Theoretical study of the normal-incidence reflective spectra for determining the thickness and refractive index of dielectric film

We theoretically study and propose the design concept of a new non-contact measurement method of the thickness and refractive index of dielectric film. The needed measurement set-up includes a probe, an optical detection head and a spectrometer. The probe is composed of two patches of dielectric substrates, and the optical detection head is used to detect the reflective spectra. After depositing a testing dielectric film on the two patches, the coating film thickness and refractive index can be determined by analyzing the normal-incidence reflective spectra of the two dielectric substrates. This method has two requirements. First, the coating dielectric films on the two substrates must be the same. Second, the two dielectric substrates respectively have higher and lower refractive indices than the testing dielectric film.     

多层介质膜光栅用高反射镜的严格耦合波分析

基于严格耦合波和增强透射矩阵的方法,提出了一种数值稳定的求解多层介质膜光学特性的机理模型.利用该模型计算了多层介质膜光栅用高反射镜的优化设计膜系.使用电子束热蒸发方式制备的多层介质膜光谱特性和理论设计的结果符合得很好,该严格耦合波模型是分析介质膜光学特性有效的稳定的数值求解方法.     

Thermal deformations of a glass spherical satellite

The effect of the kind of the reflecting coating of a glass spherical satellite on thermal deformations caused by the solar irradiation is considered. Two types of coating deposited on one of the hemispheres are considered: aluminum with a protective layer of bakelite varnish and interference dielectric coating for two orientations of the satellite orbit. Structures of a multilayer dielectric coating and technologies of its deposition are described.     

Reflective mask for projection lithography operating at a wavelength of 13.5 nm

This work is devoted to the technology of mask manufacturing and investigation of the characteristics of the reflective mask employed in the extreme ultraviolet lithography test bench designed at the Institute for Physics of Microstructures, Russian Academy of Sciences. The mask??s structure and composition have been optimized. The antireflecting (absorbing) coating and stop-layer materials that are used to etch the mask structure and the multilayer interference system, which reflects radiation at the operating wavelength, have been selected. The mask manufacturing technology is described. The measured reflective and geometrical characteristics of a mask (absorbing layer thicknesses, line widths, and line-edge roughnesses) are presented. A new direct method for certifying mask defects of 30 nm or more is proposed.     

23.4nm软X射线多层膜反射镜研制

为了满足类氖-锗X射线激光研究的需要,设计制备了23.4 nm软X射线多层膜反射镜.依据多层膜选材原则并考虑材料的物理化学特性选择新的材料Ti与Si组成材料对.设计优化材料多层膜的周期厚度(d),材料比例(Γ),周期数(N),计算出Ti/Si反射率曲线.通过实验优化各种镀膜工艺参数,制备出了23.4 nm的Ti/Si多...     

Infrared hollow fiber with a vitreous film as the dielectric inner coating layer

A vitreous material with an optimum reflective index of 1.41 for dielectric metallic hollow fiber is used for what is believed to be the first time. A smooth vitreous film is formed by the treatment of a hardener at room temperature by using the liquid-phase coating technique. Low-loss properties were obtained in both the infrared and visible wavelength regions, and the fibers are of high durability when sterilized. This hollow fiber is promising for use in medical applications or other harsh environments.     

超高阈值Pick-off反射镜的研制

 采用水中抛光技术抛制了90mm×60mm×10 mm的K₉玻璃基片,表面粗糙度达1nm。在APS1504镀膜机上,摸索了电子束蒸发镀膜的最佳工艺条件,较稳定地在该超光滑玻璃表面上镀制了对波长1054 nm、入射角45°、反射率R≥99.5%的反射膜。膜层的抗激光损伤阈值可达26 J/cm²(1054nm, 1ns),镀膜后该玻璃基片反射波前可达l /10(p-v),最终制备了超高阈值Pick-off反射镜。     

大型天文望远镜主镜镀膜技术

采取主镜镜面向上真空蒸镀制备方式,开展了大型天文望远镜主镜铝加介质保护反射膜技术研究。结合ZZS3200型镀膜设备真空室几何配置,对传统膜厚分布计算物理模型进行了修正,分别分析了铝膜与介质膜层膜厚均匀性。结果表明:理论分析与实验数据一致,直径2.4 m范围内膜厚不均匀性约5.5%。通过优化工艺,成功制备出1.8 m平面镜薄膜元件,在350~1 800 nm波段范围内,膜层平均反射率88.6%,通过了环境稳定性测验。     

500.8 nmNd∶YAG青光激光器光学薄膜的设计与制备

从双波长激光运转及和频的机理出发，对LD泵浦Nd∶YAG，LBO腔内和频500.8 nm〖JP2〗青光激光器所使用的光学薄膜进行了设计和制备.在激光反射镜的设计上，为了达到最佳的和频输出，对膜系要求进行了深入分析.采用对谐振腔一端面反射率固定不变并通过对另一腔镜基频光的透射率进行调谐的方法, 在给出合理初始结构后，利用计算机对膜厚进行了优化.并采用双离子束溅射沉积的方法，通过时间监控膜厚法成功制备出青光激光器所使用的全介质激光反射膜, 在室温下实现946 nm和1064 nm双波长连续运转，并通过Ⅰ类临界相位匹配LBO晶体腔内和频在国内首次实现500.8 nm青色激光连续输出.当泵浦注入功率为1.4 W时和频青光最大输出达20 mW.     

周期结构薄膜在折射率色散下反射区特性研究

周期性结构是光学薄膜设计的基本物理模型,给出了反射区中心波长的一般性条件,研究了在膜层材料存在折射率色散情况下,等厚周期结构和非等厚周期结构的薄膜反射区中心波长与带宽特性.研究结果表明:在等厚和非等厚周期结构中,考虑膜层材料折射率色散与忽略色散情况相比,中心波长向长波方向移动,反射级次与相对波数的线性关系偏离;在薄膜光学厚度一定的非等厚周期结构中,高折射率层光学厚度大于低折射率层时,反射级次与相对波数的线性关系偏离度高;非等厚周期结构薄膜的带宽在低反射级次上小于等厚周期结构,同时膜层的色散对反射带宽影响不大.     

Design of near-unity transmittance dielectric/Ag/ITO electrodes for GaN-based light-emitting diodes

We designed a near-unity transmittance dielectric/Ag/ITO electrode for high-efficiency GaN-based light-emitting diodes by using the scattering matrix method. The transmittance of an ultrathin metal layer, sandwiched between a dielectric layer and an ITO layer, was investigated as a function of the thickness and the optical constant of each constituent layer. Three different metals (Ag, Au, and Al) were examined as the metal layer. The analytical simulation indicated that the transmittance of a dielectric/metal/ITO multilayer film is maximized with an approximately 10-nm-thick Ag layer. Additionally, the transmittance also tends to increase as the refractive index of the upper dielectric layer increases. By tailoring the thickness of the dielectric layer and the ITO layer, the dielectric/Ag/ITO structure yielded a transmittance of 0.97, which surpasses the maximum transmittance (0.91) of a single ITO film. Furthermore, this extraordinary transmittance was present for other visible wavelengths of light, including violet and green colors. A complex phasor diagram model confirmed that the transmittance of the dielectric/metal/ITO multilayer film is influenced by the interference of reflected partial waves. These numerical findings underpin a rational design principle for metal-based multilayer films that are utilized as transparent electrodes for the development of efficient light-emitting diodes and solar cell devices.     

Film-thickness Error Analysis of Optical Disk Systems

It is difficult to exactly control the film thickness of optical disk multilayer in the actual coating process. The thickness error becomes a main factor affecting the optical characters of the film system. The thickness error′s sensitivity factor of dielectric optical multilayer is derived from the optical matrix in this paper. The effect of the thickness error on the reflectivity or reflectivity contrast of the optical disk multilayer is analyzed with a numerical calculation. The sensitivities to thickness error for different layers or in different film-thickness ranges are compared and discussed. A sketchy method defining allowable thickness error is given. Some experimental results verify the applicability of our theoretical analysis.     

用于钕玻璃啁啾脉冲放大系统光谱整形的多层介质膜反射镜

在千焦拍瓦高功率啁啾脉冲放大系统设计中,为了尽量消除增益窄化和增益饱和效应的影响,同时尽可能提高高功率激光输出脉冲信噪比参数,激光脉冲时空和光谱的整形问题备受关注.提出一种光谱整形新方法,利用特定结构的多层介质膜反射镜,可实现对大能量高功率啁啾脉冲钕玻璃放大系统中啁啾脉冲的光谱整形.研究结果表明,只要合理选择多层介质膜系的结构参数,可有效地控制其反射率分布,且在保证反射相位基本不变的条件下其调制度可超过60%.针对钕玻璃1053nm波长设计而成的光谱整形反射镜,反射带宽可达到196nm,色分辨率约为0.1 关键词： 介质反射膜 光谱整形 千焦拍瓦 啁啾脉冲     

Film-thickness Error Analysis of Optical Disk Systems

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基于梳状小波理论的颜色滤光片设计

渐变折射率薄膜因为消除了界面而克服了传统的分层介质膜的固有弊端。探讨了一种基于这种渐变膜系的设计方法。从小波理论及渐变折射率增透理论出发,以分层介质高反膜系为参照,给出了采用梳状(Rugate)滤光片设计不同类型颜色滤光片的设计原理,并以目前背投系统中使用的红、绿、蓝颜色滤光片为指标,理论设计出了具有优良光谱特性的红、绿、蓝颜色滤光片;对该设计结果进行了角度敏感性分析、偏振效应分析并与传统的反射膜叠加法得到的分层膜系进行比较,发现通过梳状滤光片理论设计的滤光片较传统的多层膜滤光片具有更小的角度敏感性和较小的偏振效应。     

基于谐振环的太赫兹宽带偏振转换器件研究

提出了一个基于谐振环结构的宽带且高效的太赫兹线偏振转换器.该结构由金属-电介质-金属三层构成,位于顶层的是基于开口谐振环的超表面,中间为介质层,底部为金属板.实验结果表明,该结构可以在0.59-1.24 THz频率范围内将线偏振的太赫兹波偏振方向旋转90°,转换率超过80%.通过计算该结构在所研究的频率范围内反射光的偏振角和椭圆角,证实了该结构可以在较宽的频率范围内实现高效的线偏振转换.对该结构在偏振转换率高的频率下表面电流和电场进行仿真,分析了高偏振转换率和宽带的机理.同时,研究了该结构的偏振转换率对入射角以及偏振角的依赖性,结果表明该结构在0°-30°入射角范围内、-10°-10°偏振角范围内均有很好的偏振转换性能.     

多层介质膜光谱调制反射镜的反应离子束刻蚀误差容限

 在千焦拍瓦高功率放大系统设计中,激光脉冲的时空和光谱整形技术一直受到人们的广泛关注。利用反应离子束刻蚀等微纳超精细加工而成的多层电介质结构反射镜可在高功率条件下实现啁啾脉冲的光谱整形。在光谱整形介质结构反射镜的设计与制造中,需要根据要求的反射率来合理提出反应离子束刻蚀误差容限指标。推导出反应离子束刻蚀误差容限的解析表达式。针对神光Ⅱ千焦拍瓦高功率放大系统设计中提出的多层介质光谱调制反射镜,分析了调制结构反射镜各层加工的容许误差,确定了反应离子束刻蚀误差容限指标。研究表明：刻蚀高折射率介质的加工误差容限为35 nm;刻蚀低折射率介质的加工误差容限为62 nm。此外,还从使用需要和加工难易的角度,对刻蚀方案进行了讨论。就加工难易程度而言,优选反应离子束刻蚀方案,且采用刻蚀并残留低折射率介质的方案更容易实现。     

Hybrid output mirror for optically pumped far infrared lasers

A hybrid metallic mesh multilayer dielectric coating mirror has been developed for use as an output mirror for optically pumped far infrared lasers. The metallic mesh provides a high reflectance in the far infrared while the multilayer dielectric coating is chosen to provide a maximum reflectivity at the pump wavelength (10 μm). This hybrid mirror has increased the output power of a CH₃F waveguide laser at 496 μm by a factor of 350 over that obtained with a hole coupling mirror. In addition, this mirror results in a far infrared output beam which has a minimum angular divergence limited only by the particular oscillating transverse waveguide mode (the EH₁₁ mode for this experiment).     

High-performance nanowire-grid polarizers

We developed a new type of wire-grid polarizer that has achieved excellent optical performance and reliability. The nanowire-grid polarizer is based on a fully optimized innovative design structure that consists of not only the core nanowire grid but also the surrounding multilayer thin-film structures. The surrounding structures are designed for antireflectivity to provide the best possible efficiency as well as for device reliability to provide the best possible handling robustness and environmental durability. The core nanowire grid utilizes nanosized high-aspect-ratio dielectric walls as a support for forming a high-aspect-ratio metal nanowire grid that significantly reduces energy loss as a result of metal absorption for the transmitted beam while providing a high extinction ratio of the blocked beam. The developed high-quality nanowire-grid polarizer has potential for use in many integrated optical applications.     

A novel optical multilayer hydrophone with a triangular pyramid substrate

A novel concept for an optical multilayer ultrasonic hydrophone with the sensing film deposited on a triangular pyramid glass substrate is proposed.Using the calculation model for the spectral coefficients’ derivatives of a dielectric multilayer optical coating,the acousto-optic sensitivity characteristic of the hydrophone is analyzed with different measurement laser polarizations and incident angles.We present a reasonable method and adjusting strategy for the optimum working point selection of the ultrasound measurement.Analytic results show that the novel hydrophone possesses all the other merits of a plate glass substrate optical multilayer hydrophone but with improved detection sensitivity.A longer measurement time without distortion decreases the difficulty of high frequency signal circuits.Spatial split of the ultrasound signal caused by the substrate’s triangular pyramid roof simplifies the spatial spot area correction,which contributes to the accurate calibration of the hydrophone’s wideband frequency response.