bluuebunny/crossref_metadata_2025 huggingface dataset:
A variational iteration method for solving El Ni?o mechanism of atmospheric physics
Authors: Mo Jia-Qi  , Lin Wan-Tao  ,   (1)安徽师范大学数学系,芜湖241000; (2)中国科学院大气物理研究所,北京100029
Published: December 2020

The El Nio atmospheric physics mechanism is studied. Using the variational iteration theory, the approximation of the solution for its model is obtained for shortcut calculation. And compared to the special case for the exact solution of the model, the first approximate solution from the variational iteration method is in excellent agreement with the exact solution in degree of accuracy.
Analysis of bifurcation and chaos in a class of piecewise smooth systems based on symbolic sequence
Authors: Li Ming  , Ma Xi-Kui  , Dai Dong  , Zhang Hao  ,   (1)西安交通大学电气工程学院，西安710049; (2)香港理工大学电子及资讯工程学系，香港
Published: December 2020

Based on the sequence of circuit topologies, a symbolic sequence method is proposed for analyzing the bifurcations and chaos in a class of piecewise smooth systems like DC/DC converters. The largest subsequence(LS) is used to distinguish the type of bifurcation and detect border collision bifurcation e. g., when a perioddoubling bifurcation occurs, the LS is unchanged; when border collision bifurcation occurs, the LS is changed; and when chaos occurs,the LS does not exist.It is shown that the duty ratio is an essential variable for describing the nonlinear dynamics of a class of piecewise smooth systems like DC/DC converters， and saturating nonlinearity is the root cause of border collision bifurcation.
Solutions of path integration for nonlinear dynamical system under stochastic parametric and external excitations
Authors: Xie Wen-Xian  , Xu Wei  , Lei You-Ming  , Cai Li  ,   西北工业大学应用数学系，西安710072
Published: December 2020

The numerical path integration based on GaussLegendre scheme is extended to the case of nonlinear dynamical system under stochastic parametric and external excitations. For the purpose of comparison between the numerical solutions and the analytic solution(if the system has) or MonteCarlo simulation, we discuss the system under parametric and external Gaussian white noise excitations. The numerical method is shown to give accurate results. Via the numerical solutions of path integration, we have studied the P bifurcation of the stochastic system.
Effect of induced magnetic field on microstructure and magnetic properties of Bi-Mn alloy
Authors: Jia Guang-Qiang  , Zhang Jin-Cang  , Liu Yong-Sheng  , Zhang Xiao-Yong  , Ren Zhong-Ming  , Cao Shi-Xun  , Li Xi  , Deng Kang  ,   (1)上海大学材料科学与工程系，上海200436; (2)上海大学物理系，上海200436
Published: December 2020

The Bi_Mn wt6% alloys were solidified from semi_solid state in a magnetic field. The microstructure and magnetic properties have been studied systematically. The results show that the samples were of a eutectic structure of double phases and have large anisotropy. It was shown that the alignment of MnBi crystals occurred along the induced field. With increasing induced magnetic field, the remanence(Mr) increased gradually, which shows that the higher the induced magnetic field, the better the alignment. The spin reorientation temperature (TSR) for MnBi alloys increases with increasing induced magnetic field. The effects of the induced field on the microstructure and the magnetic properties of Bi_Mn wt6% alloys were also discussed.
Efficiency of the third-order harmonic in gas-filled capillary driven by fs laser pulses
Authors: Chen Bao-Zhen  , Huang Zu-Qia  ,   北京师范大学射线束技术与材料改性教育部重点实验室，北京  100875;北京师范大学低能核物理研究所，北京  100875
Published: December 2020

Using a theoretical model for generation of the third_order harmonic in a gas_fi lled capillary driven by fs laser pulses, the signal_pressure curves of the thir d_order harmonic generation in a gas_filled capillary driven by fs laser pulses are discussed. It is found that when the parameters of the capillary and laser pulse are given, the generation efficiency of the third harmonic is influenced b y the waveguide modes of the third harmonic, the pressure, the walk_off and the phase modulation, and that the theoretical value of the generation efficiency of the third harmonic, which is given in this paper, approaches the experimental one.
Neutron phase contrast tomographic imaging method
Authors: Chen Jian-Wen  , Gao Hong-Yi  , Zhu Hua-Feng  , Xie Hong-Lan  , Li Ru-Xin  , Xu Zhi-Zhan  ,   中国科学院上海光学精密机械研究所，上海201800
Published: December 2020

The principle for neutron phase contrast and tomography is presented in this paper.The imaging method for neutron phase_contrast tomography is suggested.It has the merits of both neutron phase contrast and tomography.The 3D space distribution for phase objects can be reconstructed with high resolution without using interferometry.The objective space structure with near absorption coefficient can be detected and resolved.
A new expression for photoionization cross sections and its application in high density system
Authors: Ma Xiao-Guang  , Sun Wei-Guo  , Cheng Yan-Song  ,   四川大学原子与分子物理研究所，成都  610065
Published: December 2020

A new expression for photoionization cross section has been proposed based on the Beer_Lambert's law and Maxwell equations for a material.And we also proposed a function varying with the number density of the system,which includes the local field effect and the higher_order dielectric correction to the famous formula for photoionization cross section of isolated atoms,proposed by Fano and Cooper in 1968The photoionization cross sections of solid xenon have been studied by using this alternative expression which couples the macroproperty and the quantum quantity of the photoionization system,and which makes it possible for one to study the influence of induced dipoles on the photoionization.The dielectric behaviors of the matter in condensed state under several physical conditions (given the complex dielectric constants or the model of electric susceptibility of the system) are considered using our new expression for photoionization cross sections.The results show that it is reasonable in physics to calculate the cross sections of atoms in a real system by using the accurate expression.Furthermore,the more correct the model of electric susceptibility for the real system,the more accurate the cross section obtained from our formula will be.
Effect of optical magnifications on the displacement measurements in optical tweezers system
Authors: Liu Chun-Xiang  , Guo Hong-Lian  , Jiang Yu-Qiang  , Li Zhao-Lin  , Cheng Bing-Ying  , Zhang Dao-Zhong  ,   (1)山西大学量子光学与光量子器件国家重点实验室，物理电子工程学院，太原  030006; (2)中国科学院物理研究所和凝聚态物理中心光物理开放实验室，北京  100080
Published: December 2020

The effect of different optical magnifications on the amplitude and linearity of displacement signals measured by the photodiode quadrant detector in an optical tweezers system is studied both experimentally and theoretically. Based on the experimental results we find that the output signal with larger amplitude and more preferable linearity can be obtained when the magnified images of α particle have diameters of 50% to 60% of the detector diameter. Theoretical calculation confirms it.
Influence of energy-transfer up-conversion on Tm, Ho:YLF laser threshold
Authors: Zhang Xin-Lu  , Wang Yue-Zhu  , Ju You-Lun  ,   (1)哈尔滨工业大学光电技术研究所可调谐激光国家重点实验室，哈尔滨  150001; (2)哈尔滨工业大学光电技术研究所可调谐激光国家重点实验室，哈尔滨  150001;哈尔滨工程大学理学院，哈尔滨  150001
Published: December 2020

Based on the energy transfer between ions and the transition between energy leve ls of diode_end_pumped Tm,Ho:YLF laser, under the consideration of energy transf er up_conversion, the threshold rate equations are given, and the analytical for mulas of laser threshold are deduced from rate_equations. The relations between laser threshold and laser designing parameters are derived. The dependence of en ergy transfer up_conversion on the laser designing parameters is analyzed in det ail. Experiments on Tm,Ho:YLF crystals are performed to validate the present mod el.
Transfer of quantum information via cavity QED technique
Authors: Xiang  Shao-Hua  , Song  Ke-Hui  ,   怀化学院物理与电子信息科学系，怀化  418008
Published: December 2020

We present a scheme for transferring quantum information, which is based on the nonresonant interaction of two two_level atoms with a single_mode cavity field. We show that quantum information can be transferred from one atom to another atom, and from cavity mode to two atoms by manipulating the interactions between cavity field and two atoms, and the information contained in the transferred atom or cavity mode is completely erased.
Measurement of femtosecond laser pulses using PG frequency-resolved optical gating
Authors: Wang Zhao-Hua  , Wei Zhi-Yi  , Zhang Jie  ,   中国科学院物理研究所光物理开放实验室，北京  100080
Published: December 2020

A frequency_resolved optical gating (PG_FROG) with polarization gating technique is developed to diagnosis the characteristics of laser pulses generated from a 20_TW femtosecond laser amplifier. Based on the data of the correlation signal in time and frequency domains, we obtained the detail information on pulse shape, bandwidth, pulse duration and phase by using the retrieval algorithm. The measured results with different phase compensation are also presented and discussed.
Dilute granular flow distribution near roughboundary on a two-dimensional inclined channel
Authors: Bao De-Song  , Zhou Ying  , Zhang Xun-Sheng  , Tang Xiao-Wei  ,   浙江大学物理系，杭州  310027
Published: December 2020

The dilute granular flow distribution near the rough boundary of a two_dimensional inclined channel have been reported. It is caused by the increasing inclination and the width of the channel. Compared with the viscous fluids, the velocity profiles of the granular flow are more blunted than the parabolic form and the density profiles are nonuniform. In thie paper, we present the density of granular flux ξ near the rough boundary of a two_dimensional inclined channel. the results show that there is a critical width of channel Wc for the transition of the density of granular flux ξ=ρv, and the density of granular flux near the boundary decaying exponentially with incresaing inclination of the channel when the width of channel is less than Wc.
Phonon dispersion relation calculations of armchair and zigzag carbon nanotubes
Authors: Zhang Bin  , Wang Yu-Fang  , Jin Qing-Hua  , Li Bao-Hui  , Ding Da-Tong  ,   南开大学物理系，天津  300071
Published: December 2020

When we calculate the phonon dispersion relations by using the force constant parameters for two_dimensional(2D) graphite, it is necessary to consider the problem that a 3D nanotube is formed by a rolled 2D graphene sheet. The present paper reports results on phonon dispersion relations of armchair and zigzag carbon nanotubes calculated with the considerations to the effect of curvature. Based on the results of the calculations and the symmetry analysis of the structures of single wall armchair and zigzag carbon nanotubes, the decomposition of the vibration modes at the Γ point is discussed.
Growth and characteristics of Ge on Ru(0001)
Authors: Hu Fang  , Zhang Han-Jie  , Lü Bin  , Tao Yong-Sheng  , Li Hai-Yang  , Bao Shi-Ning  , He Pi-Mo  , X. S. Wang  ,   (1)新加坡国立大学物理系，新加坡  119260; (2)浙江大学物理系,杭州  310027
Published: December 2020

Scanning tunneling microscopy (STM) and x_ray photoemission spectroscopy (XPS) studies of germanium growth on Ru(0001) were carried out. STM measurements showed a typical Stranski_Krastanov growth mode of Ge on Ru(0001), i.e. first atomic wetting layer is formed in the submololayer range, and the formation of islands on top of a flat first layer occurs for subsequent layers. XPS measurements showed a weak interaction between Ge and the substrate of Ru(0001). The Ru 3d5/2 and Ru 3d3/2 corelevels of Ru(0001) are located at 2798 and 2840 eV in binding energy respectively. Upon Ge growth, up to a thickniss of about 20 atomic layers, the Ru 3d corelevels shift downward in binding energy by an amount of about 02 eV，while the Ge 3d corelevel shift upward in binding energy from the Ge low coverage limit of 289 eV to 290 eV，with a relative change of 01 eV.
Effect of the distance between electrodes on the electronic transport properties of single molecular devices
Authors: Zou Bin  , Li Zong-Liang  , Wang Chuan-Kui  , Xue Qi-Kun  ,   (1)山东师范大学物理与电子科学学院,  济南  250014; (2)中国科学院物理研究所, 表面物理国家重点实验室, 北京  100080
Published: December 2020

Basing on ab initio methods and the elastic scattering Green function theory, we have investigated electronic transport properties of metal_molecule_metal junctions by taking the 4_4′_dimercaptodibenzene molecule as an example. The molecular geometric structures, electronic structures, and current_voltage characteristics have been studied for varying the distance between the two electrodes. Numerical results show that the changes of the distance between electrodes give various influence on the extended molecule's geometric and electronic structures, which brings effects on the electronic transport properties of the molecular systems. The equilibrium state of the extended molecule is not the best situation for electronic transportation. The characteristics of electronic transportation can thus be improved by adjusting the distance between the two electrodes.
Dielectric and interface characteristics of SrTiO3 with a MIS structure
Authors: Ma Jian-Hua  , Sun Jing-Lan  , Meng Xiang-Jian  , Lin Tie  , Shi Fu-Wen  , Chu Jun-Hao  ,   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

SrTiO3 (STO) films were deposited onto the ptype Si substrates by metalorganic decomposition (MOD) technique. The dielectric and interface characteristics of STO with a metalinsulatorsemiconductor(MIS) structure were investigated. The results showed that the dielectric constant was about 105 and the dissipation factor was lower than 001 for our STO films at a frequency of 10kHz. The excellent dielectric properties were attributed to the polycrystalline structure with good crystallinity. The fixed charge density Nf and the interfacetrap density Dit were calculated to be about 15×1012cm-2 and (14—35)×1012cm-2eV-1, respectively. Both Nf and Dit were mainly connected with an interface layer with low dielectric constant formed at the interface of Si/STO.
Coexistence of ferromagnetic and antiferromagnetic phases in compound LaFe11.4Al1.6
Authors: Wang Guang-Jun  , Wang Fang  , Shen Bao-Gen  ,   中国科学院物理研究所与凝聚态物理中心磁学国家重点实验室，北京100080
Published: December 2020

A metastable state with coexistence of ferromagnetic and antiferromagnetic phases has been confirmed in compound LaFe11.4Al1.6 by thermomagnetic curves at different external fields. The temperature behavior of the critical field could be explained by taking into consideration the metastable state. The existence of the metastable state is attributed to the exchange interactions and lattice disorder.
Combination of inversion and fitting as an effective method for the analysis of NMR relaxation data
Authors: Wang He  , Li Geng-Ying  ,   华东师范大学光谱学与波谱学教育部重点实验室，物理系，上海200062
Published: December 2020

A method is proposed for analyzing the NMR relaxation data. The procedure includes using the nonnegative leastsquares (NNLS) to determine roughly the relaxation time values. Then those values are used as the initial parameters of the nonlinear fitting computation. As a result, accurate relaxation time data can be conveniently obtained without any preknowledge of the sample. This method is verified and demonstrated by computer simulations and NMR experimental results.
Self-assembling behavior and optical properties of triangular silver nanoplates
Authors: Wu Qing-Song  , Zhao Yan  , Zhang Cai-Bei  , Li Feng  ,   (1)东北大学理学院，沈阳110004; (2)中国科学院金属研究所，沈阳110015
Published: December 2020

Triangular silver nanoplates with its border size of 100±10nm and thickness of 30nm were synthesized by a chemical method. These triangular silver nanoplates were characterized by TEM, UVVis spectroscopy and xrays diffraction analysis. Results obtained showed that these triangular silver nanoplates are perfect with sharp corners and selfassembled into twodimensional ordered monolayer on the carboncovered copper grid due to the adsorption of organic molecules in between these silver nanoplates. The wellaligned silver film on Si (100) substrate showed strong surfaceenhanced Raman scattering for pyridine molecules.
A new conservation law from Mei symmetry for the relativistic mechanical system
Authors: Zhang Yi  , Ge Wei-Kuan  ,   (1)湖州师范学院物理系,湖州  313000; (2)苏州科技学院土木工程系，苏州  215011
Published: December 2020

This paper studies the Mei symmetry and conservation law of the relativistic mechanical system. The definition and criterion of Mei symmetry for the relativistic mechanical system are established, which are based upon the invariance of dynamical functions under infinitesimal transformations. A new conservation law is deduced directly from the Mei symmetry of the system, and the condition under which a Mei symmetry can lead to a new conservation law is obtained and the form ofthe conservation law is presented. An example is given to illustrate the application of the results.
Bell-like and peak-like loop solitons in (2+1)-dimensional Boiti-Leon-Pempinelli system
Authors: Zheng Chun-Long  , Fang Jian-Ping  , Chen Li-Qun  ,   (1)上海大学应用数学和力学研究所,上海  200072; (2)浙江丽水学院物理系,丽水  323000; (3)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

In this work, starting from a Painlev-Bcklund transformation and a multil inear variable separation approach, a general variable separation excitation of the three-dimensional Boiti-Leon-Pempinelli system is derived first. Then based on the derived excitation, we can construct many localized structures like pe akons and compactons etc. Meanwhile, two new types of solitary waves, i.e., a b ell-like loop soliton and a peak-like loop soliton are constructed and their e volution properties of the novel localized structures are briefly discussed.
Backlund transformation and exact solutions for (2+1)-dimensional Boussinesq eq uation
Authors: Zeng Xin  , Zhang Hong-Qing  ,   大连理工大学应用数学系，大连  116024
Published: December 2020

With the aid of the symbolic computation softwares Maple, we solve the (2 +1)-dimensional Boussinesq equation by doing proper unknown functions ansatz of the seed solutions of the equation and performing mathematical calculations to obtain a series of exact solutions，which contain soliton-like solutions and ra tional solutions. Some exact solutions include arbitrary functions, when these a rbitrary functions are taken as some special functions, these solutions possess abundant structures.
Integrability of the generalized multi-component Fermi quantum derivative nonlin ear Schrdinger model
Authors: Tian Xiao-Dong  , Yue Rui-Hong  ,   西北大学现代物理研究所，西安  710069
Published: December 2020

With the help of Lax operator, the monodromy matrix is constructed, and the Hamiltonian is obtained. By using algebraic Bethe ansatz method, it has been shown t hat the monodromy matrix satisfies the Yang-Baxter equation on both a finite in terval and an infinite interval. So the integrability of this model is proved.
Local work function measurement on Cu(111)-Au and Cu(111)-Pd surfaces
Authors: Jia Jin-Feng  , Dong Guo-Cai  , Wang Li-Li  , Ma Xu-Cun  , Xue Qi-Kun  , Y. Hasegawa  T. Sakurai  ,   (1)Institute for Materials Research,Tohoku University,Sendai  980-8577,Japan; (2)中国科学院物理研究所，北京  100080
Published: December 2020

In this paper, we report the local work function measurements on the Cu(111)-Au, and Cu(111)-Pd surfaces with scanning tunneling microscopy (STM). We successfully observed the local work function difference between the Au/Pd overlayer and the Cu substrate, the decreased work function at the step edges. We also found that the work function of the Pd film is larger than that of the bulk Pd(111). T he lower work function at step edges can be explained by the dipole moment forma tion. It is demonstrated that the local work function measurement by STM is a po werful way to identify different elements with nanometer resolution.
Relativistic microscopic description of proton-nucleus scattering at energies u p to 200MeV
Authors: Rong Jian  , Ma Zhong-Yu  ,   (1)中国原子能科学研究院，北京  102413; (2)中国原子能科学研究院，北京  102413;兰州重离子加速器国家实验室原子核理论中心，兰州  733000;中国科学院理论物理研究所，北京  100080
Published: December 2020

A new decomposition of the Dirac Brückner-Hartree-Fock (DBHF) G matrix is used to study the isospin-dependent relativistic microscopic optical potential (RMOP). The optical potential of finite nuclei can be obtained in the local den sity approximation. The energy dependence of proton-nucleus scattering for the optical potentials of finite nuclei is discussed. The differential cross section s and the resolution power in the p+4040Ca and p+208208Pb at Epp less than 200MeV are also calculated using the above RMOP. I t is found that the calculated results agree with the experimental results. It should be e mphasized that the ROMP obtained from DBHF G matrix without any free parameter s could well describe the proton elastic scattering. This RMOP can also be used for unstable nuclei. From the results of the Ca isotopes, it is found that the i sospin dependence is more important for the exotic nuclei.
Propagation of nonparaxial vector Gaussian beam
Authors: Zhou Guo-Quan  ,   浙江林学院信息物理系，光电子研究所，临安  311300
Published: December 2020

Based on the nonparaxial vectorial moment theory of light beam propagation, the propagation characteristics of nonparaxial vector Gaussian beam have been system ically investigated. The results reveal that both the second_order_moment transv ersal beam widths follow a simple hyperbolic law for propagation. The analytical expression of the beam propagation factor is presented. The concise formulae ha ve been further given for highly nonparaxial case. And the maximum transverse di vergences are 90° as the dimension of light source tends to zero. When extendin g to the paraxial case, the obtained results are slightly different from the for merly paraxial formulae. Moreover, the beam propagation factor will always be gr eater than unity. Finally, comparison between the propagation of nonparaxial vec tor Gaussian beam and that of nonparaxial scalar Gaussian beam indicates that th e divergence angles show prodigious discrepancy for Gaussian light source within two times of wavelength scales.
Theoretical study of the pump light absorption inside a three-level solid state laser medium
Authors: Qin Hua  , Fu Ru-Lian  , Gao Hong-Yun  , Liu Juan  , Shi Xin-Gang  ,   南开大学现代光学研究所，天津  300071
Published: December 2020

The theoretical solution of the pump light absorption of a laser medium is presented. It is shown that the absorption of pump light with respect to the depth in the solid medium is not a simply exponential function. When the pump photon den sity is high enough, the variation of the absorption becomes nonexponential. The se theoretical results have been verified by experiment with the medium of ruby.
The chaotic character of ion relaxation oscillation in microwave tubes
Authors: Gong Hua-Rong  , Gong Yu-Bin  , Tang Chang-Jian  , Wang Wen-Xiang  , Wei Yan-Yu  , Huang Min-Zhi  ,   (1)电子科技大学物理电子学院，成都  610054; (2)电子科技大学物理电子学院，成都  610054;四川大学应用物理学院，成都  610051
Published: December 2020

The noise caused by ion relaxation oscillation becomes a research focus in the field of microwave tubes recently because of the improvement of radars and communications requirements. In this paper, electron beam is described by beam envelope equation, and ions generated from ionization of the background gas in microwave tubes are treated as discrete macro-particles. One dimensional Particle-in-Cell(PIC) simulation code was developed, and time series of ion relaxation oscillation are obtained by using the presented method. The ion relaxation oscillation is treated as the response of a complex nonlinear dynamical system, and the time series is analyzed by the power spectrum; the phase diagram and Lyapunov exponent are restructured. From the analysis results we find that the ion relaxation oscillation has a chaotic character. The reason of chaos was attributed to the dissipative Structure of the system. This would be useful for depressing relaxation oscillation and processing signals with relaxation oscillation noise.
Theoretical and experimental studies on third harmonic generation of femtosecond Ti:sapphire laser
Authors: Liu Yun-Quan  , Zhang Jie  , Liang Wen-Xi  , Wang Zhao-Hua  ,   中国科学院物理研究所，北京  100080
Published: December 2020

In this paper, nonlinear frequency conversion of second harmonic and third harmonic of femtosecond Ti:sapphire laser is theoretically and experimentally studied. Noncolinear type Ⅰ phase matching process is chosen to generate third harmoni c of femtosecond Ti:sapphire laser, and we have obtained conversion efficiency o f 62% at 260nm output. The pulse duration is about 169fs. This work will s erve as femtosecond ultraviolet source for time_resolved electron microscopy.
Effect of a folded reflecting telescope on the pulse front in the femtosecond ch irped pulse amplification system
Authors: Han Ying-Kui  , Wang Qing-Yue  , Zhang Zhi-Gang  , Zhang Wei-Li  , Chai Lu  , Yuan Xiao-Dong  , Huang Xiao-Jun  ,   (1)天津大学精密仪器与光电子工程学院,光电信息技术科学教育部重点实验室,天津  300072; (2)天津大学精密仪器与光电子工程学院,光电信息技术科学教育部重点实验室,天津  300072;俄克拉荷马州立大学电气与计算机工程系,OK 74078,USA; (3)天津大学精密仪器与光电子工程学院,光电信息技术科学教育部重点实验室,天津  300072中国工程物理研究院激光聚变中心,绵阳  621900; (4)中国工程物理研究院激光聚变中心,绵阳  621900
Published: December 2020

The model of the pulse front tilted by a folded reflecting telescope used as a beam expander in the chirped pulse amplification system is developed, and the relationship between the pulse front aberrance and the parameters of the telesco pe is discussed. It is found that the effect of pulse front aberrance on the bea m is too strong to be ignored when the pulse duration is less than 100fs. An e ffective method is presented to overcome this problem.
Numerical simulation of erbium non-uniformly doped waveguide amplifier in the pr opagation direction
Authors: Song Qi  , Song Chang-Lie  , Li Cheng-Ren  , Li Shu-Feng  , Li Jian-Yong  ,   (1)大连理工大学物理系,大连  116024; (2)大连理工大学物理系,大连  116024;辽宁师范大学物理系,大连  116024
Published: December 2020

Design of the waveguide amplifier nonuniformly doped with Er along the propagating direction is presented. The model of waveguide amplifier is constructed by using the finite element method, including cooperative upconversion, cross rela xation and excited state absorption. The gain performances at a given length and at maximum are improved to be 1027% and 565%, respectively. Calculation res ults agree qualitatively with the experimental data of cascaded Er_doped glass s amples.
Studies on the dispersion compensation of fiber Bragg grating in high-speed opti cal communication system
Authors: Pei Li  , Ning Ti-Gang  , Li Tang-Jun  , Dong Xiao-Wei  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所,北京  100044
Published: December 2020

By optimizing the fabrication process of the chirped optical fiber Bragg grating (FBG), some key problems of FBG are solved, such as the temperature stabili ty, time delay ripple coefficient, bandwidth, compensation of polarization mod e dispersion (PMD), and so on. The FBG we fabricated can attain the temperature coefficient less than 00005 nm/℃, its bandwidth is bigger than 14nm, tim e delay ripple is less than 50 ps, and the dispersion is higher than -1000ps/n m. The average PMD of the FBG dispersion compensator is measured by the Jones ma trix eigenvalue method, and is compensated. Its PMD is improved from 91406 ps to 01521 ps. With dispersion compensation by two wide_band FBGs we fabricated, we have implemented a 40 Gb/s 122 km conventional single_mode optical fiber (G6 52) systems, with a power penalty being only 14 dB.
Study on irradiation threshold of a target irradiated by an intense pulsed ion b eam
Authors: Wu Di  , Gong Ye  , Liu Jin-Yuan  , Wang Xiao-Gang  ,   大连理工大学三束材料改性国家重点实验室,大连  116024
Published: December 2020

A pulsed voltage of magnetically insulated diode and pulsed ion beam and temperature evolution of the target including phase transition models have been built by combining Monte Carlo method and thermodynamical method. The melting and e vaporating threshold of the target can be calculated, and the temperature of the target and the ablation plasma can also be determined.
Clean up of the dust grains in a plasma cylindrical reactor by a modulated magnetic field
Authors: Xi Yan-Bin  , Zhang Yu  , Wang Xiao-Gang  , Liu Yue  , Yu Hong  , Jiang Dong-Guang  ,   大连理工大学三束材料改性国家重点实验室，大连  116024
Published: December 2020

A theoretical method of getting rid of the dust grains in a plasma cylindrical reactor is designed. The motion of ions, elections and the dust grains under the control of a modulated magnetic field has been investigated by our fluid mechanics computational simulation subsequently. The dust grains have two kinds of motion: the pulse motion and the contrary cylinder center motion.Our method depends on the second condition.
Numerical study of kinetic shear Alfvn instability in tokamak plasmas
Authors: Jian Guang-De  , Dong Jia-Qi  ,   核工业西南物理研究院,成都  610041
Published: December 2020

Kinetic shear Alfvn modes in tokamak plasmas (with or without temperature grad ient) in the full gyrokinetic limit are numerically investigated by using the integral eigenvalue equations. A new integration transformation is introduced in this work. This allows the growing and damping modes to be investigated. It is shown that, in the presence of ion temperature gradient (ITG), the threshold value of plasma pressure gradient for the shear Alfvn modes is well below that for ideal magnetohydrodynamic ballooning instability. It is also demonstrated in a m ore general sense that, without ITG, the former is identical with the latter. Th e electromagnetic instability is also found to exist in the second stable region of the ideal modes when a finite ITG is present. The results are compared with previous results of similar analyses for kinetic collisionless ballooning modes.
Measurement of neutron radiation flux and dose on HL-1M tokamak
Authors: Yang Jin-Wei  , Song Xian-Ying  , Li Xu  , Zhang Wei  , Li Wen-Zhong  , Wang Shi-Qing  ,   (1)成都理工大学工程技术学院,乐山  614007; (2)核工业西南物理研究院,成都  610041
Published: December 2020

Five BF33 long counters are arranged in all around the HL_1M tokama k to mea sure the flux and dose of neutron radiation under the situations: the emission o f D_D fusion neutron being in deuterium plasma or the emission of photo_neutron being in hydrogen plasma. The results of measurement are compared with those of calculation, both agree roughly with each other. The dose equivalent of neutron radiation is very low, the measured value is far below the national and ministry issued standards of permissible dose equivalent.
Influence of the ambient pressure of Ar on the average size of Si nanoparticles deposited by pulsed laser ablation
Authors: Wang Ying-Long  , Zhou Yang  , Chu Li-Zhi  , Fu Guang-Sheng  , Peng Ying-Cai  ,   (1)河北大学电子信息工程学院，保定  071002; (2)河北大学物理科学与技术学院，保定   071002
Published: December 2020

The nanocrystalline silicon films were prepared by pulsed laser ablation at the ambient pressures from 1 to 500 Pa of pure Ar gas. The x-ray diffraction spectrum indicates that the films are nanocrystalline, i.e. they are composed of Si nanoparticles. Scanning electron microscopy shows that with increasing gas pressur e, the average size of Si nanoparticles first increases and reaches its maximum (20nm) at 100Pa, and then decreases. The dynamics are analysed theoretically to explain the phenomenon. Furthermore, our result is compared with that in He gas.
Large-scale fabrication and magnetic properties of Ni8080Fe20 20 nanowire arrays
Authors: Fu Xiu-Li  , Wang Yi  , Li Pei-Gang  , Chen Lei-Ming  , Zhang Hai-Ying  , Tu Qing-Yun  , L. H. Li  , Tang Wei-Hua  ,   (1)Department of Physics,University of Rhode Island,Kingston,RI  02881,USA; (2)北京大学物理系,北京  100871; (3)北京师范大学物理系,北京  100875; (4)中国科学院物理研究所,北京凝聚态物理国家实验室,北京  100080; (5)中国科学院物理研究所,北京凝聚态物理国家实验室,北京  100080;北京师范大学物理系,北京  100875
Published: December 2020

Large numbers of highly ordered Ni8080Fe2020 nanow ire arrays have be en fabricated by using electrochemical deposition technique with anodic aluminiu m oxide templates. The density of Ni8080Fe2020 nan owire is as high a s 101212—101313/cm22. The Ni8080Fe2020 nanowires were grown in a preferred direction of (111) with a high aspect ratio. Compared with the bulk sample, Ni8080Fe2020 nanowire arrays have enh anced coercivity and larger remanence magnetization.
Study on the electrical parameter variation during microarc oxidation of alumini um alloys
Authors: Wu Han-Hua  , Long Bei-Hong  , Lü Xian-Yi  , Wang Jian-Bo  , Jin Zeng-Sun  ,   (1)吉林大学超硬材料国家重点实验室,长春  130023; (2)吉林大学超硬材料国家重点实验室,长春  130023;吉林大学材料科学与工程学院,长春  130012; (3)吉林大学物理科学学院,长春  130023;吉林大学超硬材料国家重点实验室,长春  130023
Published: December 2020

The variation of electrical parameters during microarc oxidation(MAO) of aluminium alloys at constant voltage has been studied by means of a laboratory-made data acquisition system. Experimental results show that the variations of the cath odic and anodic current amplitude and effective working current in an electrical loop with the duration of treatment show obviously five stages, and the variati ons of dynamic positive resistance and the rate of change of resistance in coati ngs also show different stages, while the variations of dynamic negative resista nce and the rate of change of resistance with oxidation time are not evident. Du ring the MAO process, the dynamic positive resistance is always not equal to the negative resistance, and the former is generally greater than the latter in gen eral. Scanning electron microscopy analysis shows that the surface morphology of MAO coatings is macro-porous and its variations with treatment time are in ste ps.
Study on the metamorphosis of InP self-organized islands grown on GaxxIn1-x1-xP buffer layers
Authors: Wang Hao  , Zeng Gu-Cheng  , Liao Chang-Jun  , Cai Ji-Ye  , Zheng Shu-Wen  , Fan Guang-Han  , Chen Yong  , Liu Song-Hao  ,   (1)华南师范大学信息光电子学院,广州  510631; (2)暨南大学生命科学学院,广州  510632
Published: December 2020

The morphology of InP self-organized islands grown on GaInP buffer layer was calculated by employing the combination of the elastic energy Err cause d by the stress of the buffer layer and the excessive surface energy of the island Ess. The result shows that the island morphology is affected by the mi smatch between GaxxIn1-x1-xP buffer layer and InP island. With Ga content in creasing in GaInP layer, the island elongates itself with mismatch increasing. T he island metamorphosis was elongated also with volume increasing of the island. The parameters of the buffer layer determine the volume of the island which is at the minimized state. The morphology of different InP/GaxxIn1-x1-x P systems, grown on GaAs substrate by metal organic chemical vapor deposition me thod, was consistent with our calculations.
Structural and photoluminescence characters of SnO22:Sb thin films pr epared by rf magnetron sputtering
Authors: Wang Yu-Heng  , Ma Jin  , Ji Feng  , Yu Xu-Hu  , Zhang  Xi-Jian  , Ma Hong-Lei  ,   山东大学物理与微电子学院,济南  250100
Published: December 2020

SnO22:Sb films have been prepared on glass substrates by rf magnetron sputtering method. The prepared samples are polycrystalline thin films with rutile structure of pure SnO22 and have orientation of ［110］ direction. The phot oluminescence of the samples was measured at room temperature. An ultraviolet-violet luminescence peak near 392nm was observed. The effect of different oxygen partia l pressures on the structure and luminescence was investigated, and the luminesc ent mechanism was also tentatively investigated.
Study on the growth and superhardness of TiN/SiO22 nanomultilayers
Authors: Wei Lun  , Mei Fang-Hua  , Shao Nan  , Li Ge-Yang  , Li Jian-Guo  ,   上海交通大学金属基复合材料国家重点实验室,上海  200030
Published: December 2020

Superhard and oxide-composed multilayers are promising coatings for tools working under extreme conditions. In this paper, TiN/SiO22 nanomultilayers with vari ous individual SiO22 and TiN layer thicknesses have been prepared by multi-tar gets magnetron sputtering method. The growth structure and mechanical properties of the films have been studied by x-ray diffraction, energy dispersive x-ray spectrometry, high-resolution transmission electron microscope and nanoindenter. It reveals that although SiO22 and TiN monolithic films form amorp hous and nanocrystalline structures, respectively, the TiN/SiO22 multilayers exhibit coherent epitaxial growth due to the mutual growth-promoting effect. At small Si O22 layer thickness (～1nm) S iO22 layers transform into amorphous structure and block the coherent growth of multilayers, and then the hardness and elastic modulus of the multilayers decre ase gradually with increasing SiO22 layer thickness. On the other han d, the cha nging of TiN layer thickness shows a relatively small effect on the growth struc ture and mechanical properties of the nanomultilayers.
Theoretical study on the absorption and dispersion in asymmetrically coupled qua ntum well structure
Authors: Hu Zhen-Hua  , Huang De-Xiu  ,   (1)华中科技大学光电子工程系,武汉  430074; (2)华中科技大学光电子工程系,武汉  430074;武汉理工大学物理系,武汉  430063
Published: December 2020

The absorption and dispersion behaviors of an asymmetrically coupled quantum well (ACQW) structure are studied based on V-type system. We show that the quantum-confined Stark shift due to an electric field applied along the growth direction of ACQW leads to the detuning absorption, and the corresponding linear refraction is dramatically decreased in a smaller negative-bias voltage region. This means that refraction quenching induced by an external electric field can occur in an ACQW structure. However, the absorption and the dispersion behaviors become the same as those of the lowest excitonic state in a single quantum well structure as the negative-bias voltage further increases due to the disappearance of quantum-confined Stark effect. This means that the ACQW structure has controllable dispersion by using an external field.
Excitonic energy of vertically stacked self-assmbled InAs quantum dots
Authors: Dong Qing-Rui  , Niu Zhi-Chuan  ,   中国科学院半导体研究所超晶格国家重点实验室,北京  100083
Published: December 2020

We have studied the exciton states in vertically stacked self-assembled quantum disks within the effective mass approximation. The energy spectrum of the elect ron and hole is calculated using the transfer matrix formalism in the adiabatic approximation. The Coulomb interaction between the electron and the hole is trea ted accurately by the direct diagonalization of the Hamiltonian matrix. The effe ct of the vertical alignment of the disks on the ground energy of heavy- and li ght-hole exciton is presented and discussed. The binding energy is discussed in terms of the probability of the ground wave function. The ground energy of heav y- and light-hole excitons as a function of the magnetic field is presented an d the effect of the disk size (the radius of disks) on the exciton energy is dis cussed.
Effect of quantum current magnification in a mesoscopic multi-ring coupling sys tem
Authors: Cui  Yuan-Shun  ,   淮阴师范学院物理系,淮安  223001
Published: December 2020

Based on the fact that the charge is discreteness in the mesoscopic circuit, taking 3-rings for example, the effect of quantum current magnification in a mesoscopic multi-ring coupling system has been investigated. The results show that the effect of quantum current magnification not only can be observed in a dual-ring coupling system, but also in the metallic multi-ring coupling circuit.
The influence of sputtering power on the giantmagneto-impedance of FeZrBCu film s
Authors: Wang Wen-Jing  , Xiao Shu-Qin  , Liu Yi-Hua  , Chen Wei-Ping  , Dai You-Yong  , Jiang Shan  , Yuan Hui-Min  , Yan Shi-Shen  ,   (1)山东大学物理与微电子学院,济南  250100; (2)山东大学物理与微电子学院,济南  250100;山东大学晶体材料国家重点实验室,济南  250100; (3)山东大学物理与微电子学院,济南  250100;浙江台州学院物理系,临海  317000
Published: December 2020

The giant magneto-impedance (GMI) effect has been observed at room temperature in soft magnetic alloy films of FeZrBCu prepared by radio frequency (RF) sputtering. The dependence of the soft magnetic properties and the GMI effect on the RF sputtering power has been studied. The results measured by electron probe micro-analysis show that the as-deposited films sputtered at 240W possess 29at% Cu and 8732at% Fe. This sample possesses excellent soft magnetic properties and a maximum value of GMI effect, the coercive force is about 68A/m, the saturation magnetization is about 111×1055A/m, and the maximum GMI r atios are 17% and 11% in longitudinal and transverse fields at frequency of 13MHz, respectively. In addition, the dependence of resistance R, inductance X and effective permeability μee on the frequency has been investigated, and the results show that the GMI effect is mainly a magneto-inductive effect at low frequencies.
Studies on structure and magnetic properties of uniaxial M-type SrFe12-x 12-xCrxxO1919 hexaferrite nano-crystalline
Authors: Fang Qing-Qing  , Jiao Yong-Fang  , Li Rui  , Wang Jin-Zhi  , Cheng Hui  ,   安徽大学磁性材料研究中心,物理与材料科学学院,合肥  230039
Published: December 2020

SrFe12-x12-xCrxxO1919 (x=0—10) hexaferri te nanoparticles have been fabricated using a sol-gel technique for perpendicular magnetic recording. Experimental results have shown that the values of specific saturation mag netization, σss, increase for x≤04 as the Cr doping content incre ases, and reach maximum at x=02, while the coercivity, Hcc, decreas es for x＜05 This feature is favorable to magnetic recording. It is also fou nd that the α-Fe22O33 non-magnetic phase appears after x=06 and remai ns to be a hexagonal magnetoplumbite phase for x=0—04 Magnetic measurem ents have revealed that Cr substitution can decrease the magnetization and incre ase the peak-widening for Hopkinson peak when doped with Cr3+3+.
Correlation among magnetic properties, perpendicular magnetic recording properti es and microstructure of［Co8585Cr1515/Pt］2020 multilayers
Authors: Hwang Pol  , Li Bao-He  , Yang Tao  , Zhai Zhong-Hai  , Zhu Feng-Wu  ,   (1)北京科技大学材料物理与化学系，北京  100083; (2)北京科技大学材料物理与化学系，北京  100083;北京工商大学数理部，北京  100037; (3)北京科技大学材料物理与化学系，北京  100083;金日成综合大学物理系,朝鲜平壤
Published: December 2020

The ［Co8585Cr1515/Pt］2020 multilayers w ith Pt underlayers were prepared by magnetron sputtering and the effects of sputtering Ar gas pressure on m icrostructure and magnetic properties of ［Co8585Cr1515 /Pt］2020 mul tilayers were studied. The results show that sputtering Ar gas pressure has a gr eat effect on the microstructure, perpendicular magnetic anisotropy and the coer civity of ［Co8585Cr1515/Pt］2020 mul tilayers. For all samples, we have the effective magnetic anisotropy constant K effeff＞0, and all s amples showed perpendicular magnetic anisotropy. With increasing sputtering Ar g as pressure, the perpendicular and in-plane coercivity of the samples increase, but the effective magnetic anisotropy constant decreases. The coercivity of Pt( 20nm)/［(Co8585Cr1515(05nm)/Pt(15nm)］2020 multilayers spu tter-depositied at 16Pa Ar gas pressures is increased to 130kA/m. The Pt( 20nm)/［(Co8585Cr1515(05nm)/Pt(15nm)］ 2020 multilayers display perpendicular magnetic anisotropy and can be used as perpendicular magn etic recording media. The images of atomic force microscopy show that both avera ge grain size and the surface roughness increase with increasing sputtering Ar p ressure, which leads to the enhancement of perpendicular coercivity and the decr ease of effective magnetic anisotropy constant.
Thermal stability, spectra and laser properties of Yb:lead-zinc-lanthanum-tel lurite glasses
Authors: Wang Guo-Nian  , Dai Shi-Xun  , Zhang Jun-Jie  , Hu Li-Li  , Jiang Zhong-Hong  ,   (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  100049
Published: December 2020

A series of new glasses of 70TeO22-(20-x) ZnO-xPbO-5La22O33-25K22O-25Na22O (x=0,5,10,15, 20mol %) doped with Yb22O33 is presented. Thermal stability, spectra and laser properties of Yb3+3+ ions have been measured. It has been found that the glass with x=15 has a good thermal s tability ((Txx-Tgg)>195℃), high stimulated emission cross -section of 125pm22 for the 22F5/25/2 →22F7/27/2 transition and a long fluorescence lifetime of 094ms and a broad fluorescence effective linewidth of 72nm. From the viewpoint of good potential laser parameters, it is desirab le to have high-average power and short pulse tunable laser, which can be achie ved by doping with Yb22O33.
Study on growth mechanism of low-temperature prepared microcrystalline Si thin f ilms
Authors: Gu Jin-Hua  , Zhou Yu-Qin  , Zhu Mei-Fang  , Li Guo-Hua  , Ding Kun  , Zhou Bing-Qing  , Liu Feng-Zhen  , Liu Jin-Long  , Zhang Qun-Fang  ,   (1)中国科学院半导体研究所，北京  100083; (2)中国科学院研究生院物理系，北京  100049
Published: December 2020

Microcrystalline silicon thin films at different growth stages were prepared by hot wire chemical vapor deposition. Atomic force microscopy has been applied to investigate the evolution of surface topography of these films. According to the fractal analysis, it was found that, the growth of Si film deposited on glass substrate is the zero_diffused stochastic deposition; while for the film on Si substrate, it is the finite diffused deposition on the initial growth stage, and transforms to the zero_diffused stochastic deposition when the film thickness reaches a certain value. The film thickness dependence of island density shows that a maximum of island density appears at the critical film thickness for both substrates. The data of Raman spectra approve that, on the glass substrate, the a_Si:H/μc_Si:H transition is related to the critical film thickness. Different substrate materials directly affect the surface diffusion ability of radicals, resu lting in the difference of growth modes on the earlier growth stage.
Secondary ion mass spectroscopic depth profile analysis of oxygen contamination in hydrogenated microcrystalline silicon
Authors: Zhang Xiao-Dan  , Zhao Ying  , Zhu Feng  , Wei Chang-Chun  , Mai Yao-Hua  , Gao Yan-Tao  , Sun Jian  , Geng Xin-Hua  , Xiong Shao-Zhen  ,   南开大学光电子薄膜器件与技术研究所，天津  300071;光电子薄膜器件与技术天津市重点实验室，天津  300071;南开大学光电信息技术科学教育部重点实验室，天津  300071
Published: December 2020

Oxygen contamination of samples fabricated by very high_frequency plasma_enhanced chemical vapor deposition with the variation of silane concentration and disc harge power was studied by secondary ion mass spectroscopy. The results showed t hat oxygen content in the samples depended strongly on the silane concentration and discharge power. Microcrystalline silicon thin films with higher crystallin e volume fraction has relatively higher oxygen content. Oxygen contamination of samples was also related with the background vacuum, especially for microcrystal line silicon thin films. Therefore, higher background vacuum is extremely necess ary in the fabrication of high-quality microcrystalline silicon thin films.
Experimental study on the momentum coupling efficiency of laser plasma
Authors: Zheng Zhi-Yuan  , Lu Xin  , Zhang Jie  , Hao Zuo-Qiang  , Yuan Xiao-Hui  , Wang Zhao-Hua  ,   (1)中国科学院物理研究所光物理重点实验室，北京  100080; (2)中国科学院物理研究所光物理重点实验室，北京  100080;中国科学院西安光学机械研究所瞬态光学国家重点实验室，西安  710068
Published: December 2020

During the interaction of laser with solid targets, the counteracting force is generated by the plasma, which can be used as a new type source of propulsion. Compared with the chemical propulsion, laser plasma has unique advantages such as high specific impulse and large load ratio. In this paper, the momentum generated by the laser plasma is measured during the interaction of nanosecond laser pulses with aluminum, graphite, lead and CH targets. The relation of target momentum with laser focal area in atmosphere and vacuum ambient pressure is obtained,and the comparison is performed between the experimental and analytical results. It is shown that the target momentum in vacuum is different from that in atmosphere. In vacuum, the target momentum shows a dependence on the target property. These results are different from those generated by long width pulses.
Adaptive training and pruning algorithm for variable bit rate video traffic pre diction
Authors: Xiong Tao  , Chang Sheng-Jiang  , Shen Jin-Yuan  , Zhang Yan-Xin  ,   南开大学现代光学研究所,光电信息技术科学教育部重点实验室,天津  300071
Published: December 2020

An adaptive training and pruning algorithm for variable bit rate(VBR) video traffic prediction is proposed in this paper. By simulation and comparison, the adaptive neural network model proposed in this paper is shown to be promising and practically feasible in obtaining the best adaptive prediction of real-time VBR video traffic.