bluuebunny/crossref_metadata_2025 huggingface dataset:
Controllable doublewell optical trapfor cold atoms or molecules
Authors: Ji Xian－Ming  , Yin Jian－Ping  ,   (1)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海　200062; (2)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海　200062(南通大学物理系，南通　226007
Published: December 2020

In this paper, we propose a novel scheme to form a controllable doublewell opt i cal trap for cold atoms or molecules by using a system composed of a binary π phase plate and a lens illuminated by a plane light wave. We calculate the int ensi ty distribution of the doublewell trap, and study the evolution process of th e optical trap from two wells to a single well, and derive the analytical relation between the characteristic parameters of the doublewell trap (includi ng g eometric parameters, the intensity distributions, intensity gradients and their curvatures) and the parameters of optical system. We find that our doublewell trap can be continuously changed into a singlewell trap by moving the πphas e pl ate along the x direction, and the relation between the distance of the trap ping centers of the two wells and the moving distance of the πphase plate is obt ain ed by data fitting. In addition, our doublewell scheme is not only simple and c onvenient, but also has some important and wide applications in the fields of at omic physics, atom optics, molecule optics and quantum optics and so on.
Numerical simulation of output pulse shape for “Sheng uang Ⅱ”*
Authors: Liu Ren-Hong  , Cai Xi-Jie  , Yang Lin  , Zhang Zhi-Xiang  , Bi Ji-Jun  ,   中国科学院上海光学精密机械研究所高功率激光物理国家实验室,上海　201800
Published: December 2020

Power balance between laser beams is important for high_power l aser system. This paper uses a calculation method as an exact solution for laser-amplification to simulate the output pulse shape of “Shenguang Ⅱ" laser facility. The results are preferable, as compared with the results of the experiments .
Experimental analysis of the dependence factor duringsupercontinuum generation in photonic crystal fiber*
Authors: Hu Ming－Lie  , Wang Qing－Yue  , Li Yan－Feng  , Wang Zhuan  , Zhang Zhi－Gang  , Chai Lu  , Zhang Ruo－Bing  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津　300072
Published: December 2020

An experimental study of supercontinuum generation in a photonic crystal fiber with zero dispersion wavelength 780?nm by femtosecond laser and its dependence factor is presented. Supercontinuum light with a spectrum more than one octave broad (500-1100?nm) was generated in a photonic crystalfiber by femtosecond pulses from a selfstarting, selfmode locked Ti:sapphire oscillator running at center wavelength of 810-840?nm. Different supercontinuums were generated by the 35?fs pulses with different power, central wavelength, prechirp, and the continuous noise in the femtosecond pulses. Some reasonable analysis result is obtained from the comparisons of the experimental results, and the mechanism of the supercontinuum generation is analyzed.
Research on a novel fiber Bragg grating thermal tuning scheme*
Authors: Han Qun  , Lü Ke－Cheng  , Li Jia－Fang  , Li Yi－Gang  , Chen Sheng－Ping  ,   (1)南开大学物理学院，天津　300071; (2)南开大学物理学院，天津　300071天津大学精密仪器与光电子工程学院，天津　300072
Published: December 2020

A novel fiber Bragg grating thermal tuning scheme is proposed, theoretically analyzed and experimentally studied. The device made from this scheme is named doubleshoulder beam (DSB). Experimental results demonstrate that DSB is an effective thermal tuning technique. A thermal sensitivity of 0436?nm/℃, 50 times that of the bare fiber grating, is experimentally achieved. To our knowledge, this is the largest thermal sensitivity ever demonstrated. The repeatability and lin
earity of the technique is very well. The most important advantage of DSB, as a breakthrough to conventional thermal tuning technique, is its great flexibility. It makes the thermaltuning efficiency of fiber grating no longer limited by the thermalexpansion coefficient of the drive materials, but can be designed according to practical requirements. This technique is expected to have a vast application in fields such as laser tuning, high sensitivity temperature sensing, sensor demultiplexing and so forth.
The microscopic mechanism of cholesteric liquid crystals
Authors: Bi Ya－Jun  , Yang Guo－Chen  , Guan Rong－Hua  ,   (1)河北工业大学物理研究所，天津　300130; (2)河北工业大学物理研究所，天津　300130北华航天工业学院电子工程系，廊坊　065000; (3)华北电力大学应用物理系，保定　071003
Published: December 2020

In this paper, the quantum theory is used to study the microscopic mechanism of cholesteric liquid crystals. It is proven that the form of the chrial potential can induce the cholesteric phase exactly.The expression of pitch is derived also
Group theory for carbon nanotubes and a series of novel point groups*
Authors: Yang Zheng  , Shi Yi  , Liu Fa  , Zhang Rong  , Zheng You－Dou  ,   (1)南京大学物理系，南京　210093; (2)南京大学物理系，南京　210093江苏省光电信息功能材料重点实验室，南京　210093
Published: December 2020

The geometric structure of carbon nanotubes (CNTs) is introduced, the symmetry of zigzag and armchair CNTs is analyzed and these symmetry elements are abstracted and summarized. The series of point groups Dnh which the symmetry elements of zigzag and armchair CNTs belongs to are discussed.
NcSi/SiO2 multilayer prepared by the method of laser constrained crystallization
Authors: Qiao Feng  , Huang Xin－Fan  , Zhu Da  , Ma Zhong－Yuan  , Zou HeCheng  , Sui Yan－Ping  , Li Wei  , Zhou Xiao-Hui  , Chen Kun－Ji  ,   南京大学物理系，固体微结构物理国家重点实验室，南京　210093
Published: December 2020

We prepared aSi:H/SiO2 multilayer by using layer by layer deposition of aSi:H sublayer and insitu plasma oxidation in the plasmaenhanced chemical vapor deposition system. Based on the constrained crystallization principle of aSi:H sublayer, we employed krF excimer laser to irradiate aSi:H sublayer and crystallize it. The results of Raman scattering spectroscopy and electron diffraction show that nanocrystal silicon (ncSi) has been formed within the asdeposited aSi:H/SiO2 multilayer, and that the size of ncSi can be controlled precisely according to the thickness of aSi:H sublayer. We also studied the photoluminescence(PL) property of the sample and the effect of laser energy density on PL.
Measurement and analysis of the pulsed magnetic field phase lag in the ceramic case*
Authors: Hu Hui－Yong  , Zhang HeMing  , Dai Xian－Ying  , Lü Yi  , Shu Bin  , Wang Wei  , Jiang Tao  , Wang Xi－Yuan  ,   西安电子科技大学微电子研究所,西安　710071
Published: December 2020

In this paper, static state and quasistatic state models of quantum well channel hole sheet density of SiGe pmetaloxidesemiconductor with δ doping layer are established and analyzed. The relations between hole sheet density and δ dopinglayer concentration, between holesheetdensity and undoping layer hickness at static state are also discussed, and the relations of the threshold voltage to the δ doping layer concentration, the quantum well channel hole sheet density and the thickness of the undoping layer are discussed. At last, the relation of the quantumwell channel hole sheet density to gate voltage for the quasistatic state is discussed.
Influence of level filling on optical properties of quantum well
Authors: Zhu Li　　　　　  , Zheng Hou-Zhi  , Tan Ping－Heng  , Zhou　Xia  , Ji Yang  , Yang Fu-Hua  , Li Gui－Rong  , Zeng Yu-Xin  ,   (1)四川大学物理科学与技术学院,成都　610064中国科学院半导体研究所超晶格国家重点实验室,北京　100083; (2)中国科学院半导体研究所超晶格国家重点实验室,北京　100083
Published: December 2020

In a specially designed three barrier double well tunneling structure, elect ron injecting from the emitter in combination with escaping through a resonant tunneling structure were used to adjust and control the filling of electrons in different subbands. It was observed that the occupation in the first excited electron state can result in a suppression to quantum confinement Stark effect. Mo reover, at very low bias, a series of intrigue photoluminescence peaks appeared as a small quantity of excess electron was filled in the ground state of the qua ntum well, that cannot be explained by the theory of band to band transition in the framework of single electron picture.
Investigation of high-performance hard magnetic properties of nanocomposite permanent magnets by micromagnetic finite element method*
Authors: Zhang Hong-Wei  , Rong Chuan-Bing  , Zhang Shao-Ying  , Shen  Bao-Gen  ,   中国科学院物理研究所磁学国家重点实验室，北京　100080
Published: December 2020

The microstructure with which a hard magnetic phase precipitates from the soft magne ticmatrix, is observed in nanocomposite Pr2Fe14B-αFe. The magnetic hysteresis loo ps are simulated by micromagnetic finite element method. The dependence of reman ence, coercivity and maximum energy product on the width of soft phase are discu ssed in detail. Although a single hard magnetic phase behavior is observed, the coercivity decreases monotonically with the increase of soft phase width from 0 to 12 nm. The obtained maximum energy products are 184 and 674 kJ/m3 for isotropic and anisotropic magnets, respectively.
Investigation of intergrain exchange coupling interaction of nanocrystalline permanent magnets by numerical simulation
Authors: Rong Chuan-Bing  , Zhang Hong-Wei  , Chen Ren-Jie  , He Shu-Li  , Zhang Shao-Ying  , Shen  Bao-Gen  ,   中国科学院物理研究所磁学国家重点实验室，北京　100080
Published: December 2020

The initial curves, demagnetization curves and recoil curves of Pr2Fe14B and Pr2Fe14B-α Fe nanocrystalline permanent magnets have been calculated by micromagnetic finite_element method. The validity of δm(H)curves, which can be used to determine the strength of intergrain exchange coupling interaction (IGEC), is approved by the calculated results. It is found that IGEC weakens with increasing grain size D for single-phase nanocrystalline and nanocomposite permanent magnets. Thus, the demagnetization curve shows a two-phase behavior and the δm(H) curve shows two peaks for the nanocomposite sample with D=20nm.The peak at small field can be attributed to the exchange interaction between the magnetic hard and soft grains, while the peak at large field may be due to the IGEC among hard grains.
Microwave electromagnetic characteristics of FeCoBSiO2 nano-granular magnetic films
Authors: Deng Lian-Wen  , Jiang Jian-Jun  , Feng Ze-Kun  , Zhang Xiu-Cheng  , He Hua-Hui  ,   华中科技大学电子科学与技术系,武汉　430074
Published: December 2020

FeCoBSiO2 nano-granular films were fabricated by alternately deposited mu ltilayers using radio frequency magnetron sputtering. Microstructures and morpho logy were analyzed by x-ray diffraction, scanning probe microscope and transmis sionelectron microscope.Magnetic parameters were measured by vibrating sample magnetometer.The electrical resistivity was measured by a direct current four probe method,and the complex permeability was measured by microwave resonance cavity.The mechanism of the effect of microstructures and content of SiO2 on electromagnetic characteristics was also discussed. Results show that these films have good performance at high frequencies.μ′can be larger than 70 at 2GHz.Thus,the films may be applied to the micromagnetic devices or microwave absorbers in the GHz range.
Submicron domain patterning in LiNbO3 doped MgO*
Authors: Yao Jiang-Hong  , Chen Ya-Hui  , Yan Bo-Xia  , Deng Hao-Liang  , Kong Yong-Fa  , Chen Shao-Lin  , Xu Jing-Jun  , Zhang Guang-Yin  ,   南开大学物理学院,天津  300071南开大学泰达学院应用物理学院,天津  300060
Published: December 2020

By using a microsecond pulse field, we succeeded in fabricating a uniform submic ron domain pattern with a period of 1.7μm in LiNbO3- doped 5mol% MgO. And the depth of these domain strips is, typically, about 30 to 50μm. When a pol ed field with a pulse width of 100ms is applied, the domain- inverted structure with a width of 0.5μm was obtained. Using the spontaneous domains backswitc hing and domain side- grown effects, we can explain the mechanism of the submicro n domains evolution.
Applications of improved complementary pair adaptive noise cancellation to MCG analysis*
Authors: Zhao Li　  , Chen Geng-Hua  , Zhang Li-Hua  , Huang Xu-Guang  , Zhai Guang-Jie  , Li Jun-Wen  , Tang Yu-Lin  , Feng Ji  ,   (1)中国科学院物理研究所,北京　100080; (2)中国科学院物理研究所,北京　100080中国科学院研究生院,北京　100039
Published: December 2020

How to extract the magnetocardiography (MCG) signals from the background noises and attenuate the noise is the key element of MCG　signal processing. From the aspect of software technique, a new adaptive algorithm is proposed to suppress the environmental magnetic noise of MCG in this paper. The propo sed algorithm is called improved complementary pair normalized least mean square algorithm. This adaptive structure is designed for MCG. This new algorithm prov ides the faster convergence speed and smaller steady-state error. In order to test the performance of this algorithm, the result of the simulated experiment and real MCG signal is analyzed. This method bring about the effective noise atten uation. Meanwhile, this algorithm is suitable for noise cancellation of other non-stationary signals.
Abundant Jacobi elliptic function solutions of nonlinear evolution equations
Authors: Lü Da-Zhao  ,   北京建筑工程学院基础部，北京  100044
Published: December 2020

In this paper, the twelve Jacobi elliptic functions are divided into four groups, and a new general Jacobi elliptic function expansion method is proposed to construct abundant doubly periodic Jacobi elliptic function solutions of nonlinear evolution equations. By this method, many exact doubly periodic solutions are obtained which shows the powerfulness of this method. When the modulus m→1 or 0, these solutions degenerate to the corresponding solitary wave solutions, shock wave solutions or trigonometric function (singly periodic) solutions.
Spectra analysis of the two-dimensional elliptic billiards
Authors: Xu Xue-You  , Zhang Yan-Hui  , Huang Fa-Zhong  , Lin Sheng-Lu  , Du Meng-Li  ,   (1)山东师范大学物理与电子科学学院，济南  250014; (2)中国科学院理论物理研究所，北京  100080
Published: December 2020

The correspondence between the quantum spectra and the classical orbits of the two-dimensional elliptic billiards is investigated. In order to study systems without analytic solutions in the future, an expansion method for stationary states (EMSS) to get highly accurate numerical solutions is applied and tested. The closed-orbit theory was extended to the open orbit case. By comparing the Fourier-transformed spectra with the classical orbits, we find that the peak positions in the quantum spectra match with the lengths of the classical orbits with small numerical differences. This is another example showing that semiclassical method provides a bridge between quantum and classical mechanics.
Eigenvalues of volume and area in the spin network representation
Authors: Shao Dan  , Shao Liang  , Shao Chang-Gui  , Chen Yi-Han  , Ma Wei-Chuan  ,   (1)湖北大学理论物理所，武汉  430062; (2)江汉大学物理系，武汉  430056; (3)武汉科技大学物理系，武汉  430081
Published: December 2020

By antisymmetrizing the action of grasp and binor identity, it is proved that the spin network states of 3-valent and any-valent are the eigenstates of the volume operator and the area operator, respectively. The formulas 2-32l3p∑ipσpτpρ and 2-1l2p∑jpl(j) for calculating the eigenvalue spectrums of volume and area, respectively, are obtained.
Influence of the ingot solidification microstructure on the formation kinetics of icosahedral quasicrystalline phase during the crystallization of the corresponding amorphous alloy
Authors: Tong Yu-Quan  , Shen Bao-Cheng  , Gan Yu-Sheng  , Yan Zhi-Jie  ,   (1)太原科技大学材料科学与工程学院，太原  030024; (2)太原科技大学材料科学与工程学院，太原  030024;上海交通大学材料科学与工程学院，上海  200030
Published: December 2020

Zr65Al7.5Cu12.5Ni10Ag5 ingots with different solidification microstructures are obtained by repeated arc melting of origin ingots. Under the same conditions, slices of amorphous alloys can be produced by suction casting in a copper mold. Differential scanning calorimetry (DSC) is employed to investigate the crystallization kinetics of the amorphous alloys. X-ray diffraction patterns (XRD) show that icosahedral quasicrystalline phase (I-phase) precipitates as primary phase during the crystallization of Zr65Al7.5Cu12.5Ni10Ag5 amorphous alloys. The results of Kissinger analyses suggest that the amorphous alloys made from the ingot with finer microstructure show better thermal stability, and that the I-phase precipitated becomes more stable against decomposition. Within the frame of structure heredity, the influence of ingot microstructure on the formation kinetics of I-phase during the crystallization of corresponding amorphous alloys is discussed.
One-way Hash function construction based on two-dimensional hyper-chaotic mappings
Authors: Peng Fei  , Qiu Shui-Sheng  , Long Min  ,   华南理工大学电子与信息学院，广州  510640
Published: December 2020

The design of an efficient one-way Hash function with good performance is a hot spot in modern cryptography researches. In this paper, a Hash function construction method based on two-dimensional hyper-chaotic mappings is proposed. The initial values of the two-dimensional hyper-chaotic system come from the chaotic sequence, produced by a series of operations including chaotic mappings and linear transformation based on the plain text, and then modulates the signals resulting from the iteration of the hyper-chaotic system to construct a one-way Hash function. Simulation and analysis demonstrate that the new method has the merit of convenience, high sensitivity to initial values, good Hash performance, weak collision property, and better security.
Adaptive multi-variable generalized predictive control and synchronization of chaotic systems
Authors: Dong En-Zeng  , Chen Zeng-Qiang  , Yuan Zhu-Zhi  ,   南开大学信息技术科学学院自动化系，天津  300071
Published: December 2020

This paper presents a β type multi-variable generalized predictive control method for control and synchronization of chaotic systems. Using this method, the chaotic Lorenz system, Rossler system and Chua's circuit system can be controlled to track the discretionary reference signal. The effectiveness of the proposed method is verified by numerical simulations. The advantages of the proposed method are that it can realize effective control and synchronization of chaotic systems without the knowledge of its precise model.
Synthesis, characterization and properties of B0.44C0.27N0.29 compound
Authors: Bai Suo-Zhu  , Yao Bin  , Su Wen-Hui  ,   (1)吉林大学物理学院，长春  130023;哈尔滨工业大学凝聚态科学与技术研究中心，哈尔滨  150001;中国科学院国际材料物理中心，沈阳  110015; (2)吉林大学物理学院，长春  130023;内蒙古民族大学化学学院，通辽  028043; (3)吉林大学物理学院，长春  130023;中国科学院国际材料物理中心，沈阳  110015
Published: December 2020

B-C-N compounds with different structures were synthesized by chemical reaction between Boracic acid and melamine, combined with heat treatment under vacuum and high pressure. An amorphous B-C-N precursor was prepared at 1273K under 10-3Pa. This amorphous B-C-N behaves as an insulator below 920K, and transforms into semiconductor above 920K. The B-C-N semiconductor shows different conductivity-temperature relationship in the temperature ranges of 973—1003K and 1013—1073K, and has conductivity activation energy of 0.34eV in the former range and 1.10eV in the latter range, indicating that conductivity mechanism of the B-C-N amorphous semiconductor is different in the two temperature ranges. Annealed for 40min. at 1473K under 3.5GPa, the amorphous B-C-N precursor crystallizes into hexagonal B0.44C0.27N0.29(h-BCN) compound with lattice constants of a=0.2515nm and c=0.6684nm. Four strong Raman scattering peaks were observed at 1330,1364,1588 and 1617cm-1 in the h-BCN, of which the peaks located at 1330 and 1617cm-1 are considered as characteristic Raman peaks of the h-BCN.
Experiment on PR SEW of SBN crystal
Authors: Zhang Tian-Hao  , Lu Yan-Zhen  , Kang Hui-Zhen  , Yang Da-Peng  , Zheng Jian-Ya  , Fang Zhe-Yu  , Lou Ci-Bo  , Yang Jia  , Yang Hui-Zhan  , Yin Mei-Rong  ,   南开大学物理科学学院光子学中心，弱光非线性光子学材料先进技术及设备教育部实验室，天津市信息光子材料与技术重点实验室，天津  300071
Published: December 2020

Photorefractive surface electromagnetic wave (PR SEW) at the interface between SBN crystal and air based on drift and diffusion mechanism was observed experimentally for the first time. PR SEW can be formed when laser beam was incident at an angle of 55° in proper ratio of signal beam to background beam, and the intensity of PR SEW increases along with the increasing of additional electric field.
Ultraslow light propagation in a solid
Authors: Fan Bao-Hua  , Zhang Yun-Dong  , Yuan Ping  ,   哈尔滨工业大学光电子技术研究所309信箱,哈尔滨  150001
Published: December 2020

With the spectral hole-burning effect resulting from coherent population oscillation in the homogenously broadened material， the ultraslow light propagation phenomenon with the group velocity as slow as 27.55±0.05m/s at room temperature in a ruby crystal is observed. And the group velocity in ruby crystal depends on the amplitude modulation frequency, the power of laser beam and the orientation of the crystal lattice. Lower frequency or higher power leads to slower group velocity.
Study of the multipass amplification of the chirped pulse and its inverse problem
Authors: Chu Xiao-Liang  , Zhang Bin  , Cai Bang-Wei  , Wei Xiao-Feng  , Zhu Qi-Hua  , Huang Xiao-Jun  , Yuan Xiao-Dong  , Zeng Xiao-Ming  , Liu Lan-Qin  , Wang Xiao  , Wang Xiao-Dong  , Zhou Kai-Nan  , Guo Yi  ,   (1)四川大学电子信息学院，成都  610064; (2)中国工程物理研究院激光聚变中心，绵阳  621900
Published: December 2020

The multipass amplification characters of the chirped pulse in gain medium were studied with the Schrdinger equation and population equation. The inverse problem of multipass amplification of the chirped pulse was studied and simulated by means of the Split-step Fourier and iteration methods, to find the profile of the input pulse from the given output pulse and multipass amplification parameters. The results are useful for the multipass amplification and design of the pulse shaping of the chirped pulse.
Numerical simulation of x-ray lasers pumped by grazing incidence pulses
Authors: Yan Fei  , Zhang Jie  , Dong Quan-Li  , Lu Xin  , Li Ying-Jun  ,   (1)中国科学院物理研究所光物理重点实验室，北京  100080; (2)中国矿业大学（北京）物理系，北京  100083
Published: December 2020

Numerical simulation of the Ni-like Mo x-ray laser at 189 nm (4d→4p, J=0→1) pumped by grazing incidence pulses is performed using a modified one-dimensional hydrodynamic code MEDUSA. By comparing the electron density, the electron temperature, and the absorbed laser energy density obtained by the grazing incidence and the normal incidence schemes respectively, it is clearly shown that the absorption efficiency is greatly increased in the grazing incidence scheme due to the increased absorption of driver laser in the gain region.
Singly resonant optical parametric oscillator with intracavity optical amplification
Authors: Deng Cheng-Xian  , Li Zheng-Jia  , Zhu Chang-Hong  ,   激光技术国家重点实验室，华中科技大学，武汉  430074
Published: December 2020

The Gaussian beam theory has been developed to describe the power characteristics of the steady-state operating ring cavity singly resonant optical parametric oscillator (SRO) with intracavity optical amplification (ICOASRO). The threshold of SRO can be greatly lowered with suitable parameters of the optical amplifier. Under the mean-field approximation, there are four operating domains for a ICOASRO without the second-order nonlinear coupling, meanwhile there exits a minimum pump threshold for the SRO. The characteristics of the end-pumped laser gain medium used as optical amplifier is considered. The generalized characteristics of SRO are also considered in the derivation.
The effect of electrode configuration in domain broadening of periodically poled LiNbO3
Authors: Wang Ting  , Ma Bo-Qin  , Sheng Yan  , Cheng Bing-Ying  , Zhang Dao-Zhong  ,   中国科学院物理研究所北京凝聚态物理国家实验室和中国科学院光物理重点实验室，北京  100080
Published: December 2020

The effect of LiNbO3 electrode with three different configurations o n domain broadening by using poling method appling external electric field applying exter nal electric field is studied. The effect of poling electrode configuration in d omain broadening is studied. The experiment demonstrated that under the same pol ing condition, the broadening velocities are 0.089μm/ms and 0.011μm/ms when th e angle between the poling electrode and the diagonals of hexagonal domain nucl eus are 90°and 0°，respectively, therefore the circumstance of 90°angle betwe en poling electrode and the diagonals of hexagonal domain nucleus should be avoi ded in fabricating one-dimension nonlinear photonic crystal.
Transient and steady-state multi-wave nonlinear optical properties of liquid crystal film
Authors: Miao Ming-Chuan  , Xu Ze-Da  , Hou Gang  , Fan Shang-Chun  ,   (1)北京航空航天大学电子中心，北京  100083; (2)北京航空航天大学物理系，北京  100083; (3)北京航空航天大学物理系，北京  100083;北京航空航天大学仪器科学与光电工程学院，北京  100083; (4)北京航空航天大学仪器科学与光电工程学院，北京  100083
Published: December 2020

Transient and steady-state multi-wave mixing experiments are carried out on the novel azo＋c-tube liquid crystal sample. The shape of the diffracted multi-wave consists of rings under Ar＋（514.5nm） laser pump light, and th e nonlinear refractive index is n～0.8. Using different polarization states of the pump laser light field, different reorientation models of liquid crystal molecules ar e observed. On the other hand, a Nd:YAG（532nm）pulsed laser is used, polarizati on holographic gratings are detected by a He-Ne (632.8nm)laser beam. Different p rocesses of liquid crystal molecular reorientation are also detected using the o -light beam and e-light beam of a He-Ne (632.8nm)laser.
RCS of 2-D target loaded with anisotropic magnetized plasma computed by FDTD
Authors: Xu Li-Jun  , Liu Shao-Bin  , Yuan Nai-Chang  ,   国防科技大学电子科学与工程学院，长沙  410073
Published: December 2020

The finite-difference time-domain(FDTD) method is extended to two dimensional anisotropic dispersive media-magnetized-plasma using Z transformation for the f ist time. The problem which incorporates both anisotropy and frequency dispersio n at the same time is solved for the electromagnetic wave propagation. The two d imensional FDTD formulations for anisotropic magnetized plasma are derived. The method is applied to the electromagnetic scattering of perfectly conducting cyli nder coated with anisotropic magnetized plasma. By simulating the interaction of electromagnetic wave with magnetized plasma, some bistatic numerical results ar e obtained, which indicate that an appropriate plasma coating may efficiently re duce the RCS of a metallic target.
Investigation of void in dust clouds in reactive plasma
Authors: Wu Jing  , Zhang Peng-Yun  , Song Qiao-Li  , Zhang Jia-Liang  , Wang De-Zhen  ,   大连理工大学物理系，三束材料改性国家重点实验室，大连  116024
Published: December 2020

The void in the sheath of a radio-frequency(rf) dusty plasma is investigated experimentally. Dust particles in our experiment are created in situ　using mixed reactive gases silane and ethane. Dust particles in radio frequency discharges form crystalline structure and display instabilities under certain conditions. The behaviour of the dust void as a function of rf power and gas pressure is stu died.
The study of depth distribution for ion with low energy implanted into plant seeds and mechanism of biological effect
Authors: Lu Ting  , Zhou Hong-Yu  , Ding Xiao-Ji  , Wang Xin-Fu  , Zhu Guang-Hua  ,   北京师范大学射线束技术与材料改性教育部重点实验室,北京师范大学低能核物理研究所，北京  100875
Published: December 2020

The depth distribution of 200keV Vanadium ions implanted into the dry peanut seeds have been determined by SEM+EDAX, PIXE, TPLSM and PAT. The results of measurements show that the depth of ion with low energy implanted into the dry peanut seeds are much greater than the value of depth calculated by of TRIM95 program. The mechanism of biological effect of ion with low energy implanted to the plant seed was discussed.
Molecular dynamics studies on vacancy-interstitial annihilation in silicon
Authors: Qiao Yong-Hong  , Wang Shao-Qing  ,   中国科学院金属研究所沈阳材料科学国家（联合）实验室，沈阳  110016
Published: December 2020

Molecular dynamics (MD) simulation is performed to study the vacancy-interstitial annihilation in crystalline silicon. We choose the Stillinger-Weber potential , which is commonly used for silicon, to describe the interaction between atoms. The system is relaxed under 300K and 1400K respectively. We have found that is the preferred recombination direction and propose the presence of an energy barrier in the direction. From the calculated value of energy barrier alon g we give a reasonable explanation for the difference between Tang's and Z awadzki's data.
Molecular dynamics simulation of strain effects on surface melting for metal Cu
Authors: Wang Hai-Long  , Wang Xiu-Xi  , Liang Hai-Yi  ,   中国科学技术大学中国科学院材料力学行为和设计重点实验室，合肥  230026
Published: December 2020

Molecular dynamics simulations of surface melting process at different strain values were performed for metal Cu(110). The variation of the structure and energy in the system and the movement of the interface position between solid and liquid during surface melting were observed. The interaction between atoms in the system adopts the embedded atom potential proposed by Mishin. Cu(110) surface pr emelts below thermal melting point and the thickness of quasi-liquid film grows with temperature increasing. Beyond the thermal melting point, the velocity of t he interface between solid and liquid is linearly proportional to temperature, t he melting point is extrapolated to be 1380K which accords with the experimental data of 1358K. Strain lowers the melting point and accelerates the premelting p rocess. The thickness of quasi-liquid grows with increasing strain at the same t emperature. The increase of solid free energy induced by strain is the main fact or that decreases surface thermal stability, the direction of strain relative to the surface stress also effects the premelting process.
Self-organization of ordered surface patterns in nearly free sustained Al films
Authors: Zhang Yong-Ju  , Yu Sen-Jiang  ,   (1)台州学院物理系，浙江　临海  317000;浙江大学物理系，杭州  310027; (2)中国计量学院物理系，杭州  310018;浙江大学物理系，杭州  310027
Published: December 2020

A nearly free sustained aluminum film system has been successfully fabricated o n liquid substrates by thermal evaporation method. The ordered surface pattern s with band-shaped structure, propagating from the film edges to the central reg ions, are systematically studied. The formation of these patterns is strongly d ependent on the experimental conditions (such as the nominal film thickness, de position rate, growth period in vacuum etc.) and the growth mechanism can be tra ced to a three-stage process. The experiment proves that the ordered patterns re sult from the free diffusion and aggregation of the Al atoms and atomic clusters on the liquid surfaces driven by the internal stress. Further theoretical analy sis shows that due to the characteristic boundary condition and interactions bet ween the metallic films and the liquid substrates, the nearly free sustained Al films may contain a series of sinusoidal stress distributions with different amp litudes and frequencies, and their composition results in the formation of the o rdered surface patterns.
Pseudoelasticity of Co50Ni22Ga28:Fex single crystal at room temperature and high temperature of 100℃
Authors: Dai Xue-Fang  , Liu Guo-Dong  , Liu Zhu-Hong  , Wu Guang-Heng  , Chen Jing-Lan  ,   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

The pseudo-quaternary Heusler alloys Co50Ni22Ga28:Fex (x＝0,1.5,2,2.5) single crystals have been synthesized. Excell ent pseudoelasticities were observed in compression, bending and torsion. At roo m temperature, the perfect pseudoelastic strains of 4% and 6.7% were obtained in the ［100］ and ［110］ directions of the Co50Ni22Ga 28:Fe2 single crystal under compression, respectively. The stre ss-strain curve for the Co50Ni22Ga28:Fe1.5 single crystals shows an indistinct platform on loading, and an intermar tensitic transformation occurs with unloading. The platform of the curve on load ing becomes clear and the intermartensitic transformation with unloading becomes indistinct at the high temperature of 100℃. Pseudoelastic strains of 5.5% wer e obtained in the ［001］ direction of the Co50Ni22Ga 28 :Fe2.5 single crystal. In addition, the single crystals show strong elastic anisotropy.
Mechanism of nonlinear dielectric constant of BaTiO３-based ceramics under high DC electric field
Authors: Liang Rui-Hong  , Dong Xian-Lin  , Chen Ying  , Cao Fei  , Wang Yong-Ling  ,   中国科学院上海硅酸盐研究所,上海  200050
Published: December 2020

Ba0.6Sr0.4TiO３（ＢＳＴ） and Ba(Zrx Ti1-x)O３（ＢＺＴ） (x=0.25,0.3,0.35,0.4) ceramics were pr epared by traditional ceramic processing and their structural, dielectric proper ties as well as the mechanism of its nonlinear dielectric constant under dc elec tric field were systemically examined. The results show that the phenomenologic al theory of Devonshire can be applied to BST system when the material is in the paraelectric state, and the equations εr(app)εr(0)=1［1 +αε3r(0)E2］1/3 and ε(E)=ε1 -ε2E2+ε3E4 can give a quanti tative explaination of its nonlinear dielectric behavior under high DC electric field. where εr(0) and εr(app) are the dielectric cons tants under zero DC field and under the applied field respectively, α is the an harmonic coefficient, Ｅ is the strength of electric field, ε(F) is the dielect ric constant under the applied field and ε１，ε2，ε3 is linear, nonlinear and high order dielectric constant respectively . When the BST system is in the ferroelectric or phase transition state, the dom ain and domain wall's extrinsic contributions to the nonlinear dielectric consta nt cannot be neglected, and the extrinsic contributions decrease with the increa se of the strength of the electric field. For the relaxor-like BZT system, even if it is in paraelectric state, the extrinsic contribution of polar microregion s to the nonlinear dielectric constant can be markedly observed. With the incre ase of the strength of the electric field and temperature, this contribution dec reases.
Generation and detection of terahertz radiation on reactive ion etched ZnTe surfaces
Authors: He Li-Rong  , Gu Chun-Ming  , Shen Wen-Zhong  , Cao Jun-Cheng  , Hiroshi Ogawa  , Guo Qi-Xin  ,   (1)上海交通大学物理系凝聚态光谱与光电子物理实验室,上海  200030，中国; (2)中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室,上海  20005 0，中国; (3)佐贺大学理工学部电气与电子工程系,佐贺  840-8502,日本
Published: December 2020

Electro-optic sampling technique is employed to reveal the generation of teraher tz (THz) radiation via optical rectification from reactive ion etched ZnTe surfa ces. The pulsewidth of the observed THz radiation is ～0.25ps. The electro-optic coefficient of the ZnTe samples is found to decrease with the increase of the r adio frequency (RF) power. By calculating the frequency response function, we di scuss the THz bandwidth under different values of RF plasma power.
Synthesis of carbon nanotubes using alumina template and its thermal annealing effects
Authors: Wang Sen  , Yu Guo-Jun  , Gong Jin-Long  , Zhu De-Zhang  , He Sui-Xia  , Zhu Zhi-Yuan  , Xu Hong-Jie  ,   中国科学院上海应用物理研究所，上海  201800
Published: December 2020

Highly uniform multiwall carbon nanotubes (MWCNTs) were synthesized using templ ate confining growth technique in combination with high temperature annealing. Scanning electron microscopy (SEM) images show that the morphology and dimensi on of raw carbon nanotubes (CNTs) synthesized by template confining growth techn ique is completely controlled by the template structure. Transmission electron m icroscopy (TEM) and x-ray powder diffraction (XRD) studies reveal that the tube wall has a mixed structure of amorphous carbon and graphite nanocrystallites. To reduce crystallite defects and the content of amorphous carbon, a series of hig h temperature annealing (1100—2400℃) of the raw CNTs were carried out. In addi tion, the tube wall crystallization behavior under high temperature was prelimin arily studied. The experiment results show that high temperature annealing is an effective way to improve the quality of MWCNTs.
The two generalized solutions for the stationary axisymmetric vacuum garvitational field
Authors: Wu Ya-Bo  , Dong Peng  , Zhao Guo-Ming  , Deng Xue-Mei  ,   辽宁师范大学物理系，大连  116029
Published: December 2020

In this paper by applying Ehlers transformation to Schwarzschild and Kerr soluti ons of Ernst equation and introducing the proper coordinate transformations, the two solutions of the Ernst equation, i.e., the so called generalized NUT-Taub ( GNT) solution and generalized Kerr-NUT (GKN) solution are obtained, which not on ly can reduce to the well-known Schwarzschild and Kerr solutions when the parame ter L=0, but also can also reduce to the NUT-Taub metric and Kerr-NUT metric res pectively when the parameter LM and if taking 1-LM2≈1. It is showe d that in the NUT-Taub and Kerr-NUT solutions the range of value for the paramet er l (interpreted as the gravomagnetic monopole) can't be arbitrary and should be limited by mass of the source to |l|M.
Hyperbolic phase transformation group and its applicaton to four-dimensional relativistic spacetime
Authors: Wu Ya-Bo  , Deng Xue-Mei  , Zhao Guo-Ming  , Li Song  , Lü Jian-Bo  , Yang Xiu-Yi  ,   辽宁师范大学物理系,大连  116029
Published: December 2020

The hyperbolic complex space RH defined by the Clifford algebra and the hyperbolic phase transformation group U4(H) acting on RH are endowed with definite physical meaning in this paper. The hyperbolic complex space RH is isomorphic to the 4-dimensional(4D) Minkowski spacetime, and the hyperbolic phase transformation group U4(H) in RH is just Lorentz transformation group on 4D relativistic spacetime. Furthermore, the general expressions of Lorentz transformation and the velocity transformation on 4D Minkowski spacetime are naturally derived using the composite transformations of the group U4(H). Hence, the well-known special Lorentz transformation in the special relativity(SR) is contained as a special case in our discussions.
Study on stability of the voltage-mode DC-DC converters
Authors: Zhao Yi-Bo  , Luo Xiao-Shu  , Fang Jin-Qing  , Wang Bing-Hong  ,   (1)广西师范大学物理与信息工程学院,桂林  541004; (2)中国科学技术大学近代物理系，合肥  230026; (3)中国原子能科学研究院，北京  102413
Published: December 2020

Stroboscopic maps for voltage-mode converters in the continuous conduction mode (CCM) are build up. The stability of one-periodic point is analyzed together with eigenvalues of Jacobian matrix of discrete-maps. The voltage-mode buck converter is taken as an example, and the results of theoretical analysis and numerical simulation coincide with each other, which shows that the stability analysis of the DC-DC converters is feasible using the discrete-map model.
A neuro-fuzzy method for predicting the chaotic time series
Authors: Hu Yu-Xia  , Gao Jin-Feng  ,   郑州大学电气工程学院，郑州  450002
Published: December 2020

A neuro-fuzzy approach based on a novel hybrid learning method is presented, which can generate the best fuzzy rule set automatically from the desired input-output data pairs only and can give the initial neuro-fuzzy system and the initial parameters of fuzzy membership functions. Then the parameters of fuzzy membership functions and the weights can be easily tuned by employing neural network's self-learning techniques. This approach reduces the rule matching time and accelerates the speed of the fuzzy logic referencing and improves the adaptability of the neuro-fuzzy system. Using the proposed neuro-fuzzy system and the learning algorithms we simulated the prediction of the Lorenz chaotic time series, the results demonstrate the effectiveness of the chaotic time series prediction approach.
A new chaotic circuit and its experimental results
Authors: Zhou Ping  , Luo Xiao-Hua  , Chen Hai-Yan  ,   (1)重庆邮电学院非线性系统研究所，重庆  400065; (2)重庆邮电学院通信学院，重庆  400065
Published: December 2020

This paper reports a new chaotic circuit, which consists of only a few OpAmps, capacitors, and resistors. The chaotic attractor obtained via computer simulation, has one positive Lyapunov exponent. To supplement the computer simulation, a physical circuit implementation is designed. Some experimental results are given.
Cluster-assisted multiple ionization of CS2 by intense nanosecond laser beam
Authors: Xiao Xue  , Li Hai-Yang  , Luo Xiao-Lin  , Niu Dong-Mei  , Wen Li-Hua  , Wang Bin  , Liang Feng  , Hou Ke-Yong  , Zhang Na-Zhen  ,   (1)中国科学院大连化学物理研究所，大连  116023; (2)中国科学院大连化学物理研究所，大连  116023;中国科学院环境光学与技术重点实验室,中国科学院安徽光学精密机械研究所，合肥  230031; (3)中国科学院环境光学与技术重点实验室,中国科学院安徽光学精密机械研究所，合肥  230031; (4)中国科学院环境光学与技术重点实验室,中国科学院安徽光学精密机械研究所，合肥  230031;中国科学院大连化学物理研究所，大连  116023
Published: December 2020

Photoionization of CS2 clusters seeded in helium is studied by time-of-flight mass spectrometry using a 25 ns, 532 nm Nd: YAG laser beam of intensity about 8×1010 W/cm2. Multiply charged ions of C2+, S2+ of hundreds of eV have been observed when the laser beam irradiates the most dense portion of the pulsed molecular beam. An electron re-scattering and re-colliding ionization model is proposed to explain the appearance of the multiply charged clusters under such low laser intensity.
Temperature measurement of cold atoms in a cesium magneto-optical trap by means of short-distance time-of-flight absorption spectrum
Authors: Geng Tao  , Yan Shu-Bin  , Wang Yan-Hua  , Yang Hai-Jing  , Zhang Tian-Cai  , Wang Jun-Min  ,   量子光学与光量子器件国家重点实验室，山西大学光电研究所,太原  030006
Published: December 2020

We report the basic idea and experimental demonstration of measuring the temperature of cold cesium atomic cloud confined in a magneto-optical trap (MOT) by analyzing absorption spectrum observed in the short-distance time-of-flight (TOF) method. Compared with the conventional TOF scheme, we measure the temperature of cold atomic cloud in MOT by short-distance TOF method for our small vapor cell. If the cold atomic cloud is released, it will fall and expand due to gravity and its initial velocity distribution. Utilizing a cylindrical resonant probe beam positioned several millimeters beneath the MOT (in this paper, we analyzed the cases for 3mm, 5mm, and 8mm of center-to-center distance between the MOT region and the probe beam, respectively), we can record the short-distance TOF absorption spectrum with a photodiode when cold atoms go through the probe region. Analysis of the short-distance TOF absorption spectrum yields the effective temperature of the cold cloud in MOT.
Calculation of ionization potential and geometry of small yttrium metal clusters
Authors: Mao Hua-Ping  , Yang Lan-Rong  , Wang Hong-Yan  , Zhu Zheng-He  , Tang Yong-Jian  ,   (1)四川大学原子分子物理所，成都  610065; (2)中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)重庆三峡学院化学系，万州  404000; (4)重庆三峡学院化学系，万州  404000;四川大学原子分子物理所，成都  610065
Published: December 2020

The equilibrium geometrical structures of ground state of small Yn(n＝2—8) clusters are optimized by mean of density functional theory(DFT), and the ionization potentials are calculated. The results show that the most stable structures of clusters tend to maximize the average coordination number of Y atoms. The value of ionization potential shows uo magic number or odd-even alternations, this would imply that the threshold for photoionization occurs mainly from a localized 4d orbital rather than from a 5s orbital of Y clusters. It is the first time to come up with a modification of the analytical formula of calculating ionization potential of Y clusters proposed by Tomasz, and the new analytical formula is in better agreement with experiment.
Electromagnetic scattering interaction between a conducting plate and a 2-D conducting slightly rough surface
Authors: Guo Li-Xin  , Wang Yun-Hua  , Wu Zhen-Sen  ,   西安电子科技大学理学院，西安  710071
Published: December 2020

Electromagnetic scattering with interaction between the perfect conducting plate and the 2-D conducting slightly rough surface is investigated. Taking the advantage of s newly developed technique that utilizes the reciprocity theorem, the difficulty in formulating the secondary scattered fields from the composite target is reduced to the evaluation of integral equation involving the polarization currents of the conducting plate and the scattered fields from the slightly rough surface. The polarization currents on the plate and the electromagnetic scattering field are solved by using physical optics approximation and small perturbation method, respectively, and the solution for the composite scattering cross section is obtained and calculated. In particular, the results of backscattering from the composite mode are discussed in detail.
An approach to expand the beam coefficients for arbitrarily shaped beam
Authors: Han Yi-Ping  ,   西安电子科技大学理学院应用物理系，西安  710071
Published: December 2020

We present an approach to expand the shaped beam in terms of the spheroidal wavefunctions in spheroidal coordinates for a spheroidal particle illuminated by off-axis arbitrarily shaped beam. The relations between shaped beam coefficients in spherical coordinates and the different range of mode are discussed. Once the beam-shape coefficients are determined, the solution of scattering for arbitrarily shaped beam by a homogeneous particle can be obtained.
Analytical solution to the spatial optical solitons propagating in the strong nonlocal media
Authors: Zhang Xia-Ping  , Guo Qi  , Hu Wei  ,   华南师范大学信息光电子科技学院激光传输实验室，广州  510631
Published: December 2020

This paper discusses the optical beam (1+2D) of suitable input power propagating in the strong nolocal nonlinear media,which is governed by the Snyder-Mitchell model in the cylindrical coordinate.An exact analytical solution in Laguerre-Gaussian form is obtained.It is shown that the solution in the Gaussian form is the lowest-order mode.It is found for the first time that the necklace-ring spatial soliton exists in the strong nonlocal media.
(1+2)D interaction of strong nonlocal optical spatial solitons
Authors: Xu Chao-Bin  , Guo Qi  ,   华南师范大学信息光电子科技学院传输光学实验室，广州  510631
Published: December 2020

Strong optical spatial solitons are solitons that satisfy the strong nonlocal condition.We discuss the nonplanar interaction of a pair of (1+2)D optical spatial solitons with symmetrical oblique incidence on the basis of Snyder and Mitchell's revolutionary work［Accessible solitons.Science,1997,276(6):1538—1541］.An accurate analytical solution in Gaussian form is obtained for the first time.It is shown that rrapping of two beams in a stable spiraling is possible for a large range of parameters.The spiraling structure does not depend on the initial relative phase.The projection of the wto beam centers in the transverse coordinate plane lies always in the same ellipse.It is possible to find its applications in planar all-optical swithching and all-optical interconnection in bulk media.
The mutually-trapped propagation of orthogonally polarized beam pair in plannar waveguides
Authors: Xiao Yi  , Guo Qi  ,   (1)华南师范大学信息光电子科技学院传输光学实验室，广州  510631; (2)暨南大学物理系，广州  510632;华南师范大学信息光电子科技学院传输光学实验室，广州  510631
Published: December 2020

The propagation of two orthogonally polarized coaxial light beams in plannar waveguides is studied by variational approach as well as numerical method. The condition for soliton-like mutually-trapped propagation of the two beams is obtained. We analysed the different characteristics of mutually-trapped propagation in two cases with or without linear birefringence. We find that there is an essential difference between mutually-trapping beams and the rigorous vector spatial soliton.