bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study on comparing the temperature characteristics of AlInGaAs/AlGaAs vertical cavity surface emitting lasers
Authors: Chen Min  , Guo Xia  , Guan Bao-Lu  , Deng Jun  , Dong Li-Min  , Shen Guang-Di  ,   北京工业大学电子信息与控制工程学院和北京光电子技术实验室，北京  100022
Published: December 2020

The light power-current (L-I) characteristics of vertical cavity surface emitting lasers (VCSEL)，which have the same fabrication process and structure, but different detunings of Fabry-Perot (FP) resonance from the gain peaks at room temperature, were measured in the temperature range from 261K to 369K. The relationships between the output light power, threshold current, slope efficiency and lasing wavelength and the temperature were studied using the obtained characteristics in combination with the test results of their reflectivity spectra and photoluminescence signals, as well as the simulated results of their reflectivity spectra and gain spectra at different temperatures. The temperature characteristics of the new material AlInGaAs were found. The effect which the differences between the gain spectrum and the FP resonance had on the output characteristics, especially on the threshold current had been obtained. We found that VCSEL devices with minimal threshold currents and small threshold current change with temperature at room temperature could be obtained by adjusting the detuning of Fabry-Perot (FP) resonance from the gain peak. Using this method, AlInGaAs/AlGaAs strained quantum well VCSEL devices which have the characteristic temperature of 333K, and minimal threshold current and small threshold current change with temperature in the 321K to 345K range were fabricated.
A deep sub-micrometer NMOSFET non-local transport model for ESD effect
Authors: Zhu Zhi-Wei  , Hao Yue  , Zhang Jin-Feng  , Fang Jian-Ping  , Liu Hong-Xia  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

Non-local transport characteristics of the deep sub-micrometer NMOS device are studied under electro-static discharge (ESD) stress. The result obtained shows that velocity overshoot may increase the drain current and has a great impact on the device characteristics, and that the energy relaxation time is correlated closely with the electric field of some point in the device as well as the velocity and the energy of the carriers, thus constant value is not appropriate for this parameter. The energy relaxation time and the high field mobility as functions of the carrier energy are gained by Monte Carlo calculation, and then device simulation is performed with these parameter models. Comparing ESD simulation with experimental results shows that accurate result about the I-V characteristics can be gained by using the models of the energy relaxation time and the high field mobility.
The PIC/MCC simulation of the ionization processes in electron cyclotron resonance discharge (Ⅱ)——Numerical simulation and discussion of results
Authors: Jin Xiao-Lin  , Yang Zhong-Hai  ,   电子科技大学物理电子学院，成都  610054
Published: December 2020

We present a theoretical and computational model to study the ionization of the electron cyclotron resonance (ECR) microwave discharge using a quasi-three-dimensional electromagnetic particle-in-cell plus Monte Carlo collision method. The simulation code is original. The detailed information about the distribution of charged particles and electromagnetic fields are obtained. We can conclude that the electrons absorb energy from microwave near the ECR region. Many electrons and ions are created through the ionization collisions between electrons and neutrals. And the distribution of charged particles vary gradually from anisotropic to isotropic by the frequently collisions.
Numerical simulation of neutron thick aperture imaging
Authors: Chen Fa-Xin  , Zheng Jian  , Yang Jian-Lun  ,   (1)中国工程物理研究院核物理与化学研究所,绵阳  621900; (2)中国科学技术大学近代物理系,合肥  230027; (3)中国科学技术大学近代物理系,合肥  230027；中国工程物理研究院核物理与化学研究所,绵阳  621900
Published: December 2020

Pinhole imaging of the neutron production in laser-driven inertial confinement fusion experiments can provide important information about performances of various capsules designs. In order to get good results in experiments, it is needed to judge the performance of various pinhole designs qualitatively or quantitatively before experiment. Calculation of imaging can be simply separated into pinhole imaging and image spectral analysis. In this paper, pinhole imaging is discussed, codes for neutron pinhole imaging and image showing is programed. The codes can be used to provide theoretical foundation for pinhole designing, either to provide simulating data for image analysing.
Investigation of structure and energy of edge dislocation in bcc iron
Authors: Chen Li-Qun  , Wang Chong-Yu  , Yu Tao  ,   (1)钢铁研究总院功能材料研究所，北京  100081; (2)钢铁研究总院功能材料研究所，北京  100081；清华大学物理系,北京  100084；中国科学院国际材料物理中心,沈阳  110016
Published: December 2020

Based on the theory of dislocations, we have constructed the four models of the 〈100〉{010}, 〈100〉{011}, 1/2〈111〉{011} and 1/2〈111〉{112} edge dislocations in bcc Fe using the molecular dynamics method, and the formation energy, core energy and core radius of the dislocations have been calculated respectively. The calculated results indicated that the formation energies of 〈100〉{010} and 〈100〉{011} edge dislocations are higher than those of 1/2〈111〉{011} and 1/2〈111〉{112} edge dislocations. This shows that the formation of 1/2〈111〉 edge dislocation is easier than that of 〈100〉 edge dislocation. However, the core radii of 〈100〉{010} and 〈100〉{011} edge dislocations are smaller than those of 1/2〈111〉{011} and 1/2〈111〉{112} edge dislocations. This shows that the atomic numbers locating at the singular region in the 1/2〈111〉 edge dislocation are greater than those in 〈100〉 edge dislocation. Therefore, the motion of 1/2〈111〉 edge dislocation is easier than that of 〈100〉 edge dislocation.
Intensity parametrization of 4f2→4f2 electric-dipole transition in SrAl12O19: Pr3+
Authors: Liu Feng  , Zhang Jia-Hua  , Lü Shao-Zhe  , Wang Xiao-Jun  ,   (1)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室,长春  130033; (2)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室,长春  130033；Department of Physics,Georgia Southern University,Statesboro,GA 30460 USA; (3)中国科学院长春光学精密机械与物理研究所激发态物理重点实验室,长春  130033；中国科学院研究生院,北京  100049
Published: December 2020

Intensity parametrization of the electric dipole transitions within 4f2 configuration of Pr3+ in SrAl12O19 are reported, in which the mixing of the 4f2 transitional states with the explicit 4f5d states is taken into account. A new set of phenomenological intensity parameters, Tkq, are put forward, which are obtained from a best fit of the calculated and measured relative intensities of transitions from the 3P0 level to the lower J multiplets. The fitted values, T33=3.26×10-5 and T53=-5.46×10-5, have been used to analyze the transitions originating from the 1S0 level. The present results are compared with that of the Judd-Ofelt analysis and the experimental measurements.
First-principles calculation of atomic hydrogen adsorption on Be(1010) thin films
Authors: Song Hong-Zhou  , Zhang Ping  , Zhao Xian-Geng  ,   北京应用物理与计算数学研究所,北京  100088
Published: December 2020

We present a first-principles study of the atomic hydrogen adsorption onto the Be(1010) thin film.There are two types of Be(1010)surfaces according to the interlayer spacing between the surface and its nearest-neighbor layer. We show that the H adsorption features on these two kinds of surfaces are remarkably different. The work function, averaged electrostatic potential, and the local charge density consistently show that the charge is transferred from H to Be for L-type surfaces, while the transfer process is inverted for S-type surfaces.
First principles study of potential energy curves of NiTi alloy
Authors: Jiang Zhen-Yi  , Li Sheng-Tao  ,   西安交通大学电力设备电气绝缘国家重点实验室,710049
Published: December 2020

The potential energy curves of B2 and B19′ phase for NiTi alloys were investigated with the norm-conserving and plane-wave ultrasoft pseudopotential in the local density approximation. Our results reveals that the B19′ phase is more stable than the B2 phase at absolute zero temperature due to lower potential energy of the former. In the B2 phase, the alloying atoms Au and Fe (at Ni site) occupy the equilibrium positions, whereas Ti, Zr and Al (at Ti site) and Ni atoms are displaced from their equilibrium positions. In the B19′ phase, all the above atoms are exactly located at the equilibrium positions. The martensitic transformation may mostly be ascribed to the non-global minimum positions that the Ni and Ti atoms occupy.
First-principles study of metal atoms adsorbed on SiO2 surface
Authors: Yao Hong-Ying  , Gu Xiao  , Ji Min  , Zhang Di-Er  , Gong Xin-Gao  ,   复旦大学物理系,上海  200433
Published: December 2020

The adsorption properties of metal atoms on the hydroxyl SiO2 surface have been studied by using first-principles calculation. It is found that In and Ga atoms are weekly bound to the surface, while Fe, Co and Ni atoms are bound to both Si and O atoms with strong chemical bonds. Potential energy surface and diffusion barrier calculations show that In (Ga) can easily diffuse on the surface because of a rather small diffusion barrier(0.1—0.3 eV). The obtained results are in close agreement with recent nano- synthesis experimental results.
Energy-level splitting of ground-states and Jahn-Teller effects in ruby crystal
Authors: Yin Chun-Hao  , Zhang Lei  , Zhao Ji-Ping  , Jiao Yang  , Song Ning  , Ru Rui-Peng  , Yang Liu  ,   (1)徐州师范大学物理系,徐州  221009; (2)中国矿业大学理学院,徐州  221008
Published: December 2020

The completely diagonalized Hamiltonian matrixes of order 120 of 3d3/3d7 ions configuration in the trigonal symmetry have been established by irreducible representation method and group theory, taking into account spin-orbit interaction and spin-spin interaction. The ground-state energy levels, the zero-splitting parameter and Jahn-Teller effect of ruby crystal were calculated with the matrixes. The contributions of spin doublets for the ground-state energy levels were studied. The results show that the contributions of doublets cannot be neglected. The values of theoretical calculation conform with the experiments. On this basis, the influence of spin-spin interaction on the fine structure and zero-field splitting parameter of ruby crystal was further studied, and we found that the influence of spin-spin interaction on the zero-field splitting cannot be neglected.
Control of coercivity of iron films deposited on porous silicon substrates
Authors: Qiu Xue-Jun  , Zhang Yun-Peng  , He Zheng-Hong  , Bai Lang  , Liu Guo-Lei  , Wang Yue  , Chen Peng  , Xiong Zu-Hong  ,   (1)山东大学物理与微电子学院,济南  250100; (2)西南大学物理学院,重庆  400715
Published: December 2020

Porous silicon (PS) with different porosity was obtained by anode electrochemical etching of boron-doped Si (100); the as-etched samples were then covered with Fe films by magnetron sputter technique. Analysis of surface profile and structural investigation were done by scanning tunneling microscopy and X-ray diffraction. Magneto-optical Kerr effect was employed to measure the hysteresis loops of the iron films sputtered onto PS and the reference sample on the Si substrate. The coercivity of the PS-based Fe films is larger than that of the Si-based ones, and increases with the porosity of the PS substrate. As for the PS-based samples with the same porosity, the coercivity of Fe films decreases with their thicknesses in a certain range. We found that the spongelike structure of PS can be effectively used to control the coercivity of iron films on the PS substrates.
Positron annihilation study of hot band of a continuous cast AA 2037 Al alloy after annealing
Authors: Wu Shi-Liang  , Chen Ye-Qing  , Wu Yi-Chu  , Wang Shao-Jie  , Wen Xi-Yu  , Zhai Tong-Guang  ,   (1)Chemical and Materials Engineering Department,University of Kentucky,Lexington,KY 40506-0046,USA; (2)武汉大学物理科学与技术学院，武汉  430072; (3)燕山大学材料工程学院，河北秦皇岛  066002
Published: December 2020

Hot band of a continuous cast AA 2037 Al alloy was annealed at different temperatures ranging from room temperature to 500℃ for 3h. Vacancy-solute interaction and precipitates in the hot band samples during annealing were investigated by positron annihilation techniques, coincidence Doppler broadening (CDB) of positron annihilation radiation and positron lifetime spectroscopy, and other methods. The experimental results indicated that there existed V-Cu and V-Cu-Mg complexes at room temperature. At 200℃, positron mean lifetime shows a peak value because of the formation of semicoherent particles. The characteristic shape of Mn was observed in the CDB ratio curve, which indicated the formation of V-Mg-Mn complexes or the existence of Mn clusters in the semicoherent particles. Above 250℃, coarsening and dissolution of semicoherent particles resulted in the decrease of mean lifetime and disappearance of the Mn signal, but the Cu signal increased clearly with annealing temperature. After 350℃, the Cu signal tended to saturation, which reflected that the Cu dissolved might agglomerate and cluster with vacancies during cooling the sample to room temperature, while new increase of mean lifetime might be attributed to the formation of incoherent phase, which was verified by DSC curve.
Influence of yttrium ion-implantation on oxidation behavior of nickel and property of oxide scale at 900℃
Authors: Jin Hui-Ming  , Felix Adriana  , Aroyave Majorri  ,   (1)国立安第克大学材料科学与工程学院,哥伦比亚 麦德林  23715; (2)扬州大学机械工程学院,扬州  225009
Published: December 2020

Isothermal oxidation behaviors of pure and yttrium-implanted nickel were studied at 900℃ in air. SEM and TEM were used to examine the oxide scales formed on nickel substrate. Acoustic emission (AE) technique was used to monitor the cracking and spalling of oxide film in isothermal oxidizing stage and subsequent air-cooling stage. AE signals were analyzed in time and number domain according to the related oxide fracture model. It was found that Y-implantation greatly lowered the isothermal oxidizing rate of nickel and improve the anti-cracking and anti-spalling properties of NiO oxide film. The main reason for the improvement was that Y-implantation greatly reduced the grain size of NiO and increased the high temperature plasticity and creeping ability of the oxide film. Meanwhile, Y-implantation reduced the size and number of Ni/NiO interfacial defects, hence remarkably enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.
Amplitude death in non-feedback coupled chaotic system
Authors: He Wen-Ping  , Feng Guo-Lin  , Gao Xin-Quan  , Li Jian-Ping  ,   (1)国家气候中心，中国气象局气候研究开放实验室，北京  100081; (2)扬州大学物理科学与技术学院，扬州  225002；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029；兰州大学大气科学学院，兰州  730000; (3)中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室，北京  100029; (4)中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029；国家气候中心，中国气象局气候研究开放实验室，北京  100081
Published: December 2020

Considering a non-feedback mechanism of action，the present paper shows that the steady forcing induces amplitude death in chaotic system by investigating the bifurcation figures and the spectrum of Lyapunov exponents of the R?ssler oscillator. The manner, which is very similar to that in coupled limit cycles or coupled R?ssler system, is from periodic to an equilibrium point of the forced system. Furthermore，we investigate the time series of the forced system, and find that when the strength of the forcing is beyond a critical constant，the states of the system present the periodic dynamics with a small amplitude or rest alternately.
Unified symmetry of Poincaré-Chetaev equations
Authors: Ding Ning  , Fang Jian-Hui  , Zhang Peng-Yu  , Wang Peng  ,   中国石油大学(华东)物理科学与技术学院,东营  257061
Published: December 2020

The unified symmetry and conserved quantities of Poincaré-Chetaev equations are studied. The definition and criterion of the unified symmetry are given. The Noether conserved quantity, the Hojman conserved quantity, and the Mei conserved quantity induced from the symmetry are obtained.
Synchronization control based on feedback precise linearization
Authors: Zhu Zhi-Yu  ,   江苏科技大学电子信息学院，镇江  212003
Published: December 2020

Precise linearity method which is applied to linearize nonlinear chaotic system through strict state transform and feedback strategy is discussed. Considering that some of the state variables can not be measured, the nonlinear feedback method including state observer is researched, and the corresponding control law is deduced. This kind of control method is adopted to chaos synchronization control of the Lorenz system, the simulation results show that the synchronization error of the three state variables can convergence to zero in a short time, which indicates that the control procedure proposed in this paper can guarantee high convergence speed and precision of synchronization under the prerequisite of close-loop stability.
Studies on chaotic modulation performance and internal phase shifting key encoding in injection semiconductor lasers
Authors: Yan Sen-Lin  ,   南京晓庄学院物理系，南京  210017
Published: December 2020

The chaotic modulation and demodulation in injected semiconductor lasers are studied, and a method of chaotic encoding is presented by modulating the phase of external optical injection light in semiconductor lasers. The modulation response function, demodulation response function and demodulation response factor are analyzed by small-signal analysis. It is found there are peak values about 60 MHz and the response functions and the demodulation factor decrease at high modulation frequency. A chaotic modulation-demodulation equation is theoretically deduced and its roots are given. It is found that there is a peak value at low modulation frequency and the demodulation perfomance declines at high frequency, however, modulation-demodulation of 109 Hz frequency is relalized. Synchronization is achieved and is proved feasible numerically in larger parameter range. Secure communication applications are numerically simulated with chaotic modulations of 200 Mb/s rate and 1.4 GHz frequency. Chaotic encoding is also achieved by shifting key on or off a phase-controller to encode chaotic laser state and decoding is realized under the condition of synchronization or unsynchronization. Chaotic phase key shifting is numerically simulated with a bit rate of 10 Mb/s.
Two-photon spectroscopy and Dicke narrowing of a thin atomic vapor film
Authors: Li Yuan-Yuan  , Bai Jin-Tao  , Zhang Gui-Zhong  , Zhou Yu  , Zhang Yan-Peng  , Gan Chen-Li  ,   (1)宁夏师范学院物理与信息技术系，固原  756000; (2)天津大学精密仪器与光电子工程学院，天津  300072; (3)西安交通大学电子科学与技术系，西安  710049; (4)西北大学光子学与光子技术研究所,光电子技术陕西省重点实验室，西安  710069
Published: December 2020

One-photon Dick-narrowing absorption spectroscopy from a thin atomic vapor film can be extended to the two-photon case, in which the sub-Doppler absorption structures are obtained in a cascade three-level system. The periodic line shapes of two photon spectroscopy are similar to one-photon case. It is found that Dicke-narrowing is apparent when L/λ=(2n+1)/2 (n an integer, L the film thickness, and λ the wavelength of the probe field)in the case of one-photon process, and this feature is maintained in the case of two-photon process but not in the one-photon process when L/λ=2n/2. Due to the contribution of atom-wall collision in the cell and the pump-probe scheme, a very narrow structure can be obtained when the pump and the probe fields are in counter-propagation regime.
Application of quantitative imaging to elimination of scattering effect on X-ray in-line outline imaging
Authors: Liu Li-Xiang  , Du Guo-Hao  , Hu Wen  , Luo Yu-Yu  , Xie Hong-Lan  , Chen Min  , Xiao Ti-Qiao  ,   中国科学院上海应用物理研究所,上海  201800
Published: December 2020

X-ray in-line outline imaging (XILOI) attracts much attention in recent years, for its simple setup compared with other approaches. Unfortunately, scattering effect cannot be removed directly, which restricts seriously the applications of this method to fields like biomedical radiography. The scattering effect in XILOI was investigated by digital simulation, in which the sample-detector distance (SDD) was changed step by step. The results show that there is a best imaging distance for the direct outline imaging and it is impossible to eliminate the scattering by arbitrarily changing the distance in this case. This difficulty could be overcome by quantitative phase contrast imaging(QPCI), in which SDD can be adjusted freely using a reconstruction algorithm. According to the investigation using QPCI, the scattering effect can be reduced to a minimum by increasing the SDD to a critical value, at which distinct improvement of the image quality can be achieved.
Measurement of refractive index profile of holey fiber using quantitative phase tomography
Authors: Huang Yan-Ping  , Qi Chun-Yuan  ,   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
Published: December 2020

A method to determine three-dimensional refractive index profile of holey fiber using a combination of quantitative phase microscopy and tomographic reconstruction techniques is described. Results show that the method based on the transport-of-intensity equation for phase retrieval is straightforward to measure phase profile, nondestructive to the measured fiber, and valuable to determine three-dimensional refractive index profile of holey fiber.
Design and fabrication of holographic variable line-spacing gratings for position sensor
Authors: Lou Jun  , Fu Shao-Jun  , Xu Xiang-Dong  , He Shi-Ping  ,   (1)中国科学技术大学国家同步辐射实验室, 合肥  230029; (2)中国科学技术大学国家同步辐射实验室, 合肥  230029;中国计量学院光电子技术研究所,杭州  310018; (3)中国科学技术大学力学和机械工程系,合肥  230029
Published: December 2020

Variable line-spacing gratings are widely used in spacial spectroscopic and synchrotron radiation devices, but their design and fabrication are difficult. In this paper, the geometrical theory of aspheric wave-front recording optics is briefly reviewed. The genetic algorithm is introduced to optimize parameters of holographic variable line-spacing gratings. In order to improve the efficiency of calculation. the integral expression of the objective function is also derived. Design example of holographic variable line-spacing gratings for position sensor is given to demonstrate the capability of this method. Holographic variable line-spacing gratings with large density gradient are fabricated successfully.
Spectroscopic characteristics of Nd3+-doped yttrium lanthanum oxide trans parent ceramics
Authors: Ding Jun  , Yang Qiu-Hong  , Tang Zai-Feng  , Xu Jun  , Su Liang-Bi  ,   (1)上海大学材料科学与工程学院，上海  200072; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

Nd3+-doped Y2-2x La2x O3 (x=0.08) transparent ceramics were fabricated by conventional fabrication process. Spectroscopic properties of the samples were investigated. The absorption band of Nd3+: Y1.84La0.16O3 was broad covering the wavelength range 780—850 nm. When doped with 1.5at% Nd3+, the cross sections of the sample at 820 nm and laser diode pumped 808 nm were 1.81×10-20cm2 and 1.54×10-20cm2, respectively. The strongest emission peak of the sample was centered at 1078 nm with long fluorescent lifetime, broad emission bandwidth and high quantum efficiency. Because of the additive La2O3, the spectroscopic quality parameter (XNd) of matrix was decreased from 1.6 to 0.46, thus the fluorescence branch ratio of 4F3/2—4I11/2 transition was increased to 56.82%. These properties of Nd3+: Y1.84La0.16O3 transparent ceramic are benefitial to achieve high efficient laser output and ultrashort modelocked pulse.
Influence of introducing chirp on bistable characteristics of linear negative tapered Bragg gratings
Authors: Tian Jian-Feng  , Wu Zheng-Mao  , Xia Guang-Qiong  ,   西南大学物理学院，重庆  400715
Published: December 2020

Based on the coupled mode theory, the influence of introducing the chirp on the bistable characteristics of linear negative tapered Bragg gratings is investigated. The results show that introducing positive chirp improves the bistable performance of linear negative tapered Bragg gratings, and the bistable performance can be further optimized by reasonably selecting the length of the linear negative tapered Bragg gratings with positive chirp.
On the nonlinear oscillation of internal sliding friction in particulate matter
Authors: Du Xue-Neng  , Hu Lin  , Kong Wei-Shu  , Wang Wei-Ming  , Wu Yu  ,   (1)贵州大学理学院，贵州省光电子技术与应用重点实验室，贵阳  550025; (2)贵州大学理学院，贵州省光电子技术与应用重点实验室，贵阳  550025;铜仁学院物理系，铜仁  554300
Published: December 2020

Experiments are designed to explore the sliding friction that the particulate material bears in the movement when the detecting rod goes vertically through the material contained in a round tube. The research result shows that the sliding friction makes nonlinear oscillations about an average value when the depth of the particulate pile with 2 mm particulate diameter is greater than 0.5 to 2 times the diameter of the container. When the detecting rod goes up with the uniform velocity of less than 2×10-3 m/s, the average value of the sliding friction is 0.2 to 0.5 times greater than the maximum static friction F0 and the value fluctuates within the range from F0 to 2F0. When the frequency is lower than 1.35 Hz, the intensity of various frequencies goes down exponentially with increasing frequency. The average period T of the main frequency is inversely proportional to the velocity v of the detecting rode.
Static properties of a femtosecond electron diffraction system
Authors: Liu Yun-Quan  , Liang Wen-Xi  , Zhang Jie  , Wu Jian-Jun  , Tian Jin-Shou  , Wang Jun-Feng  , Zhao Bao-Sheng  ,   (1)中国科学院物理研究所，北京  100080; (2)中国科学院西安光学精密机械研究所瞬态光学国家重点实验室，西安  710068
Published: December 2020

Ultrafast electron diffraction is an important technique to study the ultrafast phenomenon in physical, chemical and biological processes. This paper introduces a femtosecond electron diffractometer. The diameter of electron beam and deflection sensitivity of X-Y deflection plates are reported. We also demonstrate the static diffraction pattern of a 300 nm thick gold film taken by the femtosecond electron diffractometer.
Electronic theoretical study on the influence of rare earth on the stress corrosion in magnesium alloy
Authors: Liu Gui-Li  ,   沈阳工业大学建筑工程学院，沈阳  110023
Published: December 2020

The atomic models of pure boundary and that with Mg17Al12 of α phase in magnesium alloy were set up. The segregation energies of Al and rare earth atoms, the interaction energies between Al and/or rare earth atoms, and the Fermi energy levels of different systems were calculated by using recursion method. The Al and rare earth segregation at the grain boundaries, the relationship between the interaction of Al or rare earth atoms and the ordering tendency, as well as the physical nature of the influence of rare earth on the stress corrosion of magnesium alloy were discussed. Calculation results show that: Al and rare earth atoms segregate at grain boundaries, and Al atoms repel each other, leading to the formation of the ordered Mg17Al12 phases in the grain boundaries. But rare earth atoms attract each other, so atom clusters are formed in the grain boundaries. The rare earth atom cluster can attract Al atoms, make the Al atoms to infiltrate into the rare earth atom cluster, forming rare earth compound. Therefore, rare earth have the effect of restraining the forming of Mg17Al12 along grain boundaries which functions as the cathode of magnesium alloy that leads to corrosion, this reducing the sensibility of stress corrosion.
Quantum tunnelling time of cold atom passing through a laser beam
Authors: Tang Lin  , Huang Jian-Hua  , Duan Zheng-Lu  , Zhang Wei-Ping  , Zhou Zhao-Ying  , Feng Yan-Ying  , Zhu Rong  ,   (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)清华大学精密仪器系，北京  100084; (3)清华大学物理系，北京  100084
Published: December 2020

Atoms can be prepared at low temperatures by laser cooling. The center of mass motion of the cold atoms exhibits wave nature of quantum mechanics. In this paper, we study the quantum tunneling effect of a cold atomic beam propagating through a laser beam which is blue detuned. The blue detuned laser beam is physically equal to a quantum potential barrier. According to two-level model of atom, we systematically analyze the quantum reflection and transmission of the vector atomic matter wave with internal structures propagating through a laser beam. Quantum tunneling time the atomic beam spends in transmitting the laser beam is studied in details. Because of quantum wave nature, cold atoms tunneling through a laser beam can obviously have a completely different feature from that of a classical particle (hot atom).
The distribution and origination of electric field and charge in interface layer of superconductor
Authors: Yang Peng-Fei  , Chen Wen-Xue  ,   (1)陕西广播电视大学榆林市分校，榆林  719000; (2)西安邮电学院应用数学与物理系，西安  710061
Published: December 2020

Based on relativistic field equations of superconducting state, the structure and forming mechanism of interface layer of superconductor are studied for the condition of weak magnetic field. It is shown that electric field, potential difference, Hall effect and sandwich of charge density exist in this layer,which originate from the measurable effect of potential field limited by relativistic covariance. In order to verify the result of this paper, a design of experiment is given.
Approaches to convergence enhancement of multiframe blind deconvolution of astronomical images
Authors: Luo Lin  , Wang Li  , Cheng Wei-Dong  , Shen Mang-Zuo  ,   (1)成都信息工程学院，成都  610041; (2)西南交通大学理学院,成都  610031; (3)西南交通大学理学院,成都  610031;中国科学院光电技术研究所微细加工光学技术国家重点实验室,成都  610209;成都信息工程学院，成都  610041; (4)中国科学院光电技术研究所微细加工光学技术国家重点实验室,成都  610209
Published: December 2020

The convergence property of multiframe blind deconvolution applied to improve the resolution of astronomical images is influenced by initial object estimate, constraint conditions and photon noise. A method of determining band limitation of the point-spread function from the optical imaging system parameters is proposed. The initial object estimate of blind deconvolution algorithm is formed by using Knox-Thompson method to reconstruct object phase from short-exposure images. A novel method，which is used to decrease photon noise, edge effects and ringing of restoration images is developed. An improved multiframe blind deconvolution algorithm with a strict constrained optimization method of the expectation-maximization based on maximum-likelihood estimation is presented. The restored images of the simulation data,and real Mars and solar-granulation data show that the proposed multiframe blind deconvolution algorithm is valid for overcoming effects of atmospheric turbulence and photon noise and improving the resolution of real observed astronomical images, and capabel of partly removing th diffraction effect of optical system on restored images.
The meshless method for solving the inverse heat conduction problem with a source parameter
Authors: Cheng Rong-Jun  , Cheng Yu-Min  ,   (1)上海大学上海市应用数学和力学研究所，上海 200072; (2)上海大学上海市应用数学和力学研究所，上海 200072;安徽师范大学数学系，芜湖 241000
Published: December 2020

In this paper, the finite point method is used to obtain the solution of a one-d imensional inverse heat conduction problem with a source parameter, and the corr esponding discrete equations are obtained. Compared with the numerical methods b ased on mesh, the finite point method only needs the scattered nodes instead of meshing the domain of the problem. The finite point method is a meshless method in which the moving least-square approximation is used to form the meshless appr oximation functions. And the collocation method is used to discretize the govern ing partial differential equations. The finite point method has the advantages o f simpler numerical procedures, lower computation cost and arbitrary nodes. The result of a numerical example is presented to show the method is effective.
Mei symmetry and Mei conserved quantity of nonholonomic systems of non-Chetaev’s type in event space
Authors: Jia Li-Qun  , Zheng Shi-Wang  , Zhang Yao-Yu  ,   (1)江南大学理学院,无锡 214122; (2)平顶山学院电气信息工程学院,平顶山 467002; (3)商丘师范学院物理与信息工程系,商丘 476000
Published: December 2020

This paper studies the Mei symmetry and Mei conserved quantity of non-Chetaev's type in the event space. The differential equations of motion of non-holonomic s ystems of non-Chetaev's type in event spaces are established. The definition and the criteria of Mei symmetry are given. The condition and the form of Mei conse rved quantity are deduced directly from the Mei symmetry. An example is given to illustrate the application of the results.
Jacobi elliptic function solutions to the coupled KdV-mKdV equation
Authors: Pan Jun-Ting  , Gong Lun-Xun  ,   贵州师范大学理学院,贵阳 550001
Published: December 2020

Based on the new expansion of the first kind of elliptic function, a method for constructing Jacobi elliptic function solutions to nonlinear wave equations is p roposed. The method is applied to the coupled KdV-mKdV equation and some new Jacobi elliptic function solutions to the equation are obtained. Some specific kind s of solutions and their relevant figures are also presented.
Universal quantum teleflipping and telecloning of qubit
Authors: Li Yan-Ling  , Feng Jian  , Meng Xiang-Guo  , Liang Bao-Long  ,   聊城大学物理科学与信息工程学院,聊城 252059；聊城大学光通信研究所,聊城 252059
Published: December 2020

A scheme combining three processes of quantum teleportation, optimal universal quantum flipping and optimal universal quantum cloning for universal teleflipping and telecloning of arbitrary qubit is proposed. When a particular four-particle entangled state shared by the sender and three spatially separated receivers is used as quantum information channel, after the sender's Bell measurement, class ical communication and each receiver's local unitary operation, one receiver can get one orthogonal complementing state of the original unknown state with the o ptimal fidelity of 2/3, the other two receivers can respectively get one copy of the original unknown state with the optimal fidelity of 5/6. This scheme implem ents the universal quantum teleflipping and telecloning simultaneously with corr esponding optimal fidelity by using the reduced entanglement. The key to realizi ng this scheme is the construction of the particular four-particle entangled sta te shared by the sender and three receivers used as quantum information channel. The entanglement structure of the special four-particle entangled state is anal yzed.
Upper bound of the rate of entropy change of a stochastic system with double singularities driven by colored noise
Authors: Guo Yong-Feng  , Xu Wei  , Li Dong-Xi  ,   西北工业大学理学院应用数学系，西安 710072
Published: December 2020

Based on the method of transformation, this paper studies the Fokker-Planck equation of a stochastic system with double singularities driven by aussian colored noise. According to the definition of Shannon's information entropy and the Schwartz inequality principle, the explicit time dependence of the upper bound of the rate of entropy change is obtained for the first time. The relationship between the properties of double singularities, noise correlation time and dissipative parameter and their effect on the upper bound of the rate of entropy change are discussed.
Study on the structural properties of SiO molecule under the external electric field
Authors: Xu Guo-Liang  , Liu Yu-Fang  , Sun Jin-Feng  , Zhang Xian-Zhou  , Zhu Zheng-He  ,   (1)河南师范大学物理与信息工程学院,新乡 453007; (2)四川大学原子与分子物理研究所,成都 610065
Published: December 2020

Based on the obtained equilibrium structure for the ground state of SiO molecular, the ground states of SiO molecule under electric fields ranging from -0.03 to 0.03a.u. are optimized using the density functional theory DFT/B3P86 at 6-311++g(d, p)level. The effects of electric fields on the bond length, system energy, charge distribution, energy levels, HOMO-LUMO gaps and the infrared spectrum for the ground states of SiO molecule have been studied. The results show that the molecular geometry is strongly dependent on the field strength and behaves asymmetrically to the directions of the applied electric field. At the same time, the energy gaps between the HOMO and LUMO become closer as the applied electric field along the molecular axis O-Si increases, which shows that the molecule is apt to be excited under specific electric field.
The electron emission yield induced by the interaction of highly charged argon ions with silicon surface
Authors: Zhao Yong-Tao  , Xiao Guo-Qing  , Xu Zhong-Feng  , Abdul Qayyum  , Wang Yu-Yu  , Zhang Xiao-An  , Li Fu-Li  , Zhan Wen-Long  ,   (1)核科学与技术研究所,伊斯兰堡 44000,巴基斯坦; (2)西安交通大学应用物理系,西安 710049; (3)中国科学院近代物理研究所,兰州 730000; (4)中国科学院近代物理研究所,兰州 730000；西安交通大学应用物理系,西安 710049; (5)中国科学院近代物理研究所,兰州 730000；咸阳师范学院物理系,咸阳 712000
Published: December 2020

The electron emission yield of the interaction of highly charged argon ions with silicon surface is reported. The experiment was done at the Atomic Physics Research Platform on the Electron Cyclotron Resonance (ECR) Ion Source of the National Laboratory HIRFL (Heavy Ion Research Facility in Lanzhou). In the experiment, the potential energy and kinetic energy was selected by varying the projectile charge states and extracting voltage, thus the contributions of the projectile potential energy deposition and electronic energy loss in the solid are extensively investigated. The results show that, the two main factors leading to surface electron emission,namely the potential energy deposition and the electronic energy loss, are both approximately proportional to the electron emission yield per ion.
The influence of the CCSD (T) potential energy surface of the Ne-HBr complex on rotationally inelastic partial cross sections
Authors: Yu Chun-Ri  , Huang Shi-Zhong  , Shi Shou-Hua  , Cheng Xin-Lu  , Yang Xiang-Dong  ,   (1)安徽大学物理与材料科学学院,合肥 230039; (2)安徽师范大学物理系,芜湖 241000; (3)安庆师范学院物理与电气工程学院,安庆 246011;安徽大学物理与材料科学学院,合肥 230039; (4)四川大学原子与分子物理研究所,成都 610065
Published: December 2020

An analytic expression of the potential energy surface (PES) of the ground state of the Ne-HBr complex has been obtained by utilizing nonlinear least square method to fit the intermolecular interaction energies, which have been calculated at the coupled cluster singles and doubles including the connected triple excitation level and with the augmented correlation consistent polarized quadruple zeta basis set (CCSD (T)/aug-cc-pVQZ). On the basis of the above result, the partial cross sections (PCS) at the energies of 40, 60, 80 and 100meV for collisions between Ne atoms and HBr molecules have been calculated by using the quantum close-coupling method. Then the influence of the long-range attractive and the short-range anisotropic interaction of the CCSD (T) potential energy surface on the inelastic PCS has been discussed in detail. The results show: (1) The transitions of j=0 →j′=1, 2 contribute to the total inelastic PCS predominantly. The long-range attractive well of the PES results in the tail maximum of the inelastic PCS at the position of the higher J, which mainly comes from the transition of j=0 →j′=1. While the short-range repulsion results in the main peak at the position of the lower J, which mainly comes from the transition of j=0 →j′=2. The balance between the short-range repulsive and long-range attractive interaction results in a pronounced minimum in the inelastic PCS. (2) There is the same collision parameter corresponding to the maximums and minimums of the inelastic PCS at different incident energies although the corresponding quantum number J of total angular momentum is different. The collision parameter samples the same part of the PES.
First principles study of the ground-state structures and magnetism of Zrn Fe(n=2—13)clusters
Authors: Zhao Wen-Jie  , Wang Qing-Lin  , Ren Feng-Zhu  , Luo You-Hua  ,   (1)河南大学物理与电子学院，开封 475004; (2)河南大学物理与电子学院，开封 475004；华东理工大学理学院，上海 200237
Published: December 2020

The geometries，total energies，and frequencies of ZrnFe(n=2—13)clusters have been systematically investigated by using density functional theory with the generalized gradient approximation, and the equilibrium geometries at different spin multiplicities as well as the ground-state structures have been determined. The calculated results of the averaged binding energy, the second-order difference of cluster energies as well as the HOMO-LUMO gap of the ZrnFe(n=2—13) clusters indicate that the relative stabilities of Zr5Fe, Zr7Fe and Zr12Fe are stronger than that of other sized clusters. The true ground state for Zr12Fe cluster has icosahedral structure with Ih symmetry, and moreover, the stability of Zr12Fe is strongest among all the investigated clusters. In addition, not only the relative stabilities of Zr5Fe, Zr7Fe and Zr12Fe clusters are stronger than other sized clusters, but also they are all magnetic clusters (however, the magnetic moment of Zrn clusters is quenched for n≥5), thus it can be seen thant we can acquire magnetic clusters with higher stabilities by choosing appropriate doping atom. Mulliken population analysis shows that there is a weak charge transfer from Zr atoms to Fe atom except for Zr12Fe cluster, in which a small amount of charge transfers from Fe atom to Zr atoms.
Repetition rate of intense current electron-beam diodes using 20 GW pulsed source
Authors: Zhang Yong-Hui  , Chang An-Bi  , Xiang Fei  , Song Fa-Lun  , Kang Qiang  , Luo Min  , Li Ming-Jia  , Gong Sheng-Gang  ,   (1)中国工程物理研究院应用电子学研究所，绵阳 621900; (2)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北京研究生部，北京 100088
Published: December 2020

Based on the static electric-field simulation, the structures of 20 GW diode and its insulator, as well as the position and shape of guide magnetic-field are designed and optimized. Then the experiments on the repetition rate of intense current electron-beam diode are carried out on 20 GW pulsed power source, it can deliver intense electron-beam pulses of 1MV/20 kA with pulse width 45 ns and repetition rate 100Hz.
Seidel aberration of left-handed media lens systems
Authors: Lin Zhi-Li  ,   浙江大学现代光学仪器国家重点实验室，光及电磁波研究中心，杭州 310058
Published: December 2020

A general study of the Seidel aberration of the lens systems made of left-handed media is presented according to the primary aberration theory. The Seidel aberration of the planar interface between air and left-handed medium was analyzed showing that its surface shape are more abundant when it is free from spherical aberration and it could be applied to real imaging systems. Based on the Seidel sum formulae of thin lens, three types of left-handed media thin lenses free from partial Seidel aberrations are designed with specific parameters. Finally, the Seidel aberration-free lens systems based on the use of left-handed media are presented. It is pointed out that left-handed media can be used to simplify the structure of lens system for the same or superior imaging performance.
Spectral structure of CuBr laser under lower pressures
Authors: Chen Li  , Mao Bang-Ning  , Wang Yu-Bo  , Wang Li-Min  , Pan Bai-Liang  ,   浙江大学物理系，杭州 310027
Published: December 2020

Under consideration of the basic factors such as the level hyperfine structure and isotope split etc., the spectral structures of spontaneous emission of copper atom 578/511nm lines are calculated. A sealed operation CuBr laser with periodical refreshment of the buffer gas are designed and constructed. The 578/511nm spectral structures, produced by CuBr laser at lower Ne buffer gas pressure were measured under different working temperatures and exciting voltages. The spectral structure of spontaneous emission of copper atom 578/511nm lines have multi-peaks similar to their laser spectral structure, but the 578nm laser line isstrongly dependent on the working temperature and the exciting voltage. Some possible reasons are suggested to qualitatively explain the experimental results.
Morphology and mechanism of femtosecond laser-induced structural changes in lithium niobate crystal
Authors: Yu Ben-Hai  , Dai Neng-Li  , Wang Ying  , Li Yu-Hua  , Ji Ling-Ling  , Zheng Qi-Guang  , Lu Pei-Xiang  ,   华中科技大学 武汉光电国家实验室激光科学与技术部,光电子科学与工程学院,武汉 430074
Published: December 2020

The morphology and mechanism of lithium niobate (LiNbO3) crystal ablated by a femtosecond laser pulse have been studied. The ablated spots and surface diffraction grating have been examined by means of scanning electron microscopy (SEM) and atom force microscopy (AFM). Sub-diffraction limit spots in LiNbO3 crystal ablated by femtosecond laser have been obtained. The diameters of ablation spots are 400nm and 800nm when 170nJ single pulse and 100nJ 17 pulses are used, respectively. There are ripples with about 200nm periodic on the bottom surfaces of the spots at low laser energy. The result shows that the sub-diffraction limit structures may be formed by the multi-photon excitation, and the femtosecond laser ablation is an innovative tool for manufacturing LiNbO3-based optical devices.
H-shaped structure of left-handed metamaterials with simultaneous negative permittivity and permeability
Authors: Liu Ya-Hong  , Luo Chun-Rong  , Zhao Xiao-Peng  ,   西北工业大学电流变技术研究所，西安 710072
Published: December 2020

We introduce a structure made of periodic arrays of H-shaped metallic pattern that offers a potentially simple approach in building left-handed metamaterials with simultaneous negative permittivity and permeability. We have investigated experimentally the transmittance in the rectangle waveguide and found unambiguously a passband that can be tuned easily at microwave frequencies by changing the parameter t. Using phase shift experiment, prism refraction experiment and S-parameter retrieval method, we have confirmed that the H-shaped metamaterials have negative refractive indices, negative permittivity and negative permeability at the passband frequencies. Compared with the conventional left-handed metamaterials consisting of arrays of wires and split ring resonators, H-shaped left-handed metamaterials show not only magnetic resonance but also electric resonance, so they will be a good candidate in the microwave applications due to their simple structure and easy preparation.
Theoretical and experimental investigation on all-optical logic gates based on photoisomerization
Authors: Li Yan-Ming  , Chen Li-Xiang  , She Wei-Long  ,   中山大学光电材料与技术国家重点实验室，广州 510275
Published: December 2020

Based on the photoisomerization and photoinduced birefringence in azo-containing polymers, a theoretical model for all-optical logic gates is developed and a novel scheme of all-optical logic gates using pump-probe technique is presented theoretically and realized experimentally. The all-optical logic AND, OR, XOR and XNOR gate operations have been demonstrated experimentally based on the modulation of intensity or polarization of the pump beam and signal. The experimental results show a good performance, which are in agreement with the theoretical prediction.
A novel ring structure-based distributed optical fiber vibration sensing system
Authors: Sun Qi-Zhen  , Liu De-Ming  , Wang Jian  ,   (1)华中科技大学光电子科学与工程学院，武汉 430074; (2)华中科技大学光电子科学与工程学院，武汉 430074；武汉光电国家实验室，武汉 430074
Published: December 2020

A novel distributed optical fiber vibration sensing system is proposed and demonstrated, using a ring structure-based Mach-Zehnder interferometer (MZI). The direct current light-based real-time and dynamic locating technique is exploited. By introducing the ring structure into the interferometer, the linear interferometer is changed into ring type, resulting in two counter-propagating light waves, thus one MZI equally operates as two. When a vibration acts on the sensing fiber, the counter-propagating signals produce identical phase-changes simultaneously, which propagate along different paths to optical receivers. With the help of digital processing technologies to analyze the received signals, the characteristic parameters of vibration, including the spatial position, frequency and amplitude can be achieved in real time. A spatial resolution better than 40m is successfully verified in a 1.01 km prototype system of single vibration. Furthermore, the feasibility of detecting and locating multiple vibrations is theoretically analyzed and simulated.