3d过渡金属掺杂M_2@Si_(20)(M=Sc-Zn)团簇的密度泛函理论研究

利用密度泛函理论(DFT)研究3d过渡金属掺杂硅团簇的几何结构和稳定性,计算了绝热电子亲和能和垂直电离能,内嵌双金属间距,自旋磁矩等.结果表明内嵌的Sc、Ti、V、Mn金属二聚体和十二面体硅笼构成了稳定的富勒烯结构,随着d电子数目的增加其内嵌的富勒烯构型有部分畸变,总体而言Si_(20)团簇掺杂双金属后稳定性得到了提高.     

激光加热微管靶反激光方向二次谐波时空分辨结构

本文报道了高功率激光加热微管靶,从入射激光的反方向观察二次谐波的时空分辨结构,分析了激光与微管靶的相互耦合过程.在激光与等离子体细丝相互作用的理论基础上,解释了微管区域内反激光方向二次谐波辐射的特殊现象.     

锥形光纤中光波传输特性的蒙特卡罗模拟

为了分析锥形光纤中光子流的传输特性和空间分布特性,采用了蒙特卡罗算法对其进行了模拟仿真,得到了大量光子经过锥形光纤后的光子分布图.模拟实验结果表明,通过锥形光纤的大量光子集中在探测器中心,到达探测器某一位置的光子数随着该位置到探测器中心距离的增加而减少,并且在锥形光纤锥度比一定的条件下,改变锥形光纤长度,光强度随着长度的增加而下降,但通过锥形光纤的光子分布是一样的.这些研究结果对锥形光纤的设计和实际应用提供了重要依据.     

反应磁控溅射制备TiO2和Nb2O5混合光学薄膜

利用反应磁控溅射技术在BK-7基片上制备了二氧化钛和五氧化二铌均匀混合的光学薄膜.薄膜的内部微结构、表面形貌、化学成分比例以及光学性质等用X射线衍射、高分辨扫描电子显微镜、原子力显微镜、X射线光电子能谱和紫外可见近红外分光光度计进行研究;发现制备的薄膜为非晶结构,薄膜的表面平整、内部结构致密,不存在柱状结构或结晶颗粒的缺陷,TiO2与Nb2O5的成分比例大致是1∶1.54.从光学透射光谱计算的折射率和消光系数显示,在550 nm波长处的折射率为2.34,消光系数为2.0×10－4.结果表明制备的薄膜是TiO2和Nb2O5均匀混合的高质量光学薄膜.     

超短脉冲激光光束在一维反射型体全息光栅中的衍射

基于Kogelnik的耦合波理论,研究了在色散效应的影响下,超短脉冲激光光束在反射型体全息光栅中衍射的性质.研究给出了衍射光及透射光在频谱域及时间域的振幅及强度分布、光栅的光谱宽度及衍射效率随光栅参量及入射条件的变化.数值研究的结果表明,在光栅记录介质色散效应的影响下,衍射光束的光谱宽度减小,脉冲展宽,衍射效率降低.通过适当的选取光栅参量及入射条件,可以控制衍射和透射光束的频谱和时间强度分布,得到满意的衍射和透射光束的带宽和波形,从而可以将其应用于脉冲整形等技术中.     

Fabrication of polymer compound microlens by lens-on-lens microstructures

We proposed a novel method for fabricating polymer compound microlenses (PCMLs) using micro-inkjet technique and subsequent curing process. Two different types of PCMLs with sandwich microstructure (PDMS-Glycerol-PDMS), concave and convex PCMLs, have been designed and fabricated in experiments. Convex PCML has two real images and two foci. The concave PCML has one real and one virtual focal planes, which can generate one real image and one virtual image respectively. Moreover, the diameter of concave PCML can be controlled by adjusting the curing time and temperature. The proposed method is simple, efficient and suitable for realizing large-scale high numerical aperture PCMLs array, which has potential applications in diverse optical systems such as optical storage and three-dimensional imaging.     

Porous NiO hollow quasi-nanospheres derived from a new metal-organic framework template as high-performance anode materials for lithium ion batteries

Porous hollow metal oxides derived from nanoscaled metal-organic framework (MOF) have drawn tremendous attention due to their high electrochemical performance in advanced Li-ion batteries (LIBs). In this work, porous NiO hollow quasi-nanospheres were fabricated by an ordinary refluxing reaction combination of a thermal decomposition of new nanostructured Ni-MOF, i.e., {Ni₃(HCOO)₆·DMF}_n. When evaluated as an anode material for lithium ion batteries, the MOF derived NiO electrode exhibits high capacity, good cycling stability and rate performance (760 mAh g^?1 at 200 mA g^?1 after 100 cycles, 392 mAh g^?1 at 3200 mA g^?1). This superior lithium storage performance is mainly attributed to the unique hollow and porous nanostructure of the as-synthesized NiO, which offer enough space to accommodate the dramstic volume change and alleviate the pulverization problem during the repeated lithiation/delithiation processes, and provide more electro-active sites for fast electrochemical reactions as well as promote lithium ions and electrons transfer at the electrolyte/electrode interface.     

Linewidth of electromagnetically induced transparency under motional averaging in a coated vapor cell

The linewidth of electromagnetically induced transparency(EIT) in a coated Rb vapor cell was studied under a magnetic field gradient.The nonlinear broadening of the EIT linewidth with the magnetic field gradient was observed.It was found that the motional averaging of the field gradient was more pronounced at higher laser intensities and larger beam sizes.In the same regime,there was a small linewidth decrease with the increasing magnetic field gradient.We have established a Monte-Carlo model,which gave results in good qualitative agreement with our experiment.Physics pictures for the above phenomena were also suggested.These results provide an understanding of the EIT linewidth behavior under motional averaging,and should be useful for applications in quantum optics and metrology based on coated vapor cells.     

Simulation of Three-Spin Interaction in Coupled Cavities Chain

We generalize usual second-order effective Hamiltonian approximation into third-order. Employing the generalized method, we propose a scheme to generate three-spin interaction using coupled cavity chain. We show that the third order term not only improves two parties interaction but also induces direct three-spin interaction which has not been simulated before. By controlling the frequency of laser field, one can obtain next nearest neighbor interaction on the same order with the nearest neighbor’s or the three-spin interaction on the same order as next nearest neighbor’s.