200℃热处理,X射线衍射图出现衍射峰,薄膜从非晶态转变到晶态。同时,研究了晶态和非晶态相变薄膜的吸收率、透射率和反射率随波长的变化。测定了650nm激光作用下的相变薄膜的记录性能,分析了记录功率、记录脉宽对薄膜反射率衬比度的影响,在同一记录脉宽条件下,记录功率越大,反射率衬比度也越大;在同一记录功率条件下,随记录脉宽的增加,反射率衬比度也增大。结果表明,新型AgInSbTe相变薄膜在激光作用下具有较高的反射率衬比度,可获得良好的记录性能。     

Resonant x-ray reflectivity measurements of a Ni/Fe alloy thin film: A composition profile

We have measured the composition profile of a Ni/Fe permalloy (0.8 Ni/0.2 Fe) thin film using glancing incidence X-ray reflectivity. Resonant reflectivity measurements were carried out by tuning the X-ray energy below and above, close and away from the respective K-edges of Fe and Ni. The information obtained using this method allows a determination of not only the electron density but also the composition profiles of the Ni/Fe alloy thin film. This non-destructive technique is a promising tool for the determination of the chemical composition of thin film. We used a matrix formalism to describe the wave propagation in a continuous medium. In our calculations, we used linear segments to approach the local electron density profile at the interfaces and Gaussian factors to account for the rms(root mean squre) roughness due to irregularities in the boundary position. We were able to obtain excellent fits to the data and get consistent geometry and composition parameters from the reflectivity measurements at five different X-ray energies. We detected oxidation layers on the top surface and between the alloy thin film and the substrate. We observed also that the Ni/Fe composition at the interfaces deviate from that of the bulk of the thin film sample.