基于PolSK调制的四波混频型超快全光译码器

提出了一种新型的基于半导体光放大器（semiconductor optical amplifier, SOA）中四波混频（four-wave mixing, FWM）效应的超快全光译码器方案,方案中采用了偏振移位键控（polarization-shift-keying, PolSK）信号光.考虑SOA的偏振相关性,建立了这种全光译码器完整的偏振相关宽带理论模型.通过数值模拟的方法,从理论上实现了超快全光译码器,并研究了两输入信号光功率、SOA注入电流和SOA的偏振相关性对全光译码器输出特性的影响. 关键词： 全光译码器 偏振移位键控 四波混频 半导体光放大器     

氢掺杂单层石墨体系的晶格动力学研究

采用密度泛函理论研究了氢掺杂单层石墨（graphene）体系,并采用密度泛函微扰理论方法计算了体系局域振动模（LVMs）.结果显示,高频位置的LVMs数目与缺陷中氢原子数相等,而不同掺杂类型的LVMs频谱位置各不相同.研究结果及分析表明,LVMs测量是评估质子辐射下石墨样品的替位氢掺杂类型及其含量的有效方法,该方法可推广应用于研究其他掺杂体系. 关键词： 石墨 局域模式 晶格动力学     

Dielectronic recombination of Co-like tantalum

Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum: 3s²3p⁶3d_3/2³ 3d_5/2⁶ n'l', 3s²3p⁵3d¹⁰n'l', 3s3p⁶3d¹⁰n'l', 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and 3s3p⁶3d⁹4ln'l' with n' ≤ 25, and 3s²3p⁶3d⁸5ln'l' with n' ≤ 9. The l' and n' dependences of partial DR rate coefficients are investigated. The contributions from higher n'complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.     

Obtaining local reciprocal lattice vectors from finite‐element analysis

Finite‐element analysis is frequently used by engineers at synchrotron beamlines to calculate the elastic deformation of a single crystal undergoing mechanical bending or thermal load. ANSYS^® Workbench? software is widely used for such simulations. However, although ANSYS^® Workbench? software provides useful information on the displacements, strains and stresses within the crystal, it does not yield the local reciprocal lattice vectors that would be required for X‐ray diffraction calculations. To bridge this gap, a method based on the shape functions and interpolation procedures of the software itself has been developed. An application to the double‐crystal bent Laue monochromator being designed for the I12 (JEEP) wiggler beamline at the Diamond Light Source is presented.     

Rectifying effect of heterojunction fabricated in freestanding thin film of polyaniline containing azobenzene side-chain

An innovative heterojunction is fabricated between two sides of a freestanding thin film of HCl-doped polyaniline (PANI) derivative containing azobenzene side-chain, which is synthesized through an N-alkyl-substituted reaction. Of the film, the side with being irradiated by UV light during preparation is represented as `A side'; the other side without being irradiated is represented as `N side'. The electrical properties of the heterojunction are measured and the rectifying effect is observed in the {current--voltage} characteristic curves with the values of rectifying ratio (γ) being 20 at ±0.06 V at T= 77K and 4 at ±0.02V at T=300 K separately.     

利用DDA方法计算大气气溶胶粒子光学特性

大气气溶胶是大气的重要组成部分,其光学特性是研究大气辐射传输特性的重要参量。本文基于DDA方法,对不同形状气溶胶粒子的光学特性进行计算,得到气溶胶粒子的消光因子、吸收因子随波长变化的数值结果。结合Muller散射矩阵,给出了气溶胶粒子散射强度和极化度的角分布,为研究大气辐射传输提供了有效的方法。     

丙烯酰胺基光致聚合物全息光栅的动力学研究

研究了光致聚合物的光化学反应和单体扩散反应的理论模型及动力学参数. 合成了以聚乙烯醇为粘结剂,三乙醇胺为引发剂,藻红B敏化的丙烯酰胺基光致聚合物全息存储材料,通过对测定的透过率和衍射效率进行曲线拟合,分析了染料浓度对光致聚合物的摩尔吸收系数ε、量子产率Φ和光化漂白速率常数k等光化动力学参数的影响规律,以及曝光强度对聚合反应速率k₀、扩散时间常数τ_D和最大折射率调制度Δn等扩散动力 关键词： 光致聚合物 透过率 衍射效率 动力学参数     

A new car-following model with consideration of the traffic interruption probability

In this paper, we present a new car-following model by taking into account the effects of the traffic interruption probability on the car-following behaviour of the following vehicle. The stability condition of the model is obtained by using the linear stability theory. The modified Korteweg--de Vries (KdV) equation is constructed and solved, and three types of traffic flows in the headway sensitivity space---stable, metastable, and unstable---are classified. Both the analytical and simulation results show that the traffic interruption probability indeed has an influence on driving behaviour, and the consideration of traffic interruption probability in the car-following model could stabilize traffic flow.     

Theoretical Studies on the Fe-M Interactions and 31P NMR in Fe(CO)3(EtPhPpy)2MX2 (X=NCS, SCN, Cl; M=Zn, Cd, Hg)

采用密度泛函理论PBE0方法,计算了单核配合物[Fe(CO)3(EtPhPpy)2] (1)、双核配合物[Fe(CO)3(EtPhPpy)2M(NCS)2] (2:M=Zn,3: M=Cd,4: M=Hg) 和[Fe(CO)3(EtPhPpy)2CdX2] (5:X=Cl,6: X=SCN)的几何构型和电子结构,研究了Fe-M相互作用及其对31P化学位移的影响. 结果表明：配合物的稳定性(S)为S(2)>S(3)>S(4),S(3)≈S(6)>S(5).在[Fe(CO)3(EtPhPpy)2CdX2]体系中,含[SCN]-配合物的稳定性大于含Cl-的. Fe-M相互作用的强度(I )顺序为I (2)≈I (3)相似文献   

Tb3+掺杂硅酸盐玻璃发光性能的浓度依赖关系

 利用高温熔融法制备了不同浓度的Tb³⁺掺杂硅酸盐玻璃,并分别测量了紫外和X射线激发时的发射光谱。光谱结果表明,不同浓度Tb³⁺掺杂硅酸盐玻璃在紫外和X射线激发时发光行为具有相似的浓度依赖关系：低浓度Tb₄O₇掺杂时主要以蓝光(5D₃→⁷FJ)发射为主,而高浓度掺杂时以绿光(⁵D₄→⁷FJ)发射为主。Tb³⁺发光强度与掺杂浓度的关系分析表明,⁵D₃的浓度猝灭是电偶极-电偶极相互作用引起的, 而⁵D₄的浓度猝灭是交换相互作用引起的。