bluuebunny/crossref_metadata_2025 huggingface dataset:
The study of ultraviolet properties of resistant-boat evaporated LaF3 films
Authors: Shang Shu-Zhen  , Shao Jian-Da  , Fan Zheng-Xiu  , Zhao Zhu-Xin  ,   (1)华东理工大学机械与动力工程学院，上海  200237; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

The effects of depositing temperature on structure and optical properties of resistant-boat evaporated LaF3 single layers were investigated. The films were produced at different temperatures from 200℃ to 350℃ by increasing step of 50℃. The optical loss, optical constants, optical band gap and cut-off wavelength were deduced on the basis of the transmittance and reflectance curves. Profile and surface roughness measurement instrument was used to determine the rms surface roughness. Microstructure of the samples was characterized by X-ray diffraction (XRD). It was found that the total optical loss，the grain size and the rms surface roughness increased with the increasing of the depositing temperature at the short wavelength period. And the increasing total optical loss with depositing temperature was attributed to the absorption because the scattering occupied the very low percent in the whole loss. The samples deposited at higher temperature had the higher refractive index and extinction coefficient and lower optical band gap. The cut-off wavelength shifted to the long wavelength as the depositing temperature increased.
Low-loss 193nm anti_reflection coatings
Authors: Shang Shu-Zhen  , Shao Jian-Da  , Fan Zheng-Xiu  ,   (1)华东理工大学机械与动力工程学院承压系统安全科学教育部重点实验室，上海  200237; (2)中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

The optical constants suitable for designing and depositing 193nm AR coatings were calculated, and 193nm AR coatings were designed, produced and characterized on the basis of the calculated results. It was found that the extinction loss of the substrate material had such an important effect that when it was beyond a certain level the designed transmittance could not reach the ideal value. The designed and manufactured results of the single_surface AR coatings revealed that scattering loss began to play the key role when the absorbance loss decreased to a certain extent. High performance 193nm AR coatings with residual reflectance lower than 0.2% have been prepared by the resistant boat evaporation method.
Research on the electron transport and back-reaction kinetics in TiO2 films applied in dye-sensitized solar cells
Authors: Liang Lin-Yun  , Dai Song-Yuan  , Fang Xia-Qin  , Hu Lin-Hua  ,   中国科学院等离子体物理研究所太阳能材料与工程研究室，合肥  230031
Published: December 2020

The mechanics of electron transport and properties of back-reaction kinetics were investigated by intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS). The theoretical expression fitting the experimental data of five different porous TiO2 films applied in DSC and the values of absorption coefficient (α)，the diffusion coefficient (Dn)，electron lifetime (τn)，the electron transit time (τd) and IPCE can be obtained. The results showed that the electrons transit faster in the thinner films，while the electron concentration increase in the thicker films. The influence of film thickness on the electron generation，transport and recombination processes was investigated in the microscopic level in this paper.
Observation of the lightning_induced voltage in the horizontal conductor and its simulation
Authors: Yang Jing  , Qie Xiu-Shu  , Wang Jian-Guo  , Zhao Yang  , Zhang Qi-Lin  , Yuan Tie  , Zhou Yun-Jun  , Feng Gui-Li  ,   (1)武汉大学电气工程学院,武汉  430072; (2)中国科学院大气物理研究所,北京  100029; (3)中国科学院寒区旱区环境与工程研究所,兰州  730000
Published: December 2020

Characteristics of induced voltage in a horizontal conductor due to a natural lightning with 9 dart leader/return stroke sequence were analyzed. Effect of various parameters on the induced voltage was examined by numerical simulation. The induced voltage varied from a minimum of 4.6 kV to a maximum of 18.6 kV with a geometric mean of 11.2 kV. The geometric mean of the half-peak width and the down time of the induced voltage was 0.87 and 2.9 μs, respectively. The simulated results showed that the induced voltage on both ends of the horizontal conductor would increase with increasing return stroke velocity and also increase with increasing height of the horizontal conductor. The voltage would also increase with increasing of the matched grounding impedances on both ends of the horizontal conductor but the relationship was nonlinear. The induced voltage at the higher impedance end was much larger than that at the lower impedance one provided that the impedances at both ends were not matched, which indicates that good grounding can decrease effectively the induced voltage along the conductor.
The general theory of the kinetic evolution and phase transition of complex adaptive systems
Authors: Xu Bing-Zhen  ,   宁波大学理论物理研究所，宁波  315211
Published: December 2020

A new model of the complex adaptive systems is established， and the theory developed by the author on the kinetic evolution and phase transition of complex adaptive systems is extended to the general case， with which some more realistic complex adaptive systems may be described- As an application of the new model， we compare the simulation results of winning the toss with the corresponding theoretical one given in this paper- The theoretical results turn out to be in good accordance with the simulation-
The extension effect of point spread function in wavefront coding system due to off-axis illumination
Authors: Zhao Ting-Yu  , Ye Zi  , Zhang Wen-Zi  , Yu Fei-Hong  ,   浙江大学光电系现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

The off-axis illumination pupil function of the wavefront coding system with cubic phase mask is analyzed by coordinate-rotation for the first time. The approximate expression of the pupil function shows that off-axis illumination brings about the extension effect of cubic phase and defocusing. The extension effect is independent of the sign of the incident angle; however, the extension effect will get larger as the absolute value of the angle increases. This causes a decrease in modulation transfer function (MTF) and the extension effects on both sides of the point spread function (PSF) envelope. When the off-axis illumination is in the tangential plane, the extension effects of cubic phase and defocusing in y direction is larger than that in x direction, which results in larger extension of PSF and lower MTF in the y direction. When off-axis illumination is in the sagittal plane, the extension effects of cubic phase and defocusing in x direction is larger than that in the y direction, which results in larger extension of PSF and lower MTF in x direction.
Mei symmetry and Mei conserved quantity of Nielsen equation for a nonholonomic system
Authors: Jia Li-Qun  , Luo Shao-Kai  , Zhang Yao-Yu  ,   (1)江南大学理学院，无锡  214122; (2)平顶山学院电气信息工程学院，平顶山  467002; (3)浙江理工大学数学力学与数学物理研究所，杭州  310018
Published: December 2020

Mei symmetry and Mei conserved quantity of Nielsen equation with multipliers for a nonholonomic， non-conservative system of Chetaev's type are studied- The differential equations of motion of Nielsen equation with multipliers for the system，the definition and criterion of Mei symmetry，and the condition and the form of Mei conserved quantity deduced directly by Mei symmetry for the system are obtained- An example is given to illustrate the application of the results-
The critical scaling property of random percolation porous media
Authors: Liu Zhi-Feng  , Lai Yuan-Ting  , Zhao Gang  , Zhang You-Wei  , Liu Zheng-Feng  , Wang Xiao-Hong  ,   (1)中国科学技术大学力学和机械工程系，合肥  230027; (2)中国科学技术大学热科学和能源工程系，合肥  230027; (3)中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

A percolation model of random porous media， with its nonzero bonds obeying the uniform distribution， is researched in this article- The scaling exponents of the permeability are calculated at the percolation critical point- The simulation suggests that the exponents are not universal，but depending on the parameter of the uniform distribution- This indicates that even if the first negative moment of the probability density function of the nonzero bonds exists， the corresponding scaling exponent at the critical point will not be universal- Our simulation result is different from the conclusion reached by Sahimi-
Global solutions for a kind of generalized Sine-Gordon equation with strong damping
Authors: Zhang Jian-Wen  , Wang Dan-Xia  , Wu Run-Heng  ,   (1)北方工业大学理学院，北京  100041; (2)太原理工大学理学院，太原  030024
Published: December 2020

A kind of generalized Sine-Gordon equations with strong damping are studied，considering both viscosity effect and external damping- Firstly，by the aid of Galerkin method，under the initial value conditions u(x，t)∈H10 (Ω) ，ut∈L2 (Ω)，we prove the existence and uniqueness of a global weak solution u(x，t) for the initial boundary value problems and the constant dependenceof solution on the initial value- Secondly， under the initial value conditionsu(x，0)∈H10 (Ω)∩H2(Ω)，ut(x，0)∈H10 (Ω)，the course of proof of the existence of strong solution u(x，t) is also explained by using Galerkin method-
Entanglement evolution of two three-level atoms in a fermionic environment
Authors: Ma Xiao-San  , Wang An-Min  ,   (1)中国科学技术大学近代物理系，合肥  230026; (2)中国科学技术大学近代物理系，合肥  230026；安徽工业大学电气信息学院，马鞍山  243002
Published: December 2020

We study the entanglement evolution of two three-level atoms in a fermionic environment. Our results show that the entanglement evolution depends not only on the strength of the interaction between the system and environment， but also on the structure of states. For the cases of concern， we find that the stronger the interaction between the system and environment is， the faster the entanglement of the system decreases. The entanglement of pure quantum states vanishes completely when the time goes to infinity; while for the mixed state，the entanglement will be completely destroyed by decoherence in finite time. The decoherence-free subspace SDF has been identified by using linear entropy to measure decoherence. A density matrix that only can be expanded by the elements of SDF does not perceive the presence of the environment and the entanglement and its linear entropy remain unchangeable. Our analysis will shed some light on the effect of a fermionic environment on the entanglement of bosonic systems.
Stochastic resonance in an asymmetric bistable system driven by correlated noise
Authors: Zhou Bing-Chang  , Xu Wei  ,   西北工业大学应用数学系，西安  710072
Published: December 2020

The phenomenon of stochastic resonance (SR) in a bistable system subject to correlated multiplicative colored and additive white noises and a periodic rectangular signal with a constant component is investigated in the unified colored noise approximation and by applying the two-state theory. The expression of the signal-to-noise ratio (SNR) is obtained for arbitrary signal amplitude. The SNR is a non-monotonic function of intensities of multiplicative colored and additive white noises，correlation time of multiplicative colored noise and the strength of the coupling between noises， so SR appears in the bistable system. Meanwhile， it is more effective to control SR through adjusting the additive white noise intensity than adjusting the multiplicative colored noise intensity. Moreover，the effects of potential asymmetry and the strength of the coupling between noises on SNR are opposite.
The feedback control of stochastic resonance in bistable system
Authors: Lin Min  , Huang Yong-Mei  , Fang Li-Min  ,   中国计量学院计量技术工程学院，杭州  310018
Published: December 2020

A feedback method is proposed to control the stochastic resonance by feeding back the output of bistable system to the input to re-act on the system. In a typical bistable system， the signal-to-noise ratio and spectral power amplification are considered as observable variables to evaluate the stochastic resonance effect. The stochastic resonance phenomenon caused by the linear or nonlinear feedback functions are studied respectively. The theoretical analysis and numerical simulation show that the stochastic resonance is controllable， and this method is especially suitable to the system of which the parameters are fixed or difficult to vary.
The stochastic resonance control of coupled bistable systems
Authors: Lin Min  , Huang Yong-Mei  , Fang Li-Min  ,   中国计量学院计量技术工程学院，杭州  310018
Published: December 2020

Two bistable systems can become multistable through nonlinear coupling. The coupled system is more valuable than the single bistable system in theoretical research and practical application. The response characteristics of the coupled system subjecting to noise and periodic signal have been analytically analyzed to show the effect of coupled coefficient and bistable system parameters on stochastic resonance. The results show that the stochastic resonance is produced by the effect of zonal double-well potential. The schematic diagram of feedback coupled control principle has also been constructed. The method gives a reliable theoretical basis for artificially producing stochastic resonance or strengthening the effect of resonance in bistable system to control the stochastic resonance, and also for its application. The results of numerical simulation agree with that of theoretical analysis.
Phase control of inversionless gain in a closed atomic system with Doppler broadening
Authors: Ma Hui  , Bu Fan-Ge  , Qiao Hong-Xia  , Tong Dian-Min  , Fan Xi-Jun  ,   山东师范大学物理与电子科学学院，济南  250014
Published: December 2020

We studied the controlling role played by the relative phase between the probe and driving fields on inversionless gain of the probe field in a closed and Doppler broadened Λ-type three-level system with spontaneously generated coherence (SGC). It was found that：(1) Regardless of the driving field being in or off resonance, and regardless of the probe and driving fields being co- or counter- propagating, the gain maximum value always varies periodically with variation of the relative phase with the period 2π. (2) When the driving field is in resonance, the gain maximum value decreases monotonicly with Doppler width increasing, and moreover, the decreasing in the counter-propagation case is faster than that in the co-propagation case. When the driving field is off resonance, the gain maximum value does not monotonicly decrease or increase with Doppler width increasing. In both above cases, the largest inversionless gain can be gotten by adjusting the relative phase. (3) The contribution of SGC to the inversionless gain is much larger than that of the dynamically induced coherence.
Anticipated synchronization for a class of nonlinear vibration systems
Authors: Qin Wei-Yang  , Yang Yong-Feng  , Wang Hong-Jin  , Ren Xing-Min  ,   西北工业大学工程力学系，西安  710072
Published: December 2020

For the nonlinear vibration system，if the derived system can reach synchronization with the original system by linear coupling， a corresponding anticipated system can be formed to realize the anticipated synchronization. The response of anticipated system can synchronize with the future response of original system and realize the prediction for nonlinear response，even for chaos in the originalsystem. In order to realize a long-term prediction， a series of anticipated systems can be formed by the rule presented in this paper. For chaotic motion in Duffing system， a 6-level anticipated system is formed， which can predict the response of original Duffing system in about 3s.
Controlling chaos in a semiconductor laser via photoelectric delayed negative-feedback
Authors: Yan Sen-Lin  ,   南京晓庄学院物理系，南京  210017
Published: December 2020

In this paper，methods of chaos-control of a semiconductor laser are studied using a photoelectric delayed negative-feedback scheme with additive photoelectric delayed control， and the maximum Laypunov exponent of the controlled system is analyzed. Three physical models of photoelectric delayed chaos-control of an injected semiconductor laser are presented. Firstly，by adjusting the delay time or the feedback photocurrent， the chaotic laser can be conducted into period-3 state， period-5 or other multi-periodic states. Secondly， by periodic modulation of the photocurrent into the laser， the chaotic laser can be brought into a period-8 states or a period-9 state. Lastly， we make use of the photoelectric delayed negative-feedback and an additive current modulation to perform chaos-control， the chaotic laser can be stabilized into a single-periodic state or multi-periodic state.
Comparative studies on information feedback strategies in traffic networks with overlaping routes
Authors: Tian Li-Jun  , Liu Tian-Liang  , Huang Hai-Jun  ,   北京航空航天大学经济管理学院，北京  100083
Published: December 2020

Intelligent traffic systems can help road users make reasonable route choice by providing them real-time traffic information，thus alleviate congestion. Considering the existence of overlapping between routes， this paper applies the cellular automaton model to simulate and investigate the route choice behavior under two information service strategies， namely travel time feedback strategy and mean velocity feedback strategy. Our simulation results indicate that the mean velocity feedback strategy can reduce the route travel time more efficiently than the time feedback strategy， particularly in longer networks with very short or very long overlapping segments. Its advantage in improving the network utilization efficiency decreases with the route length and drops first and rises afterwards with the length of overlapping part.
Study and design of broadband nonuniform ripple-wall TE0n-TE0(n+1) mode converters
Authors: Sun Xu  , Zhao Qing  , Li Hong-Fu  ,   电子科技大学高能电子学研究所，成都  610054
Published: December 2020

Based on the coupled wave theory， this paper presents the design， numerical analysis， and simulation of two types of TE0n-TE0(n+1) ripple-wall waveguide mode converters: a uniform ripple-wall converter and a nonuniform ripple-wall waveguide converter. For the first type，17.17GHz，six-period TE02-TE03 mode converter and 34.30GHz，six-period TE01-TE02 mode converter were operative； and 34.30GHz，six-period TE01-TE02 for the nonuniform one was operative. The design study is focused on the maximization of the conversion efficiency and mode purity coupled with a broad bandwidth. The nonuniform one seems to have a significant advantage over the uniform one， its conversion efficiency reaches 99.5% at center frequency and has a conversion bandwidth of more than 1.5GHz. Simulation results agree well with the theoretical predictions.
Medium effect of nucleon-nucleon cross section on the isoscaling parameter α
Authors: Liu Jian-Ye  , Hao Huan-Feng  , Zuo Wei  , Li Xi-Guo  ,   (1)天水师范学院数理和信息学院，天水  741000；中国科学院近代物理研究所，兰州  730000；兰州重离子加速器国家实验室原子核理论中心，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000; (3)中国科学院近代物理研究所，兰州  730000；兰州重离子加速器国家实验室原子核理论中心，兰州  730000
Published: December 2020

The medium effect of nucleon-nucleon cross section σmedNN(α) on the isoscaling parameter α is investigated for two couples of central nuclear center reactions　40Ca+48Ca and　60Ca+48Ca， 112Sn+112Sn and 124Sn+124Sn with isospin dependent quantum molecular dynamics at beam nucleon energies from 40 to 60MeV. It is found that there is very obvious medium effects of nucleon-nucleon cross section　σmedNN(α) on the isoscaling parameters α. The mechanism of the above properties is also studied and discussed.
Study on the count plateau, gas gain and energy resolution of the Micromegas detectors
Authors: Zhang Xiao-Dong  , Yang He-Run  , Duan Li-Min  , Xu Hu-Shan  , Hu Bi-Tao  , Li Chun-Yan  , Li Zu-Yu  ,   (1)兰州大学核科学与技术学院，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000; (3)中国科学院近代物理研究所，兰州  730000；兰州大学核科学与技术学院，兰州  730000
Published: December 2020

In this paper, we describe the structure of Micromegas (micro mesh gaseous structure) detector which has been developed recently by our group. And its count plateau, gas gain and energy resolution in the condition of a 55Fe X-ray source and various Ar-CO2 mixtured gases are plotted as functions of mesh voltage. Based on the experimental results, we confirm that we have mastered the technique of fabricating this kind of detector with high energy resolution and excellent performance.
Relaxation effect in photoionization processes of lithium
Authors: Sang Cui-Cui  , Wan Jian-Jie  , Dong Chen-Zhong  , Ding Xiao-Bin  , Jiang Jun  ,   (1)西北师范大学物理与电子工程学院，兰州  730070; (2)西北师范大学物理与电子工程学院，兰州  730070；兰州重离子加速器国家实验室原子核理论中心，兰州  730000
Published: December 2020

Using multi-configuration Dirac-Fock method and the corresponding packages GRASP92 and RATIP, as well as the newly developed RERR06, we calculated inner- and outer-shell photoionization cross sections of configurations 1s2nl(n=2,3; l=s, p) of atomic lithium. In the calculations, the relaxation effect caused by photoionization of electrons was included. It was found that the relaxation effect plays an important role in the inner-shell photoionizational processes, contrary to the outer-shell photoionizational processes. Further, the effects of relaxation on inner-shell photoionizational processes from different states are not the same. It is more prominent for the excited states than the ground state, and for the higher excited states than the lower excited states.
Study of channeling effect by impact of highly charged ions on crystal surface of Si(110)
Authors: Peng Hai-Bo  , Wang Tie-Shan  , Han Yun-Cheng  , Ding Da-Jie  , Xu He  , Cheng Rui  , Zhao Yong-Tao  , Wang Yu-Yu  ,   (1)兰州大学核科学与技术学院，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000
Published: December 2020

The (110) crystal surface of Si was bombarded by slow highly charged ions (Pbq+，Arq+) and the secondary particle emission was measured for different incident angles. Comparing the relationship between the sputtering yield and the incident angle, channeling effect was suggested. The channeling effect in interaction of highly charged ions with Si causes the sputtering yield to depend strongly on kinetic energy. Highly charged ions can enhance sputtering yield at smaller incident angles. At incident angles from 40° to 50°, the higher the potential energy of highly charged ion, the greater the sputtering yield.
Cavity resonator based on pair of left-handed metamaterial and negative permittivity medium
Authors: Wu Qun  , Meng Fan-Yi  , Fu Jia-Hui  , Li Le-Wei  ,   哈尔滨工业大学电子与信息技术研究院，哈尔滨  150001
Published: December 2020

The resonance property of the pair of left-handed metamaterial (LHM) and negative permittivity medium is analyzed in depth, and the results are applied to the design of an improved miniaturized cavity resonator (IMCR). The IMCR is numerically simulated, and the results show that the IMCR is resonant at 10.3GHz while its length and width is only 4.58 and 5.08mm, respectively, which are half that of the conventional one's. This research may contribute in theory to the miniaturization of resonance structures based on LHM.
Characteristics of a cataphoresis He-Sr+ recombination laser
Authors: Wang Yu-Bo  , Mao Bang-Ning  , Chen Li  , Wang Li-Min  , Pan Bai-Liang  ,   浙江大学物理系，杭州  310027
Published: December 2020

A cataphoresis discharge tube of 7mm inner diameter and 38cm active length was made for the He-Sr+ laser. The recombination laser at 430.5nm and the R-M transition laser at 1.03μm were obtained with the modified Blumlein circuit by high-frequency longitudinal pulsed discharge. The laser components are concentrated on the 430.5nm wavelength. Dependence of working parameters, such as the pulse frequency, the supply voltage and the helium pressure on laser output characteristics were measured and discussed. The maximum laser output power of 819mW and specific power of 56mW/cm3 were obtained.
Influence of auxiliary violet light on holographic diffraction efficiency under different recording intensities in bacteriorhodopsin film
Authors: Han Jun-He  , Yao Bao-Li  , Gao Peng  , Chen Li-Ju  , Wang Ying-Li  , Lei Ming  ,   (1)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710119; (2)中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室，西安  710119；中国科学院研究生院，北京  100049
Published: December 2020

The photochromic bacteriorhodopsin (BR) film can be used as a rewritable holographic recording medium. Due to the scattering and the reflecting of light from the BR film, the grating contrast of the hologram is diminished during the hologram recording. When the intensity of the recording light is weak, the influence of the scattering and reflection on the grating contrast is low enough to be neglected. But in the case of intense recording light, this influence should not be overlooked. It is found that the influence of the auxiliary violet light on the holographic diffraction efficiency kinetics is distinct under different recording intensities. At weak recording light intensities, the steady diffraction efficiency are increased and the peak diffraction efficiency is suppressed by the auxiliary violet light. But for intense recording light, the steady diffraction efficiency as well as the peak diffraction efficiency are both increased by the auxiliary violet light. Based on the two-level model of BR photochromism, we give a good theoretical explanation to the above phenomena.
Evolution of atom entropy in a moving cascade three-level atom in a two-photon process
Authors: Zhang Jin-Fang  , Tan Lei  , Liu Li-Wei  , Ding Cai-Ying  ,   兰州大学理论物理研究所,兰州  730000
Published: December 2020

The entropy evolution properties of field (atom) in a moving cascade three-level atom interacting with a single-mode field are studied through two photon transitions. When the atom is initially in coherent state, the influences of the atomic motion, the field-mode structure parameter and the initial average photon number on the evolution of the entropy are discussed. The results show that the entropy evolution period of the field is dependent of the atomic motion and the field-mode structure parameter. However, the parameter of the initial average photon number will neither lengthen nor shorten the entropy evolution period of the field, but the numerical values of maximum and sub-minimum of entropy will be affected by it.
Microwave control of optical bistability and multistability in the presence of antirotating wave coupling
Authors: Li Xiao-Qi  , Wang Jian  , Wang Fei  , Hu Xiang-Ming  ,   (1)华中师范大学物理系，武汉  430079; (2)华中师范大学物理系，武汉  430079；郧阳师范高等专科学校物理系，丹江口  442700
Published: December 2020

We show the control of optical bistability and multistability via the atomic coherence induced by the microwave field in the presence of the antirotating wave coupling. Appearance or disappearance of bistability and multistability， manipulation of the hysteresis hoop widths and the threshold intensity are achieved by changing the initial phase of the microwave field. Physically， the rotating wave and antirotating wave couplings can be treated as the equivalent bichromatic excitation. Each of the coupled levels are split into an infinite set of sublevels. As a consequence， each of the bare state transitions is split into an infinite set of transitions of different frequencies. The coherent superposition of these split transitions， which depends on the initial phase of the microwave field， determines the nonlinear absorption and dispersion of the medium.
Research on group velocity slowdown in erbium-doped optical fiber under controllable absorption loss
Authors: Qiu Wei  , Zhang Yun-Dong  , Ye Jian-Bo  , Tian He  , Wang Nan  , Wang Hao  , Wang Jin-Fang  , Yuan Ping  ,   哈尔滨工业大学光电子技术研究所，哈尔滨  150080
Published: December 2020

Group velocity of the optical pulse propagation would be reduced based on coherent population oscillation effect in an absorbing medium. According to the absorption properties of erbium-doped optical fiber, there would appear a sharp absorption loss, which brought more difficulties to the actual measurement of slow light and its application in communications. From the ground rate equation of erbium-ion, the delay of optical pulse was simulated under controllable absorption loss， and experiments were implemented to verify the theoretical results. Moreover, we researched how the different pump power and fiber length effect the signal loss and the optical pulse delay.
High-gain amplification of weak Stokes signal of stimulated Brillouin scattering in water
Authors: Gao Wei  , Lü Zhi-Wei  , He Wei-Ming  , Dong Yong-Kang  ,   (1)哈尔滨工业大学光电子技术研究所，哈尔滨  150001; (2)哈尔滨工业大学光电子技术研究所，哈尔滨  150001；哈尔滨理工大学应用物理系，哈尔滨  150080
Published: December 2020

The influences of the delay time, the cell length and the pump energy on the gain amplification of weak Stokes signal of stimulated Brillouin scattering (SBS) in water are investigated theoretically and experimentally. In the experiment a frequency-doubled seed injection Nd:YAG laser with a pulse duration of 7.2 ns was used. Results showed that the pump pulse should lag the Stokes signal pulse by an amount equal to pulse half-width to obtain the maximum gain. Depending on the pump energy the signal below 10-5 mJ is linearly amplified. By using CS2 as amplifier medium, a Stokes signal of 1pJ from water is amplified with high gain (7×107) in the regime below the pump's self-SBS threshold.
The influence of nonlocality on solitons in nematic liquid crystals
Authors: Zhu Ye-Qing  , Long Xue-Wen  , Hu Wei  , Cao Long-Gui  , Yang Ping-Bao  , Guo Qi  ,   华南师范大学光子信息技术实验室，广州  510006
Published: December 2020

In this paper, we theoretically investigated the influence of nonlocality on (1+2)-dimensional spatial solitons in undoped nematic liquid crystals (NLCs). We confirmed that the nonlinear index coefficient and the general characteristic length of the nonlinear nonlocality for the NLC are dependent on the pretilt angle of the NLC molecules. Then the Schrdinger-type nonlinear equation in strong nonlocality was given and from the equation the analytical expressions of the single soliton and the critical power were respectively obtained. In experiment, we varied the degree of nonlocality by changing the bias voltage and indirectly determined the relation between the critical power and pretilt angle. At last, by comparison of analytical solutions with the numerical simulation and the experimental result, we verified that our expressions are precise.
Dynamics of semiconductor laser with optical feedback: Evolution from low-frequency fluctuations to chaos
Authors: Kong Ling-Qin  , Wang An-Bang  , Wang Hai-Hong  , Wang Yun-Cai  ,   太原理工大学物理系，太原  030024
Published: December 2020

The low-frequency fluctuations and high-dimensional chaos with 12.2 correlation dimensions were generated experimentally by a semiconductor laser with optical feedback. Extensive experimental and numerical studies were performed to reveal the evolution process from low-frequency fluctuations to chaos. Our results showed that there exists a obvious critical point for the semiconductor laser's bias current. When the bias current Ib is set below 1.03Ith, the peak-to-peak value of the low-frequency fluctuations increases at first and then decreases with the feedback strength decreasing, while its average period keeps decreasing. In this process, the output of the semiconductor laser never goes chaos. However, when the bias current Ib is set beyond 1.03Ith, chaos appears and is persistent in this range. Moreover, the peak-to-peak value of the low-frequency fluctuations increases continuouslly and its duration decreases with the decrease of the feedback strength. Three stages experienced in the process leading from stable emission and low-frequency fluctuation to chaos are established. Numerical simulations are well consistent with the experimental results.
A new safranine T sensitized photopolymer for holographic recording
Authors: Xiao Yong  , Sun Cai-Xia  , Tang Dao-Guang  , Lu Hai  , Li Ruo-Ping  , Huang Ming-Ju  ,   河南大学物理与电子学院，光学与光子技术研究所，开封  475001
Published: December 2020

A new type of holographic recording material using safranine T sensitized photopolymer based on polyvinyl-alcohol was fabricated and studied. And the material was specially exposed to the Ar+ laser of 514.5nm wavelength. The results indicate that the material has high diffraction efficiency, sensitivity and refractive index modulation. The maximum diffraction efficiency is nearly 40%, the sensitivity is 7.22×10-4cm2/mJ and the refractive index modulation is 3.65×10-4. But the Bragg-mismatch caused by the exposure must be considered during recording. Holograms were recorded in the material, and the images can be reconstructed clearly. So the photopolymer material is suitable for high-density volume holographic storage.
Research on the mechanism of reflection characteristics of laser irradiation on cat eye optical lens
Authors: Zhao Yan-Zhong  , Sun Hua-Yan  , Song Feng-Hua  , Tang Li-Ming  , Wu Wei-Wei  , Zhang Xi  , Guo Hui-Chao  ,   装备指挥技术学院光电装备系,北京  101416
Published: December 2020

Using the theory of matrix optics and expanding the aperture function into a sum of finite complex Gaussian functions, this paper theoretically deduces the mechanism of cat eye effect generated by laser irradiation on the cat eye optical lens and analyzes the reflection law of cat eye effect through numerical computation. Then an experiment is operated to validate the cat eye effect by making 532nm laser irradiate on an optical zoom lens whose focusis ranged between 12 and 72mm. By using the above method, the law governing the variation of laser reflection characteristics with the parameters of the transmitting laser beam and the cat eye optical lens, including aperture, focus and focal shift etc, is established. The study reveals that the reflection characteristics of cat eye effect are intimately correlated with the parameters of the cat eye optical lens and transmitting laser beam, furthermore, the characteristics would change obviously when there is a large change in the distance between the waist of the incident beam and the cat eye optical lens. In particular, a reasonable choice of the positive focal shift would result in a higher peak intensity at the return place than that of no focal shift, when the distance between the waist of the incident beam and the cat eye optical lens varies, whereas the former conclusion based on geometry optics was that the highest peak intensity could be obtained when the optical lens has no focal shift.
Cycle of segregation patterns in vertically vibrated binary granular mixtures
Authors: Liang Xuan-Wen  , Li Liang-Sheng  , Hou Zhao-Guo  , Lü Zhen  , Yang Lei  , Sun Gang  , Shi Qing-Fan  ,   (1)北京理工大学物理系，北京  100081; (2)北京理工大学物理系，北京  100081；中国科学院理论物理研究所，北京  100080; (3)中国科学院物理研究所，北京  100080
Published: December 2020

A new phenomenon of granular segregation is observed, in which the binary granular mixture submitted to the vertically vibration behaves in cyclic segregation patterns which switches between the Brazil nut, reverse Brazil nut and sandwich patterns with a frequency that accelerates with time. The rule of cycing is investigated, and the phase diagram is depicted. The new phenomenon is qualitatively explained in terms of the collision, friction and air dissipation, and it was experimentally verified that the cycling of segregation patterns has close relation with the presence of air.
Numerical simulation of salt finger convection in porous media
Authors: Luo Ying-Ying  , Zhan Jie-Min  , Li Yok-Sheung  ,   (1)香港理工大学土木及结构工程系，香港; (2)中山大学应用力学与工程系，广州  510275；中山大学近岸海洋工程广东省重点实验室，广州  510275
Published: December 2020

The dual-mesh hybrid numerical method is used to investigate the salt finger convection, as well as the heat and mass transfer, in saturated porous media. It is found that at low normalized porosity of porous media, saline diffusion is much faster than thermal diffusion. The fingers grow straightly to the top and bottom walls, which would lessen the saline gradient of stratified system. Also, it is indicated that the hybrid method is perfect for dealing with small scale convection in porous media because of its great veracity, efficiency and stability.
Formations of conic surfaces on diamond films induced by hot filament assisted double-bias hydrogen plasma
Authors: Meng Liang  , Zhang Jie  , Zhu Xiao-Dong  , Wen Xiao-Hui  , Ding Fang  ,   中国科学技术大学近代物理系，中国科学院基础等离子体物理重点实验室，合肥  230026
Published: December 2020

The hot filament assisted double-bias hydrogen has been employed for the surface fabrication of the as-formed chemical vapor deposited diamond films on the nanometer scale. Diamond cone arrays are successfully prepared through hydrogen plasma etching. The intrinsic columnar structure of the diamond films leads to the unevenly distributed ion etching rate, which plays an important role in the cone formation. Simultaneously, the carbon-containing species sputtered out may re-deposit on the surface. The evolvement of the characteristic surface is thus determined by the competition between the ion etching and the carbon deposition. The application of grid electrode influences the discharge characteristics at the substrate region. By controlling the grid current, the surface structure of diamond films may be significantly tuned. Moreover, by introducing small amounts of methane in the etching process, the increased concentration of carbon-containing species enhances the secondary diamond nucleation on the film surface, which further promotes the uniformity of the diamond cone arrays.
Measurements of release sound velocities of tin with reverse-impact method
Authors: Hu Jian-Bo  , Zhou Xian-Ming  , Tan Hua  ,   中国工程物理研究院流体物理研究所，冲击波物理与爆轰物理国防科技重点实验室，绵阳  621900
Published: December 2020

In this paper, reverse-impact method for measuring release sound velocities was improved through special treatment of the impacted face of the window, and using time-resolved velocity interferometer system for any reflector. Our experimental technique solved the problem that bulk and longitudinal sound velocities can not be obtained simultaneously using the original method reported in the literature, due to the effect of release behaviors in the buffer. With the modified reverse-impact method, sound velocities of tin were measured with higher accuracy (measuring errors of longitudinal and bulk sound velocities being about 2% and 5%, respectively) in the range of 37—80 GPa. The experimental results are consistent with thermodynamic theoretical values.
Effective shear modulus in shock-compressed aluminum
Authors: Yu Yu-Ying  , Tan Hua  , Hu Jian-Bo  , Dai Cheng-Da  , Chen Da-Nian  , Wang Huan-Ran  ,   (1)宁波大学力学与材料科学研究中心，宁波  315211; (2)中国工程物理研究院流体物理研究所，冲击波物理与爆轰物理国防科技重点实验室，绵阳  621900
Published: December 2020

A method to determine the effective shear modulus under shock loading conditions by using longitudinal and bulk sound velocities along the quasi-elastic release was introduced in present paper. The effective shear modulus was calculated for LY12 aluminum over shock pressures range of 20—70 GPa. Results show that the effective shear modulus decreases linearly with the stress, reaching to zero at the reverse yield point, and the effective shear modulus at first release can be depicted by the modified Steinberg-Cochran-Guinan model. Using the effective shear modulus data, simulation has been successful in reproducing the experimental data with quasi-elastic release behavior, showing smooth transition from elastic wave to fully plastic wave.
Study on discontinucous energy dissipation mechanism of friction
Authors: Gong Zhong-Liang  , Huang Ping  ,   华南理工大学机械工程学院,广州  510640
Published: December 2020

Based on the composite oscillator model of atomic-scale wearless friction, a quantum mechanics model is proposed for analyzing the energy dissipation. The analysis indicates that the energy dissipation is discontinuous in a sliding process. The energy absorbing ability of an atom on a contact surface is discrete when the atom jumps from one equilibrium state to another. At the same time, the ability of a contact surface atom to absorbe the interfacial potential energy is stronger in a high energy state than in a low energy state. This will provide the theoretical basis for analyzing the periodical change in friction.
Franz-Keldysh effect in two-photon absorption
Authors: Cui Hao-Yang  , Li Zhi-Feng  , Li Ya-Jun  , Liu Zhao-Lin  , Chen Xiao-Shuang  , Lu Wei  , Ye Zhen-Hua  , Hu Xiao-Ning  , Wang Chong  ,   (1)云南大学工程技术研究院，昆明  650091; (2)中国科学院上海技术物理研究所功能材料器件中心，上海  200083; (3)中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

The Franz-Keldysh effect in the two-photon absorption process in the space charge region of an Hg0.695Cd0.305Te photodiode is demonstrated. By employing as the exciting light source a pulsed laser beam at λ0=7.92μm from an optical parametric generator and difference frequency generator pumped by a pico-second Nd:YAG laser, the photo-response has been measured as a function of the excitation intensity. The peak intensity of the pulsed photo-response shows a quadratic dependence on the incident intensity. A relationship between the pulsed photo-voltage and the incident optical intensity has been established with an equivalent RC circuit model to derive the degenerate single beam two-photon absorption coefficient. The results show that the two-photon absorption coefficient within the space charge region of the photodiode is about a factor of 2.7 higher than that outside the space charge region, implying an electric field induced enhancement of the two-photon absorption. This indicates that the Franz-Keldysh effect exists not only in the one-photon absorption process but also in the two-photon absorption process.
The site preference of 3d transition metals in NiAl and its effects on bond characters
Authors: Shang Jia-Xiang  , Yu Xian-Yang  ,   北京航空航天大学材料科学与工程学院，北京  100083
Published: December 2020

The site preference of 3d transition metals in B2-NiAl intermetalics and its effects on bond characters are investigated by the pseudopotential plane wave method. The formation energy results show that Sc, Ti, V and Zn prefer to occupy the Al site, while Cr, Mn, Fe, Co and Cu prefer to occupy the Ni site in NiAl. By analyzing changes in crystal lattice constants, Mulliken population, overlap population and valence charge density, the crystal lattice distortion and bond characters are discussed. The results show that the lattice distortions of Sc, Ti, V and Zn doped NiAl play an important role in determining the alloy properties. The strong repulsion interaction and anti-bonds as well as charge transfer between the dopant atom and the nearest_neighbor Ni atoms are observed, which makes the fraction of covalent bonds to be decreased and the fraction of the metallic bonds to be increased by Sc, Ti, V and Zn substituting the Al sites of NiAl. The bond character changes a little by Cr, Mn, Fe, Co and Cu substituting the Ni sites of NiAl.
A method of accelerating molecular dynamics simulation for atomic diffusion in metallic interface
Authors: Zhang Xian-Ming  , Yang Li-Hong  , Wu Yong-Quan  , Shen Tong  , Zheng Shao-Bo  , Jiang Guo-Chang  ,   (1)宝山钢铁股份有限公司,上海  201900; (2)上海大学上海市钢铁冶金重点实验室,上海  200072
Published: December 2020

Many interesting long-time dynamic properties of solid interface, such as deep diffusion, pervasion and phase forming, cannot be simulated directly using traditional molecular dynamics (MD) because of nanosecond timescale limitations. Thus, a simpler bias potential form has been proposed within the Voter's hyper dynamics scheme. In this method, the potential energy wells are raised by adding a coefficient, which was defined as the accelerating factor, to the original potential. So, the escape rate from potential wells was enhanced, which extends the timescale by several orders of magnitude comparing to the traditional MD simulations. What's more important, the features of potential surface are reserved even without any in_advance knowledge of the location of either the potential energy wells or saddle points. We demonstrate this method by applying it to the mutual diffusion of atoms in Mg/Zn interface with different accelerating factors using a simple Lennard-Jones potential. The results showed that long-time MD simulation can be realized very easily by our approach.
Influences of flux and interruption on InAs/GaAs quantum dot superlattice growth
Authors: Song Yu-Xin  , Yu Zhong-Yuan  , Liu Yu-Min  ,   北京邮电大学理学院，北京  100876；北京邮电大学光通信与光波技术教育部重点实验室，北京  100876
Published: December 2020

Kinetic Monte Carlo simulations are applied to study the growth of self-assembled vertical ordering InAs quantum dot superlattice on GaAs substrate. The study is focused on the influences of flux and interruption time at the initial stage when the first sub-monolayer is forming on the wetting layer. We demonstrate that uniform sized and regularly ordered island arrays can be obtained by controlling flux and interruption time, by means of studying the surface morphology, average island size, island size distribution and the standard deviation of island size distribution comprehensively. The size and order of island arrays will greatly affect the location and size of quantum dots in subsequent three-dimensional growth.
The electronic theory study of the influence of Pd on the passivation of Ti alloys
Authors: Zhang Guo-Ying  , Zhang Hui  , Liu Yan-Xia  , Yang Li-Na  ,   (1)辽宁大学物理系，沈阳  110036; (2)沈阳师范大学物理科学与技术学院，沈阳  110034
Published: December 2020

The electronic structure parameters of Ti alloys, such as density of states, Fermi energy level, environment-sensitive embedding energy etc, have been calculated by recursion method. The larger environment-sensitive embedding energy of Pd in the bulk of Ti alloy than that on the surface of Ti alloy indicates that Pd is apt to segregate on the surface. The negative formation energy of Pd clusters suggests that the distribution of Pd atoms on the surface of Ti alloy is in the form of atom clusters. The range of the local density of states of Pd is narrow, while that of Ti is wide. So a peak appears in the total density of states of Ti alloys between -20 and -15 eV. This peak has a significant effect on the Fermi level. It makes the Fermi energy of the surface Ti alloys with more Pd atoms low. So the microcells form between the area with more Pd atoms and the area with fewer or without Pd atoms on the surface of Ti alloys. Ti dissolves preferentially in the corrosive media. This leads to form a layer of Pd atomic clusters on Ti alloy surface. The Pd atomic layer serves as the electrocatalytic surface, facilitating the passivation of Ti alloys and improving the corrosion resistance.
Antiferromagnetic quantum phase transition near x=1.00 in NiS2-xSex system
Authors: Yang Jin-Hu  , Wang Hang-Dong  , Du Jian-Hua  , Zhang Zhu-Jun  , Fang Ming-Hu  ,   浙江大学物理系,杭州  310027
Published: December 2020

There may be an antiferromagnetic quantum phase transition near x=1.0０ in NiS2-xSex system. The polycrystalline samples of NiS2-xSex (x=0.96, 0.98, 1.00, 1.05, 1.10 and 1.20) were prepared by the solid state reaction method, and the measurements of their structure, magnetization and resistivity were carried out. It is found that the temperature dependence of susceptibility is typical characteristic of a strongly correlated electron system. Similar to high Tc superconductors, the relationship between resistivity and temperature displays a linear behavior in a wide temperature range from 50 to 300 K. For NiS2-xSex(x=0.98 and 1.00) samples, its ρ(T) is proportional to T3/2 at lower temperatures (3—30 K), which shows a non-Fermi-liquid behavior. But for NiS2-xSex (x=1.10 and 1.20) samples, its ρ(T) is proooportional to T2 at lower temperatures (3—30 K), which shown the Fermi-liquid behavior. The antiferromagnetic quantum spin fluctuation related to quantum phase transition is discussed in detail.