bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct measurement of the temporal structure of narrow bandwidth femtosecond XUV using ultra-short laser via differential photoelectron energy spectrum
Authors: Ge Yu-Cheng  , Li Yuan-Jing  , Kang Ke-Jun  ,   清华大学工程物理系粒子技术与辐射成像国家专业实验室，北京  100084
Published: December 2020

A method is introduced to directly measure the temporal structure of femtosecond XUV which has a narrow bandwidth using sub_picosecond duration laser. Calculati on shows that such a temporal structure can be reconstructed from the differenti al photoelectron energy spectrum excited by XUV or x ray, modulated by a laser field and measured at 90° or 0° with respect to the linear laser polarizatio n. The effectiveness and nonlinearity of the method are investigated. Energy res olution and bin(s) are important parameters for measurement and calculation. The method has a broad temporal measurement range and can be used for researches of dynamic processes associated with atomic motions.
Wigner functions for the photon-added and photon-depleted even and odd coherent states
Authors: Yang Qing-Yi  , Sun Jing-Wen  , Wei Lian-Fu  , Ding Liang-En  ,   (1)华东师范大学物理系光谱学与波谱学教育部重点实验室，上海  200062; (2)华东师范大学物理系光谱学与波谱学教育部重点实验室，上海  200062;广西大学物理系，南宁  530004; (3)上海交通大学物理系，上海  200030
Published: December 2020

By using the definition of Wigner function in Fock states representation，Wigner functions for the photon_added and photon_depleted even and odd coherent states is reconstvucted. The results show that photon_added even and odd coherent stat es always demonstrate non_classical characteristics but photon_depleted even and odd coherent states demonstrate non_classical characteristics only when k t ake odd and even number respectively.
Experimental study of continuous-variable quantum teleportation
Authors: Zhai Ze-Hui  , Li  Yong-Ming  , Wang Shao-Kai  , Guo Juan  , Zhang Tian-Cai  , Gao Jiang-Rui  ,   量子光学与光量子器件国家重点实验室，山西大学光电研究所，太原  030006
Published: December 2020

The experimental demonstration of quantum teleportation for continuous variables using the squeezed_state entanglement generated by a type II phase matching opt ical parametric amplifier(OPA) is reported. Type II OPA operating at deamplification can generate amplitude_anticorrelated and phase_correlated entanglements, which can be used in quantum teleportation scheme by direct Bell_ state measurement. The correlation of 2dB was obtained with a pair of KTP crystals in the cavity. The inferred teleportation fidelity is 060,which when correlated for the e fficiency of detection by the output observer, gives a fidelity of 057 The i mperfect factors in detection are also discussed.
Spectrum broadening of ultrashort pulse propagation in cascaded hollow fibers and pulse compression
Authors: Song Zhen-Ming  , Pang Dong-Qing  , Zhang Zhi-Gang  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院超快激光实验室，光电信息技术科学教育部重点实验 室(天津大学)，天津  300072
Published: December 2020

The spectrum broadening and pulse compression of the ultrashort pulse propagatio n in cascaded hollow fibers,by solving the generalized nonlinear Schrdinger eq uation with the split_step Fourier Method,are discussed.The simulation shows tha t the technique using cascaded hollow fibers is a reliable route to achieve few to mono-cycle pulses of high energy.
Strain and elasticity of static granular matter
Authors: Wang Huan-You  , Cao Xiao-Ping  , Jiang Yi-Min  , Liu Mario  ,   (1)蒂宾根大学理论物理研究所，蒂宾根  72076，德国; (2)中南大学物理科学与技术学院，长沙  410083,中国; (3)中南大学物理科学与技术学院，长沙  410083,中国;蒂宾根大学理论物理研究所，蒂宾根  72076，德国
Published: December 2020

This paper shows that for a static cohesionless granular material simply averaging in space the strains inside grains does not result in its macroscopic strain , so the fields of displacement vector and strain tensor do not have the propert y of coarse-graining. However this gives no disturbance to the validity of the n otions of strain and elasticity for the granular material because they are based on the equilibrium thermodynamics.
Control of population and atomic coherence by adiabatic rapid passage
Authors: Zhou Yan-Wei  , Ye Cun-Yun  , Lin Qiang  , Wang Yu-Zhu  ,   (1)浙江大学光学研究所, 杭州  310027，中国; (2)浙江大学光学研究所, 杭州  310027，中国;College Lasertek Inc. Houston,TX 77380, USA
Published: December 2020

Robust control of atomic coherence and population transfer among Zeeman sublevel s in the ground states of atom is investigated theoretically using adiabatic rap id passage on a nanosecond time scale. It is shown that a slight change in the p ump pulse time delay relative to the Stokes pulse leads to a significant modific ation of atomic coherence and population transfer. This coherence control of qua ntum state and population is presented by numerical simulations based on self-co nsistent set of density matrix equations and Maxwell equations.
FDTD simulation for plasma photonic crystals
Authors: Liu Shao-Bin  , Zhu Chuan-Xi  , Yuan Nai-Chang  ,   (1)国防科技大学电子科学与工程学院,长沙  410073; (2)南昌大学理学院,南昌  330047
Published: December 2020

Plasma photonic crystals are artificially periodic structures, which are compose d of plasmas and dielectric structures (or vacuum). In this paper, the piecewise linear current density recursive convolution (PLCDRC) finite-difference time-do main (FDTD) method is applied to study the plasma photonic crystals and those co ntaining defects. In time-domain, the electromagnetic(EM) propagation process an d reflection/transmission electric field of Gauss pulses passing through the pla sma photonic crystals are investigated. In frequency-domain, the reflection and transmission coefficients of the pulses through the two kinds of crystals are co mputed. The results illustrate that the plasma photonic crystals mostly reflect for the EM wave of frequencies less than the plasma frequency, and mostly transm it for EM wave of frequencies higher than the plasma frequency. In high frequenc y domain, the plasma photonic crystals have photonic band gaps, which is analogo us to the conventional photonic crystals.
Potential safe termination by laser ablation of high-Z impurity in the HL-1M tokamak
Authors: Zheng Yong-Zhen  , Feng Xing-Ya  , Zheng Yin-Jia  , Guo Gan-Cheng  , Xu De-Ming  , Deng Zhong-Chao  ,   核工业西南物理研究院，成都  610041
Published: December 2020

A preliminary experiment for triggering a plasma current quench by means of injection of high_Z impurities has been performed on the HL_1M before the major disruption.Using injection of impurity with higher charge of the nuclei allows u s to increase the radiation cooling on a 3?ms time scale and the electronic tem perature loss contract is 80% before current terminates.It can be a simple and p otential approach to decrease significantly the plasma thermal energy and the ma gnetic field energy before a disruption and to a safe plasma termination.
Scanning tunneling microscopy studies of alkane and alkanol adsorbed on graphite
Authors: Chen Yong-Jun  , Zhao Ru-Guang  , Yang Wei-Sheng  ,   人工微结构和介观物理国家重点实验室,北京大学物理学院,北京  100871
Published: December 2020

The behavior of tetradecane and octadecanol adsorbed on graphite in solid-gas interface is investigated at room temperature by STM. The studies reveal that tetradecane and octadecanol on graphite are self-assembled into a high degree of two-dimensional order, and the lamellar structure, which is similar to that of STM observation in solid-liquid interface, is obtained. But the high-resolution images give striking differences in molecular arrangement, lattice constant and orientation of molecules in one lamella, and we attribute these differences to the solvent effect suggested in previous neutron diffraction studies.
Influence of structure on adhesion of grains in CVD diamond films
Authors: Ma Bing-Xian  , Yao Ning  , Jia Yu  , Yang Shi-E  , Lu Zhan-Ling  , Fan Zhi-Qin  , Zhang Bing-Lin  ,   郑州大学物理工程学院，郑州大学教育部材料物理重点实验室，郑州  450052
Published: December 2020

Diamond thin films of different structures were prepared by using chemical vapor deposition on WC(6%Co) substrates under different conditions.Reman spectroscopy was used for the quality evaluation of the diamond films.The cracking size in indentation tests was used for the evaluation of adhesion strength,and the influence of structure of diamond films on the adhesion was studied.Results obtained show that: (1) The buffer role of sp2_carbon between grain boundaries greatly affect the residual stress of the film,hence the cracking size decreases steadily with increasing sp2 content.(2) The increase of nucleation density is mainlyh due to the contribution of the diamond seed grains left. In this case,the increase of nucleation density cannot effectively improve the chemical adhesioe force between the film and the WC substrate,and cannot improve the adhesion between the film and the substrate.(3)For thinner films there is no compressive stress among diamond grains,hence the cracking size does n t increase apparently with increasing deposition time.Strong compressive stress emerges only after the thickness increases to a certain value,and then the cracking size increases rapidly with increasing deposition time.
Study on the phase transformation behavior of TiO2 thin films in an electric field
Authors: Zhou Feng  , Liang Kai-Ming  , Wang Guo-Liang  ,   清华大学材料科学与工程系，北京  100084
Published: December 2020

TiO2 thin films, which were heat-treated with an applied electric fie ld, were prepared by sol-gel method. The phase transformation behavior of TiO2 thin fil ms was studied by differential thermal analysis, atomic force microscopy and Ra man spectroscopy respectively. It was indicated that the phase transformation of non-crystalline to anatase could be accelerated with an applied electric field. Studies on photo-catalytic degradation showed that the photo-catalytic activity of TiO2 thin films in an applied electric field became higher.
Energetics and structures of high-temperature copper cluster studied by Monte Carlo method
Authors: Li Gong-Ping  , Zhang Mei-Ling  ,   兰州大学现代物理系，兰州  730000
Published: December 2020

Monte Carle method and embedded-atom potential were utilized to study the energetics and structures of high_temperature copper clusters, which contained 55 ato ms. First, we calculated the energetics and structures of Cu55 at 2 00?K.T he results that we got well accord with those Suleyman Ozcelik et al obtained. I t is shown that this method is reliable. Then, the system was cooled from 12000 ?K, in a step of 1000?K, the energetics and structures were measured while th e system reached equilibrium. At each temperature, the Monte Carlo Stepsare 10 6. From the simulation we found that above 10000?K, the system only contain a few atoms that are combined together and unsteady,so single atoms are getting more. Between 10000 and 6000?K, the structure of the system gradually changes to forming nucleating center, other atoms nucleated with nucleating center; Atta ined equilibrium at 5000?K, the system atom is already complete combinative tog ether without the monatomic, the energy is -11206?eV; Further lower the tempe rature, the system construction becomes from irregular、dissymmetrical to regula r、symmetrical forming a double icosahedral shape, the energy is -16850?eV; W ith visual displaying, a very clear evolving structural diagram was achieved wit h lower in temperature.
Studies on the strain and its effect on defects in heteroepitaxial ZnO films prepared by LP-OCVD method
Authors: Sun Xian-Kai  , Lin Bi-Xia  , Zhu Jun-Jie  , Zhang Yang  , Fu Zhu-Xi  ,   (1)中国科学技术大学物理系,合肥  230026; (2)中国科学技术大学物理系,合肥  230026;中国科学技术大学结构分析实验室,合肥  230026
Published: December 2020

High_quality ZnO films have been epitaxially grown on Si substrates by low_pressure metal organic chemical vapor deposition(LP_MOCVD) and two kinds of samples have been prepared:one is ZnO directly grown on Si while the other one grown with a SiC buffer layer.According to the results of Raman spectra,XRD,AFM,and photoluminescence,it is indicated that the tensile strain in the epitaxial ZnO films has a great influence on the crystalline quality of ZnO films,and the SiC buffer layer can effectively modulate the tensile strain,hence reduce the concentration of defects and improve the film quality.Then,from the defect formation mechanism,we suggest that for ZnO/Si,the large tensile strain results in high concentration of non_radiation recombination centers,which largely reduce the intensity of UV and green emissions; but for ZnO/SiC/Si,the small tensile strain results in oxygen antisite defects OZn in ZnO films,which enhance the green emis sion in photoluminescence.
Study on the giant magnetoimpedance effect of FeCuCrVSiB multilayered films
Authors: Chen Wei-Ping  , Xiao Shu-Qin  , Wang Wen-Jing  , Jiang Shan  , Liu Yi-Hua  ,   (1)山东大学物理与微电子学院,济南  250100; (2)浙江台州学院物理系,临海  317000;山东大学物理与微电子学院,济南  250100
Published: December 2020

Giant magneto-impedance (GMI) effect of a multilayered film with the structure o f (FM/SiO2)3/Ag/(SiO2/FM)3 (FM≡FeCu CrVSiB) was studied. The multilayere d film was deposited by radio frequency sputtering onto a single crystal Si subs trate. A constant magnetic field of about 72kA/m was applied along the longitudi nal direction of the film plane during deposition process, and then the samples were annealed at different temperatures. Results obtained show that the multila yered film has good soft magnetic properties and GMI effect even though in the a s-deposited state. The maximum magnetoimpedance ratios are about 45% and 44% in longitudinal and transverse cases, respectively. After the samples were annealed at 230℃ for 90min, the best GMI effect could be obtained. The maximum longitud inal and transverse magnetoimpedance ratio up to 251% and 277% were obtained at the frequency of 8.5MHz, respectively. The GMI effect in this multilayered struc ture is much stronger than the one in FeCuCrVSiB/Ag/FeCuCrVSiB sandwiched film w ith the same thickness of total magnetic layers.
Modeling analysis of inhomogeneous coatings prepared by double-source co-evaporation
Authors: Shen Zi-Cai  , Wang Ying-Jian  , Fan Zheng-Xiu  , Shao Jian-Da  ,   (1)中国科学院上海光学精密机械研究所,上海  201800; (2)中国科学院上海光学精密机械研究所,上海  201800;中国科学院研究生院,北京  100039
Published: December 2020

A practical modeling for inhomogeneous coatings, which are prepared by double-source co-evaporation, is proposed in this paper, and then, the relationship between the deposition rate of inhomogeneous coatings and that of double-sources co-vaporation is discussed. The deposition rate of inhomogeneous coatings is close to the sum of the evaporation of the two materials when their bulks are close to or the amount of small molecules is far more than big ones. When the bulks of molecules of the two materials is different, the deposition rate of inhomogeneous coatings will vary with the ratio of their bulks and their deposition rates. Some deposition rates of inhomogeneous coatings in different situations are also detailed in this paper.
Photoluminescence study of (GaAs1－xSbx/InyGa1－yAs)/GaAs bilayer quantum well grown by molecular beam epitaxy
Authors: Xu Xiao-Hua  , Niu Zhi-Chuan  , Ni Hai-Qiao  , Xu Ying-Qiang  , Zhang Wei  , He Zheng-Hong  , Han Qin  , Wu Rong-Han  , Jiang De-Sheng  ,   中国科学院半导体研究所 超晶格与微结构国家重点实验室,北京  100083
Published: December 2020

Photoluminescence study of (GaAs1-xSbx/InyG a1-yAs)/GaAs bilayer quantum wells (BQWs) grown by molecular beam epitaxy (MBE) were carried out. Temperature and excitation power dependent photoluminescence (PL) s tudy indicated that the band alignment of the BQWs is type - Ⅱ. The origin of the double-peak luminescence was discussed. Under optimized growth conditions, t he PL emission wavelength from the BQWs has been extend up to 131 μm with a s ingle peak at room temperature.
Symmetries and Mei conserved quantities for systems of generalized classical mechanics
Authors: Zhang Yi  ,   苏州科技学院土木工程系，苏州  215011
Published: December 2020

In this paper, the symmetries and a new type of conserved quantities called Mei conserved quantities for systems of generalized classical mechanics are studied. In the high-dimensional extended phase space, the differential equations of motion of the systems are established, and the criteria for Mei symmetries, Noethe r symmetries and Lie symmetries of the systems are given. The conditions, under which the above three symmetries can respectively lead to the Mei conserved qu antities, and the form of the Mei conserved quantities are obtained. Finally, an example is given to illustrate the application of the results.
Symmetry and stability of a relativistic birkhoff system
Authors: Zhang Kai  , Feng Jun  ,   西北大学物理系，西安  710069
Published: December 2020

Relationships among the three symmetries——Noether symmetry,Lie symmetry and M ei symmetry of a relativistic Birkhoff system have been obtained. Some stabilit y criteria are given by using Liapunov method. Finally the conservation quanti ty and the stability of the relativistic Birkhoff system are correlated by the Energy－Casimir functional, and an example is given, to illustrate the applicat ion of the method.
New variable separation excitations, rectangle-like solitons and fractal solitons in the Boiti-Leon-Pempinelli system
Authors: Fang Jian-Ping  , Zheng Chun-Long  , Zhu Jia-Min  ,   (1)浙江丽水学院物理系，丽水  323000; (2)浙江丽水学院物理系，丽水  323000;上海大学应用数学和力学研究所，上海  200072
Published: December 2020

Using an extended Riccati mapping approach,we obtain a new type of varable separation solutions for the (2+1)-dimensional Boiti-Leon-Pempinelli system.Based on the derived solutions,two new kinds of soliton excitations,i.e.rectangle-like soliton and fractal soliton are constructed in this paper.
Visualization of the solution of Jacobi elliptic expanding function
Authors: Zheng Qiang  , Yue Ping  , Gong Lun-Xun  ,   贵州师范大学理学院, 贵阳  550001
Published: December 2020

Thanks to the powerful software MATLAB, this paper gets the beautiful figures of a kind of Jacobi elliptic function-sn(x,k);and as an example, we also d raw the figures of solution of Jacobi expanding function of KdV equation in two different parameters.
Theoretical model of laser-induced dispersion optical filter
Authors: Zhang Yun-Dong  , Sun Xu-Tao  , He Zhu-Song  ,   哈尔滨工业大学光电子技术研究所,可调谐激光技术国家级重点实验室，哈尔滨  150001
Published: December 2020

The semi-classical theory was utilized to establish the theoretical model of la ser-induced dispersion optical filter (LIDOF). By solving the density matrix equ ations, we gained the susceptibility. The theoretical transmission curve of K- 694nm LIDOF was obtained, which agrees basically with the experimental result.
Prediction of the chaotic time series using support vector machines for fuzzy rule-based modeling
Authors: Cui Wan-Zhao  , Zhu Chang-Chun  , Bao Wen-Xing  , Liu Jun-Hua  ,   西安交通大学电子与信息工程学院, 西安  710049
Published: December 2020

Based on the powerful nonlinear mapping ability of support vector machines and the characteristics of fuzzy logic which can combine a prior knowledge into fuzzy rules, the forecasting model of the support vector machine for fuzzy rules-bas ed model in combination with Takens' delay coordinate phase reconstruction of ch aotic time series has been established; and the least squares method for large-s cale problems is used to train this model. Moreover, based on this model, relati onships among the prediction performances of this model, the embedding dimension and the delay time are discussed. Finally, the Mackey-Glass equation and the t ime series that Lorenz systems generate are applied to test this model, respecti vely, and the results show that the support vector machine for fuzzy rule-based modeling can not only acquire knowledge and generate fuzzy rules from the given data, reduce the number of support vectors greatly, but also predict chaotic ti me series accurately, and even if the embedding dimension is unknown and the del ay time is appropriately selected, the predicted results are satisfactory. These results imply the support vector machine for fuzzy rule-based modeling is a go od tool to study chaotic time series in practice.
Synchronization of symmetrically nonlinear-coupled chaotic systems
Authors: Yu Hong-Jie  , Liu Yan-Zhu  ,   上海交通大学工程力学系,上海  200240
Published: December 2020

The synchronization of two symmetrical nonlinear-coupled chaotic systems is discussed. A special nonlinear-coupled term is constructed by suitable separation between linear and nonlinear terms of the chaotic system. The phenomenon of stab le chaotic synchronization has been found in a certain region of the coupled str ength α=05. The stability of the synchronous state is examined by the sta bility criterion of linear systems and the conditional Lyapunov exponent. The Lo renz system and the hyper-chaotic Rssler system are treated as numerical exam ples. It is shown that the proposed method is effective for chaotic synchronizat ion of time-continued systems and hyper-chaotic systems.
Study on the three-dimensional theory of super thin multi-layered films irradiated by the continuously modulated laser
Authors: Yan Chang-Chun  , Xue Guo-Gang  , Liu Cheng  , Gao Shu-Mei  ,   徐州师范大学物理系,徐州  221116
Published: December 2020

On the basis of heat conduction equations and under special boundary conditions,the temperatute fields of multilayered heated uniaxial films can be acquired in the cylindrical coordinate system by Hankel transformation and retransformation.As an example with specific parameters,the special growth conditions for three-layered films are discussed.The larger are the lognitudinal heat conductions vs transverse ones of thin films for higher thermal diffusivity,the larger are chan ges of phases of the temperature fields in the thin films.However,it is faintly influencing for the lognitudinal heat conductions vs transverse ones of thin fil ms for lower thermal diffusivity,and the smaller is light absorbing coefficient, the more evident is the influence on phases because of frequency change.
CDW-EIS calculation in He2++H impact ionization
Authors: Ning Ye  , He Bin  , Liu Chun-Lei  , Yan Jun  , Wang Jian-Guo  ,   (1)北京应用物理与计算数学研究所计算物理实验室,北京  100088; (2)中国工程物理研究院研究生部,北京  100088
Published: December 2020

The He2+＋H Impact Ionization process is investigated using a continu um distorted wave method with the eikonal initial-state(CDW-EIS) approximation.The total,single- and double-differential cross sections are obtained in the projectile energy ranges from 30keV/u to 2000keV/u.The total cross sections are compared with the existing theoretical and experimental data.When the projectile energy is larger than 100keV/u,our results are in good agreement with the experimental measurements,while about 50% less than experimental data in the lower energy range.The ionization mechanism of soft-collisions,electron captured to continuum states and binary-encounter collisions are also displayed.
Transmission technigue of repetition pulse and intense current electron-beam
Authors: Zhang Yong-Hui  , Ma Qiao-Sheng  , Xiang Fei  , Gan Yan-Qing  , Chang An-Bi  , Liu Zhong  , Zhou Chuan-Ming  ,   (1)中国工程物理研究院,绵阳  621900; (2)中国工程物理研究院应用电子学研究所,绵阳  621900; (3)中国工程物理研究院应用电子学研究所,绵阳  621900;中国工程物理研究院研究生部,北京  100088
Published: December 2020

The stability condition of intense annular electron beam transmission is analyzed and deduced. Based on the static electric-magnetic field simulation, the position and configuration of the guide magnetic-field and its magnitude as well as its power supply are designed. Then the experiments of repetitive rate and inte nse current electron-beam diode are carried out on CHP01 generator, and the ima ge of the intense annular electron beam is measured too. The results show that t he designed 1-s magnetic field satisfies to the stability condition of intense annular electron beam transmission. It can stably transmit intense current elect ron-beam pulse of 800kV/8kA, pulse width 40ns, repetition rate 100Hz. And now t he 1-s magnetic-field system is successfully used on CHP01 accelerator.
Applications of a simplified non-Gaussian field model to wave propagation in turbulent media
Authors: Chen Jing-Yuan  , Chen Shi-Gang  , Wang Guang-Rui  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)中国工程物理研究院北京研究生部，北京  100088
Published: December 2020

In order to study the optical effects of turbulent intermittency,a simplified non-Gaussian random field model has been constructed,which can model atmospheric dielectric permittivity(or refractive-index) fluctuation approximately.Four arbitrary functions enter into the characteristic functional of this model.Using the properties of the atmospheric turbulence,such as the statistical homogeneity,the single-point probability distribution and the spectrum of the refractive-index fluctuations,these functions can be selected or determined.With these given functions,we have studied the statistical properties,especially the mean field adn the mutual coherence function,of a plane partially coherent incident wave.A simple example of numerical simulation has also been presented.
Experimental investigation on temporal and spectral characteristics of femtosecond-scaled ultra-broadband Ti:sapphire oscillator
Authors: Xie Xu-Dong  , Wang Qing-Yue  , Wang Zhuan  , Zhang Wei-Li  , Chai Lu  ,   (1)天津大学精密仪器与光电子工程学院超快激光研究室,教育部光电信息技术科学重 点实验室,天津  300072; (2)天津大学精密仪器与光电子工程学院超快激光研究室,教育部光电信息技术科学重 点实验室,天津  300072;俄克拉荷马州立大学电气与计算机工程系，激光与光子学研究中心，斯蒂尔沃特 OK  74078; (3)天津大学精密仪器与光电子工程学院超快激光研究室,教育部光电信息技术科学重 点实验室,天津  300072;中国工程物理研究院激光聚变研究中心,绵阳  621900
Published: December 2020

In this letter, we systematically investigated the temporal and spectral characteristic of ultra-broad band Ti:sapphire oscillator in femtosecond regime. Pulse formation in temporal regime was observed while the spectral shape evolved fro m hyperbolic secant shape into multi-peak one and the bandwidth increased from 40 to 180nm. Experimental results showed that pulse shortening mainly occurred n ot at its bottom part but at its central section while the spectrum was broadene d, and at the same time the relative energy at the bottom part increased.
Influence of pump laser parameters on stimulated Brillouin scattering
Authors: Deng Shao-Yong  , Guo Shao-Feng  , Lu Qi-Sheng  , Cheng Xiang-Ai  ,   国防科技大学光电科学与工程学院，长沙  410073
Published: December 2020

Numerical simulation was performed to study the stimulated Brillouin scattering(SBS) amplifier of self-Stokes-seeding. Chracteristic parameters such as Stokes laser,energy reflectivity,evolvement and distribution of maximum stress,pulse compression and SBS fidelity in fused silica were discussed for different Stokes ratio,wavelength,energy,pulse duration and interaction time.The focused Gaussia n pump laser was used.We got conclusions that the damage in near-front side of SBS medium was the characteristic of SBS; tuning parameters of pump laser, super -sonic stress formed in SBS process would damage the SBS medium not only on the front side, but also the damage near the focus;and the damage near the focus wo uld be made earlier when both parts were damaged.
Analytical solution in the Hermite-Gaussian form of the beam propagating in the strong nonlocal media
Authors: Zhang Xia-Ping  , Guo Qi  ,   华南师范大学信息光电子科技学院激光传输实验室，广州  510631
Published: December 2020

In this paper, it is discussed that the optical beam with a suitable input powe r propagates in the nonlocal nonlinear media,which is governed by the nonlocal nonlinear Schrdinger equation (NNLSE).A new approxiamate linear model for the NNLSE is presented for the strong nonlocal media with the spatially symmetrica l real response functions by use of Taylor expansion. An exact analytical solut ion with the Hermite-Gaussian form is obtained.It is shown that the solution in the Gaussian form is the lowest-order mode.It is found that the anisomer ousty spatial soliton exists in the strong nonlocal media.
CTMC calculation of Si2+ + H impact ionization
Authors: Liu Chun-Lei  , He Bin  , Ning Ye  , Yan Jun  , Wang Jian-Guo  ,   (1)北京应用物理与计算数学研究所计算物理实验室，北京  100088; (2)北京应用物理与计算数学研究所计算物理实验室，北京  100088;中国工程物理研究院研究生院，北京  100088
Published: December 2020

The Si2+ + H collision ionization is studied using classical trajecto ry Mo nte-Carlo (CTMC) method. The total cross section as functions of the energy of i ncident projectile, single differential cross section and double differential cr oss section as a functions of the energy and the angle of the ejected electron a re calculated. The ionization mechanisms of soft collision, electron capture to the continuum state,binary encounter collision are demonstrated. The effect of “saddle point" is also discussed by calculating the ejected electron distributi on depending on the ratios of distances between electron and target and between electron and projectile.
Comparison of wakefield and relativistic effects on the self-phase modulation and frequency shift of intense laser pulse propagation
Authors: Wu Guo-Hua  , Guo Hong  , Liu Ming-Wei  , Deng Dong-Mei  , Liu Shi-Xiong  ,   (1)北京大学信息科学技术学院量子信息与测量教育部重点实验室，北京  100871; (2)华南师范大学传输光学实验室，广州  510631; (3)华南师范大学传输光学实验室，广州  510631;湖南科技大学物理学院，湘潭  411201
Published: December 2020

The relativistic effect and wakefield effect on the propagation of an intense laser pulse in plasma are compared in the resonant and non-resonant cases in detai l. The effect of wakefield, which depends on the initial pulse shape and width, leads to the asymmetry of pulse self-phase modulation. In the long pulse limit, the wakefield effect is negligible compared to the relativistic effect; in the short pulse limit, it balances the relativistic effect. Under the resonant cond ition, most of the photons within the pulse decelerates.
First-principles study of electronic structure for CoSi
Authors: Pan Zhi-Jun  , Zhang Lan-Ting  , Wu Jian-Sheng  ,   上海交通大学材料科学与工程学院教育部高温材料及测试开放实验室,上海  200030
Published: December 2020

In this paper, by using the linearized augmented plane wave based on the density functional theory of the first principles, the parameters of a unit cell were o ptimized for CoSi firstly. The steady state energy of a many-particle system was -134684297Ry. The corresponding volume and lattice parameter of the unit cell in the steady state were 5899360a.u.3 and 04438nm respectively. Secondly, the calculations of the electronic structures for CoSi and CoSi075A l025 were performed. At the same time, the characteristics of electronic structures of CoSi and CoSi075Al025 were analyzed. The shape of density of states of CoSi in this paper is almost the same as that of the exist ing calculations except for some differences. The Fermi level of CoSi075 Al025 shifted slightly, compared with that of CoSi. Finally, the int rinsic relations between the electronic structures of CoSi and CoSi075Al 025 and their respective thermoelectric properties were discussed in det ail. The increase of material factor B of CoSi075Al025 w as attributed to the doping with Al. Therefore, doping was a practicable means t o improve the thermoelectric property of CoSi.
Influence of process parameters on the electrical properties of n-type and p-type Bi2Te3-based pseudo-ternary thermoelectric materials by the hot-pressing method
Authors: Lü Qiang  , Rong Jian-Ying  , Zhao Lei  , Zhang Hong-Chen  , Hu Jian-Min  , Xin Jiang-Bo  ,   (1)哈尔滨师范大学物理系，哈尔滨  150025; (2)哈尔滨师范大学物理系，哈尔滨  150025;牡丹江医学院电子技术教研室，牡丹江  157011; (3)哈尔滨师范大学现代教育技术中心，哈尔滨  150025
Published: December 2020

Seebeck coefficient and electrical conductivity of the N-type and P-type Bi 2Te3-based alloys prepared by melting/grinding/hot-pressing met hod for different process parameters (temperature and pressure of hot-pressing)were measured,and the effects of process parameters were analyzed.It has been found that the temperature and pressure of hot-pressing play very important roles in enhancing both Seebeck coefficient and electrical conductivity of the Bi2Te3-based alloys.The phenomena are different from those of Bi2Te3 single cry stal and its oriented crystal in the electrical properties.Better electrical properties may be obtained.
Transition films from amporphous to microcrystalline silicon and solar cells
Authors: Hao Hui-Ying  , Kong Guang-Lin  , Zeng Xiang-Bo  , Xu Ying  , Diao Hong-Wei  , Liao Xian-Bo  ,   (1)中国科学院半导体研究所表面物理国家重点实验室,凝聚态物理中心，北京  1000 83; (2)中国科学院半导体研究所表面物理国家重点实验室,凝聚态物理中心，北京  1000 83;中国地质大学（北京）材料科学与工程学院,北京  100083
Published: December 2020

A series of hydrogenated silicon films near the threshold of crystallinity was p repared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PE CVD)from a mixture of SiH4 diluted in H2. The effect of h ydrogen di lution ratios R= ［H2］/［SiH4］ on the microstructure o f the films was investigated. The photoelectronic properties and stability of the film s were studied as a function of crystalline fraction. The results show that t he diphasic films gain both the fine photoelectric properties like a-Si:H an d high stability like μc-Si:H. By using the diphasic silicon films as the intrinsic layer, p-i-n junction solar cells were prepared. Current-voltage (J-V) characteristics and stability of the solar cells were measured under an AM15 solar simulator. We observed a light-induced increase of 52% in the ope n-circuit voltage (Voc) and a light-induced degradation of ～29% in efficiency.
Influence of double-percolation phenomenon on shielding effectiveness of Ni-based conductive silicone rubber
Authors: Li Peng  , Liu Shun-Hua  , Chen Guang-Yun  ,   大连理工大学材料科学与工程系，大连  116023
Published: December 2020

By measuring the electrical resistivity of RTV silicone rubber with Ni powder, t he percolation threshold of Ni-based conductive silicone rubber was determined. When N234 was filled in Ni-based conductive silicone rubber,double-percolation p henomenon was found other than percolation law. After fitting of the experimenta l results,the mechanism of the double-percolation phenomenon was presumed. As fo r the shielding effectiveness of high conductive silicone rubber, the result sh ows that it can be described well with the Schelkunoff theory.The influence of double-percolation phenomenon on shielding effectiveness of the rubber was investigated.
Piezomodulated-reflectivity study of GaAs/Al0.29Ga0.71As single quantum well
Authors: Wang Chong  , Chen Ping-Ping  , Zhou Xu-Chang  , Xia Chang-Sheng  , Wang Shao-Wei  , Chen  Xiao-Shuang  , Lu Wei  ,   中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

We report here that we have built a set of piezomodulated-reflectivity measureme nt system, and obtained piezomodulated-reflectivity spectra of two GaAs/Al0 .29 Ga0.71As single quantum well samples in which the well widths a re 5 and 25nm respectively. From these spectra, the transitions between electron and heavy and light hole subbands can be easily identified. Furthermore, we have ob served the optical transition related to spin-orbit split-off of GaAs buffer. Ef fective mass theory is applied to calculate the transition energy between electr on and hole subbands. Then the spectral structures are assigned based on the cal culated results. It is found that these calculated results agree with experiment al ones very well.
Optical nonlinearities of iron films prepared by pulsed laser deposition
Authors: Wang Wei-Tian  , Guan Dong-Yi  , Zhou Yue-Liang  , Lü Hui-Bin  , Chen Zheng-Hao  ,   (1)烟台大学光电信息科学技术学院，烟台  264001; (2)中国科学院物理研究所光物理实验室，北京  100080
Published: December 2020

Thin films of iron were fabricated on MgO(100) substrates using pulsed laser dep osition technique. The crystalline property and surface roughness of the films w ere investigated by x-ray diffraction and atomic force microscopy, respectively . It is found that the Fe films deposited at 500 and 800℃ are of single phase, and no diffraction from randomly oriented grains or impurity phases can be obser ved. The nonlinear optical properties of continuous 9 nm-thick iron film were d etermined using the z-scan method. The results show that the ultra-thin ir on film exhibits large nonlinear refractive coefficient, n2= 709×1 0-5cm2/kW, and nonlinear absorption coefficient, β=-552×10 -3(cm/W), at the wavelength of 532 nm.
The analysis of nonlinear Kronig-Penney superlattice by a two-dimensional real-valued map
Authors: Zhu Ya  , Zhou Qian  , Tian Qiang  ,   (1)北京师范大学物理系,北京  100875; (2)铜仁高等师范专科学校物理系,铜仁  554300;北京师范大学物理系,北京  100875
Published: December 2020

The wave transportation in nonlinear Kronig-Penney model is investigated by a two-dimensional real map.The maps for different nonlinear parameters under the condition of fixed wave vector are calculated, and the corresponding evolution of the square of wave displacement along the nonlinear superlattice is also numerically calculated. The nonlinear parameter of the nonlinear Kronig-Penny superlattice has a distinctive modulation effect on the Bloch wave vector of the wave function in the superlattice. In response to the increase of the nonlinear parameter, the map evolutes from a finite number of dots to a closed orbit or an attractor, which corresponds to a periodic function, quasiperiodic function or chaos.
Study on temperature dependence and e+ irradiation time dependence of positron annihilation parameters about SEBS triblocks copolymer
Authors: Jiang Zhong-Ying  , Yu Wei-Zhong  , Xia　Yuan-Fu  ,   (1)南京大学物理系，南京  210093; (2)南京大学物理系，南京  210093;伊犁师范学院物理系，伊宁  835000; (3)清华大学物理系，北京  100084
Published: December 2020

Positron annihilation lifetime spectroscopy was used to study e+ self -irradiation effect of 22Na on positron annihilation parameters of SEBS, tem perature dependence of free volume hole radius and free volume hole fractional, based on the classic model of Eldrup, presenting the linear variation of fractional free volume versus temperature in vacuum the range below Tg and ab ove Tg, respectively. We also discuss the thermal expansion coefficient a nd the constant A in free volume fractional formula by combining the free volume theory of WLF and the classical model of Eldrup.
Study on nonlinear characteristics of two synchronizing uncoupled Hindmarsh-Rose neurons
Authors: Wu Ying  , Xu Jian-Xue  , He Dai-Hai  , Jin Wu-Yin  ,   (1)Department of Mathematics and Statistics,McMaster University,Hamilton   L8S4K1,Canada; (2)西安交通大学航天航空学院，西安  710049
Published: December 2020

Modulating the current input of two uncoupled Hindmarsh-Rose neurons by using the membrane potential of Hindmarsh-Rose neuron under different initial conditions, the evolution mechanism of synchronization process of the two neurons is revealed by analyzing interspike interval sequences. When periodic stimulation is u sed, the full synchronization is realized in two identical neurons, and the sync hronized response of modulated neurons can be different from the stimulation sig nal; and phase synchronization can be obtained in two neurons with different par ameters:two neurons with small parameter mismatch can be synchronized to the per iodic response different from the stimulation signal, and two neurons with big p arameter mismatch can only be synchronized to the response in phase synchronizat ion with stimulation signal. When chaotic stimulation is used, two systems can o nly be synchronized to the response being in phase synchronization with stimulat ion signal. Obviously, chaotic stimulation is more helpful in encoding and deco ding information. Analyzing the relation between the largest condition Lyapunov exponents and the stimulation strength shows that when the largest condition Lya punov exponents of the two systems are both negative is the necessary condition for synchronization. The chaotic stimulation signal can more easily synchronize two neurons than periodic stimulation signal, implying that the effect of chaoti c stimulation is stronger than periodic one, and the experiments also confirm th is conclusion.
A harmonized multi-time difference scheme and its stability
Authors: Zhang Li-Xin  , Qian Wei-Hong  , Gao Xin-Quan  , Chou Ji-Fan  ,   (1)北京大学物理学院，北京  100871; (2)兰州大学大气科学学院，兰州  730000; (3)兰州大学大气科学学院，兰州  730000;北京大学物理学院，北京  100871
Published: December 2020

In this paper, a harmonized multi-time difference scheme is established, which can be easily constructed on any numerical difference scheme of ordinary differential equations. A sufficiently stable condition is proved in mathematics. If the memorial coefficients determined by an improved method of least square, it is expected that this new scheme can integrate stably in a longer period, and a better result can be achieved.
Unification of different integral variational principles
Authors: Huang Yong-Chang  , Li Xi-Guo  ,   (1)北京工业大学应用数理学院,北京  100022;中国高等科学技术中心（世界实验室）,北京  100080; (2)中国科学院近代物理研究所,兰州  730000;兰州重离子加速器国家实验室,兰州  730000
Published: December 2020

In terms of a mathematical expression of the quantitative causal principle, this paper gives a unification of Hamilton, Voss, Hlder, Maupertuis-Lagrange varia tional principles of integral style of the second-order Lagrangians, and finds t he intrinsic relations among all the different integral variational principles. It is proved that f0= 0 is just the result satisfying the quantitati ve ca usal principle． The Noether conservation charges of Hamilton, Voss, Hlder, Ma upertuis-Lagrange variational principles are shown up, and the intrinsic relatio ns among the Noether conservation charges of all the integral variational princ iples are discovered. Our investigations make the expressions of the past scrappy numerous variational principles be unified into a relative consistent system o f all the variational principles in terms of the quantitative causal principle, and show that all the variational principles become deductions of the quantitat ive causal principle.
The mean first-passage time for an asymmetric bistable system driven by multiplicative and additive noise
Authors: Jin Yan-Fei  , Xu Wei  , Ma Shao-Juan  , Li Wei  ,   西北工业大学应用数学系,西安  710072
Published: December 2020

In this paper, the effects of asymmetry of the potential on the mean first-passage times (MFPTs) in two opposite directions are investigated in an asymmetric b istable system driven by multiplicative noise and additive noise. We find that t he MFPTs in two opposite directions are no longer symmetric in an asymmetric bis table system. Furthermore, we calculate the MFPTs of an asymmetric Duffing model . Numerical results show that: (1) The MFPTs depend on the initial states in th e asymmetric bistable system, namely, T+(xs1→xs2) is not equal to T-(xs2→xs1). (2) The effec ts of noise intensity on the MFPTs T+(xs1→xs2) and T-( xs2→xs1) are different in the same kind of parameter plan e. There exists a peak on each of the curves of lnＴ- versus Ｄ,as we ll as the “resonant activation”, while the variation of lnＴ+ ver sus Ｄ is monotonic. (3) The influence of the asymmetry coefficient r on Ｔ± is entirely different. The curves of lnT- versus r have mon o-valleys but the variation of lnＴ+ versus r is monotonically risi ng.
Generalized synchronization of bidirectionally coupled chaos systems
Authors: Zhang Ping-Wei  , Tang Guo-Ning  , Luo Xiao-Shu  ,   广西师范大学物理与信息工程学院,桂林  541004
Published: December 2020

The conditional entropy is used to assess the generalized synchronization of bidirectionally coupled chaotic systems. By increasing the coupled strength, the generalized synchronization appears when there is a sharp minimum of the conditional entropy. We apply this criteria to the case of the coupled Rssler-Lorenz an d Rssler-Rssler system to test our method. Numerical results show that it is very effective and robust.
A cellular automaton model for mixing traffic in two-lane system
Authors: Zheng Rong-Sen  , Tan Hui-Li  , Kong Ling-Jiang  , Liu Mu-Ren  ,   (1)广西师范大学物理与信息工程学院,桂林  541004; (2)玉林师范学院物理与信息科学系,玉林  537000
Published: December 2020

Based on the Nagel-Schrekenberg(NS) model,we present a mixing traffic flow model for a two-lane traffic system. In this model,the stochastic noise P in NS model is replaced by accelerating probability Pa and braking probabil ity Pd. The fundamental diagrams of the mixing traffic under differen t conditi ons are given by the numerical simulations. We found that the lane-changing prob ability,the mixing rate and acceleration, the braking probability have a great i nfluence on the mixing traffic flow. The slow cars have a decisive action on the mixing traffic.
Monte-Carlo method in calculating the γ spectrum of plutonium volume source
Authors: Hao Fan-Hua  , Hu Guang-Chun  , Liu Su-Ping  , Gong Jian  , Xiang Yong-Chun  , Huang Rui-Liang  , Shi Xue-Ming  , Wu Jun  ,   (1)北京应用物理与计算数学研究所,北京  100088; (2)中国工程物理研究院核物理与化学研究所,绵阳  621900
Published: December 2020

A multi-step Monte-Carlo method is established for calculating the γ spectrum of plutonium volume source. The γ spectra of a spherical plutonium source is calculated by using a multi-step and direct mothed,and compared with the expe rimental γ spectrum. The calculated results are in agreement with the experm ental results whithin 10%. It is proven by the calculated result of Steve Fett er model that the multi-step calculation converges faster than the direct metho d in the calculation of the γ　spectrum of plutonium volume source with shields .
Effect of barrier capacity on dielectric characteristics of ACu3Ti4O12 ceramics
Authors: Zhou Xiao-Li  , Du Pi-Yi  ,   (1)台州学院物理系,临海  317000浙江大学硅材料国家重点实验室,杭州  310027; (2)浙江大学硅材料国家重点实验室,杭州  310027
Published: December 2020

ACu3Ti4O12 (A=Ca, Y or La) ceramic materials have been successively fabricated by using the solid-state reaction method. In the temperature range of 50—300 K, the dielectric characteristics of the samples are measured and the relationship among the AC conductivity, external frequency and temperature is analyzed. It has been found that if the relative content of Ca in the CaCu 3Ti4O12 crystals with identical components is greater than or equal to 0 776, the dielectric constant of the samples can reach the value of 104 For the ceramic compounds with a 3+ covalence in the `A' site such as La2/3 Cu3Ti4O12 and Y2/3Cu3Ti4O12, however, the dielec tric constant is only of the order of 103 Further analysis shows that the di electric constant of the ACu3Ti4O12 materials is mainly related to the number density of the barrier capacity in the samples. The relationship amo ng the conductivity, frequency and temperature depends on the combination of act ion of electrons, phonons and external field.
Quantum electrodynamics theory of high-order above-threshold ionization
Authors: Yu Xiao-Guang  , Wang Bing-Bing  , Cheng Tai-Wang  , Li Xiao-Feng  , Fu Pan-Ming  ,   (1)中国科学院物理研究所，北京  100080; (2)中国科学院物理研究所，北京  100080;井冈山学院物理系，吉安  343009
Published: December 2020

Based on the nonperturbative quantum electrodynamics, we study the high-order above-threshold ionization (ATI) induced by rescattering process. By using a form al scattering theoretical approach, an analytic form of the high-order ATI spect rum is obtained. We discuss the interference effect of different ATI channels on the high-order ATI. The high-order ATI spectra due to the rescattering of electrons from different incident angles are also given.
Absolute differential, elastic integral and moment transfer cross sections for electron scattering from O2 and CF4 at intermediate- and high-energies
Authors: Shi De-Heng  , Sun Jin-Feng  , Zhu Zun-Lue  , Liu Yu-Fang  , Yang Xiang-Dong  ,   (1)河南师范大学物理系，新乡  453007; (2)河南师范大学物理系，新乡  453007;四川大学原子与分子物理研究所，成都  610065;空军第一航空学院基础部，信阳  464000; (3)四川大学原子与分子物理研究所，成都  610065
Published: December 2020

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the absolute differential cross sections, the elastic integral cross sections, and the moment transfer cross sections for electron scattering from O2 and CF4 i n the energy range 300—1000eV by using additivity rule model at Roothaan-Hartree-Fock level. The quantitative absolute differential cross section, elastic integral cross secti on, and moment transfer cross section results are compared with those obtained b y experiments and other calculations wherever available, and good agreement is o btained. It is shown that the additivity rule model together with the complex op tical model potential modified by incorporating the concept of bonded atom can g ive better results than the one unmodified by it. So, the introduction of the bo nded-atom concept in complex optical model potential betters the accuracy of the absolute differential cross sections, the elastic integral cross sections, and the moment transfer cross sections.