bluuebunny/crossref_metadata_2025 huggingface dataset:
Normalized intensity fluctuation for bias signal modulation in a single-mode laser driven by colored correlated noises
Authors: Han Li-Bo  , Cao Li  , Wu Da-Jin  , Wang Jun  ,   (1)华中科技大学激光技术国家重点试验室,武汉 430074; (2)华中科技大学激光技术国家重点试验室,武汉 430074;长江大学物理系,荆州 434020; (3)华中科技大学物理系,武汉 430074
Published: December 2020

Using the linear approximation method, the normalized intensity fluctuation(NIF) for bias signal modulation is calculated in a gainnoise model of a singlemo de laser driven by colored correlated noises, in which each is colored; and the influences of the strength of bias signal modulation, the frequency of period si gnal, the correlation strength and correlation time of noises on NIF is studied in detail. We observed that a minimum appears in the NIF versus pump noise inten sity curve and quantum noise intensity curve; the normalized intensity fluctuati ons of a singlemodel laser for bias signalmodulation and direct signal modul ation are compared.
Analyses of guiding properties of light-induced planar waveguides in LiNbO3:Fe crystals
Authors: Zhang Peng  , Zhao Jian-Lin  , Yang De-Xing  , Wang Mei-Rong  , Sun Yi-Dong  ,   西北工业大学应用物理系,西安 710072
Published: December 2020

To our knowledge, we first deduced the analytic expression of the indexchanged istribution in LiNbO3:Fe crystal induced by a Gaussian sheet beam considering th e photorefractive onecenter model and the photovoltaic charge carriers transp or tmechanism. A planar waveguide structure was fabricated by sheet beam illuminat ion employing the sandwich method in LiNbO3:Fe crystal. The index distribu tion i n the waveguide region was measured by using interferometric technique and the g uiding test was also performed. The rationality of the deduced analytic expression was demonstrated by the fitting results of the measured data point. Based on the ray equation, the guiding properties of the light-induced waveguide were analyzed by using numerical simulation. The results show that the interferom etric technique is valid for measuring the index distribution of waveguide with large width, and the guiding properties of the lightinduced waveguide structures depend on the waveguide width strongly. Using sheet beam with small width, planar waveguide structure with high quality can be fabricated in LiNbO3:Fe cryst al . And the analytic expression of the indexchangedistribution can be employed to predict the guiding properties of the lightinduced waveguide.
Octave-spanning spectrum generation in Ti: sapphire oscillator
Authors: Wang Zhuan  , Wang Qing-Yue  , Han Ying-Kui  , Cao Shi-Ying  , Zhang Zhi-Gang  , Chai Lu  ,   天津大学精密仪器与光电子工程学院超快激光研究室,光电信息技术科学教育部重点实验 室,天津 300072
Published: December 2020

A Ti: sapphire oscillator emitting an octavespanning spectrum that ra nges from 460nm to 1000nm is demonstrated. To our knowledge, it is the first tim e that a supercontinuum extending beyond 500nm in the blue end is generated from a femtosecond oscillator. The selfQswitched and selfmodelocked Ti: sapphi re oscillator uses chirped mirrors and a prism pair for dispersion compensation. Th ese results will make the measurement of carrierenvelope offset frequency simp ler and improve the stability of optical frequency metrology at the same time.
Characteristics of two-electron-temperature in inductively coupled CF4 plasmas
Authors: Huang Song  , Ning Zhao-Yuan  , Xin Yu  , Gan Zhao-Qiang  ,   苏州大学物理科学与技术学院，苏州 215006
Published: December 2020

The characteristics in low-pressure inductively coupled CF4 plasma have been-inv estigated using a Langmuir probe method. Results for the CF4 gas have shown that there are two electron populations: one with low temperature and high densit y and the second w ith higher temperature and lower density, in this region. Fast electron temperat ure The, slow electron temperature Tceand mean electron tem perature Te decrease , while their densities nhe,nce, ne increase with in creasing r.f. input pow er. Our findings suggest that the dependence of two-electron-temperature on r. f.input power can be explained by the thermodynamic equilibrium of the collision between electrons and particles.
Shock wave driven by x-ray radiation from cylindrical hohlraum on Shenguang Ⅱlaser
Authors: Jiang Shao-En  , Li Wen-Hong  , Sun Ke-Xi  , Jiang Xiao-Hua  , Liu Yong-Gang  , Cui Yan-Li  , Chen Jiu-Sen  , Ding Yong-Kun  , Zheng Zhi-Jian  ,   中国工程物理研究院激光聚变研究中心，绵阳 621900
Published: December 2020

A high Z cylindrical hohlraum was used to produce xray radiation flux, whic h was used to drive shock waves in an Al step sample. The radiation temperature i s 15 5eV. Experiments were carried ont on `Shenguang II' laser facility, with eight 2 50J, 0.35μm wavelength, 1ns Gaussian laser pulses. The planar and preheatfre e s ho ck wave was generated and a clear image of shock and preheat wave was obtained . The shock wave velocity and pressure was 31.2km/s and 17.5×1011Pa, respectively.The radiation temperature measured by streaked pyrometer, was consistent with th at measured with a soft x-ray spectrometer which views through the laser entran ce hole.
Plasma-induced transformation of carbon nanotubes to nanocrystalline diamond
Authors: Sun Li-Tao  , Gong Jin-Long  , Zhu Zhi-Yuan  , Zhu De-Zhang  , He Sui-Xia  , Wang Zhen-Xia  ,   中国科学院上海应用物理研究所，上海 201800
Published: December 2020

Structural phase transformation from multiwalled carbon nanotubes to nanocr ystalline diamond by hydrogen plasma posttreatment was carried out. Ultrahigh equivalent diamond nucleation density above 1011 nuclei/cm2 was easily obtained . The diamond formation and growth mechanism was proposed to be the consequence of the formation of sp3 bonded amorphous carbon clusters. The hydrogen chemi so rption on curved graphite network and the energy deposited on the carbon nanotu bes by continuous impingement of activated molecular or atomic hydrogen are resp onsible for the formation of amorphous carbon matrix. The diamond nucleates and grows in the way similar to that of diamond CVD processes on amorphous carbon films. The present method of hydrogen treatment provides a controllable way for the CVD of high quality diamond films.
The calculation of strain distribution in quantum dots with Green method
Authors: Guo Ru-Hai  , Shi Hong-Yan  , Sun Xiu-Dong  ,   哈尔滨工业大学应用物理系,哈尔滨 150001
Published: December 2020

There is considerable interest in the study of self_assembled quantum dots as on e of the new optoelectronic materials in the field of physics. It is interest ing in theory, and also applications. In this article, we consider the InAs isla nds buried in GaAs, because of large lattice mismatch (≈-0.067), which makes s t rain effect to be the main factor in the formation of quantum dots. Most methods for calculations of strain distribution are based on the numerical solution of qu antum dots structures, which need heavy calculations work. We present a detailed process to derive an analytical formula for the strain distribution in some f am iliar shapes of quantum dots with Green function method, and discuss their influ ence on the strain distribution in quantum dots by taking into account the anisotr opy of elastic properties and shape. The results showed that the strain distribu t ions in the major part of the quantum dot structure are very similar for differe nt shapes and that the characteristic value of the hydrostatic strain component depends o nly weakly on variation of the shape of quantum dots.
Highly deep levels in solid C70/p-GaAs structures
Authors: Ran Guang-Zhao  , Chen Yuan  , Chen Kai-Ｍao  , Zhang Xiao-Lan  , Liu Hong-Fei  ,   (1)北京大学物理学院，北京 100871; (2)北京有色金属研究院，北京 100088; (3)福州大学电子科学与应用物理系，福州 350002
Published: December 2020

An acoustoelectric current is induced by a surface acoustic wave (SAW) launched along the quasionedimensional electron channel defined in a GaAs/Al x Ga1-x As heterostructure by split gates. Using the WKB approxima tion, the acoust oelectric current is calculated when only one electron is captured in the quantu m well. We discussed the effect on acoustoeletric current caused by SAW power, S AW frequency, gate voltage and sourcedrain bias.
Calculation of acoustoelectric current in a quasi-one-dimensional electron channel
Authors: Gao Hong-Lei  , Li Ling  , Gao Jie  ,   四川大学物理科学与技术学院，成都 610064
Published: December 2020

An acoustoelectric current is induced by a surface acoustic wave (SAW) launched along the quasionedimensional electron channel defined in a GaAs/Al x Ga1-x As heterostructure by split gates. Using the WKB approxima tion, the acoust oelectric current is calculated when only one electron is captured in the quantu m well. We discussed the effect on acoustoeletric current caused by SAW power, S AW frequency, gate voltage and sourcedrain bias.
In-situ photo-modulated reflectance study on the interface of Al and GaAs surface quantum well
Authors: Yuan Xian-Zhang  , Miao Zhong-Lin  ,   (1)温州师范学院物理与电子信息学院，温州 325027; (2)中国科学院上海技术物理研究所，红外物理国家实验室，上海 200083
Published: December 2020

We have studied the optical properties of the interface of Al and GaAs surface q uant um well by insitu photoreflectance (PR) spectroscopy in a molecular beam e pitax y (MBE) system. The intermixing of Al and GaAs surface quantum wells forms an AlxGa1-xAs barrier layer on GaAs, which would shift the inte r_band transition peaks of the GaAs quantum well. Based on the calculation using effective mass approximate method, we fi nd that the intermixing length is 0.5nm, which is an important parameter in sem iconductor technology.
First principles study of interstitial Mn self-compensation effects in (Ga,Mn)As
Authors: Guo Xu-Guang  , Chen Xiao-Shuang  , Sun Yan-Lin  , Zhou Xiao-Hao  , Sun Li-Zhong  , 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，200083
Published: December 2020

The effects of interstitial Mn (MnI) atoms on the electronic and magnet ic properties of (Ga,Mn)　As are studied within the pseudopotential plane_wave f rame work based on the density functional theory. Numerical results show that MnI atoms are donors in GaAs. The Mn atoms that substitute for Ga sublattices (MnGa) and MnI are antiferromagnetically coupled. The static electrical interaction makes the MnGaand MnI atoms tend to form MnGa_MnI pairs. The MnI atoms not only compensate the holes, and reduce the hole density of (Ga,Mn)As, but also deactivate MnGaatoms. The existence of MnI atoms are very disadvantageous for obtaining (Ga,Mn)As samp les having high Curie temperatures.
Interaction of the optical activity and electro-optic effect and its influence on the optically active crystal electro-optic Q switcher
Authors: Yin Xin  , Wang Ji-Yang  ,   山东大学晶体材料研究所，晶体材料国家重点实验室，济南 250100
Published: December 2020

In this paper, the interaction between the optical activity and electr o_optic effect has been studied, and its influence on the electro_optic Q s witcher made of the optically active crystal has also been studied.
Fabrication and photonic band gap property of the two-dimensional square lattice based on silicon
Authors: Zhou Mei  , Chen Xiao-Shuang  , Xu Jing  , 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

Two_dimensional air_cylinder photonic crystals were fabricated based on silicon by using the multiplex inductively coupled plasma system supplied by STS company . Photonic band gap was theoretically calculated by using the finite different t ime domain (FDTD) method, and the reflection spectrum was measured experimentall y using the microscope infrared spectrometer instrument. We find that the reflec tion measurements are in good agreement with the theoretically expected behaviour.
Z-scan measurements on photoisomerization of azobenzene polymer and their theoretical interpretation
Authors: Liang Jian-Chu  , Wang Xiao-Sheng  , Luo Duan-Bin  , She Wei-Long  , Wu Shui-Zhu  , Zeng Fang  , Tang Tian  , Yao Sheng-Lan  ,   (1)华南理工大学材料学院高分子系, 广州 510640; (2)中山大学光电材料与技术国家重点实验室,广州 510275
Published: December 2020

Z_scan experiments are performed on the azobenzene polymer (DR_13_PMMA) films with He_Ne laser. It is found that the relation between the cha nge of refractive index of the sample and the light intensity behaves like a sat u rable effect, whose relative parameters are alterable with light intensity. It i s also found that the change of refractive index induced by linearly polarized l ight is distinctly greater than that induced by circularly polarized light. The phenomena are explained by using the theory based on the effect of angular hole burning of photoisomerization.
Small angle x-ray scattering study of precipitation in Al-Zn-Mg-Cu alloys
Authors: Du Zhi-Wei  , Zhou Tie-Tao  , Zhao Hui  , Feng Lin-Ping  , Dong Bao-Zhong  , Chen Chang-Qi  ,   (1)北京航空航天大学材料科学和工程学院,北京 100083; (2)中国科学院高能物理研究所同步辐射实验室,北京 100039
Published: December 2020

The evolution of microstructural parameters (mean size and volume fracti on) of precipitates in three types of Al_Zn_Mg_Cu alloys during ageing has been studied by synchrotron_radiation small angle x_ray scattering (SAXS). The influe nce of Zn content on the precipitation has been analyzed. The results show that the precipitates are in nanometer scale for the three types alloys (A, B, C) . Th e maxima of the precipitate volume fractions forA, Band Cincrease wi th Zn content and are about 0.023—0.028, 0.052—0.054 and 0.04 respectively The evolution of volume fra ction at a certain temperature is consistent with the kinetic process of precipi tate nucleation, growth and Ostwald ripening.
High electric-field-induced strain of Pb (Mg1/3Nb2/3)O3-PbTiO3 crystals and their application in multilayer actuators
Authors: Feng Zu-Yong  , Luo Hao-Su  , Yin Zhi-Wen  , Guan Chun-Lin  , Ling Ning  ,   (1)中国科学院光电技术研究所，成都\ 610209; (2)中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室，上海 \ 201800; (3)中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室，上海 201800
Published: December 2020

An optimum composition range （29％≤x≤31%） of 〈001〉 oriented (1_x)P b(Mg1/3Nb2/3)O3_xPbTiO3(PMNT) crystals was ascertain ed for multilayer actuator applications, which exhibited high_strain and low_hyster esis behavior. A nearby -2kV/cm negative E_field can be applied to PMNT ferr oele ctric samples with low hysteresis. Forty_layer PMNT strain actuators with indiv idua l element sizes of 7mm×7mm×0.7mm were fabricated from their optimum composit ions, with displacements of 38.1μm at E_fields from -1.5 to 10 kV/cm. Wh en a 4 kg load was added to the PMNT multiplayer actuators, the displacements we re decreased to 34 μm.
Influence of rf power on the microstructure and magnetic properties of Fe-Si-B-Nb-Cu thin films
Authors: Shi Wang-Zhou  , Liang Rui-Sheng  , Ma Xue-Ming  , Yang Xie-Long  ,   (1)华东师范大学物理系,上海\ 200062; (2)华东师范大学物理系,上海\ 200062;汕头大学物理系,汕头\ 515063
Published: December 2020

Fe_Si_B_Nb_Cu alloy thin films were deposited by radio frequenc y (rf) magnetro_sputtering. Their microstructures have been analysed by x_ray di ffraction (XRD) and Mssbauer spectrum. The results show that the thin films, p repared by low rf power, are amorphous. With the increase of rf power, the depo sited thin films were turned to be a mixted structure composed of nano_crystals and amorphous matrix. The nano_crystals contain α_Fe(Si) and α_Fe(B) solid solutio ns, which are in nanometer size, their relative volume fractions, atomic assembly features , magnetic moment orientations and macro_magnetic properties are changed under d ifferent rf powers.
The discussion on Lagrange equation containing third order derivatives
Authors: Ma Shan-Jun  , Xu Xue-Xiang  , Huang Pei-Tian  , Hu Li-Yun  ,   江西师范大学物理与通信电子学院,南昌　330027
Published: December 2020

In this paper, the third order Lagrange equation is obtained, by which can be obtained motion equation of a body. This equation contains third order rate of change of generalized coordinates and the rate of change of force. In addition, the third order Lagrange equation and the fraditional Lagrange equation are used to solve the same problem of the motion of a body, and their results are discussed. Finally, it is pointed out that the third order Lagrange equation provides a method of obtaining equation of motion which is different from that of the traditional Lagrange equation.
Gazeau-Klauder and Klauder-Perelomov coherert states for the anharmonic oscillator
Authors: Cheng Yan-Fu  ,   中南民族大学物理系,武汉　430074
Published: December 2020

Using the Kinani-Daoud method we have constructed the Gazeau-Klauder(GK) and KlauderPerelomov(KP) coherent states for the anharmonic oscillator. It is shown that the two types of coherent states have totally different forms in their expressions. We have also discussed the resolution of unity of the two coherent states and the Hilbert space of each state. The study of Mandel Q pa rameter of the states shows that GK coherent state coincides with the sub-Poissonian and KP coherent state coincides with the super-Poissonian statistical distributions.
A nonuniform ratchet model with Gausstransition rates for Brownian motor
Authors: Li Wei  , Zhao Tong-Jun  , Guo Hong-Yong  , Ji Qing  , Zhan Yong  ,   (1)河北工业大学电气工程学院,天津　300130; (2)河北工业大学理学院,天津　300130; (3)河北工业大学理学院,天津　300130；河北工业大学电气工程学院,天津　300130
Published: December 2020

A nonuniform ratchet model with Gauss-transition rates is proposed to discuss the directional motion of Brownian particles in an asymmetrical periodic potential. It is assumed that the particles experience several internal states in a single mechanical-chemical circle. In this model, the transition rates between diff erent states are position-dependent, which have the form of Gaussian function. For any internal states, the probability distribution as a function of time and position may be expanded near the transition points to any rank if necessary. Fin ally, the focus of our study is concentrated on a two-state model, in which we choose (M, K)=(2, 2) and calculate the average current as a function of the transition width, temperature and transition rate. It is revealed that the trans ition width influences the current greatly.
The driven-effect of external fluctuation on phase separation of binary mixtures
Authors: Feng Wen-Qiang  , Zhu Yue-Jin  ,   (1)宁波大学物理系,宁波　315211; (2)宁波大学物理系,宁波　315211；南京大学固体微结构物理国家重点实验室,南京　210093
Published: December 2020

Using the Monte Carlo method, we have investigated the effect of the external noise on the phase-separation dynamics in binary mixtures. It is found that the addition of the fluctuation has speeded up the pattern growth, and driven the system to form［1,1］oriented tilted strip formation. When the noise intensity is fixed and the noise acting probability is less thanp=0.015, the noise will erase the effect of the deep quench, and the system will avoid being frozen.With the increase of the noise acting probability, the structure factor will grow linearly. If the noise intensity is adequate, in an appropriate noise acting probability region, the system can form a high-oriented tilted strip pattern.
Average path length of Internet with power law degree distribution
Authors: Li Ying  , Shan Xiu-Ming  , Ren Yong  ,   清华大学电子工程系,北京　100084
Published: December 2020

The average path length of Internet with power law degree distribution is stud ied in this paper. The main work is to give a formula to compute the average pat h length . The essential of Internet or many other complex networks is to realize the least cost (the smallest total number of edges) and the best benefi t (the short average path length), which can be expressed as two optimization fa ctors to minimize the average degree and the average path length . By analyzing the main factor affecting , we find the main property of p ath length distribution P(l), and then give a formula of P(l) only inclu ding one parameter α. This work shows that P(l) and a direct relation with P(k),and α represent the effective link between nodes and the tota l number of networks on . This formula makes it possible that if we get the α of P(k)～k-α, we can calculate easily. The simulati on shows the formula is quite exact. Our method is successful. In the end, we di scuss that the parameter αis very important for Internet design.
A method for controlling hyperchaos of Er-doped fiber laser——Nonlinear time-delay feedback modulating-parameter
Authors: Zhang Sheng-Hai  , YangHua  , Qian Xing-Zhong  ,   中国人民解放军信息工程大学理学院数理系，郑州  450001
Published: December 2020

We present a method of nonlinear time-delay feedback modulating/parameter to control chaos/hyperchaos.A scheme of controlling the hyperchaotic dualring Er-doped fiber laser by using this method is proposed.Numerical simulation shows th at a hyperchaotic dual-ring Er-doped fiber laser can be successfully controlle d into different periodic states by this method only when the delay time and fee dback intensity are suitably matching.
Step scan time resolved spectroscopy and its application to photoconductivity of Si solar cells*
Authors: Zhu Jian-Min  , Shen Wen-Zhong  ,   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
Published: December 2020

We report on the establishment of Fourier transform step-scan time-resolved photoconductivity spectroscopy to study the solar cell's minority carrier lifetime ,which has close relationship with its conversion efficiency.Three typical Si so lar cells are selected in our experiments,including both the monocrystalline and polycrystalline silicon samples.We find that the rise and decay curves of the t ransient photoconductivity can be well described by two simple exponential funct ions.Due to the participation of recombination centers,the recombination minorit y carrier lifetimes are generally smaller than those of generation.In order to p rove the reliability of our experimental results,we extract the bulk lifetime an d the effective diffusion length of the three samples.Furthermore,we analyze the correlation of the minority lifetime with the shortcircuit current,open volta ge and conversion efficiency,by the aid of the investigation of solar cells' dark I-V characteristics and load characteristics.In addition,we also discuss in detail other applications of the established stepscan time-resolved spect roscopy.
Nonparaxial vector Gaussian beams diffracted at a circular screen*
Authors: Liu Pu-Sheng  , 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华中科技大学激光技术国家重点实验室，武汉  430074
Published: December 2020

By using the vector Rayleigh diffraction integrals, an analytical expression for the diffraction of nonparaxial vector Gaussian beams at a circular screen is de rived. The diffracted on-axis field and farfield expressions and free-space pro pagation equation of nonparaxial vector Gaussian beams, as well as the paraxial Fresnel and Fraunhofer diffraction formulae of Gaussian beams diffracted at a ci rcular aperture are treated in a unified way as special cases of our general res ult. Numerical comparative examples are given to illustrate the intensity distri butions and far-field behavior of nonparaxial vector Gaussian beams. It is show n that for the diffraction at the circular screen both the f-parameter and truncation parameter affect the beam nonparaxiality.
Experimental studies of Ni-like Ta x-ray laser
Authors: Wang Chen  , Wang Wei  , Wu Jiang  , Dong Jia-Qin  , Sun  Jin-Ren  , Wang Rui-Rong  , Fu Si-Zu  , Gu Yuan  , Wang Shi-Ji  , Huang Guan-Long  , Lin Zun-Qi  , Zhang G uo-Ping  , Zhang Tan-Xin  , Zheng Wu-Di  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)中国科学院上海光学精密机械研究所，上海  201800; (3)中国科学院上海激光等离子体研究所，上海  201800
Published: December 2020

The experimental studies of Ni-like Ta x-ray laser at near “water window" on Shenguang Ⅱ laser facility were reported. By using a new scheme of united driving of fundamental- and double-frequency laser, the distinct spectrum signal of N i-like Ta x-ray laser at 4.48 nm was obtained under the total drive energy of 400J. The efficient gain-length product was about 5.5
Nonlinear optical properties of mixed Cd0.35Hg0.65Ga2S4 crystal*
Authors: Huang Jin-Zhe  , Ren De-Ming  , Hu Xiao-Yong  , Qu Yan-Chen  , Y.Andreev  , P.Geiko  , V. Badikov  , G.Lanskii  ,   (1)Institute for Optical Monitoring SB RAS,Tomsk  634055,Russia; (2)Kuban State University,Krasnodar  350040,Russia; (3)哈尔滨工业大学光电子研究所，哈尔滨  150001; (4)哈尔滨工业大学光电子研究所，哈尔滨  150001;哈尔滨理工大学电子科学与技术系，哈尔滨  150080;
Published: December 2020

The linear and nonlinear optical properties,as well as phase-matching of mixed Cd0.35Hg0.65Ga2S4 nonlinear crystal are investigated. Da mage threshold is determined in comparison with the widely used middle IR crystal under identical experimental conditions. CO2 laser second harmonic generatio n (SHG) is realized in this crystal at a phase-matching angle in well coi ncidence with estimation.
Induced focusing due to two optical beams　counterpropagating in self-defocusing nonlinear media*
Authors: Jiang Xiu-Juan  , Li Hua-Gang  , Guo Qi  , Hu Wei  ,   华南师范大学传输光学实验室,广州　510631
Published: December 2020

In this paper,a research work is done on two optical beams co-propagating in opp osite directions in two-dimensional self-defocusing nonlinear media.Numerical re sults show that the probe beam can be induced to focus due to cross-phase modula tion by the pump beam under certain conditions.We also discuss the effect on the focusing of the probe beam from the four parameters:the specimen length,the ini tial amplitudes of the pump beam and the probe beam,and the initial transversal distance between the centers of the two beams.We find that some of them have opt imum values,which result in the strongest focusing.
Low temperature fabrication of nanostructured Si-SiOx　and Si-SiNx composite films and their photoluminescence features
Authors: Ji Ai-Ling  , Ma Li-Bo  , Liu Cheng  , Wang Yong-Qian  ,   中国科学院物理研究所与凝聚态物理中心,表面物理国家重点实验室,北京　100080
Published: December 2020

Silicon nanoparticles were fabricated in both silicon oxide and nitride matrices by using plasmaenhanced chemical vapor deposition, for which a low substrate t emperature belowo 50℃ has been found most favorable. High-density (up to 4.0 ×1012cm-2, from TEM micrograph) amorphous silicon nanoparticles with an averaged size down to 3　nm have been obtained. Strong roomtemperature photoluminescence was observed in the whole visible light range from the deposits that were postannealed at 500 ℃ for two minutes. Careful comparison shows that the Si-SiNx　films provoke a significantly more effective photoluminescence than Si-SiOx films f abricated with similar processing parameters, especially in the green and blue light range. Theis low- temperature procedure for fabricationg light-emitting silicon structures opens up the possibility of manufacturing silicon-based tunable high-efficiency light-e mitting devices.
The two internal friction peaks in rapidly cooled Fe71Al29 alloy*
Authors: Wang Qiang  , Zhou Zheng-Cun  , Han Fu-Sheng  ,   (1)合肥工业大学材料科学与工程学院，合肥　230001; (2)中国科学院固体物理研究所，合肥　230031
Published: December 2020

Three internal friction peaks were found around 180℃ (termed as P1),340℃ (termed as P2) and 510℃(termed as P3) in rapidly cooled Fe71Al29 alloy,while only the　P3 peak can be observed in slowly cooled sp ecimens.Only the P1 and P2 peaks were investigated using a computer- controlled inverted torsion pendulum in the present study.The P1 and P2 peaks in air-cooled specimens disappear during cooling or after long term ag eing at 350℃.They decline even disappear with increasing ageing time.Both the P1 and P2 peaks have relaxation features and their activation energy values are H1=1．03±0．08eVfor the P1 peak and H2=1．64±0．05eV for the P2 peak.It is suggested that P1 peak originates from the nearestneighbor jumps of Al atoms within tetrahedral lattices and P2 peak from the next-nearest-neighbor jumps of Al atoms within tetrahedral lattices in quenched alloys.
Theoretical study on the atomic structure, electronic states, and STM image of c(2×2) Cu(001)/O surface
Authors: Tao Xiang-Ming  , Tan Ming-Qiu  , Xu Xiao-Jun  , Cai Jian-Qiu  , Chen Wen-Bin  , Zhao Xin-Xin  ,   浙江大学物理系，杭州　310027
Published: December 2020

Abstract In this article we have studied the surface structure, rel axation, and oxygen absorbed c(2×2) Cu(001) surface by using ab initio projector augmented wave and Car-Parinello method. It i s concluded that the bond length between oxygen and surface Cu atom is 0.194nm which yields a perpendicular distance of 0.069nm from O to Cu(S). The absor ption of oxygen produces a hybridized band and yields the well localized surface states a t 6.7 eV below E＿F. The calculated work function for this absorbed sur face is 5.29 eV. We also calculate the scanning tunneling microscope images in the Tersoff-Hamann approach and make comparison with available experimental observ ations.
Oxide overlayer effect on the measurement of the parameters of interband critical point: A fractional-dimensional space approach*
Authors: Tao Ke-Yu  , Zhang Yue-Li  , Mo Dang  ,   中山大学理工学院，光电材料与技术国家重点实验室，广州　510275
Published: December 2020

The fractional-dimensional space approach and analysis of spectroscopic ellipsometry are used to study an oxide overlayer effect on the measurement of the parameters of interband critical point (CP) of Si by a Si-SiO＿2 model. There sults of the calculation show that the oxide overlayer effect can influence the calculated CP parameters derived from an optical spectrum by decreasing t he ampl itude and dimensionality, and increasing the lifetime broadening. Moreover, the effect is enhanced with increasing thickness of the overlayer. However, this eff ect on threshold energy is shown to be very small and can be ignored.
Ab initiocalculation of the voltage profile curve of Li insertions in InSb
Authors: Liu Hui-Ying  , Hou Zhu-Feng  , Zhu Zi-Zhong  , Huang Mei-Chun  , Yang Yong  ,   (1)集美大学计算科学与应用物理系，厦门　361021; (2)厦门大学固体表面物理化学国家重点实验室，厦门　361005; (3)厦门大学物理系，厦门　361005
Published: December 2020

InSb is an important non-carbon-bearing anode material for lithium (ion) batteri es. An ab initiomethod with first-principles pseudopotentials based on the density functional theory has been used to calculate the total energies, formation energies and equi librium volumes of Li intercalations in InSb in 125 possible cases. Comp aring with the experimental voltage profile curve, we have picked out the possib le reaction routes of Li insertions in InSb and a theoretical voltage pr ofile curve is reached. Our results show that, from bulk InSb to bulk Li＿3Sb, the re are no possible reaction routes undergoing five or more intermediate ph ases. The most favored route for undergoing only one intermediate phase is Li+In＿4Sb＿4→Li＿1In＿4Sb＿4,11Li+Li＿1In＿4Sb＿4→Li＿12Sb＿4+4In；whereas there exists only one reaction route for undergoing four intermediate phases, that is, Li+In＿4Sb＿4→Li＿1In＿4Sb＿4,2Li+Li＿1In＿4Sb＿4→ Li＿3In＿4Sb＿4,4Li+Li＿3In＿4Sb＿4→Li＿7In＿3Sb＿4+In,3Li+Li＿7In＿3Sb＿4→Li＿10In＿2Sb＿4+In,2Li+Li＿10In＿2Sb＿4→Li＿12Sb＿4+2In..
Quantum lattice dynamical effects on the low-energy excitations in spin-Peierls systems
Authors: Xu Jing  , Wang Zhi-Guo  , Shi Yun-Long  , Chen  Yu-Guang  , Chen Hong  ,   (1)同济大学物理系,上海　200092; (2)雁北师范学院物理系,大同　037000; (3)雁北师范学院物理系,大同　037000；同济大学物理系,上海　200092；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

Using the bosonization technique and Gaussian wave functional method, we investi gate the low-energy excitations of a spin-Peierls chain where the spins interact with quantum phonons. The results show that the energy gap of the one- and two- particle excitation states decrease gradually when spin-phonon coupling constant decreases or the phonon frequency increases. A quantum phase transition from a gapless spin-fluid phase to a gapped dimerized phase occurs at a nonzero critica l value of the spin-phonon coupling. Our results indicate that the two-particle excitation spectrum is much more sensitive to spin-phonon coupling constant than the one-particle excitation spectrum.
Effects of proximity coupling and substitutions for Ba-sites on the transition temperature and ARPES of high-T＿c superconductors
Authors: Yang Zhi-Hong  , Shi Da-Ning  , Luo Da-Feng  ,   (1)南京航空航天大学理学院，南京　210016; (2)南京航空航天大学理学院，南京　210016；南京邮电学院应用数理系，南京　210003; (3)南京邮电学院应用数理系，南京　210003
Published: December 2020

Abstract Taking into account the proximity effects of the CuO chain on the hig h-T＿c superconductivity, we introduce an S-N (superconducting-normal) model with d-wave Cooper pairing in the S layer. The hopping interaction between the S and N layers shows the suppression effect on the transition temperature T＿c from the Green's function obtained in the Nambu space. Based on this model, we investigat e the negative effects of the substitution for Ba-site on the transition tempera ture T＿c in the Y-Ba-Cu-O system. Experimental observations are qualita tively con sistent with our theoretical results. Finally, the hump/dip/peak structure in th e line shapes of the angle-resolved photoemission of the high-T＿c supercond uctors has also been discussed in the framework of the S-N model.
Effectivity of Hamiltonian terms of "forbidden" 3-magnon interaction
Authors: Shi Qing-Fan  , Li Liang-Sheng  , Zhang Mei  ,   (1)北京理工大学理学院，北京　100081; (2)广东工业大学计算机学院，广州　510090
Published: December 2020

Analyzing the effectivity of "forbidden" 3-magnon processes locally excitated in magneto-ordered crystals, we successfully constructed the corresponding effe ctive 4-magnon interaction terms by the unitary transformations.
Characteristics of the ZnxMg1-xO fil ms grown by electrophoresis method
Authors: Wang Zhuang-Bing  , Xu Xiao-Liang  , Chen Ying-Ying  , Zhou Shi-Ming  , Kong Ning  , Guo Jia  , Liu Hong-Tu  , Shi Chao-Shu  ,   (1)合肥工业大学物理系,合肥　230009; (2)中国科学技术大学结构分析开放实验室，合肥　230026;中国科学技术大学物理系,合肥　230026; (3)中国科学技术大学物理系,合肥　230026
Published: December 2020

A series of ZnxMg1-xO films are prepared with electro phoresis deposition. The x-ray diffraction of the film is consistent with that of the multicrystal ZnO, it shows the structure of the ZnxMg1-xO film agree with the polycrystal of ZnO. The photoluminescence study of the ZnxMg1-xO film shows that there are two promine nt peaks in the ultraviolet region of the emission spectra, corresponding to the light emission of free and bound excitons, respectively. The intensity of the emi ssion spectra is invariable in the visible region, and no new peaks including the green band exist. This phenomenon indicates that the oxygen in the film keeps a fine stoichiometry with other elements, and restrains the emission of the green band based on the oxygen vacancies. On the other hand, the blue shift of the UV peaks in the photoluminescence spectra is found to be associated with increasing Mg content in ZnxMg1-xO films, and the intensity of peaks is also reinforced significantly with increasing annealing temperature.
Luminescence properties and energy transfer in the mixed thin film of Alq3 and PVK
Authors: Sun Shi-Ju  , Teng Feng  , Xu Zheng  , Zhang Yan-Fen  , Hou Yan-Bing  ,   北京交通大学光电子技术研究所，北京　100044
Published: December 2020

In this paper, the properties of fluorescence were studied of the thin films with different component ratios of polyvinyl carbazole(PVK)and Alq3. The energy transfer between PVK and Alq3 was studied through analysis of absorption spectra, excitated spectra, emission spectra of the thin films. When the content of Alq3 was high enough，the peak of Alq3 was quite evident in the abs orption spectra and excitated spectra, at the same time the emission spectra was the characteristic emission band of Alq3.When the content of PVK was high enough, the peak value of PVK is much greater than that of Alq3. At this time the extraordinary strong characteristic emission band of Alq3 and the feeble charac teristic emission band of PVK was observed. It is proved that the energy can transfer from PVK to Alq3 in a wide concentration range and it is most efficient at the concentration of 1∶7. A model Hamitonian based on single chain model including the dopant was put forward to simulate the experiment .This model can explain the experimental results very well.
Control of grain size during low-temperature growth of polycrystalline silicon films
Authors: Huang Rui  , Lin Xuan-Ying  , Yu Yun-Peng  , Lin Kui-Xun  , Yao Ruo-He  , Huang Wen-Yong  , Wei Jun-Hong  , Wang Zhao-Kui  , Yu Chu-Ying  ,   (1)广东韩山师范学院物理系，潮州　521041; (2)华南理工大学应用物理系，广州　510641; (3)汕头大学物理系，汕头　515063
Published: December 2020

Polycrystalline silicon thin films were prepared at high-speed by plasma-enhanced chemical vapor deposition technique at low temperatures using SiCl4 and H2 as source gases. It was found that the grain growth is strongly affected by the relative concentration of different active radicals in the gas-phase space. On the other hand, the relative concentration depends on the deposition conditions. With the decrease of the rf power and the H2/ SiCl4 flow ratio, and the increase in the reaction pressure, the grain size increases. By changing the deposition conditions, variations of the relative concentration were analyzed. It is suggested that the “gas-phase crystalline" is of crucial importance to the grain growth.
Distribution and spectrum properties of uranium in U:CaF2 crystal
Authors: Su Liang-Bi  , Yang Wei-Qiao  , Dong Yong-Jun  , Xu Jun  , Zhou Guo-Qing  ,   中国科学院上海光学精密机械研究所，上海　201800
Published: December 2020

Transparent and integral U:CaF2 single crystals with diameter of 75mm were successfully grown by temperature gradient technique. The distribution coefficient of uranium in Ca F2 is equal to 0.53, which was calculated using the formula, K0=Cs/Cl.The calculated concentrations of uranium in CaF2 according to general distribution equation, Cs=K0C0(1-g)K0-1, are consistent with the measured values, indicating that the process of crystal growth was nearly in equilibrium. Unit cell paramenters and optical absorption spectra of U:CaF2 crystals grown under different conditions have been analyzed. Results indicate that the growth atmospheres determine the valences of uranium ions and the mechanism of charge compensation: the uranium ion is U4+ with green color in the absence of Pb F2; uranium is apt to form U3+with radius most close to that of Ca2+ in the presence of Pb F2 as a scavenger. From the beginning part to the end of U3+:Ca F2 crystal, only optical densities of all absorption bands gradually increase with the concentration of uranium. With increasing concentration of doped uranium, the color of the as grown U:Ca F2 crystals change from pink to brownish. The 5mm thickness periphery of the U3+:Ca F2 crystal with a yellow color was confirmed to contain mixed valences of U2+ and U3+, as a result of the reduction effect of graphite crucible.
The investigation on the nucleation mechanism of Au-containing glass in an electric field
Authors: Wang Guo-Liang  , Liang Kai-Ming  , Liu Wei  , Zhou Feng  ,   清华大学材料科学与工程系，北京　100084
Published: December 2020

The investigation on the nucleation mechanism of Au-containing glass in an electric field By means of x-ray diffraction, scanning electron microscopy and absorption spec troscopy, we have studied Au-containing glass which is heat-treated under a n a pplied electric field. The experimental results are consistent with the conclusi ons obtained from a new thermodynamic model, which is proposed based on the static electromagnetic theory and thermodynamic theory in order to describe the nucl eation process of glass doped with metals. As a key factor in the model, the ele ctric energy change is calculated by two methods in this study. One is based on some approximation treatment, and the other the finite element method. The resul ts obtained by the two methods are similar and can explain the experimental results fairly well.
A time-dependent interface stability during directional solidification of a single phase alloy(Ⅱ)Comparison with experimental results
Authors: Huang Wei-Dong  , Lin Xin  , Li Tao  , Wang Lin-Lin  , Y. Inatomi  ,   (1)Institute of Space and Astronautical Science,Kanagawa 229,Japan; (2)西北工业大学凝固技术国家重点实验室，西安　710072
Published: December 2020

In situ observation on the interface instability and the solute transport boundary layer in front of the solid/liquid interface is carried out during the di rectional solidification of SCN-1.5at%Salol. Based on this, and in combination with the experimental results of SCN-1.1 wt%Eth, SCN-0.43wt%C152 alloys, the morp hological instability of a solidifying planar interface is systematically invest igated during directional solidification with and without the convection. It is found that the interface stability analysis in our previous paper describes corr ectly the time-dependent evolution of interface instability. Both the incubation time ti for instability and the incubation time tb for breakdown of the planar interface can be determined from the time-dependent instability so lution, and the convection obviously shortens the incubation time ti for i nstability and the incubation time tb for breakdown of the planar interface. The steady-state instability solution overestimates the unit amplitude devel oping rate by an order of magnitude, as compared to the experimental value, while the time-dependent solution underestimates the experimental result.
Self-assembly under gravity sedimentation of large size silica particles
Authors: Zhou Qian  , Dong Peng  , Cheng Bing-Ying  ,   (1)石油大学重质油国家重点实验室，北京　102249; (2)中国科学院物理研究所光物理开放实验室，北京　100080
Published: December 2020

Highly monodispersed colloidal silica particles in sizes ranging from 700 to 1300 nm were synthesized by a two-step method. The transmission electron microscope images showed that the mean standard deviation of these particles is less than 5%. Silica particle size range for self-assembly in the gravitational sedimentation was broadened through adjusting the viscosity of media in silica suspensions. The synthetic opals with particle diameters ranging from 700 to 1300 nm were obtained,and their optical characteristics were examined. Scanning electron microscope images showed that the synthetic opals have a face-centered-cubic structure and have partial photonic band-gaps. This provides the foundation for the study of complete photonic crystals with wavelengths within near-infrared and infrared regions and for the fabrication of other macroporous materials.
Effect of atmospheric turbulence on the propagation properties of spatially partially coherent polychromatic light
Authors: Ji Xiao-Ling  , Xiao Xi  , 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; (3)四川师范大学电子工程学院，成都　610064;四川大学激光物理与化学研究所，成都　610064
Published: December 2020

Based on the propagation law of partially coherent light, the longdistance pro pagation of the spatially partially coherent polychromatic light through the atm osphere is studied. It is shown that the atmospheric turbulence gives rise to sp ectral shift and to beam spreading of spatially partially coherent polychromatic-light whether the scaling law is satisfied or not. The influence of turbulence on beam spreading of the spatially partially coherent polychromatic light is sma ller than that of spatially fully coherent polychromatic light. However, the inf luence of bandwidth on the intensity distribution is relatively small.
Improvement and extension of the thin film brick wall model without cut-off
Authors: Sun Xue-Feng  , Jing Ling  , Liu Wen-Biao  ,   (1)北京师范大学物理学系，理论物理研究所，北京　100875; (2)北京师范大学物理学系，理论物理研究所，北京　100875;驻马店学院数理系，驻马店　463300
Published: December 2020

Applying the generalized uncertainty relation to the thin film brick wall model, the method of calculating black hole entropy without cutoff was first proposed in 2002. However, it was then only determined that the upper bound of entropy is proportional to the event horizon. Since the method is studied more deeply, the entropy itself is found proportional to the horizon too. The relation between the ratio coefficient and the second-order uncertainty parameter is also discusse d. Moreover, the non-spherical Rindler horizon is studied, and the expected res ult is given. It is apparent that the cut-off in the brick wall model is something related to the quantum theory of gravity.
Discussion on the characteristics of the quantumradiation of unstationary and slowly-changing Reissner-Nordstr?m black hole
Authors: Yang  Shu-Zheng  ,   西华师范大学物理与电子信息学院，南充　637002
Published: December 2020

Taking into account the case that the mass M and charge Q of Reissner-Nordstr?m black hole varying slowly with time t, the discussion on the quant um radiation characteristics of the black hole shows that the thermal radiation spectrum of charged Dirac particles is connected with the black hole's evaporati on rate together with the factors M(t), Q(t) etc. changing with time, and that the maximum energy of the quantum nonthermal radiation of nonstationary and slowly-changing Reissner-Nordstr?m black hole is equal to the chemical potential in the quantum thermal radiation spectrum.
Thermal analysis and structure transformation of Mn12-Ac magnetic molecular crystals
Authors: Liu Ying  , Ge Pei-Wen  , Su Shao-Kui  , Zhang Li-Juan  , Wang Yun-Ping  ,   (1)北京化工大学理学院，北京　100029; (2)中国科学院物理研究所，北京　100080; (3)中国科学院物理研究所，北京　100080;北京化工大学理学院，北京　100029
Published: December 2020

The thermal stability of Mn12-Ac[Mn12(CH3COO)16(H2O)4O12]52CH3COOH54H2O magnetic molecular crystals was investigated by TG-DTA from room temperature to 270℃. According to the results of XRD and TG,we found that Mn12-Ac lost the crystal water and the acetic acid molecules of solvation which were located between the adjacent molecules in the temperature range from 25℃ to 1 10℃. At the same time, 4H2O which were linked with 4 Mn3+ were lost. The crystalline structure of Mn12-Ac single crystal was destroyed during this course. However, the core structure in the molecule was well preserved. From 180℃ to 230℃, a further transformatio n took place, Mn12-Ac lost all the CH3COO- ions and turned intoγ-Mn2O3, with a little amount of Mn3O4.
Non－Noether conserved quantity of a general form for mechanical systems with variable mass
Authors: Fang Jian－Hui  , Liao Yong－Pan  , Zhang Jun  ,   (1)河西学院物理系，张掖　734000; (2)石油大学(华东)物理科学与技术学院,东营　257061
Published: December 2020

In this paper, we study the non-Noether conserved quantity of Lie symmetry for m echanical systems with variable mass under a general infinitesimal transformatio n. The Hojman theorem is further generalized. The non-Noether conserved qu antity o f a general form for mechanical systems with variable mass is obtained. An examp le is given to illustrate the application of the result.
The approximate solution for a combustion model
Authors: Han Xiang－Lin  ,   湖州师范学院理学院，湖州　313000
Published: December 2020

Using the homotopic theory, an approximate solution for a class of nonlinear pro blems is first discussed.Then,the precision is raised by using variational inter active methods.Finally, a combustion model is applied and the approximate soluti on is obtained.
Critical temperature of Bose-Einstein condensation
in an external potential
Authors: Yu Xue－Cai  , Mo Ying  ,   电子科技大学光电信息学院,成都　610054
Published: December 2020

Expressions for critical temperature of Bose-Einstein condensation (BEC) in an e xternal potential, which are different from published results in the literatur e, are presente d. The results reveal the relation between the critical temperature of BECgas and the external potential, and demonstrates proporti onality of critical temperature in external potential to the value T0c at which th e potential is absent. In addition, a criterion for the validity of potential is also prese nted, which is based on the comparison between the potential and the product  kT 0c. This comparison shows that only when the external potential is nearly eq ual to or larg er than kT0c, the increase of critical temperature is significant. A s the potential is much smaller than kT０c, the potential has no effects on the BEC gas.
Chaos control of Lorenz system via RBF neuralnetwork sliding mode controller
Authors: Guo Hui－Jun  , Liu Jun_Hua  ,   西安交通大学电气工程学院，西安　710049
Published: December 2020

A novel adaptive radial basis function(RBF) neural network sliding mode strat egy is developed to con trol Lorenz chaos with parametric uncertainties and external disturbances. Based on the controllable canonical form of system state error at its unstable equili brium, a sliding surface is defined as the only input to the RBF controller. Onl y seven RBFs are required for the controller and their weights ar e trained on-line based on the sliding surface approaching condition. The simula tio n results show that this method is feasible and effective, and the robustness to parametric uncertainties and external disturbance is provided.