Ultraviolet wave plates based on monolithic integration of two fully filled and planarized nanograting layers

We successfully fabricated a high-performance half-wave plate for the 405 nm wavelength based on monolithic integration of two nanograting layers. Each of the nanograting layers functions as a quarter-wave plate. Both of the nanograting layers were fully filled and planarized to achieve the monolithic integration. UV-nanoimprint lithography, along with thin-film deposition, high-aspect-ratio reactive ion etching, and trench-filling technologies, was used in fabrication and integration of the individual nanograting layers. High-aspect-ratio nanogratings with sub-50 nm linewidths and 100 nm spacing were fabricated to achieve good optical performance at the near-UV wavelength. The ability to integrate multiple nanostructure-based optical layers opens a path for integrated multifunction devices, as well as a new strategy for driving both miniaturization and cost.     

CCD对高空间分辨率波前干涉检测的影响

推导并用实验验证了光强与入射波前在单位像元面积里成近似线性关系,从而得到入射波前经CCD采样后的功率谱密度（PSD）公式.根据该公式,模拟分析了影响CCD采集系统的系统传递函数的各个因素：入射波前、CCD的填充因子及CCD的曝光时间,得出了他们与系统传递函数的定性关系,并且通过实验明确CCD曝光时间对高空间分辨率波前检测不确定度的影响,为高空间分辨率干涉设计提供了理论依据.     

维生素A酸在银溶胶液中的表面增强拉曼散射光谱

将水中不溶的药物维生素A酸(VAA)溶于氯仿中,然后与银溶胶液混合,振摇,取静置分层后的上层溶胶液测定表面增强拉曼光谱,氯仿在银溶胶中无表面增强效应,不干扰维生素A酸的测定。与固体粉末拉曼光谱相比较,对光谱峰归属进行了解释。通过分析CO伸缩振动带和ν(COO)振动峰明显增强的现象,讨论了维生素A酸分子在银颗粒表面可能的吸附取向,并推断维生素A酸在银表面的吸附发生在COO-基团。以维生素A酸表面增强拉曼光谱在1583cm-1处的峰强度对浓度进行线性回归,求得线性回归方程Y=10×108+95585,在10×10-6～50×10-5mol·L-1范围呈良好的线性关系,最小检测限为10×10-7mol·L-1。结果表明,维生素A酸表面增强拉曼光谱峰数量少,灵敏度高,是定量分析痕量维生素A酸的很好方法。     

电力机车用高温超导变压器电流引线导热路径延伸方法的研究

按照车用高温超导变压器对电流引线的要求,以有限元体传热学为分析基础,对电流引线进行了传热计算,给出了初步设计方案。针对车载变压器的有限空间,提出了通过将引线绕制成螺线管状的方法来解决引线的导热路径长度较长与空间可用高度不够的矛盾,并通过热损耗分析得出下端绕制方式优于上端绕制方式的结论。     

Light induced microstructure transformation in a-Si：H films

A series of a-Si:H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition (HW-MWECR-CVD), subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared (FTIR) spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.     

Electric field enhancement in guided-mode resonance filters

Electric fields inside guided-mode resonance filters (GMRFs) may be intensified by resonance effects. The electric field enhancement is investigated in two GMRFs: one is resonant at normal incidence, the other at oblique incidence. It is shown that the two GMRFs exhibit different behaviors in their electric enhancement. Differences between the electric field distributions of the two GMRFs arise because coupling between counterpropagating modes occurs in the first case. It is also shown that the order of the electric field of maximum amplitude can be controlled by modulation of the dielectric constant of the grating.     

Reactive scattering damage to DNA components by hyperthermal secondary ions

We have observed reactive scattering damage to fundamental DNA building blocks by the type of hyperthermal secondary ions that are produced along heavy ion tracks in biological media. Reactions include carbon abstraction by N+, and hydrogen abstraction by O- and N+, at collision energies down to 1 eV. Our results show that localized reactive scattering by hyperthermal secondary fragments can lead to important physicochemical damage to DNA in cells irradiated by heavy ions. This suggests a fundamentally different picture of nascent DNA damage induced by heavy ion tracks, compared to conventional (x or gamma) radiation tracks.     

蒙特卡罗临界计算全局计数效率新算法研究

为提高蒙特卡罗临界计算时全局计数的整体效率, 对比分析了新提出的均匀计数密度算法、均匀径迹数密度算法和原有的均匀裂变点算法. 以大亚湾核反应堆pin-by-pin模型的全局体平均通量计数和中子沉积能计数为例, 前两种算法较均匀裂变点算法都获得了整体效率的提高. 上述算法已经在自主开发的并行蒙特卡罗输运程序JMCT上予以实现.     

钾掺杂对三联苯的超导特性探寻

新型超导材料的设计合成及其超导机理的探索是目前凝聚态物理学领域的重要研究方向. 本文采用高真空热烧结方法制备了钾掺杂对三联苯粉末材料并表征了它们的晶体结构、分子振动、磁学及超导特性. X射线衍射图谱和拉曼光谱表明在烧结样品中除存在钾掺杂对三联苯和KH外, 还含有苯环重组的C₆₀和石墨成分. 拉曼光谱中部分峰位的红移进一步证实钾成功掺入对三联苯分子晶体中并将4 s电子转移到C原子上. 零场冷却磁性测量结果表明: 多数样品在整个温度测量区间表现为居里顺磁性, 但少数样品呈现出抗磁性, 而且在17.86, 10.00 和6.42 K三个温度点出现磁化率突降的反常行为, 其中17.86 K处的突降很可能源于钾掺杂C₆₀引起的超导转变, 而后两者可能与钾掺杂对三联苯导致的超导相关. 研究结果有助于理解金属掺杂芳香烃有机超导体这一新兴超导家族的晶体生长和物理特性, 同时也提供了一种低温制备C₆₀和石墨的新方法.     

New side-pump scheme for large mode area fiber lasers by wrapping polished fibers conjugate caustic removed

With the purpose of uniform gain coefficient along the axial direction in the core of gain guided and index anti-guided fiber, a new kind of side-pump scheme by wrapping particularly treated fibers around the central GGIAG fiber is reported in this paper. According to leakage mode analysis on wrapped fiber and numerical simulation on this pumping structure having ytterbium doped central fiber and conventional wrapped side fiber, we find this kind of pump scheme can improve the uniformity of gain coefficient along the fiber direction, and also, it can support multi channels of pumping sources by adding more side fibers to improve the total effective incident pumping power.