反常声电光偏转器

本文介绍的新型声光偏转器可提高传统光偏转器的带宽，制作了一个ＬＮ反常声电光偏转器，中心频率为６０ＭＨｚ测试结果表明，带宽由原来的２６ＭＨｚ提高到３７ＭＨｚ。     

中性束束流品质对偏转系统窗口设计的影响

介绍了EAST第一条中性束注入束线内部偏转系统的结构。以参数为80 keV,70 A的氘束作为参考束,分析了经过中性化气体靶后,束流中高能粒子的能量成分;通过计算不同能量离子的偏转半径,说明了束截面在纵向的扩展情况;阐述了束散角的产生原理,分析了束散角对偏转系统窗口设计的影响。结果表明,偏转系统入射窗口和出射窗口尺寸一般和入射束的尺寸一致;偏转系统入射窗口和回转窗口的尺寸和相对位置满足一定条件,可使装置的热负荷相对较小,且各部分热负荷相对均匀。     

偏振光通过透镜的偏振状态分析

采用菲涅尔原理和琼斯矩阵理论,分析了偏振光经过透镜后偏振状态的变化规律,得到了任意入射偏振光通过单透镜后偏振状态的一般表达式,讨论了偏振光通过共焦双透镜后的偏振分布.分析结果表明对于单透镜,入射光偏振方向相对于入射面±45°时有最大的偏转量;入射偏振光在共焦双透镜作用下的偏振方向偏转量是单透镜时的2倍.     

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为EAST装置中性束注入器设计了一套用于将剩余离子在线电偏转的结构,并对系统各设备的核心参数进行了估算。在4.41kV偏转电压作用下,该电偏转系统可提供80keV氘离子束偏转所需的偏转电场。在偏转电场调制情况下,该电偏转系统可有效降低极板表面的热负荷,进而满足EAST中性束注入器稳态运行的需要。     

LiNbO3电光偏转器的研究

从电光效应出发，对ＬｉＮｂＯ３电光偏转器的基本品质因子进行研究，导出了偏转器的设计公式，用有限差分法计算了四柱面电极电光偏转器的电场分布，对不同结构参数，给出了梯度线性度和结构因子。     

中性束注入器电偏转系统的参数设计与估算研究

为EAST 装置中性束注入器设计了一套用于将剩余离子在线电偏转的结构,并对系统各设备的核心参数进行了估算。在4.41kV 偏转电压作用下,该电偏转系统可提供80keV 氘离子束偏转所需的偏转电场。在偏转电场调制情况下,该电偏转系统可有效降低极板表面的热负荷,进而满足EAST 中性束注入器稳态运行的需要。     

双目显微系统光路偏转与平行性检测

针对双目系统中各自光路的偏转和2条光路之间的不平行会增加轴外像差,降低成像质量,并造成双目视觉的不同一性,引起使用者的不适,提出一套激光检测和评价双目系统光路偏转和平行性的方法。将待测系统拆分成元件,先检测元件的光路偏转和平行性,然后逐步组合元件,实验测得待测双目系统光路存在0.5 mm以上的光路偏转距离,入射平行光出射系统后夹角达0.8左右。结果表明,该方法可以应用于显微镜工业生产和检测之中。     

平面波导偏转光栅特性分析

本文借助由偏转波耦合方程得出的偏转系数R就平面波导偏转光栅的角度特性以及频率特性进行了讨论。分析表明,偏转光栅的这些特性主要决定于入射波与偏转波间耦合系数|K|与光栅长度L的乘积|K|L,而不单独依赖于|K|或L。     

新型KTP电光偏转器的设计和分析

设计了新ＫＴＰ电光偏转器，当通光口径Ｄ＝４ｍｍ，长度Ｌ＝４０ｍｍ时，其时间分辨率为１８０ｐｓ，从而可获得最窄宽度为４００ｐｓ的整形激光脉冲，而相同结构的ＬｉＮｂＯ３电光偏转器最窄只可获得宽度为８３０ｐｓ的整形激光脉冲，分析了电光偏转器设计中影响其性能指标的因素，指出利用恒温炉装置可消除激光脉冲在传播过程中的波面畸变。     

温度对闭路光伏明空间孤子演化和自偏转的影响 (英文)

通过考虑扩散效应的影响，采用数值方法研究了温度对光伏光折变介质中的明空间孤子演化和自偏转的影响。结果表明，当晶体温度变化时，明孤子可以呈现为稳定态、较大周期的压缩和膨胀态，或塌陷态。同时，明空间孤子中心偏转距离随温度增加而增加，在一个特定温度处达到最大值，之后随温度增加而减小，在高温和低温区域此偏转距离趋于零。孤子的最大偏转距离和对应的特定温度随入射孤子波强度的增加而增加。进一步采用微扰方法研究了明孤子自偏转过程，其结果与数值方法获得的结果一致。     

Si基外延Ru2Si3电子结构及光学性质研究

采用基于第一性原理的赝势平面波方法,对异质外延关系为Ru₂Si₃ （100）//Si（001）,取向关系为Ru₂Si₃［010］//Si［110］正交相的Ru₂Si₃平衡体系下的能带结构、态密度和光学性质等进行了理论计算.计算结果表明：当晶格常数a取值为1093 nm时,正交相Ru₂Si₃处于稳定状态并且是具有带隙值 关键词： 外延 第一性原理 电子结构 光学性质     

通信用声光可调谐滤波器

介绍了以LN为基底的集成型和以TeO2为材料的体型通信用声光可调谐滤波器(AOTF)的工作机制,并对其结构和性能进行了比较分析,指出了各自需要解决的主要问题。讨论了用作OADM的声光可调谐滤波器对偏振分束器的要求及偏振分束器对滤波器性能的影响。提出了有必要对TeO2器件应用于通信领域的可能性进行更为深入的研究。     

Dissociation of non-screw dislocations in B.C.C. lattice

A non-planar dissociation of non-screw 1/2[¯111] (110) dislocations is proposed. The dissociation is possible for dislocations of [1¯11] and [1¯10] directions and the dislocations of these directions become sessile. The [1¯11] and [1¯10] directions are in agreement with experimentally observed shape of dislocations in the (110) glide plane.     

碲酸盐玻璃的拉曼光谱研究

本文测试了TeO2-ZnO和TeO2-BaO两种二元系统不同金属氧化物浓度下玻璃的拉曼光谱,通过比较这两种碲酸盐玻璃系统拉曼光谱的异同,表明碲酸盐玻璃系统中随着金属氧化物浓度的增加,使玻璃网络中的TeO4双三角锥向TeO3三角棱锥转化,并且在TeO2-BaO二元玻璃中出现了非桥氧键。同时初步研究了TeO2-ZnO-Na2O三元玻璃的拉曼光谱,发现当TeO2-ZnO二元玻璃中加入5mol%的Na2O时,其结构并没有发生显著的变化。     

Zeeman studies of the 0.839eV emission in SI GaAs:Cr

The multi-structured zero phonon transitions of the 0.839eV emission observed in SI GaAs:Cr have been investigated by Zeeman measurements. Magnetic splittings for the directions [111], [110] and [100] as well as angular dependence studies in the (110) plane show that the centre has a symmetry axis along [111] with a small orthorhombic distortion. The emissions cannot be due to the isolated [100] Jahn-Teller distorted Cr²⁺ ions observed in magnetic resonance but to [111] centres such as the (Cr²⁺-donor) pairs as suggested by White.     

Spin orientation of electrons by unpolarized light pulses in low-symmetry quantum wells

The spin dynamics of electrons in low-symmetry quantum wells (QWs) under conditions of interband excitation by ultrashort unpolarized light pulses is investigated. It is shown that after the transmission, spin polarization appears in the system after a time comparable with the electron momentum relaxation time for an electron pulse and then vanishes. The microscopic theory of spin orientation of electrons by optical pulses carrying zero angular momentum is developed for asymmetric QWs grown from semiconductors with the zinc blende lattice along the [110] crystallographic direction. Pumping with unpolarized light in such structures in the normal incidence geometry induces a spin in the QW plane along the [1[`1]0][1\bar 10] axis.     

Design of broadband achromatic metasurface device based on phase-change material Ge2Sb2Te5

Based on the phase-change material Ge₂Sb₂Te₅ (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems.     

Compton profiles and nesting of Fermi surfaces for B2-TiNi and B2-TiPd

The band structures of the shape memory alloys B2-TiNi and B2-TiPd are calculated by the full potential linearized augmented plane wave method with the local density approximation. The theoretical Compton profiles for B2-TiNi and B2-TiPd are calculated. In addition, the three-dimensional (3D) occupation number densities obtained by Lock-Crisp-West (LCW) analysis are presented for the first time. These 3D occupation number densities are in good agreement with the Compton scattering experiment for TiNi. Both shape memory alloys are based on martensitic transformation, which is caused by soft phonons. The charge-density wave is created by nesting of Fermi surfaces, which leads to phonon softening. To examine the nesting vectors quantitatively, we calculate the generalized susceptibility χ(q). χ(q) shows peaks at 0.315[110]2π/a and 0.4[111]2π/a for TiNi and at 0.275[110]2π/a and 0.395[111]2π/a for TiPd. Although the nesting vector in the [110] direction agrees with that from the phonon experiment, the nesting vector in the [111] direction differs from that in the experimental results.     

有限口径非周期亚波长衍射聚焦偏转器的严格矢量优化

有限口径非周期亚波长衍射光学器件的亚波长结构特性使得传统标量衍射理论失效,必须借助严格电磁理论进行器件的设计。提出一种循环平面波谱算法(IterativePlaneWaveSpectrumAlgorithm,IPWSA)作为器件优化算法,利用二维时域有限差分方法作为严格电磁计算模式,根据Farn方法对器件面型进行亚波长处理,设计出有限口径非周期具有亚波长结构的衍射聚焦偏转器件,偏转角为24.8°,该器件可与激光器集成构成微型集成光学系统,也可以用在红外量子阱系统中。详细分析了算法原理,设计实例验证了算法的优化效果。     

Optical anisotropy of surface-emitting ZnSe/BeTe LEDs

The electric field-induced in-plane optical anisotropy (Pockels effect) of ZnSe/BeTe multi-layered heterostructures has been studied by analysing the linear polarization of the spatially indirect photoluminescence. A pronounced quantum-confined Pockels effect was found in ZnSe/BeTe double-barrier structures. A tight-binding model is proposed which consistently interprets the experimental findings and suggests a new mechanism for the effect as realized in type-II heterostructures. The model takes into account that the ZnSe/BeTe heterosystem exhibits a type-II band alignment with large band offsets and that in the zinc-blende lattice the chemical bonds are oriented in 〈111〉 directions and, when shifted along the [001] principal axis, alternatively change their orientation in the (001) plane from [1 1 0] to [110] and vice versa. A light-emitting diode based on a single ZnSe/BeTe interface is demonstrated.