类镍Au~(51+)离子电子碰撞激发特性的研究

利用全相对论扭曲波方法和研究电子碰撞激发过程的计算程序REIE06系统计算了类镍Au~(51+)离子从基态(3s~23p~63d~(10))n=3壳层3 l(l=s、p、d)电子激发到4 l、5 l(l=s、p、d、f)的碰撞激发强度和截面,研究了在不同入射电子能量下截面的变化规律,通过对类镍Au51+离子涉及X射线激光跃迁的相关能级电子碰撞激发速率的计算,分析了等离子体中电子温度对碰撞过程的影响.部分计算结果与其它理论及实验结果进行了比较,取得了很好的一致性.     

高离化态类氖离子的电子碰撞激发特性研究

利用基于多组态Dirac-Fock(MCDF)理论方法的原子结构和性质计算程序GRASP92和全相对论扭曲波电子碰撞激发计算程序REIE06,系统计算了类氖离子(Z=50—57)激发组态2s22p53l和2s2p63l(l=s,p,d)的能级结构和碰撞激发截面,总结了碰撞激发截面随入射电子能量的变化规律,讨论了实验中感兴趣的(2p1/23d3/2)1→2s22p61S0(标记为3C线)与(2p3/23d5/2)1→2s22p61S0(标记为3D线)跃迁线强度比值的沿等电子系列特性和强组态相互作用对高离化态类氖离子截面的影响.     

类铜Au50+离子电子碰撞激发特性的研究

利用全相对论扭曲波（RDW）方法,系统计算了类铜Au50+离子的外壳层电子4s激发到4l 、5l （ l= s、p、d、f,除去4s-4s ）和内壳层电子3l （l = s、p、d）激发到4l 、5l （l = s、p、d、f）的碰撞激发截面,研究了在不同入射电子能量下截面的变化规律,给出了3d-4f 和3d-5f 精细结构能级的碰撞激发截面。部分计算结果与其它理论及最新实验结果进行了比较,取得了很好的一致性。     

类铜Au50+离子电子碰撞激发特性的研究

利用全相对论扭曲波（RDW）方法，系统计算了类铜Au50+离子的外壳层电子4s激发到4l 、5l （ l= s、p、d、f，除去4s-4s ）和内壳层电子3l （l = s、p、d）激发到4l 、5l （l = s、p、d、f）的碰撞激发截面，研究了在不同入射电子能量下截面的变化规律，给出了3d-4f 和3d-5f 精细结构能级的碰撞激发截面。部分计算结果与其它理论及最新实验结果进行了比较，取得了很好的一致性。     

类氦Fe~(24+)离子的电子碰撞激发及辐射级联特性研究

基于全相对论扭曲波(RDW)电子碰撞激发计算程序REIE06,系统计算了类氦Fe~(24+)离子基态1s~(21)S_0到激发态1s2s和1s2p精细结构能级的碰撞强度和截面,分析了在不同入射电子能量下碰撞强度的变化规律,详细研究了在6.86 Ke V和9.94 Ke V能量下,碰撞辐射级联效应对类氦Fe~(24+)离子w线(1s~(21)S_0→1s2p~1P_1)、x线(1s~(21)S_0→1s2p~3P_2)、y线(1s~(21)S_0→1s2p~3P_1)和z线(1s~(21)S_0→1s2s~3S_1),x/w、y/w和z/w线强度比值的影响,总结了一些有意义的结论.部分计算结果与其它实验和理论结果进行了比较,取得了很好的一致性.     

金等离子体M带谱3d→4f和3d→5f电子离子碰撞激发强度

电子离子碰撞激发强度在超组态碰撞辐射模型中真实模拟非局域热动平衡金激光等离子体M带谱跃迁中离子的平均电离度、电荷态分布和能级布居数等离子的电离态特性是必不可少的.基于全相对论扭曲波电子碰撞激发计算程序REIE06,系统计算了高离化态金离子(Au51+、Au50+、Au49+)精细结构能级3d→4f和3d→5f的碰撞强度,计算中详细考虑了电子关联效应和Breit相互作用对碰撞强度的影响.计算结果与可获得的其它理论及实验结果进行了比较,取得了好的一致性.     

激光金等离子体中Au~(50+)离子E1、M1跃迁的理论研究

根据全相对论组态相互作用(RCI)方法和多组态Dirac-Fock(MCDF)方法,考虑量子电动力学(QED)效应和Breit修正,选取重要的电子组态,系统计算了激光金等离子体中类铜Au~(50+)离子nl-n′l′(n=4,l=s,p,d,f;n′=4,5,l′=s,p,d,f)电偶极(E1)跃迁和磁偶极(M1)跃迁的跃迁波长、跃迁几率和振子强度,并得到Au~(50+)离子部分激发态能级结构。计算得到的能级与波长与其他已有的理论和实验结果进行了比较,得到了较为满意的结果。分别采用长度规范和速度规范对电偶极(E1)跃迁参数进行了计算和比较,得到了很好的收敛。计算结果还表明,对于高Z高离化态离子,某些禁戒跃迁占有重要地位。     

类Li钙离子精细结构能级和软X射线光谱的理论计算

用多组态HFR方法计算了类Li等电子序列钙(Ca,Z=20)离子1s~2nl(n=2～6,l=0～5)组态的所有能级和电偶极跃迁的软X射线光谱,其中4f→3d,5f→3d及5d→3p、4d→3p由于其下能级跃迁速率较大,容易形成粒子数反转因而可作为激光跃迁,5f→3d、6f→3d跃迁已处于“水窗”波段,而4f→3d的激光跃迁(5.77nm)已为我们最近的实验所证实.并将我们的计算结果与其它理论计算和实验数据进行了比较.     

高离化态类镍离子电子碰撞激发过程的相对论扭曲波理论研究

利用相对论扭曲波方法和新发展的研究电子碰撞激发过程的计算程序REIE06,系统计算了电子碰撞激发高离化态类镍Gd³⁶⁺和Rn⁵⁸⁺—U⁶⁴⁺(Z=86—92)离子从基态到4l(l=s,p,d,f)次壳层精细结构能级的碰撞强度和截面.研究了随等电子系列变化时,从基态到与X射线激光有关的3d⁹4p和3d⁹4d激发态能级的电子碰撞激发截面随Z的变化,讨论了强的组态相互作用对高离化态类镍离子截面的影响.通过对Gd³⁶⁺离子涉及X射线激光跃迁的相关能级电子碰撞激发速率系数的计算,分析了等离子体中电子温度对碰撞过程的影响.同时,目前部分计算结果与以往的理论结果进行了比较,得到了很好的一致性. 关键词： 电子碰撞激发 相对论扭曲波方法 高离化态类镍离子     

超精细结构效应对辐射光谱圆极化特性的影响

在相对论多组态Dirac-Fock方法和密度矩阵理论的基础上,利用发展的全相对论扭曲波程序,系统研究了超精细结构效应对纵向极化电子碰撞激发过程以及退激发辐射光谱圆极化特性的影响.计算得到了类氦Sc~(19+)和~(205)Tl~(79+)离子1s~2 ~1S_0→1s2p ~3P_2超精细结构层次上M_F能级的碰撞强度,考察了辐射衰变过程中发出特征光子的极化特性,并分析了E1-M2量子干涉效应以及电子-电子间相互作用的相对论修正对退激发辐射光子圆极化度的影响.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.