bluuebunny/crossref_metadata_2025 huggingface dataset:
SnO2:(Cu,In) films with high transmittance in ultraviolet region
Authors: Zhang Zhi-Guo  ,   Institute of Functional Materials, Quanzhou Normal University, Quanzhou 362000, China
Published: December 2020

By reactive evaporation method, the SnO2:(Cu,In) transparent conductive films are prepared on glass, Corning7059 glass and quartz glass substrates separately. The element contents are analyzed, the distributions of all elements in the films are given, and the transmittances of samples are also measured. The results show that the UV transmittance of individual sample is high, and the transmittance of the film depends on annealing process. The resistance-temperature characteristics are measured and explained. The relationship between optical band gap and absorption coefficient is discussed. The simple method in which the transmittance curve is used to determine the optical band gap is given. The relation between mobility of the extended state and mobility edge with Fermi level is discussed. The results show that the preparation of copper and indium co-doped tin oxide transparent conductive films has achieved the purpose of reducing the cost, and some particular samples have wide band gap.
Photo-absorption coefficient approximation of hydrogenated silicon films
Authors: Guo Li-Qiang  , Ding Jian-Ning  , Yang Ji-Chang  , Wang Shu-Bo  , Ye Feng  , Cheng Guang-Gui  , Ling Zhi-Yong  , Fan Hui-Juan  , Yuan Ning-Yi  , Wang Xiu-Qin  ,   Low-dimension Material Micro/Nano Device and System Center, Changzhou University, Changzhou 213164, China;,   Low-dimension Material Micro/Nano Device and System Center, Changzhou University, Changzhou 213164, China;Key Laboratory of New Energy Engineering, Changzhou 213164, China;,   Micro/Nano Science and Technology Center, Jiangsu University, Zhenjiang 212013, China;,   Micro/Nano Science and Technology Center, Jiangsu University, Zhenjiang 212013, China; Low-dimension Material Micro/Nano Device and System Center, Changzhou University, Changzhou 213164, China;Key Laboratory of New Energy Engineering, Changzhou 213164, Ch
Published: December 2020

Hydrogenated silicon films are prepared on Corning 7059 glass by the plasma enhanced chemical vapour deposition technique with radio frequency ( RF),power,(13.56 MHz) and DC bias. The microstructures of hydrogenated silicon films investigated by Raman spectra. The photo-absorption coefficient is calculated by utilizing an established photo-absorption model. The I-V characteristics of hydrogenated silicon film solar cells are simulated by using software AMPS. The results show that photo-absorption coefficient curves and I-V curves are both consistent well with experimental data. At the same time, the difference between experimental results are calculated results were analyzed.
Infrared quantum-cutting analysis of Er0.3Gd0.7VO4 crystal for solar cell application
Authors: Chen Xiao-Bo  , Yang Guo-Jian  , Zhang Chun-Lin  , Li Yong-Liang  , Liao Hong-Bo  , Zhang Yun-Zhi  , Chen Luan  , Wang Ya-Fei  ,   (1)Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China; (2)Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

Recently the infrared quantum cutting has achieved an exciting development in enhancing the efficiency of solar cell. The infrared quantum cutting of Er0.3Gd0.7VO4 crystalline is studied in the present paper. It is found that the approximate quantum cutting efficiencies of 1532.5 nm 4I13/2→4I15/2 fluorescence, when the 2H11/2 and 4G11/2 levels are excited, are about 178.55% and 177.61% respectively. Especially, effective three-photon and four-photon infrared quantum cuttings of Er0.3Gd0.7VO4 crystalline excited by visible and near-violet light are found for the first time in the present paper. An interesting "peak - valley" conversion phenomenon in the excitation spectrum is also observed. It is also the first time for us to find the first-order infrared quantum cutting based single species Er3+ ion for Er0.3Gd0.7VO4 crystalline.
Influence of magnetic field on efficiency and current in Co-based organic light emitting diode
Authors: Wang Jin  , Jiang Wen-Long  , Hua Jie  , Wang Guang-De  , Han Qiang  , Chang Xi  , Zhang Gang  ,   College of Information Technology, Jilin Normal University, Siping 136000, China
Published: December 2020

Efficiency and current measurements of ferromagnetic Co thin layer based organic light emitting diode, which has a structure of ITO/Co/NPB/Alq3/LiF/Al, are performed as a function of magnetic field at room temperature.The efficiency first increases by up to 18.8% as magnetic field increased to about 80 mT, and then appears to be almost saturated. The changes result from the spin-polaried injection of Co and the magnetic field effects(MFEs), both of which increase the fraction of siglets among the total excitons, and the former is primary. The changing rate of current through the device is found to increase by up to 6.9% at about 60 mT, and then decrease slowly with magnetic field increasing. These observations are explained in terms of the MFEs of polaron pairs dissociation and magnetic-field dependence of triplet-charge reaction in excited states.
Simulation of crystal growth using phase-field crystal method
Authors: Xing Hui  , Chen Chang-Le  , Jin Ke-Xin  , Tan Xing-Yi  , Fan Fei  ,   The Laboratory of Condensed Matter Structure and Properties, School of Science, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The phase-field crystal (PFC) model is used to simulate crystal growth from undercooled liquid by the finite difference method. The effects of phase region and undercooling on crystal growth process are analyzed. The simulation results show that crystal growth is inhibited in the region of liquid-crystal coexistence where liquid-crystal boundary becomes thicker gradually. In the single crystal phase region, crystallization is enhanced with undercooling increasing,while liquid-crystal boundary becomes thinner. It is found that there is a linear relationship between crystal growth velocity and undercooling.
preparation and properties of Sn-Al thin-film electrode material for lithium ion batteries
Authors: Hou Xian-Hua  , Yu Hong-Wen  , Hu She-Jun  ,   School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 China
Published: December 2020

Nano-level Sn-Al alloy thin-film electrode materials prepared by magnetic sputtering technology are characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The charge/discharge and the cyclic voltammograms of the film electrodes are tested by the high precision battery testing system. The results indicate that the materials prepared by direct current and radiofrequency methods have a large difference in performance. The films prepared by DC method have small particles and excellent cycling stability. Its initial discharge capacity and efficiency are 1060 mAh/g and 71.7%, respectively, and the specific capacitance is over 700 mAh/g after 30 cycles. But the films prepared by RF method have the bigger particles and inferior cycle performance, and its specific capacitance initially increases but after 5 times cycle it declines.
Reduction of aliasing artifact in Micro CT
Authors: Luo Zhao-Yang  , Yang Xiao-Quan  , Meng Yuan-Zheng  , Deng Yong  ,   Brinton Chance Center of Biomedical Photonics, National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Micro CT system is a recently developed imaging technique for small animal, which have very high spatial resolution and sensitivity, and is widely used in drug development, cancer detection et al. But in Micro CT, the artifact, specially the aliasing artifact, become serious as the extremely high spatial resolution, which is the major degeneration of image quality. In this paper, we studied the cause of artifact, and simulated it in computer. Finally, we proposed an algorithm to reduce the artifact in CT slice, with artifact elimination rate of 70% or more, and the improved image contrase
Effect of opening angle on dilute-dense flow transition in two-dimensional granular flow
Authors: Huang De-Cai  , Hu Feng-Lan  , Deng Kai-Ming  , Wu Hai-Ping  ,   Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Computer simulations are performed to investigate the effect of opening angle on dilute-dense flow transition in a two-dimensional granular flow. Two methods, i.e. the fixed inflow rate and the fixed particle number, are adopted. Both results show that larger opening angle results in an increase of maximum outflow rate in dilute-dense flow transition when the opening angle is larger than zero. When granular flow keeps a dilute flow, the outflow rate is irrelative with the opening angle. When the flow becomes a dense flow, the dense flow rate inereases with opening angle increasing. Further studies show that the granules flow out with a higher velocity when the opening angle increases. The linear relationship between maximum outflow rate and granule flow velocity is observed.
Solitary wave series solution for generalized (3+1)-dimensional nonlinear Burgers system
Authors: Mo Jia-Qi  , Wen Zhao-Hui  ,   (1)Depratment of Mathemtics, Anhui Normal University, Wuhu 241003, China; (2)Institute of Applied Mathematics, Anhui University of Finance and Economics, Bengbu 233030, China
Published: December 2020

A class of generalized (3+1)-dimensional nonlinear Burgers system is studied. Using the homotopic mapping method, the corresponding mapping expansions are constructed and using the iteration method the series solution of travelling wave for a solitary wave is obtained.
Greenhill formula for an exact model of elastic rod
Authors: Xue Yun  , Weng De-Wei  ,   School of Mechanical Engineering, Shanghai Institute of Technology, Shanghai 200235, China
Published: December 2020

Greenhill formula for Kirchhoff elastic rod is extended to that of exact model of the rod. Under the assumption of the plane cross section, the configuration of an extensible and shearable elastic rod is expressed as a history of the cross section with arc coordinate. A special solution which describes equilibrium in straight line state of the rod is obtained from a differential equilibrium equation. A linear perturbation equation is derived and its general solution is obtained in which the integral constants are determined by constrained conditions at two ends of the rod. The condition for a non zero solution of the integral constants to exist leads to the Greenhill formula of exact elastic rod model, which shows that the boundary of stable area of the force screw is a closed curve and of symmetry and the inference of extensible and shearable to stability of the rod is dependent on three factors: the difference in flexibility between shear and extension of a section of the rod, the bending stiffness, and the length of the rod.
Circuit design and implementation of Lorenz chaotic system with one parameter
Authors: Sun Ke-Hui  , Yang Jing-Li  , Ding Jia-Feng  , Sheng Li-Yuan  ,   School of Physics Science and Technology, Central South University, Changsha 410083, China
Published: December 2020

To study the characteristics of the chaotic systems and their applications, an electronic circuit of simplified Lorenz chaotic system with one parameter is designed and experimented with discrete components. The system parameters correspond to the circuit element parameters. By regulating the variable resistor in the circuit, dynamic behaviors including limit cycle, pitchfork bifurcation, period-doubling bifurcation, chaos, and route to chaos by period-doubling bifurcation, are observed. The necessary condition for the existence of chaos in the fractional-order simplified Lorenz system is deduced. The lowest order of the fractional-order simplified Lorenz system and the variation law of the lowest order with system parameters are determined. Circuit simulations and experiments show that the simplified Lorenz system has rich dynamic characteristics, and that theoretical analysis and circuit experiment are accordant with each other.
Influential factors and analysis of detecting buried trash in scattering media
Authors: Zhou Fei  , Ding Tian-Huai  ,   Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China
Published: December 2020

Detection of buried trash in scattering media is a very important research project. Detection efficiency is influenced by several imaging parameters, such as incident light intensity, trash buried depth, medium refractivity, medium scattering coefficient and medium anisotropic factor. Firstly, current Monte Carlo algorithm is revised. Secondly, influential laws of those parameters are researched by simulating a great number of photons propagating in a scattering medium. The results indicate that light intensity, trash buried depth and medium refractivity greatly affect both reflection and transmission imaging results; and their influential laws are similar. Detection efficiency of reflection imaging can be improved by increasing light intensity, reducing trash buried depth or medium refractivity. Detection efficiency of transmission imaging can be improved by increasing light intensity, reducing medium refractivity and scattering coefficient, or increasing anisotropic factor. These conclusions have universal significance of guidance in the detection of buried trash in scattering media.
Frequency measurement of 0.14 THz high-power terahertz pulse
Authors: Wang Guang-Qiang  , Wang Jian-Guo  , Li Xiao-Ze  , Fan Ru-Yu  , Wang Xing-Zhou  , Wang Xue-Feng  , Tong Chang-Jiang  ,   (1)Department of Engineering Physics, Tsinghua University, Beijing 100084, China; (2)Department of Engineering Physics, Tsinghua University, Beijing 100084, China;Northwest Institute of Nuclear Technology, Xi’an 710024, China; (3)Northwest Institute of Nuclear Technology, Xi’an 710024, China; (4)Northwest Institute of Nuclear Technology, Xi’an 710024, China;School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

The subharmonic heterodyne combined with cut-off waveguide method is proposed to measure the frequency of 0.14 THz high-power nanosecond pulse in this paper. Using the cut-off waveguide method, the frequency range of the terahertz pulse is determined, in which two non-standard rectangular waveguides with cut-off frequencies of 0.125 and 0.15 THz are separately used as a receiver. According to the preliminary result, the subharmonic order is chosen to be 8, while the frequency of local oscillator is set to be in a range of 15—20 GHz. A series of tests on the 8th harmonic mixer is done using the pulses in Ka-band and the 0.14 THz continuous wave source, separately. Experimental results indicate that the mixer can be used in the heterodyne measurement of 0.14 THz nanosecond pulse. Finally, the heterodyne measurement is carried out on the high-power terahertz puls source, and an accurate frequency of 0.1465 THz is determined in this experiment. This novel method, which greatly reduces the frequency requirement of the local oscillator, is proved to have a good performance in the frequency measurement of 0.14 THz nanosecond pulse, and probably provides a new idea for frequency measurement of pulses in the long-wavelength terahertz-band.
Measurement of orbital angular momentum of Laguerre-Gaussian beam by using phase vortices of interference fields
Authors: Chen Xiao-Yi  , Li Hai-Xia  , Song Hong-Sheng  , Teng Shu-Yun  , Cheng Chuan-Fu  , Liu Man  ,   (1)College of Physics and Electronics, Shandong Normal University, Jinan 250014, China; (2)School of Mathematical and Physical Sciences, Shandong Institue of Light Industry, Jinan 250353, China;College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

The phase and the zero-contour of the real part and the imaginary part of the interference field on a far-field plane generated by multi-aperture diffraction screen are simulated. It is found that when the orbital angular momentum quantum number of incident beam is equal to zero, at the center of interference field the zero-lines cannot cross each other, therefore, thereby the phase vortices cannot form. When the orbital angular momentum quantum numbers of incident beam are opposite to each other in sign, namely -1 and +1 at the center of interference field the zero-lines are perpendicular to and cross each other, the signs of the phase vortices at the corresponding positions in interference fields are also opposite to each other. When the orbital angular momentum quantum numbers of incident beam are equal to ±2 and ±3, there are four zero-lines that cross each other at the center of interference fields, where the topological charge values of phase vortices are just equal to the orbital angular momentum quantum numbers of the Laguerre-Gaussian beam. Therefore, these results can be used to measure the orbital angular momentum of optical vortex beam.
Analysis on thermal effect of laser-diode array end-pumped composite rod laser by finite element method
Authors: Liu Quan-Xi  , Zhong Ming  ,   Southwest Institute of Technical Physics, Chengdu 610041, China
Published: December 2020

A numerical model of the rod laser medium pumped by laser-diode array (LDA) end is set up. Considering the influence of temperature correlation of the thermodynamic parameters of the material and heat transfer coefficient between air and medium, using the thermal conduction equations and the thermal-elastic equations, the transient distributions of temperature and thermal stress and strain in the composite rod medium and un-composite rod medium are calculated by the finite element analysis method. The effects of pump power and heat transfer coefficient and time on transient distributions of temperature and thermal stress and strain in the medium are analyzed. The results indicate that the positions of maximal temperature maximal tensile stress and maximal axial strain of the composite rod are different from those of the un-composite rod. And the maximal temperature, maximal tensile stress and maximal axial strain of the composite rod are respectively 73 per cent, 60 per cemt, and 33 per cent of the corresponding values of the un-composite rod. It is obvious that the thermal effect of the composite rod is greatly reduced. The theoretical results provide theoretical reference for the design of solid laser pumped by LDA and experimental study.
Investigation on stimulated Brillouin scattering medium——perfluoropolyether at high and low temperatures
Authors: Hasi Wu-Li-Ji  , Li Xing  , Guo Xiang-Yu  , Lu Huan-Huan  , Lü Zhi-Wei  , Lin Dian-Yang  , He Wei-Ming  , Fan Rui-Qing  ,   National Key Laboratory of Tunable Laser Technology, Institute of Opto-Electronics, Harbin Institute of Technology, Harbin 150080, China
Published: December 2020

In this paper, the stimulated Brillouin scattering (SBS) media perfluoropolyether (PFPE) with unique physicochemical properties and SBS properties are researched. The PFPE has a small absorption coefficient and can be used to increase the load-ability of SBS system. The PFPE with a high boiling point and a low pouring point can operate at high and low temperatures, respectively. The SBS properties of PFPE have been analyzed in detail and validated in Q-switched Nd:YAG laser system. The experimental results indicate that the media not only have good SBS characteristics but also can be used in a wide temperature range, thereby has great advantage for experimental investigation on SBS phase-conjugated mirror at different temperatures.
Tunability in metamaterials with mechanical rotation
Authors: Fan Jing  , Cai Guang-Yu  ,   (1)Department of Electronics and Electrical Engineering, Nanyang Institute of Technology, Nanyang 473004, China; (2)Department of Mechanical and Electrical Engineering, Nanyang Institute of Technology, Nanyang 473004, China
Published: December 2020

We study the tunable resonance characteristics of double split ring resonator (DSRR) at microwave band numerically. For the incident electromagnetic wave parallel to the incident plane, the DSRR structure shows magnetic and electric resonances at different frequencies respectively. When the E polarization along the two splits of the DSRR, the magnetic and the electric resonances have the strongest resonant intensities. As the DSRR metamaterial rotates along the H field, the frequencies of magnetic and electric resonances are kept unchanged, however, the resonant intensities decrease rapidly. The tunable metamaterial proposed in this paper only need rotate the metamaterial without structure changes or additional applied field, and has potential applications in electromagnetic switch and phase modulation. This simple tunable method could be used for higher frequency metamaterial, and expend the applications at terahertz and optical frequencies.
Preliminary investigation on the design and experiment of a spatial filter for dual band high power microwave
Authors: Li Guo-Lin  , Shu Ting  , Yuan Cheng-Wei  , Zhang Jun  , Jin Zhen-Xing  , Yang Jian-Hua  , Zhong Hui-Huang  , Yang Jie  , Wu Da-Peng  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A spatial filter/diplexer for gigawatt level high power microwave is theoretically and experimentally investigated in this paper. The spatial filter consists of several cylindrical rods which are located in the near field of the applied radiating antenna. The S/X dual band microwaves are reflected and transmitted by the spatial filter in the same propagation directions. In the low power experiments, the transmitted and the reflected patterns are very close to that of the applied antenna. The measured reflection and transmission efficiencies, calculated from the power densities in the far-field region, are about 96% and 97% respectively. In addition, the spatial filter has the isolation level higher than 25 dB and the cross polar level much lower than -25 dB. Under the illumination by S/X band high power microwave with a pulse magnitude of about 1.5 GW and duration of about 100 ns, no microwave breakdown is observed.
Analysis of model coupling in photonic crystal fiber with triangular structure triple-core
Authors: Li Peng  , Zhao Jian-Lin  , Zhang Xiao-Juan  , Hou Jian-Ping  ,   Key Laboratory of Optical Information Technology of Shaanxi Province, Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, School of Science, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The coupled-mode equations in photonics crystal fiber with triangular structure triple-core (TTC-PCF) are achieved based on the coupled-mode theory, thereby the directional coupling between the cores in this structure is numerically studied in detail. The influences of the fiber structure and the incident wavelength on the coupling coefficient, and the effect of the amplitude ratio of the inject beams at the input end on the transfer of energy between the cores are analyzed. From the results, it can follow that continuous modulation of the coupling intensity between the cores can be achieved by changing the amplitude ratio of the inject beams. The coupled-mode theory and the beam propagation method present the results well consistent with each other. The unique coupling transmission performance of the TTC-PCF shows its possible applications in the design and the preparation of coupling strength continuously tunable fiber directional coupler and large mode field fiber lasers.
Experimental generation of 58 MeV quasi-monoenergetic electron beam by ultra-intense femto-second laser wakefield
Authors: Zhang Bao-Han  , Wang Xiao-Fang  , Dong Ke-Gong  , Gu Yu-Qiu  , Zhu Bin  , Wu Yu-Chi  , Cao Lei-Feng  , He Ying-Ling  , Liu Hong-Jie  , Hong Wei  , Zhou Wei-Min  , Zhao Zong-Qing  , Jiao Chun-Ye  , Wen Xian-Lun  ,   Key Laboratory of Basic Plasma Physics of Chinese Academy of Sciences, Department of Modern Physics,University of Science and Technology of China, Hefei 230026, China;,   Key Laboratory of Basic Plasma Physics of Chinese Academy of Sciences, Department of Modern Physics,University of Science and Technology of China, Hefei 230026, China;Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900,;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Monoenergetic electron bunches can be generated by the interaction between the ultra-intense laser and underdense plasma on the mm scale. In the experiment conducted on the SILEX-Ⅰ, by the interaction between an ultra-intense femtosecond laser pulse and 2.7 mm supersonic He gas jet, a 58 MeV quasi-monoenergetic electron beam with 15.5% energy spread and 15 mrad beam divergence is produced. The total charge of the electron beam is about 15.4 nC when the laser power is 70 TW. In this paper the experimental conditions, the method and main results are presented.
Effects of Si content on phase composition and thermoelectric properties of higher manganese silicide
Authors: Luo Wen-Hui  , Li Han  , Lin Ze-Bing  , Tang Xin-Feng  ,   State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
Published: December 2020

MnSi1.70+x(x=0, 0.05, 0.1, 0.15) compounds have been prepared by induction melting-annealing procedure combined with spark plasma sintering method. The phase composition and the thermoelectric properties of higher manganese silicide (HMS) with different Si contents are investigated. The results indicate that the samples with x＜0.1 include HMS phase and MnSi phase, and the relative content of MnSi phase decreases with x value increasing. The sample with x=0.1 is single phase HMS. The phase compositions of the sample with x＞0.1 are HMS and Si. As x value inereases the electrical conductivity of the sample gradually decreases, while the Seebeck coefficient increases because metallic MnSi phase decreases. The carrier concentration and the effective mass of the sample at room temperature decrease and the carrier mobility increases with x value increasing. In the sample with x=0.1, the impurity phase content is the least, which results in the lowest thermal conductivity and a minimum value of 2.25 W ·m-1K-1 at 800 K. The maximum ZT value of 0.45 is obtained at 850 K for MnSi1.80.
First-principles investigation on the phase transitions of BiFeO3
Authors: Ding Hang-Chen  , Shi Si-Qi  , Jiang Ping  , Tang Wei-Hua  ,   Center for Optoelectronic Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018, China
Published: December 2020

Using the first-principles method based on density functional theory, we investigate the structural properties of seven different phases of BiFeO3 including R3c, R3m, P4mm, Cm, Pm3 m, R3 m and R3 c and structural transition. The results show that the ground state has the R3c phase, and that phase transitions can occur among these phases, which may be characterized by two types of structural transitions. One is the relative displacement between octahedral FeO6 and Bi3+, and the other is the rotation of octahedral FeO6 along the [111] axis. Furthermore, the BiFeO3 film is found to be able to change from R3c phase to P4mm phase, owing to the substrate effect.
Positron annihilation study of photoluminescence of porous silicon treated by water vapor annealing
Authors: Li Zhuo-Xin  , Wang Dan-Ni  , Wang Bao-Yi  , Xue De-Sheng  , Wei Long  , Qin Xiu-Bo  ,   Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China;,   Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000, China;Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China;,   Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Porous silicon (PS) treated by water vapor annealing and vacuum annealing has been studied by positron annihilation lifetime spectroscopy and age-momentum correlation measurement. It is found that after water vapor annealing, non-radiative defects are reduced and defects dominating light source appear. These two types of defects change the lifetime and the S parameter of the positron annihilation and cause a drastic enhancement in the photoluminescence (PL) efficiency. Defects that cause the PL of PS show no obvious change after annealing at 300 ℃ in vacuum, therefore the PL of the sample is not influenced.
Study of physical constraint equation of sand-dust atmosphere
Authors: Zhao Jian-Hua  , Zhang Qiang  ,   College of Atmospheric Science, Lanzhou University, Lanzhou 730000, China;Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province, Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China
Published: December 2020

The closed physical constraint equations of sand-dust atmosphere are established based on both the interaction of wind-blown-sand two-phase flows and the mass change. Ideal analysis of the equations shows the following findings: (1) the density of the sand-dust atmosphere is bigger than that of the pure atmosphere, which will reduce the velocities of air parcels of the former to some extent; (2) velocity difference between sand-dust particles and air can make the fine particles located in a high-speed region and the coarse particles located in a low-speed region; (3) temperature difference between sand-dust particles and air can make the particles tend to enhance convection through acting as a heat source in updraft and a cold source in downdraft; (4) the constant-volume mass-specific heat capacity of the sand-dust atmosphere can give rise to the generation of new temperature gradient on an isobaric surface and then enhance the entrainment at the boundary of a sand-dust cloud; (5) the gas constant of the sand-dust atmosphere can lead to the generation of new pressure gradient on an isothermal surface and also enhance the entrainment at the boundary of a sand-dust cloud; (6) mass change can largely affect density, velocity and temperature of the sand-dust atmosphere. In brief, compared with the sand-dust cloud given by equations based on passive scalar, the real sand-dust cloud is high and great. Besides this, its inner convection and its entrainment at the boundary are active, and its horizontal motion is slow.
Approximate finite-time stable control of Lorenz Chaos system
Authors: Zhao Jian-Li  , Wang Jing  , Wei Wei  ,   National Engineer Research Center of Advanced Rolling, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

In the paper, the finite-time stability control problem for the Lorenz chaos system is studied. Considering the existence of uncertainty and nonlinearity in the Lorenz chaos system, a control method is proposed, which makes the controlled Lorenz system achieve approximate finite-time stability. And one kind of extended state observer is improved and designed to solve the unknown problem of uncertainty and nonlinearity for the controlled Lorenz system. The approximate finite-time stability of the closed-loop system is analysed by introducing the singular perturbation theary. Simulation results show the effectiveness of the control method and observer.
Relativistic effect of ultracold Fermi gas in a strong magnetic field
Authors: Men Fu-Dian  , He Xiao-Gang  , Zhou Yong  , Song Xin-Xiang  ,   College of Physics Science and Technology, China University of Petroleum(East China), Dongying 257061, China
Published: December 2020

Based on the single particle energy spectrum of weak relativity and Poissons formula,the thermodynamic potential function of Fermi gas in a strong magnetic field is derived. Furthermore, by using the thermodynamic relationships, the analytical expressions of statistic characteristic quantities of the system at low temperatures are obtained, and the influence mechanism of relativistic effect on the statistic properties of the system is analysed. It is shown that the relativistic effect becomes more significant with the magnetic field increasing. Compared with the corresponding oscillating amplitude, the monotonic term, which is caused by the relativistic effect, is much larger than the amplitude for the total energy, however, for the chemical potential and magnetic moment, they are almost of the same order.
Bright metastable noble gas atomic beam and atom trap using laser cooling
Authors: Cheng Cun-Feng  , Yang Guo-Min  , Jiang Wei  , Pan Hu  , Sun Yu  , Liu An-Wen  , Cheng Guo-Sheng  , Hu Shui-Ming  ,   Hefei National Laboratory for Physical Sciences at the Micro-scale,Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Metastable noble gas atomic beam is widely used in atomic and molecular physics studies.Using radio-frequency discharge and transverse laser cooling, we produced a well-collimated intense meta-stable Krypton beam.Numerical simulation is also used to analyze the trajectories of atoms in an optic field produced by transverse cooling laser beams.The charactersisticl of the atomic beam are determined by measuring the laser induced fluorescence.The atomic beam flux measured at 230 cm downstream is 1.61016 atoms/(s*sr), which is enhanced by two orders of magnitude.The Kr atoms are finally trapped in a magneto-optic trap.A total of 1.31010 meta-stable 84Kr atoms can be simultaneously trapped with a loading rate of 3.01011 atoms/s.The same setup is also successfully used to obtain a bright metastable atomic argon beam and trap.
Changes in the degree of paraxiality for Laguerre-Gaussian beams
Authors: Cui Xue-Cai  , Lian Xiao-Xu  , Lü Bai-Da  ,   Institute of Laser Physics & Chemistry, Sichuan university, Chengdu 610064, China
Published: December 2020

Taking the Laguerre-Gaussian (L-G) beam for example, the changes in the degree of paraxiality for monochromatic beams are studied in detail. It is shown that the beam parameters, including mode indiex, relative waist width, propagation through a paraxial ABCD optical system, and diffraction by an aperture may change the degree of paraxiality. But the degree of paraxiality remains unchanged in free-space propagation. The results are illustrated by numerical examples and interpreted in physics by relating the degree of beam paraxiality with the far-field divergence angle.
The Hansch-Couillaud frequency locking mechanism of dual-wavelength external cavity resonance system based on diffusion bonded KTP crystal
Authors: Yan Xiao-Juan  , Li Zhi-Xin  , Zhang Yong-Zhi  , Wang Le  , Hu Zhi-Yu  , Ma Wei-Guang  , Zhang Lei  , Yin Wang-Bao  , Jia Suo-Tang  ,   Laser Spectroscopy Laboratory of Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Taiyuan 030006, China
Published: December 2020

Dual-wavelength external cavity resonance is achieved by Hansch-Couillaud(HC) frequency locking technology based on diffusion bonded KTP crystal. The HC frequency locking scheme based on diffusion bonded KTP crystal is analyzed theoretically and experimentally. The results show that the laser frequency can be locked to the resonance peak of e1-light or e2-light, compared with the results of a single KTP crystal. The longitude mode frequency of bow-tie cavity is locked at the frequency of 938nm laser firstly, and then the longitude mode frequency of bow-tie cavity is locked at the frequency of 1583 nm laser. The phase correlated locking of three components is realized.
Two-dimensional photonic crystal band gap characteristics
Authors: Yuan Gui-Fang  , Han Li-Hong  , Yu Zhong-Yuan  , Liu Yu-Min  , Lu Peng-Fei  ,   Beijing University of Posts and Telecommunications, Key Laboratory of Information Photonics and Optical Communtications, Beijing 100876, China
Published: December 2020

The plane wave expansion method is used to calculate the band gap of two-dimensional photonic crystal in the E and H polarization, with Taking into account the effects of filling ratio, lattice structure, and relative dielectric constant ratio on the maximum absolute band gap. The results show that either square or triangular array arrangement, it is easier for the dielectric cylinder type photonic crystal to form TM-polarized mode band gap; while, in the air-hole photonic crystal it is much easier to form TE-polarized-mode band gap. For a given filling ratio, with the increase of relative dielectric constant, the maximum gap width does not always increase, but it is peaked. Similarly, for a given relative dielectric constant, with the increase of filling ratio, it is also peaked for the maximum gap width. Moreover, no matter the erystal is air hole type or dielectric cylinder type in structure, the triangular lattice structure is much easier to form bands gap.
Soliton pulse propagation and optical delay properties in photonic crystal waveguide
Authors: Liu Ling-Yu  , Tian Hui-Ping  , Ji Yue-Feng  ,   Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The bright soliton pulse propagation and the slow light delay time properties of 2D cubic and triangular lattice photonic crystal line defect waveguide (PCW) with circular Si-rods near the left edge of the guidedmode are investigated. By using the plane-wave expansion (PWE) method, the ralues of soliton required peak power P0 and delay time TS of the waveguided with different radii of the first two rows of Si-rods adjacent to the waveguide, r1 and r2, and waveguide width D are numerically investigated. Adjusting the waveguide structure can bring in optimized cubic and triangular lattice waveguide, of which P0 is reduced by 81.17% and TS is increased by 66.32% for cubic lattice waveguide; P0 is reduced by 73.7% and TS is increased by 67.63% for triangular lattice waveguide. These results show that the soliton transmission performance in the photonic crystal line defect waveguide can be effectivly optimized.
High speed real-time optical sampling system based on optical parametric amplification
Authors: Wang Wen-Rui  , Yu Jin-Long  , Luo Jun  , Han Bing-Chen  , Wu Bo  , Guo Jing-Zhong  , Wang Ju  , Yang En-Ze  ,   School of Electronic & Information Engineering, Tianjin University, Tianjin 300072, China;,   School of Physics and Electronic Science, Shanxi Datong University, Datong 037009, China
Published: December 2020

We propose a novel technique to achieve a high speed real-time optical sampling system based on optical parametric amplification in high nonlinear fiber (HNLF). Linearly chirped pulses are obtained by the dispersive propagation of short pulses emitted by a mode-locked fiber laser. The pulses are then fed into an HNLF together with signal under sampling. Thanks to the optical parametric amplification effect in the HNLF, the amplitude information will be modulated onto the linearly chirped pulses. By employing optical band-pass filters or wavelength division multiplexing (WDM) technology before the receivers, simultaneous high speed optical sampling and optical serial-to-parallel conversion are achieved. We demonstrate the feasibility of the scheme by optical sampling a 10 Gb/s on-off keying (OOK) signal at a sampling rate of 40GS/s and simultaneously converting it into four 10 GS/s sampling outputs. And the 10 Gb/s OOK signal is reconstructed later by the four sampling outputs. The scheme is simple and of low cost, which makes it a good candidate in high speed real-time sampling system.
An improved design method for C-band photonic crystal fibers with flat near-zero dispersion
Authors: Yang Wang-Xi  , Zhou Gui-Yao  , Xia Chang-Ming  , Wang Wei  , Hu Hui-Jun  , Hou Lan-Tian  ,   Institute of Infrared Optical Fibers and Sensors,Yanshan University,Qinhuangdao 066004,China;,   State Key Laboratory of Metastable Material Science & Technology,Yanshan University,Qinhuangdao 066004,China;,   School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China
Published: December 2020

The innermost air holes of photonic crystal fibers deform easily during the draw process, resulting in serious influcence on the practical fiber dispersion. Based on the multipole method, the simulation in the paper only changes the air holes in the secondlayer and the third layer to adjust the dispersion, while the innermost air holes each are set to have a smaller parameter. The simulation shows that this simple dispersion control method can also make zero-dispersion point quickly move and keep the dispersion flat. Based on the detailed analysis, we propose C-band near-zero flat dispersion photonic crystal fiber with the dispersion coefficient varying from -0.24ps/(km nm) to 0.33 ps/(km nm). Simulation shows that the air holes increasing from the fifth layer have little influence on the dispersion of previously proposed fiber, So by increasing the layers of air holes we can obtain an ideal confinement loss. This method is also applicable for the design of PCF operating in S and L bands with similar properties.
Nonlinear Rossby envelope waves under the influence of forcing dissipation and effect topographic effect
Authors: Song Jian  , Yang Lian-Gui  , Liu Quan-Sheng  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051,China;School of Mathematical Science, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

In barotropic fluids, based on the quasi-geostrophic potential vorticity equation, an inhomogeneous nonlinear Schrdinger equation including topographic forcing and an external source is derived by employing the perturbation method and stretching transforms of time and space. With the inspection of the evolution of the amplitude of Rossby envelope solitary waves, it is found that effect, topography effect and an external source are the important factors, the solitary Rossby wave is induced though the basic stream function has a shear flow. On the assumption that nonlinear and topographic effects are balanced, an inhomogeneous equation is derived, and the results show that the topography and Rossby waves interact in the barotropic flow. The inhomogeneous nonlinear Schrdinger equation describing the evolution of the amplitude of solitary Rossby envelope solitary waves as the change of Rossby parameter (y) with latitude y, topographic forcing and the external source is obtained.
One-dimensional imaging diagnostics of imploding dynamics for planar wire array Z pinch
Authors: Sheng Liang  , Wang Liang-Ping  , Li Yang  , Peng Bo-Dong  , Zhang Mei  , Wu Jian  , Wang Pei-Wei  , Wei Fu-Li  , Yuan Yuan  ,   Northwest Institute of Nuclear Technology Xin 710024, China
Published: December 2020

The primary experiment results of imploding dynamics for single and double planar wire arrays, acquired by optical streak camera, are presented and analyzed. The results show that the interaction of adjacent single wire plasma for single planar wire array is not dus entirely to inelastic collisions, while a part of plasma can move into the center and form precursor plasma across the plane of wire array; the current of outer wire is larger than that of the interior of wire, the time of ablation stage is ~65% of the total imploding time, and only a part of mass participates in the imploding stage.
Measurement of low-pressure Hugoniot data for bismuth with reverse-impact geometry
Authors: Tan Ye  , Yu Yu-Ying  , Dai Cheng-Da  , Tan Hua  , Wang Qing-Song  , Wang Xiang  ,   Laboratory for Shockwave and Detonation Physics, Institute of Fluid Physics,China Academy of Engineering Physics, Mianyang 621900,China
Published: December 2020

Hugoniot data for Bi are determined through measuring the impact velocity and the particle velocity at the sample/window interface on a powder gun or a two-stage light gas gun in a shock pressure range from 10 to 45 GPa, using reverse-impact geometry. The used experimental technique avoids the difficulty in accurately measuring the shock wave velocity resulting from the poor start synchronigm of electric pins under low shock pressure. The obtained Hugoniot data (shock wave velocity D versus particle velocity u) indicates that the D-u curve does have a discontinuity at a particle velocity of ~0.9 km/s, which is likely to be caused by the shock-induced solid-liquid phase transformation.
Properties of terahertz surface plasmon ploaritons on carbon nanotube film with periodic grating
Authors: Wang Yue  , He Xun-Jun  , Wu Yu-Ming  , Wu Qun  , Mei Jin-Shuo  , Li Long-Wei  , Yang Fu-Xing  , Zhao Tuo  , Li Le-Wei  ,   Department of Electrical Science and Technology, Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China;,   School of Electronics and Information Technology, Harbin 150001;,   State Key Laboratory of Millimeter Wave, Southeast University, Nanjing 210096, China,   Department of Electrical and Computer Engineering, National University of Singapore 119260, Singapore
Published: December 2020

Based on the dielectric property of carbon nanotube film, the surface plasmon ploariton propagation and localization phenomena on the carbon nanotube film are investigated using THz time-domain spectroscopy technique. The simulation results show that in the gate period of 168um, the resonance peaks of surface plasmon mode are at 0.99THz and 1.95 THz, which are consistent with the theoretical results. Further analysis demonstrates that both the gate thickness and the width have an important effect on the properties of surface plasmon ploaritons.
Fabrication of graphene nanoribbons through mechanical cleavage and their electronic transport properties at low temperature
Authors: Ma Li  , Tan Zhen-Bing  , Tan Chang-Ling  , Liu Guang-Tong  , Yang Chang-Li  , Lü Li  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Acadeny of Sciences, Beijing 100190, China
Published: December 2020

We have fabricated graphene nanoribbons (GNRs) of length up to tens of microns through mechanical cleavage, and performed electron transport measurements on devices made of the GNRs down to a low temperature of 0.3 K. Fabry-Perot interference was observed in the conductance of the devices as functions of both bias voltage and gate voltage. The result indicates that our mechanically cleaved GNRs are of high quality, in which the electrons form an ideal one-dimensional system at low temperatures.
Decoupled states and anti-resonance in the Aharonov-Bohm interferometer with embodied quantum-dot ring
Authors: Wu Li-Jun  , Han Yu  , Gong Wei-Jiang  , Tan Tian-Ya  ,   Department of Physics, Liaoning University, Shenyang 110036, China;,   School of science, Shenyang Ligong University, Shenyang 110159, China;,   College of Sciences, Northeastern University, Shenyang 110004, China
Published: December 2020

Using the Anderson model Hamiltonian and the non-equilibrium Green's function method, the decoupled states and antiresonance presenting in the electronic transport through N-quantum-dot ring embodied in A-B interferometer are studied theoretically. We find that the symmetry of the coupled-dot system and the magnetic flux through the Aharonov-Bohm (A-B) interferometer are two physical mechanisms responsible for the decoupled states. Even-odd parity oscillations occur in linear conductance spectra of such a highly symmetric quantum dot ring, due to even or odd molecular state decoupling from the leads by tuning the structure parameters, i.e., the magnetic flux. The results provide a new model for the designing of the nano-device.