13.9nm软X射线激光用大面积多层膜分束镜研制

 基于分束镜反射率和透射率的乘积为衡量标准的原则,设计了13.9nm软X射线激光干涉测量所需的多层膜分束镜，用磁控溅射法在有效面积达10mm×10mm，厚100nm的氮化硅窗口上镀制Mo/Si多层膜,实现了分束镜制作。用表面轮廓仪实测分束镜面形精度达到nm量级，同步辐射反射率计测试表明,分束镜的反射率和透射率乘积约4%。     

用不同的Mo靶溅射功率制备Mo/Si多层膜

 用磁控溅射法制备了周期厚度和周期数均相同的Mo/Si多层膜，用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时，Mo/Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo/Si多层膜的软X射线反射率。研究发现，随着Mo靶溅射功率的增大，Mo/Si多层膜的表面粗糙度增加，Mo的特征X射线衍射峰也增强，Mo/Si多层膜的软X射线峰值反射率先增大后减小。     

研究扩散屏障层对Mo/Si多层膜软X射线反射率影响的模拟

在特定波长下,用四层结构模型模拟了Mo/Si多层膜的软X射线反射率.研究了扩散屏障层dMo-on-Si和dSi-on-Mo对Mo/Si多层膜软X射线反射率的影响.研究发现,扩散屏障层并不总是损害Mo/Si多层膜的光学性能,通过合理设计dMo-on-Si和dSi-on-Mo厚度,增加dMo-on-Si与dSi-on-Mo的比值,也能提高多层膜的软X射线反射率.     

单发实验测量软X射线多层膜反射镜反射特性

 提出了一种单发实验测量软X射线波段多层膜反射镜反射特性的简易方法。实验采用激光等离子体软X射线源作为光源,用平焦场光栅谱仪分光,在光路中引入掠入射镜以消除高级次谱的影响,用软X光CCD记录,在一发激光打靶实验中,测量了设计中心波长为13.9 nm的Mo/Si多层膜反射镜的反射特性。     

Mo/Si软X射线多层膜的界面粗糙度研究

 用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo/Si多层膜系列, 利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo/Si多层膜的新鲜表面近似等同于同一多层膜的内界面，通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加，Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小，多层膜的峰值反射率先增加后减小。     

入射光单色性与界面粗糙度对多层膜反射性能的不同影响

多层膜界面粗糙度、入射光单色性对软X射线多层膜实际反射率均有影响。利用数学卷积积分,理论上推导出一个在入射光不同单色性下精确计算多层膜反射率的公式。利用给出的理论计算公式,简要分析了入射光不同单色性、不同界面粗糙度对Mo/Si多层膜反射率的影响。理论分析发现这两种因素对Mo/Si多层膜反射率影响完全不同:入射光低的单色性不但极大降低Mo/Si多层膜峰值反射率,而且使反射曲线的半峰全宽增加;而界面粗糙度是降低Mo/Si多层膜反射曲线上各点对应值,基本不改变Mo/Si反射曲线的半峰全宽,不改变反射曲线的形状。说明这两个因素在软X射线的长波段对多层膜反射性能的影响不同。     

中心波长为13．9nm的正入射Mo／Si多层膜

用由铜靶激光等离子体光源等组成的反射率计对自行设计的周期厚度为7.14nm的120层Mo/Si多层膜进行极紫外(EUV)波段反射率测量。由于多层膜层数增加所引起的吸收、膜层界面之间的扩散以及镀膜过程中的膜厚控制误差或表面被氧化(污染)等原因,正入射Mo/Si多层膜在13.9nm处的反射率低于理论计算值73.2%,最后用原子力显微镜(AFM)测量其表面粗糙度为σ=0.401nm。     

软X射线多层膜与衰减膜研究

 本文采用随机数的方法，发展了一种普适的多层膜设计方法，这种方法除可设计一般的周期多层膜，更重要的是它可以根据选定的评价因子，设计不同要求的非周期多层膜。用磁控溅射方法完成软X射线多层膜制备，X射线衍射、卢瑟福背散射、俄歇电子谱和反射率的相对测试用来表征多层膜结构和特性，所得结果说明多层膜的结构完整，周期参数正确。用离子束溅射方法成功地制备了有一定反射率和透过率的软X射线半反半透分束镜；分析了Ag和Zr衰减膜中的杂质含量与分布及其对衰减膜特性的影响，并对衰减系数进行了修正，为实验提供优质的衰减膜。     

13 nm窄带Si/Mo/C多层膜反射镜

基于多层膜准单色覆盖50~1500 eV能谱的多能点发射光谱测量系统可获得聚龙一号装置Z-pinch等离子体X射线源的能谱结构和总能量等信息。考虑装置的条件,在13 nm处的多层膜需要工作在掠入射角60。常规的Mo/Si多层膜尽管反射率最高,但其带宽较大,不能满足多层膜准单色的要求。因此提出将Mo和C共同作为多层膜的吸收层材料与Si组成Si/Mo/C多层膜,可使反射率降低较小而带宽明显减小。采用磁控溅射方法制备了Si/Mo/C多层膜,其掠入射X射线反射测量表面多层膜的结构清晰完整,同步辐射工作条件下反射率测量,得到Si/Mo/C多层膜在13 nm处和掠入射角60时的反射率为56.5%,带宽为0.49 nm（3.7 eV）。     

一种软X射线多层膜界面粗糙度的计算方法

提出一个利用多层膜小角X射线衍射谱衍射峰积分强度计算多层膜界面粗糙度的公式。用磁控溅射技术制备Mo／Si多层膜，用波长为0．154nm的硬X射线测量样品在小掠入射角区的衍射曲线，分别用本文公式和反射率曲线拟合方法计算了样品的界面粗糙度。实验结果表明：由本文公式获得的界面粗糙度近似于拟合方法获得的界面粗糙度，它们略等于多层膜界面实际粗糙度。     

软X射线多层膜分束镜的研制

介绍了软件Ｘ射线多层膜分束镜的制备,采用蚀基底法和氯化钠脱膜分离法制备且获得了大面积的Ｍｏ／Ｓｉ多层膜分束镜。     

High-throughput, high-damage-threshold broadband beam splitter for high-order harmonics in the extreme-ultraviolet region

We demonstrate a high-throughput and high-damage-threshold beam splitter for high-order harmonics in the soft-x-ray region that uses Si and (or) SiC plates set at Brewster's angle with respect to the pump wavelength. The beam splitters are guaranteed to have a damage threshold of at least 0.8 TW/cm2 (average power density, 0.25 W/cm2) and an attenuation rate of 10(-4)-10(-5) for a 30-fs pump pulse. The measured reflection efficiency at the 27th harmonic (29.6 nm) was 0.56 for Si and 0.45 for SiC. These beam splitters are useful not only for high harmonics but also for longitudinally pumped x-ray lasers.     

Design of form-birefringent multilayer nonpolarizing beam splitter

Nonpolarizing beam splitters, which are based on the form birefringence of subwavelength multilayer binary gratings, have been proposed. The design is based on effective-medium theory and thin-film theory. Rigorous coupled-wave analysis is used to optimize the design of this nonpolarizing beam splitter. The simulation shows that the structure can eliminate polarization effect and provide high reflectivity.     

Dense plasma diagnostics with an amplitude-division soft-x-ray laser interferometer based on diffraction gratings

We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma.     

Fringe visibility and correlation in Mach-Zehnder interferometer with an asymmetric beam splitter

We study the wave-particle duality in a general Mach-Zehnder interferometer with an asymmetric beam splitter from the viewpoint of quantum information theory. The correlations (including the classical correlation and the quantum correlation) between the particle and the which-path detector are derived when they are in pure state or mixed state at the output of Mach-Zehnder interferometer. It is found that the fringe visibility and the correlations are effected by the asymmetric beam splitter and the input state of the particle. The complementary relations between the fringe visibility and the correlations are also presented.     

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...     

Photonic crystal beam splitters

In this work, the beam splitter with two input ports and two output ports in two-dimensional photonic crystals is studied through the finite-difference time-domain method. The beam splitter consists of two orthogonally cross line defects. The diameter of the two diagonal air holes at the intersection of the two line defects was modified. The input light can be identically divided into the two output ports. The beam splitters can be applied in the photonic crystal Mach-Zehnder interferometers or photonic crystal optical switches.     

硅光子晶体TE模式光下路分束器设计

设计了基于自准直效应的硅光子晶体TE模式13和12光下路分束器。13光下路分束器由4个分束镜组成,而12下路分束器由3个分束镜和1个反射镜组成。利用多光束干涉原理推导出光下路分束器各个出口的透射谱理论公式。通过选择合适的分束镜,可以得到不同分束比例的光下路分束器。对于13光下路分束器,设计了1∶1∶1和1∶2∶3两种分束比例;对于12光下路分束器,设计了1∶1和1∶2两种分束比例。再利用时域有限差分软件数值模拟了透射谱,其结果与理论设计一致。当下路波长为1550 nm时,13和12两种光下路分束器的大小均约为10 m 10 m,自由光谱区为36 nm,覆盖了整个光通信C波段。     

Robust one-beam interferometer with phase-delay control

A robust one-beam interferometer with external phase-delay control is described. The device resembles a Mach-Zehnder interferometer in which the two arms are together in one collimated beam. However, the proposed device is not an amplitude-division interferometer but a wave-front division one. The phase-delay control occurs at the interferometer output with the help of two polarizing beam splitters, a quarter-wave plate, a Faraday rotator, and a polarizer. An additional phase delay is introduced by application of an electrical current to the Faraday rotator or by rotation of the polarizer (the latter is of topological origin), which permits the use of techniques of phase-stepping interferometry.