bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel array of surface hollow optical micro-traps
Authors: Ji Xian-Ming  , Mu Ren-Wang  , Yin Jian-Ping  ,   (1)教育部光谱学与波谱学重点实验室，华东师范大学物理系，上海  200062; (2)南通大学理学院，南通  226007; (3)南通大学理学院，南通  226007;教育部光谱学与波谱学重点实验室，华东师范大学物理系，上海  200062
Published: December 2020

In this paper, we propose a new scheme to form an array of surface hollow optical micro-traps for cold atoms (or molecules) by using a phase grating with four phase steps and an array of microlens, study the intensity distribution of 2D array of surface hollow optical micro-traps, and calculate the corresponding optical potential for cold 85Rb atoms, and discuss some potential applications of our hollow micro-trap array in atom and molecule optics. Our study shows that when our grating-lens system is illuminated by YAG laser with a power of 1W, a 2D array of surface hollow optical traps with 104 micro-wells will be generated in an area of 1cm2. Each optical trap has some novel characteristics, such as smaller trapping volume, higher effective intensity and its intensity gradient. The corresponding optical potential for trapped 85Rb atoms can reach 190μK, which is high enough to trap cold atoms or cold molecules, and can be used to realize an all-optical atomic and molecular Bose-Einstein condensations, even to prepare novel optical lattices, and so on.
Propagation of vectorial off-axis Gaussian beams beyond the paraxial approximation
Authors: Gao Zeng-Hui  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都  610064; (2)四川大学激光物理与化学研究所，成都  610064;宜宾学院光电信息研究所，宜宾  644007
Published: December 2020

Based on the vectorial Rayleigh-Sommerfeld diffraction formulation, a solution of the electric-magnetic wave equation is found, which represents vectorial nonparaxial off-axis Gaussian-beams whose propagation equation in free space is expressed in a closed form. The on-axis and far-field expressions of vectorial nonparaxial off-axis Gaussian beams, the propagation equation of vectorial nonparaxial Gaussian beams and the paraxial results are treated as special cases of our general expression. It is shown that the f parameter plays an impotant role in determining the beam nonparaxiality, whereas the off-axis parameters additionally affect the nonparaxial behavior of vectorial nonparaxial off-axis Gaussian beams. Moreover, unlike the on-axis case, there exists the longitudinal component of the field in the y direction for the off-axis case.
Third-order nonlinear optical properties of bromo［tri-α-(2,4-dimethyl-3-pentyloxy) subphthalocyanine］ boron
Authors: Xia Chun-Hui  , Chen Zhi-Min  , Wu Yi-Qun  , Song Ying-Lin  ,   (1)哈尔滨工业大学应用物理系，哈尔滨  150001; (2)黑龙江大学化学化工与材料学院功能材料实验室，哈尔滨  150080
Published: December 2020

The third-order nonlinear optical properties of a new subphthalocyanine complexe (bromo［tri-α-(2,4-dimethyl-3-pentyloxy) subphthalocyanine］ boron) was studied by Z-scan using 8ns laser pulses at 532nm. It was found that the compound shows a strong reverse saturation absorption (β=3.7×10-10 m/W) and nonlinear self-focusing refraction effects (n2=7.2×10-11 esu). The third-order nonlinear susceptibility (χ(3)) is 1.1×10-11esu.The effects of cone-chaped molecular structure and axially heavy-atom (Br) substitution on third-order nonlinear optical properties are also discussed.
First-principle calculations of structural properties and effective-mass of zinc-blende ZnTe and CdTe
Authors: Duan He  , Chen Xiao-Shuang  , Sun Li-Zhong  , Zhou Xiao-Hao  , Lu Wei  ,   中国科学院上海技术物理研究所红外物理国家重点实验室,上海  200083
Published: December 2020

The electronic band structures of zinc-blende ZnTe and CdTe are calculated by using a self-consistent full-potential linearized augmented plane-wave method within the first-principle formalism. In order to clarify the electronic properties near the Brillouin-zone (BZ) center and give an effective guideline on the material design for electronic and optical devices, we link the first-principle band calculations with the effective-mass approximation. The electronic properties are analytically studied on the basis of the effective-mass Hamiltonian for zinc-blende symmetry. The effective-mass parameters, such as crystal-field splitting, spin-orbit splitting, electronic effective mass,and the hole effective mass and the corresponding Luttinger-like parameters, are determined by reproducing the calculated band structures near the BZ center. The obtained results are in good agreement with available experimental and theoretical values.
Performance of polymer light-emitting diodes with saturated red-emitting poly(fluorine-co-4,7-dithien-2-yl-2,1,3-benzothiadiazole-carbazole or triphenylamine)
Authors: Hou Lin-Tao  , Hou Qiong  , Peng Jun-Biao  , Cao Yong  ,   (1)华南理工大学高分子光电材料及器件研究所,广州  510640; (2)华南理工大学高分子光电材料及器件研究所,广州  510640;华南理工大学特种功能材料及其制备新技术教育部重点实验室，广州  510640
Published: December 2020

Since electron or hole injection is a limiting factor for most electroluminescen t polymers, a matching of the work function of cathodes and anodes and the LUMO ＼HOMO energy level of polymers is one of the important factors for high perform ance polymer light emitting devices. In this paper, we report the effect of the cathodes on the performance of the device based on saturated red emitter, three- component copolymer poly (fluorine-co-4, 7-dithien-2-yl-2, 1,3-benzothiadiazole- carbazole or triphenylamine) copolymers. By thermal deposition in combination wi th spin-coating of electron injection layer, we investigated the influence of va rious cathode meterials with different ionization potentials in order to optimiz e the balance of the electron and hole injection. The external quantum efficien cy reached 1.49% with luminance 466cd/m2，the EL spectrum peak is loc ated at 657nm with the color coordinate: x=0.69, y=0.30 for PFO-5Cz-15DBT.
Structure and magnetism of Co ultrathin films grown on Pd/Cu(100) monolayer
Authors: Lu Ya-Feng  , Przybylski M.  , Wang Wen-Hong  , Yan Long  , Shi Yi-Sheng  , Barthel J.  ,   (1)Max Planck Institute for Microstructure Physics,Weinberg 2,D-06120 Halle,G ermany; (2)Max Planck Institute for Microstructure Physics,Weinberg 2,D-06120 Halle,Germany; (3)西北有色金属研究院，西安  710016;Max Planck Institute for Microstructure Physics,Weinberg 2,D-06120 Halle,G ermany
Published: December 2020

We have grown epitaxial Co films on a single monolayer of Pd on Cu(100) substrate at room temperature. The interlayer of Pd was grown by pulsed laser deposition, whereas the Co layer was prepared by thermal deposition. A layer-by-layer growth mode continues until at least 11 ML Co layers in comparison to 4 ML on Pd(100)substrate, which is due to a reduced lattice mismatch between Co and the Pd/Cu(100) substrate in comparison to the Co on Pd(100) system. Compared to Co films on Pd(100), a larger slope of the thickness dependence of longitudinal magneto-o ptical Kerr rotation has been found in the Co/Pd/Cu(100) films with thickness ab ove 2 ML. We have also found an increase of longitudinal magneto-optical Kerr ro tation for Co/Pd/Cu(100) in comparison to Co/Cu(100) system which may be attribu ted to the Co/Pd interface effect.
Effect of CH4-doping on configuration and dielectric properties of SiCOH low-k films
Authors: Yu Xiao-Zhu  , Wang Ting-Ting  , Ye Chao  , Ning Zhao-Yuan  ,   苏州大学物理科学与技术学院，江苏省薄膜材料重点实验室，苏州  215006
Published: December 2020

Carbon-doped oxide materials (SiCOH films) with k of 2.45 and good thermal stability at temperature 485℃ are prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) from the mixture of decamethylcyclopentasioxane (D5, ［Si(CH3)2O］5) and methane (CH4). T he chemical structures of D5 as a liquid source and films deposited with differe nt methane flux are studied by Fourier transform infrared spectroscopy. The resu lts indicate that the increase of methane is of great advantage to the reservati on of ring structure of D5 as well as the formation of high density CHn fragments in films. The decrease of dielectric constant is induced by the com bined action of several factors: lower density of films caused by high density o f CHn fragments and formation of intrinsic pores, lower polarization caused by the formation of Si-C bond and decrease of-OH bonds.
From regional to global dynamics structure of the climatic proxy
Authors: Wan Shi-Quan  , Feng Guo-Lin  , Dong Wen-Jie  , Li Jian-Ping  ,   (1)国家气候中心气候研究开放实验室，北京  100081; (2)国家气候中心气候研究开放实验室，北京  100081;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; (3)兰州大学大气科学学院，兰州  730000;国家气候中心气候研究开放实验室，北京  100081; (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
Published: December 2020

Global change science is a new research domain nowadays, and one of the most imp ortant studies of which is the climate change,to which great attention is paid b y all governments in world. It is mainly based on the climatic proxy that we can study the past climate change. Although many achievements have been obtained, m ajority of the results are limited to the external characteristics of the proxy due to lagged analysis methods. For example, we judge if the climate is flood / drought or cold/warm through linear trend of the time series, however, we do not know whether it is a natural variation or the result of external forces, the me chanism is not uncovered. Because complexity of the open global climate system, there are different characteristics among the climatic proxies from different re gion of the world, from which it is difficult to reveal the intrinsic general pr inciples i.e. the globality. For the further study on the past climate change, e specially to reveal the rulcs of the global climate change in past 2000a and pre dict future climate change, a new method making use of the dynamical lag correla tion exponent (named Q index in the text), a dynamics exponent based on the phas e-space reconstruction, is introduced in this paper, which can effectively disce rn the similarities or differences between the dynamics of the two series. With Q index, we analyze the dynamics structure of some typical climatic proxies. The results show that the dynamics of climatic proxies are almost similar, and the regional climate keeps the same change with the global. In other words, regional climate is controlled by the global climate change. Besides, there are two dyna mics jump periods (namely 700—900a and 1300—1700a) in past 2000a of the climat e system, which may correspond to the periods of the medieval warm period and th e little ice age, respectively.
Contribution of high spin field to the entropy of Vaidya-Bonner black hole
Authors: Zhang Jian-Hua  , Zhang Qing-Song  ,   (1)东华大学材料学院，上海  200051; (2)山东省菏泽学院物理系，菏泽  274015
Published: December 2020

The contribution of gravitational field of spin 2 to the entropy of Vaidya-Bonne r black hole is calculated by using thin film brick-wall model proposed by Zhao Zheng et al., which is found to be A/2 in nature unit system. It is shown to be just two times the scalar field and 4/7 times the Dirac field when the truncatio n factor is the same as scalar fields.
Microcanonical statistics of Kerr black holes and the bootstrap condition
Authors: Wang Li-Ping  , Zhu Jian-Yang  ,   (1)北京师范大学物理系，北京  100875; (2)阜阳师范学院物理系，阜阳  236041;北京师范大学物理系，北京  100875
Published: December 2020

The microcanonical statistics of the Kerr black holes is analyzed. We have set u p an inequality in the microcanonical density for both continuous spectrum and d iscrete spectrum, and have verified that Kerr black holes obey the statistical b ootstrap condition. It is then used to show that the most probable configuration in the gases of Kerr black holes is that one black hole acquires all of the mas s and all of the rotation at the high-energy limit, so rotation does not break t he bootstrap property.
Stability and approximate solution of nonlinear dynamic system of a cylinder with two end faces in relative rotation
Authors: Wang Kun  ,   燕山大学理学院，秦皇岛  066004
Published: December 2020

For the nonlinear dynamics system of a cylinder with two end faces in relative rotation, a qualitative analysis of the autonomous system dynamics equation is performed. The stability of the solution of the equation is established, and approximate solution of the equation under special conditions is obtained by averaging method.
Fabrication process and power and lifetime characteristics of very-small-aperture laser
Authors: Song Guo-Feng  , Gan Qiao-Qiang  , Qu Xin  , Fang Pei-Yuan  , Gao Jian-Xia  , Cao Qing  , Xu Jun  , Kang Xiang-Ning  , Xu Yun  , Zhong Yuan  , Yang Guo-Hua  , Chen Liang-Hui  ,   (1)北京大学物理系，北京  100871; (2)复旦大学材料科学系，上海  200433; (3)中国科学院半导体研究所，北京  100083; (4)中国科学院半导体研究所，北京  100083;中国科学院研究生院，北京  100039; (5)中国科学院研究生院，北京  100039
Published: December 2020

High output power very-small-aperture laser has been created on 650nm edge emitting laser diodes.The far-field output power is 0.4mW at the 25mA driving current,and the highest output power exceeds 1mW. The special fabrication process is described and the failure mechanism leading to the short lifetime of the devices is discussed.
Fabrication of straight waveguide in two-dimensional photonic crystal slab and its light propagation characteristics
Authors: Han Shou-Zhen  , Tian Jie  , Feng Shuai  , Ren Cheng  , Li Zhi-Yuan  , Cheng Bing-Ying  , Zhang Dao-Zhong  ,   中国科学院物理研究所，北京  100080
Published: December 2020

Using focused ion beam lithograph, we fabricated W3 straight waveguide in two-dimensional photonic crystal slab on SOI (silicon on insulator) wafer. The light propagation was observed on top and from the end of the sample. The transmission dip and mode distribution at the outlet of ridged waveguide were measured. The results show that light can propagate in the photonic crystal waveguide.
Structural transition of Fe80Cu20 alloy induced by annealing
Authors: Yan Wen-Sheng  , Yin Shi-Long  , Fan Jiang-Wei  , Li Yu-Zhi  , Liu Wen-Han  , Hao Lu-Yuan  , Pan Zhi-Yun  , Wei Shi-Qiang  ,   (1)河海大学数学物理系，南京  210024; (2)中国科学技术大学国家同步辐射实验室，合肥  230029; (3)中国科学技术大学化学物理系，合肥  230026; (4)中国科学技术大学结构分析开放研究实验室，合肥  230026; (5)中国科学技术大学物理系，合肥  230026
Published: December 2020

The extended x-ray absorption fine structure (EXAFS) and x-ray diffraction (XRD) techniques have been used to study the dependence of structural changes on annealing temperature for metastable body centered cubic (bcc) Fe80Cu20 alloy synthesized by mechanical alloying. In the temperature range from 300 to 873 K, the lattice constant of the bcc-structured phase exhibits a nearly linear decrease with the increase of annealing temperature. This is mainly due to the segregation of Cu atoms from the bcc Fe80Cu20 alloy to form the face centered cubic (fcc) Cu phase. Annealing at 603 K results in an increase of the average Cu—Cu distance RCu—Cu by about 0.003 nm, and about 50% Cu atoms are segregated from the bcc Fe80Cu20 alloy. After annealing at 773K, two phases of bcc α-Fe and fcc-Cu are almost completely separated from the as-milled bcc Fe80Cu20 alloy.
Theoretical study on the influence of the microstructure of Fe73.5Cu1Nb3Si13.5B9 on its giant magneto-impedance effect
Authors: Yang Quan-Min  , Wang Ling-Ling  , Sun De-Cheng  ,   (1)湖南大学应用物理系，长沙  410082; (2)连云港师范高等专科学校化学系，连云港  222006; (3)连云港师范高等专科学校物理系，连云港  222006
Published: December 2020

Based on the experimental results of atomic force microscope observation of the microstructure and the giant magneto-impedance (GMI) effect of Fe73.5Cu1Nb3Si13.5B9 nanocrystalline alloy, we propose a model for exploring the influence of the microstructure on the GMI effect in this kind of Fe-based nanocrystalline soft magntic alloy which explains successfully the GMI behavior at low frequency. The model possesses the main features of the sandwiched model while eliminating its deficiencies. This model is called the mesoscopic model. We also point out the influence of the electrical conductivity σ and the permeability μ of nanocrystal grains on the GMI effect of the Fe-based nanocrystalline alloys.
Effect of grain size on thermoelectric properties of CoSb3 compound
Authors: Yu Bo-Lin  , Qi Qiong  , Tang Xin-Feng  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

The effects of grain size on thermoelectric properties of CoSb3 compound was investigated systematically. The results indicate that the lattice thermal conductivity κp of CoSb3 compound decreases significantly, the Seebeck coefficient α increases remarkably, and the band gap Eg increases and electrical conductivity σ decreases, when the grain size decrease from μm-scale to nano-scale. The dimensionless thermoelectric figure of merit ZT of CoSb3 compound with grain size of 200nm reaches 0.43 at 700K, about 4 times that of sample with grain size of 5000nm.
Theoretical study on the transport in metal/organic bi-layer thin films
Authors: Jiang Yi-Ming  , Xie Heng-Bo  , Guo Feng  , Liu Ping  , Li Jin  ,   复旦大学材料科学系，上海  200433
Published: December 2020

Ag/TCNQ (7,7,8,8-tetracyanoquinodimethane) bi-layer films with different thickness were prepared by physical vapor deposition method. The metal-organic complex Ag-TCNQ is formed through transport. The transport behavior in the film was studied using transmission spectrum to monitor the process. Tunneling model and non-tunneling model were established respectively based on whether the tunneling condition was met. Theoretical analysis was carried out in detail. The results of our theoretical models are in good agreement with the experiment data.
Adsorption geometry of C2H4 and C2H on Ni(110) surface
Authors: Li Bo  , Bao Shi-Ning  , Cao Pei-Lin  ,   浙江大学物理系，杭州  310027
Published: December 2020

The favorite adsorption sites of ethylene (C2H4) and acetylide (CCH) on the Ni(110) surface are investigated by the theoretical calculation of the pseudo-potential plane-wave method. At low coverage the ethylene molecule occupies approximately the midway between the short-bridge and atop sites. The C-C axes of molecules are almost parallel to the ridges of the Ni atoms. The tilt angle of C-C axis relative to the Ni surface is about 12°. The C—C bond length is 0.147nm. At high coverage(0.5ML), ethylene molecules form a c(2×4) phase. The local adsorption sites of two ethylene molecules in a surface unit mesh are found to be quite similar to that at low coverage, but the C—C bond lengths are shorter than that in the case of the low coverage. The adsorption site of cetylide, decomposed from ethylene, is similar to that of the ethylene molecule on the surface, but there is a small displacement towards the atop site, the C—C bond length is 0.131nm, and the hydrogen atom bonds with the carbon a an atop site, the tilt angle of C-H axis relative to the Ni surface is about 45°.
Near edge x-ray absorption fine structure studies of local structure of dihexyldisulfide multilayer
Authors: Wu Tai-Quan  , Tang Jing-Chang  , Zhu Ping  , Li Hai-Yang  ,   (1)浙江大学物理系，杭州  310027; (2)浙江大学物理系，杭州  310027;浙江大学硅材料国家重点实验室，杭州  310027
Published: December 2020

The multiple-scattering cluster (MSC) method is employed to calculate the S 1s near edge x-ray absorption fine structure (NEXAFS) of single dihexyldisulfide molecule and dihexyldisulfide multilayer. The local structure model of the dihexyldisulfide multilayer is proposed. The MSC calculation shows that the neighboring dihexyldisulfide molecules are parallelly arranged in an ordered square cross section with side of 0.47 nm. The discrete variational Xα method is employed to calculate the electronic structure of the single molecule and multilayer, which confirms the MSC results, and reveals the physical origin of all the features in the S 1s NEXAFS spectrum. The analysis of the interaction between the dihexyldisulfide molecules shows that the local structure of the multilayer has the property of self-assemblage.
Effective interaction between charged plane and charged colloidal particle in electrolyte
Authors: Yang Tao  , He Dong-Hui  , Zhang Qing-Lan  , Ma Hong-Ru  ,   (1)宁夏大学物理电气信息学院，银川  750021; (2)宁夏大学物理电气信息学院，银川  750021;上海交通大学理论物理研究所，上海  200240
Published: December 2020

The effective interaction between two infinite, uniformly charged planes immersed in electrolyte solution having only monovalent counterions is calculated using Poisson-Boltzmann equation. Meanwhile, the influence of the boundary (a infinite, uniform charged plane) on a charged colloid sphere is investigated using the Derjaguin approximation. It is found that there is only repulsive force between two charged planes in the absence of microion correlation. Furthermore, the variation in the boundary condition has little effect on their effective interaction. The conclusions are similar with that of the charged-plane and charged-colloid-sphere system.
Quantum constraint dynamics and tracking control of a thermal dissipative qubit
Authors: Zhu Jing-Min  , Wang Shun-Jin  ,   (1)四川大学物理系,成都  610064; (2)四川大学物理系,成都  610064;兰州重离子加速器国家实验室核理论中心,兰州  730000
Published: December 2020

Quantum constraint dynamics and tracking control strategy to stabilize the coherence of a decoherent system is applied to a dissipative qubit system at a finite temperature. By using a control field dependent on the dynamical state of the qubit through the constraint equations, we show that the quantum state of the qubit can be preserved within a finite time duration by the feedback effect of the qubit system. It is also shown that the temperature plays a negative role in the control strategy.
Studies on Liu chaotic system and its experimental confirmation
Authors: Wang Fa-Qiang  , Liu Chong-Xin  ,   西安交通大学电气工程学院，西安  710049
Published: December 2020

In this paper, the Liu chaotic system is discussed. Its basic dynamical behaviors, such as the phase portrait, Lyapunov exponents, Poincaré mapping, power spectrum are studied. The influence of system parameter on the chaotic system is discussed through Lyapunov exponents spectrum and bifurcation diagram. Various attractors are demonstrated not only by computer simulation but also by the realization of an electronic circuit.
Effects of spontaneous emission noise in semiconductor lasers on chaotic optical communication systems
Authors: Li Xiao-Feng  , Pan Wei  , Ma Dong  , Luo Bin  , Zhang Wei-Li  , Xiong Yue  ,   西南交通大学信息科学与技术学院,成都  610031
Published: December 2020

A chaotic optical communication system based on external optical feedback is constructed. By introducing the Langevin noise sources, the master-slave rate equations including spontaneous emission noise characteristics are deduced. Utilizing the obtained mathematical model, two kinds of possible chaos synchronization in the system, i.e. complete chaos synchronization and generalized mode-locking chaos synchronization, are studied. The effects of the spontaneous emission noises of the two lasers on the two types of synchronization as well as the chaotic outputs of the transmitter and receiver are discucsed. Finally, for a sequence of pseudorandom digital bits at 2.5Gb/s bit rate, the encoding/decoding process basing on chaotic masking method is presented, and the effects of noise on decoding performance are examined.
Chaotic controlling via phase periodicity in optical injection semiconductor lasers
Authors: Yan Sen-Lin  ,   南京哓庄学院物理系，南京  210017
Published: December 2020

In this paper, a method of chaotic controlling is presented via controlling the phase in semiconductor lasers under to external optical injection. Chaos can be controlled to a periodic state or multi-periodic states by periodically modulating a phase-controller to control the injection light phase. Under the conditions of different intensities of injection light, numerical results shou thet: (1) Chaos is controlled into periodic state, dual-periodic state, triple-periodic state, four fold-periodic state and multi-periodic state respectively by a method of half-wavelength periodic modulation; (2) Chaos can be controlled into periodic state or multi-periodic state by the method of quarter-wavelength periodic modulation. Injection-locking phenomena in laser is produced under the conditions of high frequency modulation, where the frequency_locking domain is from 19GHz to 21GHz; (3) Chaos is also controlled into periodic state and multi-periodic state by a method of a wavelength periodic modulation.
Self-organization of light driven atoms induced by recoil effect in a harmonic trap
Authors: Zhang Lin  , Kong Hong-Yan  , Yang Guo-Jian  ,   (1)宝鸡文理学院非线性研究所，宝鸡  721007; (2)北京师范大学物理系，北京  100875
Published: December 2020

In this paper, the collective dynamic behaviors of N two-level atoms pumped by two-mode light field in a harmonic trap are investigated. When atoms are driven by the intense pump field, the atomic oscillating modes in the trap are continually excited by the photon recoil effect, which discretely changes the atomic detuning from the pumping field. Under proper resonant conditions the weak probe field will be greatly amplified and the atomic spatial structures will be spontaneously formed in the phase space.
Refractive index analysis of graded index coatings prepared by glancing angle deposition
Authors: Shen Zi-Cai  , Kong Wei-Jin  , Liu Shi-Jie  , Shen Jian  , Shao Jian-Da  , Fan Zheng-Xiu  ,   (1)中国科学院上海光学精密机械研究所,上海  201800; (2)中国科学院上海光学精密机械研究所,上海  201800;中国科学院研究生院,北京  100039
Published: December 2020

Glancing angle deposition is a novel method for the preparation of coatings, it can be used to prepare graded index coatings. In this paper, the packing factor of the coatings prepared by glancing angle deposition is analyzed under the conditions that the flux arrival angle of coating material is α and the columnar microstructure inclination angle of coatings is β. And then the relation between the refractive index of the coatings, the flux arrival angle and the columnar inclination angle is discussed based on Drude theory.
Improving the off-center resolution in position emission tomography using depth-of-interaction information
Authors: Liu Hua-Feng  ,   浙江大学现代光学仪器国家重点实验室,杭州  310027
Published: December 2020

It is well known that if the depth of interaction(DOI) within the crystal can be measured, the parallax error can be corrected and the resolution should be uniform throughout the field of view. We have investigated the spatial resolution of off-center sources in a positron emission tomography (PET) ring detector configuration using our proposed DOI detector. It is confirmed that the depth-encoding detector provides better spatial resolution for the oblique incidence of gamma-rays.
The application of an improved 2D fractal model for electromagnetic scattering from the sea surface
Authors: Wang Yun-Hua  , Guo Li-Xin  , Wu Zhen-Sen  ,   西安电子科技大学理学院，西安  710071
Published: December 2020

In this paper, an improved 2D fractal model is present for modeling the sea surface, the fractal spectrum of which satisfies the positive or negative power law for spatial wave numbers smaller or larger than the fundamental wave number, respectively. The spatial correlation function and the spectrum of this improved model show good agreements with those given in the literature for different windspeed. Based on the Kirchhoff approximation, the scattering coefficient and the scattering intensity coefficient of this new model are derived and evaluated. The angular distributions of backscattering intensity coefficient of the improved fractal sea model are compared with those of the conventional model, the influence of the incident frequency, windspeed and wind-direction on the backscattering intensity coefficient is also discus sed in detail.
Enhancement of nonlinear-optical signals in a cascade three-level system
Authors: Du Dan  , Hu Xiang-Ming  ,   (1)华中师范大学物理科学与技术学院,武汉  430079; (2)华中师范大学物理科学与技术学院,武汉  430079;南华大学数理学院,衡阳  421001
Published: December 2020

In this paper we show that non-maximal coherence can lead to more efficient nonlinear frequency conversion than maximal coherence does. For this purpose we exemplify with the three-level cascade system (with no maximal coherence) to calculate the intensity of nonlinear-optical signal. A comparison is made between the Ξ system and the Λ system (with maximal coherence). The generated intensity is calculated by employing a nonperturbative approach. It is shown that under the conditions of the two-photon resonance and the same parameters, the largest intensity from the Ξ system is about twice as large as that from Λ system. The difference is analyzed in terms of dressed states. It is shown that both the spontaneous emission on the coupling transition and the spontaneous emission mediated three photon process play a contrary role for the two systems. These two processes enhance the generation of nonlinear signals for Ξ system but act contrarily for the Λ systems.
Properties of Bi doped Al2O3-GeO2-M (M=Na2O, BaO, Y2O3) glasses
Authors: Wang Xue-Jun  , Xia Hai-Ping  ,   宁波大学光电子功能材料研究所，宁波  315211
Published: December 2020

The GeO-B2O3-Na2O (GBNB)，GeO2-Al2O3-Na2O(GANB), GeO2-Al2O3-BaO(GABB)and GeO2-Al2O3-Y2O3(GAYB) glasses doped with bismuth of 1mol% concentration were prepared by melting method and measurement of their DTA curves, absorption and emission spectra and fluorescence decay curves were carried out. It was found that the absorption edges of GBNB，GANB，GAYB，GABB were red-shifted. Since the absorption edges are ascribed to the charge transfer transition from Bi3+ 6s2 to Bi5+ 6s0，we conclude that the content of Bi5+ in GBNB, GANB, GAYB, and GABB glasses increased gradually. Near infrared super-broadband emission of GANB, GABB and GAYB samples were observed to be center-peaked at ～1220nm. The fluorescence intensity, FWHM and emission lifetime of GABB，GAYB，GANB were reduced gradually. The super-broadband emissions may be due to the formation and fluorescence of Bi5+. It could be deduced from the absorption and emission spectra that the introductions of BaO and Y2O3 into GeO2-Al2O3 glass were advantageous to the formation of Bi5+ in the glass. The mechanism of BaO and Y2O3 composition affecting the formation of Bi5+ in the GeO2-Al2O3 glass is discussed.
Photonic crystal field-sensitive polarizer and switch modulated by nemaic liquid crystals
Authors: Yin Jian-Ling  , Huang Xu-Guang  , Liu Song-Hao  , Hu She-Jun  ,   (1)华南师范大学物理与电信工程学院，广州  510631; (2)华南师范大学信息光电子科技学院，广州  510631
Published: December 2020

Compared with the photonic crystal (PC) structures composed of Si circular, the PC structrures composed of triangular lattice of air holes in a dielectric slab are more easily fabricated and integrated. The tunability of directional band gap in a two-dimensional photonic crystal of air holes in a semiconductor matrix is demonstrated numerically, using the plane wave expansion calculation. Numerical simulations show that the photonic crystal band gaps are modulated by nematic liquid crystals infiltrated in the air holes. Then the band gap can be controlled easily under the influence of the external electric field. So the results can serve as a field-sensitive polarizer. These results are in agreement with that of Liu. However, the tunable field-sensitive polarizer based on the phenylacetylene liquid crystals instead of 5CB liquid crystals has the wider frequency range. Moreover, the transmission spectrum of the photonic crystal infiltrated by liquid crystal is analyzed, using finite difference time domain (FDTD) method. Numerical simulations show that the shift of the spectrum modulated by liquid crystal can be used to design a novel switch.
Electro-optic effect induced by thermal poling in SiO2 ridge waveguides
Authors: Cao Xia  , Qin Hai-Yan  , Cheng Li-Hua  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

The structure of silica ridge waveguides with upper-cladding is optimized by theoretical simulation. Based on this design, a Mach-Zehnder electro-optic modulator is fabricated by micro-electronics techniques, which is used for the study of electro-optic effect and nonlinear effect induced by thermal poling. The nonlinear effects in silica are improved after thermal poling, with 0.093pm/V and 8.50×10-22(m/V)2 achieved in the experiment for linear electro-optic coefficient and second-order electro-optic coefficient，respectively. The physical mechanism of the enhancement of nonlinear effects in silica by thermal poling is also analyzed theoretically.
Influence of charge and discharge processes of dust particles on the dust plasma conductivity
Authors: Shi Yan-Xiang  , Ge De-Biao  , Wu Jian  ,   (1)西安电子科技大学理学院,西安  710071; (2)中国电波传播研究所,电波环境特性与模化技术国家重点实验室,北京  102206
Published: December 2020

The formulation of conductivity and dielectric susceptibility for the dust plasma at weak ionization is deduced by solving the Boltzmann’s equation and Shukla’s equation, which are the governing equations on dust particle charge and discharge processes, provided that the weak external electromagnetic field is imposed and the space dispersion neglected. The proper parameters of a solid rocket exhaust plume are then substituted into the derived formulae. The calculated results show that the radius and concentration of dust particles have significant influence on the conductivity and dielectric susceptibility.
The influence of initial physical parameters on laser pulse in the relativistic laser-plasma system
Authors: Jin Xing-Yu  , Qiu Xi-Jun  , Zhu Zhi-Yuan  ,   (1)上海大学理学院物理系, 上海  200444; (2)中国科学院上海原子核研究所, 上海  201800
Published: December 2020

The present paper studies the influence of the interaction of incident pulsed laser and cold plasmas on the laser pulse in the relativistic laser-plasma system, taking the electron density fluctuation into account. For different initial parameters, the change of the laser-pulse width is analyzed in detail. The self-compression of the laser pulse is particularly discussed. Numerical calculation demonstrates that the pulse self-compression can be effectively achieved with the increase of the intensity and width of the laser pulse and the decrease of background plasma density. For initial laser-pulse parameters a0=0.12 and τ=70 and plasma density n0＝0.3, the ratio of compressed laser pulse to initial one is near to 1/10. And hence optimized theoretical parameters for the self-compression of the laser pulse are given.
Relativistic effects on resonance absorption in laser-plasma interaction
Authors: Xu Hui  , Sheng Zheng-Ming  , Zhang Jie  ,   中国科学院物理研究所光物理重点实验室，北京  100080
Published: December 2020

The relativistic effects on resonance absorption, occurring when a high intensity p-polarized laser pulse is incident obliquely onto inhomogeneous plasma, are discussed by use of one-dimensional particle-in-cell simulation. It is found that the absorption rate decreases with the increase of the amplitude of the incident pulse until the laser intensity reaches about 3.4×1017W/cm2. This is mainly owing to the relativistic effect of the electrostatic field driven near the critical surface. At high light intensities, because of the relativistic effect of the laser pulse itself in plasma the plasma wave breaking, and the excitation of the parameter instabilities, the absorption begins to increase with the light intensity. For a given scale-length, similar intensity-dependence of the absorption is found for different incident angles and different initial electron temperatures.
Simulation study of effect of cooling rate on evolution of microstructures during solidification of liquid metal Cu
Authors: Yi Xue-Hua  , Liu Rang-Su  , Tian Ze-An  , Hou Zhao-Yang  , Wang Xin  , Zhou Qun-Yi  ,   (1)湖南大学应用物理系，长沙  410082; (2)湖南大学应用物理系，长沙  410082;井冈山学院物理系,  吉安  343009
Published: December 2020

A molecular dynamics simulation has been performed on the solidification process of liquid metal Cu by adopting the quantum Sutton-Chen many-body potentials at four different cooling rates. Through the pair distribution function，bond-type indices, coordination number, MSD, and visualized analysis, it is found that the cooling rate plays a critical role in the evolution of microstructures of liquid metal Cu. At the cooling rate of 1.0×014K/s, the amorphous structures will be formed in the system; at the cooling rate of 1.0×1013K/s, 1.0×1012K/s and 1.3×1011K/s, the mixed crystal structures of fcc and hcp formed mainly with 1421 bond-type will coexist in the system, and their corresponding crystallization temperatures are 373K, 773K, 873K, respectively. Namely, slower the cooling rate, higher the crystallization temperature, and higher the degree of crystallization; and slower the cooling rate, greater the number of 1421 bond-type, greater the proportion occupied by fcc in the mixed crystal. At the same time, it is found that the variation of the mean coordination number of atoms is closely related to that of 1551, 1441, 1661　bond-types, which reflects that the varying rule of the symmetric configurations in the system is related to the variation of the coordination number. In visualized analysis, the amorphous and crystal structures in 2D cross sections and the concrete structures of both the basic clusters of fcc and hcp in 3D were displayed by means of center-atom method.
Molecular dynamics simulation of motion of single-walled carbon nanotubes on graphite substrate
Authors: Li Rui  , Hu Yuan-Zhong  , Wang Hui  , Zhang Yu-Jun  ,   清华大学摩擦学国家重点实验室,北京  100084
Published: December 2020

Motion of single-walled carbon nanotubes on graphite substrate is investigated by using molecular dynamics simulation in this paper. Following a relaxation to the equilibrium state, a uniform force is applied to carbon nanotubes for a period of time to set them into motion. After the applied force being removed, carbon nanotubes move relative to the substrate in decelerating speed until they come to a full rest in the end. Different tube radius and chiral angles are selected during simulation. The results show that motion of carbon nanotubes is mainly affected by the chiral angle but independent of tube radius. When the chiral angle is 30°, periodic transition between sliding and rolling is observed due to the periodic change of atomic configuration during the motion. When chiral angle is between 28.3° and 30°, sliding and rotating take place at the same time. When chiral angle is less than 26.3°, only sliding is observed. Different chiral angles result in different atomic configurations in the contact region between carbon nanotubes and graphite substrate, which gives rise to different styles of motion.
Broadband yellow luminescence in the photoluminescence spectra of n-GaN implanted by the different ions
Authors: Zhang Xiao-Dong  , Lin De-Xu  , Li Gong-Ping  , You Wei  , Zhang Li-Min  , Zhang Yu  , Liu Zheng-Min  ,   (1)兰州大学现代物理系,730000; (2)中国科学院高能物理研究所,100080
Published: December 2020

The n-type gallium nitride (GaN) films were implanted with oxygen, nitrogen, magnesium, silicon and gallium ions at room temperature in the dose range from 1013 to 1016 cm-2. All implanted samples were annealed at 900℃ for 10 min in a flowing nitrogen environment. The effects of the implantation ions on the broad yellow luminescence (YL) band were systematically investigated using the photoluminescence (PL) spectra taken at room temperature. A formula based on a semi-empirical model which was proposed by us was deduced, and with it, the experimental data was analyzed and the influence of implanted ions on the intensity of YL band was determined. We can confirm that the effects of the Mg (1016/cm2), Si (≤1014/cm2) and Ga(≥1015/cm2) implanted ions on the YL band are larger than that of the N and O implanted ions.
The tunnel conductance and tunnel magnetic resistance of NM/FI/NI/FI/NM double spin filter junction
Authors: Zhu Lin  , Chen Wei-Dong  , Xie Zheng-Wei  , Li Bo-Zang  ,   (1)四川师范大学物理系与电子工程学院,成都  610066; (2)四川师范大学物理系与电子工程学院,成都  610066;中国科学院物理研究所,北京  100080
Published: December 2020

Based on the NM/FI/FI/NM double spin filter junction (NM represents the nonmagnetic metal layer and FI the ferromagnetic insulator or semiconductor layer), a new type of double spin filter junction NM/FI/NI/FI/NM (NI represents the nonmagnetic insulator layer) is discussed. By inserting an nonmagnetic insulator layer between the ferromagnetic insulator layers, the adverse influence on the tunneling magnetic resistance (TMR) caused by the magnetic coupling at the interface between the ferromagnetic insulator (FI) layers can be avoided. Using the free-electron approximation and transfer matrix method the dependence of the tunneling conductance and TMR on the thickness of the FI layer and the NI layer and on the bias voltage in the double spin filter junction NM/FI/NI/FI/NM are studied.
Fabrication and magnetic properties of Fe100－xPdx nanowire arrays
Authors: Chen Li-Jie  , Li Yang-Xian  , Chen Gui-Feng  , Liu He-Yan  , Liu Xiao-Xu  , Wu Guang-Heng  ,   (1)河北工业大学材料学院，天津  300130; (2)中国科学院物理研究所,北京凝聚态物理国家实验室，北京  100080
Published: December 2020

Fe100-xPdx nanowire arrays with different compositions have been fabricated in anodic aluminum oxide templates by electrodeposition. Around x=30, the nanowire arrays still show rather high coercivity (7.48 kA/m) and axial anisotropy. But increasing the Pd content to x=50, the magnetization easy axis is tuned to be perpendicular to the nanowires. It is attributed to the discontinuous magnetic layer being separated by non-ferromagnetic sheets grown in the Fe50Pd50 nanowires, such that the shape anisotropy overturns the easy axis. The formation of the laminated structure in Fe50Pd50 nanowires has been discussed based on the growth kinetics.
Effect of Cu on the magnetism of Zn1－xFexO DMS
Authors: Wei Zhi-Ren  , Li Jun  , Liu Chao  , Lin Lin  , Zheng Yi-Bo  , Ge Shi-Yan  , Zhang Hua-Wei  , Dong Guo-Yi  , Dou Jun-Hong  ,   河北大学物理科学与技术学院，保定  071002
Published: December 2020

Diluted magnetic semiconductor Zn1-xFexO and Zn1-xFexO:Cu crystals were synthesized by hydrothermal method with 3molL-1 KOH as mineralizer, with 35% fill factor, under the reaction temperature of 430℃ for 24h. When Zn(OH)2 doped with FeCl2·6H2O was used as precursor, different shapes of Fe doped ZnO crystals were synthesized, of which the atomic percentage of Fe in the bigger crystals were 0.49%—0.52%. The magnetization of the crystals lowered with increasing temperature, a superconducting quantum interference device (SQUID) was used for measuring magnetism. Compared with Zn1-xFexO crystals the magnetization of Zn1-xFexO:Cu crystals doped with Cu increased obviously in the high temperature region, and at room temperature they were ferromagnetic.
Slow positron annihilation study of Al film reflector after proton irradiation
Authors: Wei Qiang  , Liu Hai  , He Shi-Yu  , Hao Xiao-Peng  , Wei Long  ,   (1)哈尔滨工业大学空间材料与环境工程实验室，哈尔滨  150001; (2)哈尔滨工业大学空间材料与环境工程实验室，哈尔滨  150001;天津大学材料科学与工程学院，天津  300072; (3)中国科学院高能物理研究所核分析技术重点实验室，北京  100049
Published: December 2020

The spectral reflectance is measured after 60 keV proton irradiation by the spectrophotometer. The microscopic mechanism of irradiation damage of Al film reflector is studied by the slow positron annihilation technique and X-ray diffraction. The results show that the spectral reflectance of Al film reflectors decreases in the wavelength range of 200—800nm with increasing proton irradiation fluence and the radiation damage is mainly concentrated on the Al film of the reflector. The implanted protons may fill the dcfccts in Al film layer, thus decreases the electron density of Al film and enhances the interband transition of loose bound electrons. The interband transition can be excited by electromagnetic waves ranging from UV to visible and the spectral reflectance decreases in the corresponding wave band, which eventually results of the degradation of optical property of the reflector.
Analytical solution for a class of coupled linear second-order differential equations limited by transformations
Authors: Yang Peng-Fei  ,   陕西广播电视大学榆林市分校，榆林  719000
Published: December 2020

By using the function and equation transformations,a coupled linear second-order differential equations are reduced to a nonlinear first-order Elliptic equation. And the analytical solutions to coupled transformations that include first-order and second-order transformations are given.The special approximate solution to a superconductivity question derived from a reference is reformed by using the new result given in this paper, and the existence of electric field in the surface of superconductor is validated.
The generalized uncertainty relation and the thermodynamic quantities near the black holes
Authors: Liu Xiao-Ying  , Zhang Jia  ,   (1)湛江师范学院物理系，湛江  524048; (2)湛江师范学院物理系，湛江  524048；广西师范大学物理信息工程学院，桂林  541004
Published: December 2020

The thermodynamic quantities of massless scalar, neutrino, electromagnetic, massless Rarita-Schwinger and gravitational fields near the general spherically symmetric static black holes are investigated by using the modified equation of state density due to the generalized uncertainty relation. It is shown that the thermodynamic quantities depend not only on the characteristic of the black hole but also on the spin of the fields and the size of minimal length.
Chaotic synchronization problem of finite-time convergence based on Terminal slide mode control
Authors: Wang Xiao-Feng  , Si Shou-Kui  , Shi Guo-Rong  ,   (1)海军航空工程学院基础部，烟台  264001; (2)海军驻西安航空设备军事代表室，西安  710043
Published: December 2020

In this paper, the problem of finite-time synchronization is proposed. Terminal slide mode control is combined with chaos synchronization. Chaos synchronization is regarded as tracking problem in control system. Sufficient condition for constructing Terminal slide mode by introducing nonlinear function into linear slide mode function is given. Corresponding the Terminal slide mode controller is given too. To verify the feasibility and effectivness of this control strategy, the synchronization for Duffing chaotic system is illustrated.
Exact quantum motions of two ions in a two-dimensional paul trap
Authors: Wu Yun-Wen  , Hai Wen-Hua  ,   湖南吉首大学物理系，吉首  416000;湖南师范大学物理系，长沙  410081
Published: December 2020

We investigate the exact quantum motions of two ions in a two-dimensional Paul trap. When the Coulomb-correlation of the system is considered, we obtain a set of exact solutions of the system and the corresponding perturbed solutions, containing the exact discrete eigenstates and eigenenergies, and the approximate piecewise continuous spectra and the band structure. Taking several quantum states with lower quantum numbers as examples, we compute the average distances between two ions and give the plots of probability distribution of the two ions.
Fermion condensate and Dirac operator determinant with external gauge fields and dynamical fermion self energy
Authors: Yang Hua  , Liu Zeng-Ping  , Wang Xue-Lei  , Zhang Sheng-Hai  ,   (1)河南师范大学物理系，新乡  453002; (2)信息工程大学理学院数理系，郑州  450001; (3)信息工程大学理学院数理系，郑州  450001；河南师范大学物理系，新乡  453002
Published: December 2020

The calculation of Dirac operator determinant in non-Abelian gauge theory is generalized from only containing hard fermion mass to that containing momentum dependent fermion self energy, and the calculation of determiant and fermion condensate is generalized to the case with arbitrary external gauge fields.
Probing the high density behavior of the symmetry energy by using the neutron-proton differential flow
Authors: Zhang Fang  , Zuo Wei  , Yong Gao-Chan  ,   (1)兰州大学物理与技术科学学院，兰州   730000; (2)中国科学院近代物理研究所,兰州  730000；中国科学院研究生院,北京  100049
Published: December 2020

Based on the isospin- and momentum-dependent transport model IBUU04, we investigated the neutron-proton differential flow in the 132Sn+124Sn mid-central collisions at beam energies of 400MeV/A, 600MeV/A and 800MeV/A by adopting two different symmetry energies. It was found that the neutron-proton differential flow as a function of rapidity is very sensitive to the density dependence of symmetry energy， especially at incident energies around 400MeV/A.
Interaction of an atom with a field with varying frequency without rotating-wave approximation
Authors: Jia Fei  , Xie Shuang-Yuan  , Yang Ya-Ping  ,   同济大学物理系，上海  200092
Published: December 2020

The interactions between a two-level atom and a coherent field with a time-varying frequency without rotating-wave approximation have been investigated. The typical cases of the frequency of the field varying with time in the sine and rectangle forms have been considered. It is found that the collapse-revival phenomena and quick oscillations due to virtual photon processes of the atomic population inversion are deformed as the frequency changes with time in the sine form. The rectangular frequency modulation can lead to some new collapses and revivals in the evolution of the atomic population inversion. The sudden jumping of the field frequency can also lead to the sudden change of the quick oscillations due to virtual photon processes.