A novel optical beam splitter based on photonic crystal with hybrid lattices

A novel optical beam splitter constructed on the basis of photonic crystal(PC) with hybrid lattices is proposed in this paper.The band gap of square-lattice PC is so designed that the incident light is divided into several branch beams.Triangular-lattice graded-index PCs are combined for focusing each branch.Computational calculations are carried out on the basis of finite-different time-domain algorithm to prove the feasibility of our design.The waveguide is unnecessary in the design.Thus the device has functions of both splitting and focusing beams.Size of the divided beam at site of full-width at half-maximum is of the order of λ/2.The designed splitter has the advantages that it has a small volume and can be integrated by conventional semiconductor manufacturing process.     

HT-7托卡马克slide-away放电充气对等离子体行为的影响

本文研究了slide-away放电条件下的等离子体约束性能;分析了充气对等离子体约束性能以及反常多普勒共振不稳定性的影响.研究了等离子体密度的提升对slide-away放电过程中逃逸电子辐射行为的影响.研究结果发现:slide-away放电充气可以抑制逃逸电子反常多普勒不稳定性,但是使得等离子体约束状态变差,逃逸电子辐射增强.     

Edge states at the interface between monolayer and bilayer graphene

The electronic properties for monolayer-bilayer hybrid graphene with zigzag interface are studied by both the Dirac equation and numerical calculation in zero field and in a magnetic field. Basically there are two types of zigzag interface dependent on the way of lattice stacking at the edge. Our study shows they have different locations of the localized edge states. Accordingly, the energy-momentum dispersion and local density of states behave quit differently along the interface near the Fermi energy EF=0.     

一种用于土壤非金属养分测试的光纤探头式分光光度计

针对测土配方施肥技术中要求快速、便捷、高效地进行土壤养分测试的需求,文章基于浸入式光纤探头、平场凹面全息光栅、二极管线阵检测器开发了一种光纤探头式分光光度计用于土壤养分中非金属元素的快速、准确测试。基于国家计量检定规程JJG 178—2007对紫外、可见、近红外分光光度计的性能检测方法测试的该仪器的波长最大允许误差与波长重复性、基线平直度、透射比最大允许误差与透射比重复性均达到了国标第Ⅲ级别标准,其最小光谱带宽、噪声与漂移、杂散光基本达到了国标第Ⅳ级别标准。基于该仪器测试的土壤硝态氮、铵态氮、有效磷、有效硫、有效硼、和有机质含量与基于商用的国产单光束和进口双光束分光光度计测试的结果呈极显著的线性相关关系,其回归方程的斜率接近于1,且对比数据之间无显著性差异。因此,该光纤探头式分光光度计可用于土壤非金属养分的快速、准确测试。     

ICP-MS法测定不同采收时间宽叶荨麻中微量元素含量

采用微波消解,ICP-MS法分析不同采收时间宽叶荨麻中18种微量元素Al,Ba,Ca,Co,Cr,Cu,Fe,K,Li,Mg,Mn,Mo,Na,Ni,P,Pb,S和Zn的含量。该方法的相对标准偏差在1.2%～5.3%之间,加标回收率在95.4%～101.2%之间。结果表明宽叶荨麻中K,P,S,Ca,Na含量较高;Fe,Mg,Mn,Zn含量次之;有潜在生理毒性的元素Al,Cr,Pb的含量较低,并且在宽叶荨麻中微量元素呈现明显的季节性动态变化,此结果为进一步研究宽叶荨麻药理药效与微量元素的关系以及更好的开发这一资源提供理论数据。     

拱形激光二极管侧抽运Nd:YAG固体激光器的实验研究

详细阐述了同心抽运、同心冷却的激光二极管紧包侧抽运Nd：YAG激光器的实验研究工作。这种抽运结构使晶体内的增益场与谐振腔基模实现了良好的匹配,易于得到良好的光束质量和大能量输出,基模提取效率高。模拟分析了晶体内的增益场以及横截面内的温度分布,从不同角度探讨了激光二极管的温度特性对器件工作的影响。研究了晶体的热致退偏效应对器件调Q工作的影响．并且初步探讨了不同腔长、不同腔型下器件的工作情况,这些实验结果对进一步优化使用这种抽运结构有指导意义。所设计的激光器在工作频率6Hz时．得到了斜效率为44．3％的多模调Q输出。在抽运能量735mJ时,得到最大输出能量135mJ,脉宽7．6ns的调Q脉冲,光光效率为18．4％,插头效率为11．0％,光束发散角小于1．5mrad。     

A 168-W high-power single-frequency amplifier in an all-fiber configuration

We present a high-power,single-frequency,narrow linewidth fiber amplifier based on master oscillator power amplification chains in an all-fiber configuration.The effect of the delivery fiber on the maximum output power is studied.A home-made 1064-nm seed laser with a 20-kHz linewidth is boosted to 129 W,and limited by stimulated Brillouin scattering(SBS) when the delivery fiber is 1.2 m long.By shortening the delivery fiber length to 0.7 m,the SBS threshold is increased efficiently and the maximum output power rises to 168 W with an 82.9% power conversion efficiency.The experimental results indicate that the output power can be further raised by shortening the delivery fiber length and increasing the pump power.     

Spectroscopy of stripe order in La1.8Sr0.2NiO4 using resonant soft x-ray diffraction

Strong resonant enhancements of the charge-order and spin-order superstructure-diffraction intensities in La1.8Sr0.2NiO4 are observed when x-ray energies in the vicinity of the Ni L2,3 absorption edges are used. The pronounced photon-energy and polarization dependences of these diffraction intensities allow for a critical determination of the local symmetry of the ordered spin and charge carriers. We found that not only the antiferromagnetic order but also the charge-order superstructure resides within the NiO2 layers; the holes are mainly located on in-plane oxygens surrounding a Ni2+ site with the spins coupled antiparallel in close analogy to Zhang-Rice singlets in the cuprates.     

光腔模式及光束传输的特征向量算法

发展了一种新颖的适用于光腔模式及光束传输模拟计算的特征向量法.该方法的核心是基于菲涅耳-基尔霍夫衍射积分理论构造了一种新的光腔传输矩阵,通过求解激光谐振腔的本征积分方程,即可一次求解得到表征腔镜上多个光场模式振幅及相位分布的特征向量组;而谐振腔内或腔外任意地方的光场分布,也可采用该方法进行光束传输模拟而求得.对与该方法有关的单元划分、形函数选取、误差及稳定性分析等问题进行了论述,分析表明:合适的单元划分和形函数选取有利于提高计算速度、精度和稳定性.     

圆芯型边孔光纤双折射的有限元分析

对网芯型边孔光纤固有双折射的研究结果进行了报道。在对边孔光纤固有烈折射的产生机理和计算原理进行研究的基础之上,采用有限元法分析了网芯型边孔光纤的内部应力分布和双折射的大小。研究结果表明圆芯型边孔光纤的几何双折射较小,以应力双折射为主;边孔的存在导致光纤纤芯和包层区域的应力分布发生了较大的变化。文章提出了两边孔的连线方向为边孔光纤的快轴方向．并就不同的边孔结构对光纤双折射的影响进行了研究,发现网芯网孔型边孔光纤的同钉双折射随边孔张角的增加而成指数关系增长．可通过增大边孔半径和减小两孔间距提高边孔光纤的双折射。