bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of femtoseond Ti:sapphire laser at 10MHz repetition rate by extending laser cavity with a telescope
Authors: Zhao Yang-Ying  , Han Hai-Nian  , Teng Hao  , Wei Zhi-Yi  ,   中国科学院物理研究所光物理重点实验室，北京  100190
Published: December 2020

We demonstrated a femtosecond Ti:sapphire oscillator at 10?MHz repetition rate by introducing a specially designed multi-pass telescope to increase the cavity length. Stable mode locking laser with average power of 200 mW is obtained under 532?nm laser pump of 5?W power, corresponding to a single pulse energy of 20?nJ. Based on this laser, we further explored the characteristics of pulse duration and spectrum with the net intracavity group-delay dispersion （GDD）. The result indicates that the near-bandwidth-limited pulse can be obtained when a little net negative GDD exists, the optimized pulse duration as short as 56?fs was generated in this case. The positive GDD will lead to a widened pulse with the increase of positive GDD, and the pulse duration can extend to more than 600?fs with the largest allowable positive GDD.
High power 2μm intracavity doubly resonant optical parametric oscillator
Authors: Cui Qian-Jin  , Xu Yi-Ting  , Zong Nan  , Lu Yuan-Fu  , Cheng Xian-Kun  , Peng Qin-Jun  , Bo Yong  , Cui Da-Fu  , Xu Zu-Yan  ,   (1)中国科学院物理研究所,北京凝聚态物理国家实验室,北京  100190; (2)中国科学院物理研究所,北京凝聚态物理国家实验室,北京  100190；中国科学院研究生院，北京  100190
Published: December 2020

A high power intracavity optical parametric oscillator （OPO） with a type Ⅱ KTiOPO4（KTP） is reported. The OPO is placed in a high power, linearly polarized diode-side-pumped Nd∶YAG laser cavity. By a suitable design of the OPO cavity, a maximum of 295 W at 2?μm is reached with repetition rate of 5?kHz. The output power characteristic of OPO is investigated. The fluctuation of OPO output power in less than 1.4%.
The relation between UV conversion efficiency and focused green Gaussian beam waist in BBO crystal
Authors: Hu Miao  , Ge Jian-Hong  , Chen Jun  , Liu Chong  ,   (1)杭州电子科技大学通信工程学院,杭州  310018; (2)浙江大学现代光学仪器国家重点实验室,杭州  310027
Published: December 2020

Here we present a theory which predicts the process of ultraviolet generation by frequency doubling of focused green Gaussian beam in BBO crystal. In this theory, phase matching acceptance angle, walk-off angle and the divergence of fundamental beam have been considered. Numerically computed results show that the variations of the waist of Gaussian beam can lead to changes in conversion efficiency and in the ultraviolet transverse intensity distribution of far-field. Comparison between the numerical simulation and experimental results supported our theoretical analysis.
Nonlinear propagation of circularly polarized light in magneto-optic fiber Bragg gratings
Authors: Qiu Kun  , Wu Bao-Jian  , Wen Feng  ,   电子科技大学宽带光纤传输与通信网技术教育部重点实验室,成都  610054
Published: December 2020

The theoretical model of magneto-optic fiber Bragg gratings （MFBG） is proposed and the nonlinear coupled-mode equations for circularly polarized light in MFBG is derived for the first time. Our analysis shows that the coupling between right- and left-handed circularly polarized light along with the magnetically circular birefringence （the Faraday effect） resulting from the nonlinear effects and the grating structure is responsible for the coupling of forward and backward guided optical waves with identical states of polarization. In the MFBGs, the reversal of transmission characteristics and lower power threshold of nonlinear bistable switching can be achieved under appropriate magneto-optic bias. The MFBG-based pulse reshaping scheme by utilizing cross-phase modulation （XPM） of right- and left-handed circularly polarized light has a great advantage in magnetic adjustability over that based on conventional fiber gratings and is useful for the development of dynamically controllable all-optical 3R regenerators.
Theoretical analysis of novel Brillouin scattering properties in photonic crystal fibers based on silica rod model
Authors: Huang Yan  , Zhang Wei  , Wang Yin  , Huang Yi-Dong  , Peng Jiang-De  ,   清华大学电子工程系集成光电子学国家重点实验室，北京  100084
Published: December 2020

Based on an approximate model for acoustic waves in a silica rod with circular cross section, we theoretically investigated the dispersion properties of the hybrid acoustical modes and the acousto-optical interactions in the small core photonic crystal fiber. The calculation result shows that the dual-peaked Brillouin scattering gain coefficient spectrum is caused by the mode coupling of the hybrid acoustical modes in the small fiber core. Together with the dispersion properties of the acoustical modes, the influence of the pump wavelength and temperature on the dual-peaked Brillouin scattering gain coefficient spectrum are also calculated via their influences on the acoustic wave vector and material parameters. Our theoretical results agree with the experimental results well. And we also discuss the limit of application of this model through comparing the theoretical and experimental results.
Rotating azimuthon in strongly nonlocal nonlinear media
Authors: Dai Ji-Hui  , Guo Qi  ,   华南师范大学光子信息技术广东省高校重点实验室，广州  510631
Published: December 2020

In strongly nonlocal nonlinear media, the evolution of the optical beam is governed by Snyder-Mitchell model. By applying the variational method, we obtain an approximate analytical solution of Snyder-Mitchell model, i.e., the rotating azimuthon, which has an inherent rotation. Under certain conditions, the rotating azimuthon can be reduced to the radially symmetric optical vortex soliton.
Study on new periodic structures of left-handed material composed of hexagonal SRRs and metal wires
Authors: Zhang Chun-Min  , Sun Ming-Zhao  , Yuan Zhi-Lin  , Song Xiao-Ping  ,   (1)武汉邮电科学研究院，武汉  430074; (2)西安交通大学理学院，西安  710049
Published: December 2020

We studied new left-handed material composed of hexagonal split resonant rings （SRRs） based on trigonal resonators and metal wires through simulation and experiment. Simulated negative permeability material based on periodic structures of trigonal SRRs, in contrast to simulation result based on closed split resonant rings （CSRRs）, we found that the trigonal SRRs can generate negative permeability, and multilayer SRR simulation shows the coupling can enhance the resonant frequency and broaden resonant frequency band. We designed a new kind of left-handed material combined with hexagonal resonator based on trigonal resonators and copper wires. Simulation shows that the structures have good left-handed property. We have fabricated experimental samples which show negative refraction when the frequency lies in 93—108 GHz rangc. This has important significance on design and study of new types of periodic structures of left-handed materials.
Development of full-field optical coherence tomography system
Authors: Yang Ya-Liang  , Ding Zhi-Hua  , Wang Kai  , Wu Ling  , Wu Lan  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

A full-field optical coherence tomography system using an achromatic phase shifter based on a rotating half-wave plate to implement phase shifting is developed. The phase shifter can achromatically introduce phase shift of eight times the rotating angle of the half-wave plate, and can rapidly provide various phase shifts for various algorithms. Real phase shift is measured and the result demonstrates that the system gives a phase shift of eight times the rotating angle of the half-wave plate, showing the achromatic phase shifter model is correct. Imaging experiment results of a mirror using Hariharan algorithm show that the system has high phase shift precision. A coin as the sample is imaged to demonstrate the performance of the system.
Gain characteristic of ultraviolet single photon imaging system
Authors: Zhang Xing-Hua  , Zhao Bao-Sheng  , Liu Yong-An  , Miao Zhen-Hua  , Zhu Xiang-Ping  , Zhao Fei-Fei  ,   (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

Single-photon-counting imaging technology has been widely used in ultraweak bioluminescence, space environment detection and nuclear radiation detection. The structure and working principle of an ultraviolet single photon imaging system based on the microchannel plates and the wedge and strip anode are introduced. The gain characteristic of dark count of two and three microchannel plates is investigated under different voltages respectively. The experimental and fitted results show that the dark count pulse height distribution of microchannel plate has exponential distribution, and the dark count rate rises as the voltage increases. It is shown that the gain becomes more homogeneous as the voltage increases by measuring the pulse height distribution under different voltages. Then the effects of microchannel plate voltage and distance on system resolution with two microchannel plates are tested. It is revealed that the system resolution rises as the voltage of microchannel plate increases, and can be improved also by increasing the distance of microchannel plate properly.
Investigation of co-doping Al3+ in ytterbium-doped silica-based fiber
Authors: Yan Feng-Ping  , Wang Lin  , Wei Huai  , Fu Yong-Jun  , Jian Wei  , Zheng Kai  , Mao Xiang-Qiao  , Li Jian  , Liu Li-Song  , Peng Jian  , Jian Shui-Sheng  ,   全光网络与现代通信网教育部重点实验室，北京交通大学光波技术研究所，北京  100044
Published: December 2020

The characteristics of co-doping Al3+ in ytterbium-doped silica-based fiber used for high-power cladding pumped laser were analyzed based on experimental analysis. The results show that the optimum mole percent of Al3+ to Yb3+ is 9—11 for high concentration of ytterbium-doped silica-based fiber at which low concentration quenching probability, high absorption coefficient and proper numerical aperture can be obtained. Meanwhile, ytterbium-doped silica-based fiber preforms were fabricated by MCVD and special solution doping technique. By soot layer temperature experiment and test of the related parameters of the drawn fiber, the results show that the optimum temperature for making soot layer can be accurately controlled and the absorption coefficient at 976 nm was as high as 620 dB/m with good repeatability. This conclusion makes a useful reference for fabrication of ytterbium-doped Al3+ co-doped fiber.
A geoacoustic inversion method based on bottom reflection signals
Authors: Yang Kun-De  , Ma Yuan-Liang  ,   西北工业大学航海学院，西安  710072
Published: December 2020

It is important for underwater acoustic modeling and passive localization to estimate the geoacoustic properties with high accuracy. A geoacoustic inversion scheme was presented, which uses a broadband source to generate the linear frequency-modulated signal at different ranges and depth. The signal was received by a vertical array. The bottom reflection loss was extracted by matched filtering and then used to estimate the sea-bottom density and sound speed. Meanwhile, an inversion method based on sub-bottom reflection was investigated using the experimental data. Because the direct arrivals in the water were influenced strongly by the internal waves, the first sea-bottom reflection was taken as the reference path to calculate the relative arrival time and amplitude of sub-bottom reflections. Firstly the sediment sound speed and thickness were estimated using different source depth and receiver depth. Then the sediment attenuation was estimated by assuming that it has linear frequency dependence. The estimated values of the sediment properties compared well with the core data, chirp sonar data, and the matched field inversion results.
Saturation of stimulated Raman scattering in laser-plasma interaction
Authors: Zhang Lei  , Dong Quan-Li  , Zhao Jing  , Wang Shou-Jun  , Sheng Zheng-Ming  , He Min-Qing  , Zhang Jie  ,   中国科学院物理研究所光物理重点实验室，北京  100190
Published: December 2020

The saturation of stimulated Raman scattering （SRS） through Langmuir decay instability （LDI） and electron trapping in laser-plasma interaction process is studied. Analytical expressions for the saturation time of SRS are obtained for both the LDI and electron trapping schemes in 1-D homogeneous plasma irradiated by unrelativistic laser beams. The simple analytical model agrees well with numerical simulation and experiment in respect of the dependence of the saturation time of SRS on the parameters of lasers and plasmas.
The effect of the oscillating sheath on the electron-wall collision frequency in Hall thruster
Authors: Yu Da-Ren  , Zhang Feng-Kui  , Li Hong  , Liu Hui  ,   哈尔滨工业大学能源科学与工程学院，哈尔滨  150001
Published: December 2020

The effect of oscillating sheath on the near-wall conductivity is studied by using two-dimensional particle-in-cell （PIC） method. The results show that when the secondary electron emission （SEE） coefficient is greater than 1, the sheath is in the state of oscillation, in which the electron-wall collision flux periodically oscillates along the direction parallel to the wall, and the order of oscillating wavelength is the same as that of the electrostatic wavelength. The order of electron-wall collision frequency is 1—2 orders higher than the frequency of the classic shell state, and the contribution of collision frequency to the current in the channel cannot be neglected. Though the oscillating shell increases electron-wall collision frequency compared to classic shell, it prevents electron-wall collision at the same time.
Molecular dynamical investigation on plastic behavior of Cu(100) twist-grain boundary under uniaxial tension
Authors: Liu Xiao-Ming  , You Xiao-Chuan  , Liu Zhan-Li  , Nie Jun-Feng  , Zhuang Zhuo  ,   清华大学航天航空学院，北京  100084
Published: December 2020

Misfit dislocation structures at twist-grain boundary and its effect on grain boundary strength are investigated by using molecular dynamics simulation with EAM potential. The results reveal that the density of misfit dislocations which are formed on small angle twist-grain boundary is increased as the twist angle increased. Dislocations nucleate at each unit of the dislocation networks and the yield stress is increased as the density of misfit dislocations increases since grain boundary is strengthened by the interaction between dislocation networks. Face defect is formed at large angle twist-grain boundary, and the dislocations nucleate at the atomically sharp corner of the grain boundary. The yield stress is kept almost at the same value since there is little effect on the nucleation force of dislocation on face-defect grain boundary.
Fabrication of InP nano inner cladding fiber and its amplification propertg based on quantum size effect
Authors: Wang Jin  , Zhang Ru  ,   北京邮电大学理学院光通信与光波技术教育部重点实验室，北京  100876
Published: December 2020

We uses improved chemical vapour deposition and drew fibres with InP nano thin films. Based on the hydrogen atom model, we calculate the corresponding size of the InP particle aB=8313 nm. By the quantum size-effect, we calculate the change of the energy band of particles with different sizes and the corresponding light absorption wavelength. From the system testing, the fibres have gain at 906—1044 nm, 1080—1491 nm and 1524—1596 nm. The results showed that the energy level of inner cladding materials creates a red shift when the thickness of thin-film is 5—50 nm. The fibre creates optical amplification.
Density functional study on the geometric and electronic properties of MC20F20 （M=Li, Na, Be, Mg）
Authors: Cao Qing-Song  , Deng Kai-Ming  , Chen Xuan  , Tang Chun-Mei  , Huang De-Cai  ,   南京理工大学应用物理系，南京  210094
Published: December 2020

The generalized gradient approximation （GGA） based on density functional theory（DFT）is used to analyze the geometric and electronic properties of the endohedral fullerene MC20F20 （M=Li, Na, Be, and Mg）. The analysis of geometric structure indicates that the C—C bond length increases with the atomic number M, while the C—F bond length hardly changes. The doping energy of all kinds of MC20F20 is negative, indicating that the encapsulation would proceed under certain conditions. The electronic structure demonstrates that MC20F20 （M=Li and Na） and MC20F20 （M=Be and Mg） have different energy gaps and magnetic moments. The energy gaps of MC20F20 （M=Li and Na） are very small, while the energy gaps of MC20F20 （M=Be and Mg） are larger than that of C60 On the other hand, the MC20F20 （M=Li and Na） have 1μB magnetic moment, whereas the magnetic moments of MC20F20 （M=Be and Mg） are zero.
Comparison of the compositions and structures of electrodeposited Cu-poor and Cu-rich Cu(In1-xGax)Se2 films before and after selenization
Authors: Ao Jian-Ping  , Yang Liang  , Yan Li  , Sun Guo-Zhong  , He Qing  , Zhou Zhi-Qiang  , Sun Yun  ,   南开大学光电子薄膜器件与技术研究所，天津市光电子薄膜器件与技术重点实验室，天津  300071
Published: December 2020

Cu-poor and Cu-rich near stoichiometric Cu (In1-x Gax)Se2(CIGS) precursor films were obtained by one-step electrodeposition from acid aqueous baths, and the compositions and structures of the as-deposited films before and after selenization were investigated. The straightforward experimental evidence was first obtained, which showed that Cux Se compound was conglomerated as rather large crystal grains which was distributed on the surface of the film for the Cu-rich films after seleniztion. The results indicated that the film composition was changed barely after selenization. When the ratio Cu/(In+Ga)＜1.1, there were many cracks on the surface of CIGS after selenization. When Cu/(In+Ga)＞1.2, no cracks were formed on the surface of the thin films. The efficiency of solar cells bnilt directly from Cu-poor films after selenization achieved above 2%, which is pending further investigation. Furthermore, the efficiency of solar cells bult from Cu-rich CIGS films after selenization and deposition of a few In, Ga and Se by PVD has achieved 6.8%.
First-principles study of electrical structures and optical properties of Co:MgF2 crystal
Authors: Zhang Ji-Hua  , Ding Jian-Wen  , Lu Zhang-Hui  ,   湘潭大学物理系，纳米物理和稀土发光研究所，湘潭  411105
Published: December 2020

Based on the density functional theory, the geometries, electrical structures and optical properties of Co-doped MgF2 system （Co:MgF2） are studied by first-principles ultra-soft pseudopotential plane-wave approach. With Co-doping increasing, a tetragonal-rhombic structural transition is obtained in Co:MgF2 The band gap decreases with increasing Co-doping, and a semiconductor-conductor transition is observed. Also, the calculations show that the static dielectric constant and the absorption coefficient can be remarkably modulated by Co-doping, indicating the potential applications of Co: MgF2 optical system.
Calculation of the electronic structure of Y-doped SrTiO3
Authors: Xu Xin-Fa  , Shao Xiao-Hong  ,   北京化工大学理学院,北京  100029
Published: December 2020

The geometrical and electronic structures, and also the dopant formation energies, lattice constants, band structure and density of states （DOS） of Sr1-xYxTiO3 with x=00, 0125, 025 and 033 are calculated from the first principles of plane wave ultra-soft pseudo-potential method based on density functional theory. The results of dopant formation energy show that Y preferentially enters the Sr site in SrTiO3 Electronic structure results show that pure SrTiO3 is an insulator and the Fermi energy is at the top of valence band. When doped with Y, the Fermi energy of the system goes into the conduction band and the system undergoes an insulator-to-metal transition. Due to the appearance of the carrier impurity from Y doping, there is a significant distortion near the bottommost conduction bands.
Ferromagnetism and the optical properties of Cu-doped AlN from first-principles study
Authors: Lin Zhu  , Guo Zhi-You  , Bi Yan-Jun  , Dong Yu-Cheng  ,   华南师范大学信息光电子科技学院光电子材料与技术研究所，广州  510631
Published: December 2020

The geometrical structure of Cu doped 32-atom supercell of AlN was optimized by using the ultra-soft pseudopotential method of total-energy plane wave based on density functional theory （DFT） . Density of states，band structure and optical properties were calculated and discussed in detail. The results revealed that The Cu dopants were found spinpolarized. Band structures show a half metallic behaviour. The band gap of Cu-doped AlN reduced and the absorption ability to infrared visible light strengthened obviously,the loss of energy decrease The ferromagnetic ground state in Cu-doped AlN can be explained in terms of p-d hybridization mechanism. These results suggest that Cu-doped AlN may present a promising dilute magnetic semiconductor.
Effect of the tensile force on the electronic energy gap of graphene sheets
Authors: Wei Yong  , Tong Guo-Ping  ,   浙江师范大学数理与信息工程学院，金华  321004
Published: December 2020

The external force can make a graphene sheet tighten and change its electronic structure. By using the tight-binding method, the energy bands of graphene sheets with zigzag shaped edges and armchair shaped edges drawn by the tensile force are investigated based on considering the nearest-neighbor interaction, and the analytic relations between the energy gaps besides the energy bands of π-electrons for two types of graphene sheets and the tensile force are obtained . Through numerical calculation, we found that the energy gaps broaden as the tensile force increases besides that the tensile force can make graphene open an energy gap,and moreover, the energy gap of graphene with zigzag edges broadens more easily.
Atomistic simulation of mechanical properties of martensitic transformation under dynamic compression
Authors: Shao Jian-Li  , Qin Cheng-Sen  , Wang Pei  ,   北京应用物理与计算数学研究所，北京  100088
Published: December 2020

Molecular dynamics simulation （MD） was used to investigate the microscopic mechanism of martensitic transformations in Fe single crystals driven （along ［001］ orientation） by an accelerating piston. Simulated results revealed that the above compression process can be divided into five stages, namely the elastic compression, softening of elastic ratio, phase transformation （bcc to hcp）, over-relaxation of stress and elastic compression of high-pressure phase. The slipping laws of atoms and properties of stress are analysed in detail. Atoms can only slip along longitudinal direction under elastic compression, and when the longitudinal stress is beyond 10 GPa, local atoms begin to slip along lateral direction and form embryos, which is just the microscopic nature of the softening of elastic ratio.The stacking fault （fcc） is a more steady origin of crystal nucleation than the twin boundary. After the phase transformation, the atoms undergo an over-relaxation of stress （i.e., the lateral stress is larger than the longitudinal stress）, and this state disappears when the longitudinal stress is beyond about 36 GPa.
Submilliampare threshold 1.3μm vertical-cavity surface-emitting lasers
Authors: Lao Yan-Feng  , Cao Chun-Fang  , Wu Hui-Zhen  , Cao Meng  , Gong Qian  ,   中国科学院上海微系统与信息技术研究所，信息功能材料国家重点实验室，上海  200050
Published: December 2020

We present the design and fabrication of 13 μm vertical-cavity surface-emitting lasers （VCSELs）. This laser exhibits continuous-wave single-mode operation up to 82℃. The theshold current as low as 051 mA and a slop efficiency of 029 W/A have been achieved. This laser is composed of a wafer-bonded GaAs/Al（Ga）As distributed Bragg reflector （DBR） and a dielectric SiO2/TiO2 DBR with InAsP/InGaAsP strain-compensated multi-quantum wells grown in the cavity. The effect of cavity mode-gain offset on device performance is then discussed.
Analysis of the leakage current in GaN-based heterostructure buffer layer
Authors: Zhang Jin-Cheng  , Dong Zuo-Dian  , Qin Xue-Xue  , Zheng Peng-Tian  , Liu Lin-Jie  , Hao Yue  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件重点实验室，西安  710071
Published: December 2020

The relations between the buffer leakage current and the characteristics of nucleation layer of AlGaN/GaN heterostructure have been obtained by comparative study of depletion capacitance of C-V characteristics in GaN-based heterostructure. The results showed that, the heterostructure material based on a sapphire substrate with a low-temperature GaN nucleation layer and SiC substrate with a high-temperature AlN nucleation layer have smaller buffer leakage current and lower carrier concentration of the background GaN buffer layer than that based on a sapphire substrate with a low-temperature AlN nucleation layer. A thorough analysis shows that, there is an n-type GaN conductive layer near the GaN/substrate interface in buffer layer based on the thinner nucleation layers. Contrarily, high resistivity GaN buffer layers appear in heterostructure materials based on thicker nucleation layer. One of the main causes of device leakage is the n-type GaN conductive layer. Appropriately improving the quality and thickness of nucleation layer can effectively reduce the carrier concentration, raise the resistivity and suppress the leakage current of the GaN buffer layer.
Deep level transient spectroscopy and photoluminescence studies of CdS/CdTe thin film solar cells
Authors: Li Bing  , Liu Cai  , Feng Liang-Huan  , Zhang Jing-Quan  , Zheng Jia-Gui  , Cai Ya-Ping  , Cai Wei  , Wu Li-Li  , Li Wei  , Lei Zhi  , Zeng Guang-Gen  , Xia Geng-Pei  ,   四川大学材料科学与工程学院，成都  610064
Published: December 2020

Impurities and deep levels in CdS/CdTe thin film solar cells with no back-contact layer were studied by deep level transient spectroscopy and photoluminescence. They could lower the device performance notably. Distribution of net carrier concentration was obtained. Two deep levels at Ev+0.365 eV and Ev+0.282 eV were determined with concentration of 1.67×1012 cm-3 and 3.86×1011 cm-3, respectively, and with capture cross section of 1.43×10-14 cm2 and 1.53×10-16 cm2, respectively. They are attributed to chemical impurities like Au and/or a singly charged tellurium vacancy complex, or related to O atoms introduced by the deposition of CdTe in O2 and Ar ambient.
Organic red light-emitting diodes with a soluble luminescent compound and a novel TPBI/Ag cathode
Authors: Li Chun  , Peng Jun-Biao  , Zeng Wen-Jin  ,   华南理工大学高分子光电材料与器件研究所，特种功能材料教育部重点实验室，广州  510640
Published: December 2020

Soluble small red molecule No. 2 was introduced as the emitter for light-emitting diodes （PLED） with different cathodes. N-arylbenzinmidzoles （TPBI） was used as hole-blocking layer （HBL） to lower cathode barrier and facilitate electron injection.With TPBI/Ag cathode， the quantum efficiency was increased by 57%.The reason for the efficiency increase is that interfacial dipole layer was formed at the interface between TPBI and Ag, and possibly coordinated reaction between Ag and N atom in TPBI leads to a superior contact between TPBI/Ag.
Epitaxial growth of La0.67Sr0.33MnO3 on glass by laser molecular beam epitaxy
Authors: Zhang Ying-Tang  , He Meng  , Chen Zi-Yu  , Lü Hui-Bin  ,   (1)北京航空航天大学理学院，北京  100083; (2)北京航空航天大学理学院，北京  100083；中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100190；陕西理工学院材料学院，汉中  723003; (3)中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100190
Published: December 2020

La067Sr033MnO3 thin films have been deposited by laser molecular beam epitaxy system on glass substrates. The measurement of X-ray diffraction shows that the La067Sr033MnO3 thin film is a good orientation of c axis，and the magnetoresistance values of -378%, -268% and 607% at 88, 220 and 300 K, respectively, under 3 T magnetic field were observed.
Magnetomechanical modeling of magnet immersed in magnetic fluid and controllability of self-suspension
Authors: Liu Gui-Xiong  , Xu Chen  , Zhang Pei-Qiang  , Wu Ting-Wan  ,   (1)华南理工大学机械与汽车工程学院，广州  510640; (2)华南理工大学理学院，广州  510640
Published: December 2020

A magnet stably suspending in magnetic fluid is influenced by several factors. The key to analyze prerequisites of suspension of immersed body in magnetic fluids is the establishment of an exact mathematical model. The magnetomechanical modeling of spherical magnet encased in spherical vessel is established. The influence on magnetic force by magnetic conductivity, remnant magnetism and radius of magnet, radius of container and off-centering of magnet is analyzed. The conclusion has universal character. The calculation results indicate that various parameters has inerratic influence to magnetic force, and the conditions for self-suspension always exist. The relation between various parameters and the self-supension position is discussed on the basis of analyzing features of suspension balance position, and methods of controlling self-suspension position are discussed.
The structure and potential energy function investigation on SiX2(X=H，F) molecules
Authors: Jiang Li-Juan  , Liu Yu-Fang  , Liu Zhen-Zhong  , Han Xiao-Qin  ,   (1)河南师范大学物理与信息工程学院，新乡  453007; (2)河南师范大学物理与信息工程学院，新乡  453007;新乡学院物理系，新乡  453003
Published: December 2020

Using the QCISD/6-311++G(3df,3pd) and B3P86/6-311++G(3d2f) respectively, the possible ground-state structures of SiH2 and SiF2 molecules have been optimized. The results show that the ground state of SiH2 molecule is of C2v symmetry and in the 1A1 state, whose angle, equilibrium nuclear distance and dissociation energy are 92.5025°, 0.15149nm and 3.7098eV, respectively, The results also show that the ground state of SiF2 molecule is of C2v symmetry in the 1A1 state, whose angle, equilibrium nuclear distance and dissociation energy are 100.7079°, 0.16014nm and 14.1391eV, respectively, and their harmonic frequencies and force constants have been calculated. The present paper correctly determines the dissociation limits based on group theory and atomic and molecular reactive statics (AMRS). Analytical potential energy functions for the ground states X1A1 of SiX2(X=H，F) have been derived using many-body expansion method. The structure and energy of SiX2(X=H，F) can correctly reappear on the potential surface. Molecular reaction kinetics of SiH+H and SiF+F based on the potential energy functions is discussed briefly.
Ferromagnetism of C doped ZnO: first-principles calculation and Monte Carlo simulation
Authors: Chen Shan  , Wu Qing-Yun  , Chen Zhi-Gao  , Xu Gui-Gui  , Huang Zhi-Gao  ,   福建师范大学物理系，福州  350007
Published: December 2020

In this work, the electronic structure and the stability of ferromagnetism of C-doped ZnO are studied by first-principles calculations and Monte Carlo simulation. The calculated results indicate that the ferromagnetic ground state is stabilized by its half-metallic electronic structure which originates from the strong hybridization between Zn-3d and C-2p electrons. Meanwhile, by using the coupling strength obtained from first-principles calculations and Monte Carlo method, the Curie temperatures of ZnO1-xCx （x=555%, 833% and 125%） are predicted to be 210, 260 and 690 K, respectively, which is generally consistent with theroetical and experimental results. The electronic transfer resulting from C doping, and the changes between spin-up and spin-down electron changes for s, p and d electrons of C, Zn, O atom are analyed in detail. The simulated results show that, the local magnetic moments of ZnO1-xCx originate mainly from the hybridization interaction between Zn-3d and C-2p electrons, while the magnetic coupling between the local magnetic moments is preferentially the RKKY coupling.
Synthesis and magnetic, optical properties of Co doped ZnO room-temperature ferromagnetic semiconductor
Authors: Cheng Xing-Wang  , Li Xiang  , Gao Yuan-Ling  , Yu Zhou  , Long Xue  , Liu Ying  ,   北京理工大学材料科学与工程学院,北京  100081
Published: December 2020

Co-doped ZnO polycrystalline was synthesized with sol-gel method. Room temperature ferromagnetism （FM） was observed in the synthesized sample. Studies onits structural and optical properties indicate that the FM is originated from the Co substitution for Zn in ZnO crystalline lattice, and the temperature of sample synthesis significantly affects the FM and photoluminescence of the corresponding samples, suggesting that Zn interstitial could be responsible for the origin of the FM.
Analysis and application of time domain dielectric spectroscopy based on wavelet transform
Authors: Ren Lei  , Chen Xiang-Guang  , Liu Chun-Tao  ,   北京理工大学化工与环境学院，北京  100081
Published: December 2020

At present, the time domain dielectric spectroscopy is mainly used to analyze thin liquids or materials composed of molecular orderly substances. The various relaxation processes need to be unrelated or be superposed linearly. But it will be clearly limited when the method is applied to the complex heterogeneous mixture analysis. In order to widen its scope of application, the analysis method is improved in this paper by using the wavelet transform. Through the analysis of the oil-water mixture, the experimental results show that the time domain dielectric spectroscopy based on wavelet transform can not only offer the whole spectral information but exhibit the time domain and frequency domain information of various components. Therefore, the analysis method of time domain dielectric spectroscopy based on wavelet transform can be used to analyze complex heterogeneous mixtures.
Research on new type of slow light structure based on 2D photonic crystal coupled cavity waveguide
Authors: Lu Hui  , Tian Hui-Ping  , Li Chang-Hong  , Ji Yue-Feng  ,   北京邮电大学电信工程学院光通信与光波技术教育部重点实验室,北京  100876
Published: December 2020

The structure of 2D rods PhC CCW is studied, and it is found that the group velocity discreases quikly with the increase of lattice number between two rod defects. When 7×7 supercell unit is chosen, the largest group velocity νg-max of the guided mode is about 1/251 times that of photonic crystal line defect waveguide. Radius of the four rods around the cavity of the 7×7 supercell unit are adjusted, νg-max of the new strcture can reach 589×10-4c, and it's about 1/5 that of unadjusted structure. Finally, by making comparisons, it is found that the structure has the best slow-light characteristic when the radius of the up and down rods are changed.
Green polarized electroluminescence from poly （9, 9-dioctylfluorene-alt- benzothiadiazole）
Authors: Zhu De-Xi  , Zhen Hong-Yu  , Ye Hui  , Liu Xu  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

Polarized green electroluminescence has been achieved at the peak wavelength of 550 nm from alternate copolymer poly （9, 9-dioctylfluorene-alt- benzothiadiazole） （PFBT）, which was synthesized by polycondensation. The liquid crystalline state of this copolymer under certain thermal treatment results in the uniaxial orientation of the conjugated backbones on an alignment layer. A rubbed-hole injection layer poly（3,4-ethylenedioxythiophene）:polystyrenesulfonate （PEDOT:PSS） was utilized as the alignment layer. Polarized absorption and photoluminescence spectra indicate the good alignment of the copolymer films with an ordering parameter of 075. Polarized polymer light-emitting diodes were fabricated with the structure of ITO/PEDOT:PSS/PFBT/LiF/Al. An electroluminescence polarization ratio of about 4 was achieved at a voltage of 15 V, with the luminance of 450 cd/m2 and luminous efficiency of 021 cd/A.
Electroluminescence from Si-rich SiNx/N-rich SiNy multilayer light-emitting devices
Authors: Huang Rui  , Dong Heng-Ping  , Wang Dan-Qing  , Chen Kun-Ji  , Ding Hong-Lin  , Xu Jun  , Li Wei  , Ma Zhong-Yuan  ,   (1)南京大学物理系，固体微结构物理国家重点实验室，南京  210093; (2)南京大学物理系，固体微结构物理国家重点实验室，南京  210093；韩山师范学院物理与电子工程系，潮州  521041
Published: December 2020

SiN-based multilayer light-emitting devices, which employed Si-rich SiNx/N-rich SiNy multilayer as luminescence active layer, were fabricated by plasma enhanced chemical vapor deposition （PECVD）. Strong visible electroluminescence （EL） from the devices was observed at room temperature. By adjusting the Si/N ratio of the barrier layer, the effect of barrier on the electroluminescence properties was further investigated. The experimental results show that the performance of the devices can be significantly improved by controlling the Si/N ratio of the barrier layer.
Experimental differential investigation of state-selective single electron capture in slow He2+-He collisions
Authors: Zhu Xiao-Long  , Ma Xin-Wen  , Li Bin  , Liu Hui-Ping  , Chen Lan-Fang  , Zhang Shao-Feng  , Feng Wen-Tian  , Sha Shan  , Qian Dong-Bin  , Cao Shi-Ping  , Zhang Da-Cheng  ,   (1)中国科学院近代物理研究所，兰州  730000; (2)中国科学院近代物理研究所，兰州  730000；中国科学院研究生院，北京  100049
Published: December 2020

State-selective single electron capture in He2+-He collisions at energies ranging from 20 to 40 keV have been studied experimentally by means of cold target recoil ion momentum spectroscopy. The differential cross sections have been obtained by measuring the longitudinal and transverse momenta of recoil ions. The results show that single electron capture into L shell is the dominant reaction channel, which was qualitatively explained with reaction window theory. The measured state-selective cross sections agree with the semi-classical close-coupling calculations, but have some deviations from the results of photon emission measurement. Total angular differential cross sections show that the single electron capture into ground state mainly contributes at small angles, and the single electron capture into excited states contributes at large angles. The oscillating structures of angular differential cross sections are observed, and can be understood by the interference of molecular orbits during the collision processes. The measured angular differential cross sections are compared with other experiments and the quantum-mechanical calculation.
Spectra of Rydberg states of Sm atom measured with autoionization detection method
Authors: Qin Wen-Jie  , Dai Chang-Jian  , Zhao Hong-Ying  , Xiao Ying  ,   天津理工大学理学院，显示材料与光电器件教育部重点实验室，天津  300384
Published: December 2020

Isolated-core excitation and autoionization detection method are combined to measure even-parity high-lying excited states of Sm atom. The experimental results are classified and discussed in detail in the light of different autoionization channels. With the information of energy levels and their relative intensities converging to different thresholds, the Rydberg states are identified from the valence states in the same region. In addition, with the effective technique to recognise different types of high-lying states, the spectroscopic properties of Rydberg states and valence states in the region between 41800 cm-1 and 43800 cm-1 are discussed and analyzed in detail.
A method for constructing exact solutions of nonlinear evolution equation with variable coefficients
Authors: Taogetusang  , Sirendaoerji  ,   内蒙古师范大学数学科学学院，呼和浩特  010022
Published: December 2020

A function transformation method for constructing exact solutions of the variable coefficient nonlinear evolution equations is proposed. The method together with the the second kind of elliptic equation and the symbolic computation system Mathematica is used to construct the new exact Jacobi elliptic function solutions, the degenerated soliton-like solutions and trigonometric function solutions of the composed KdV equation with forced variable coefficients.
Power law phenomena based on human behaviors
Authors: Wei Wei-Feng  ,   北京交通大学电子信息工程学院，北京  100044
Published: December 2020

Various phenomena governed by power law distributions are common in nature and in society, thus their study has broad and far-reaching significance. This paper focuses on a kind of power law phenomenon originating from human behaviors, for instance, popular web page or blog distribution and so on. It is pointed out that human behaviors are rational and selfinterested. On the basis of this, we established a model and found that variables of this kind obeyed a new distribution which was named as the Wei distribution rather than Zipf distribution. Based on Wei distribution, Yule distribution was generated through changing the restrictions. Moreover, in the paper, we describe the meaning of Yule distribution and set up a new distribution which would characterize the reallife conditions more faithfully. It is illustrated further that the human behavior theory could be applied generally to explaining this kind of power law phenomenon and the model could be expanded easily. Besides, we put forward a function to compare different kinds of distributions. This paper supports the reductionism in power law phenomena, which means that simple human behaviors lead power law to be universal.
Time scales of the evolution in bistable system and the reinforcement of stochastic resonance
Authors: Lin Min  , Fang Li-Min  ,   中国计量学院计量测试工程学院，杭州  310018
Published: December 2020

Stochastic fluctuations in the single potential well and probability transitions between the two potential wells exist in the bistable system under the action of noise. These two kinds of movements in different hierarchies have different time scales, and the fluctuations in the low hierarchy potential well have effects on the transitions between high hierarchy potential wells. When time scale of the first input periodical signal and noise-induced probability transitions between the potential wells achieves stochastic synchronization, the phenomenon of stochastic resonance happens. When the second driven periodic signal, the time scales of which matches that of the intrawell fluctuations, is introduced into the system, the phenomenon of frequency absorption happens and the effect of stochastic resonance in bistable system is reinforced.
Mei symmetry and Mei conserved quantity of Nielsen equations for nonholonomic systems of unilateral non-Chetaev’s type in the event space
Authors: Jia Li-Qun  , Cui Jin-Chao  , Luo Shao-Kai  , Zhang Yao-Yu  ,   (1)江南大学理学院,无锡  214122; (2)江南大学理学院,无锡  214122；平顶山学院电气工程学院,平顶山  467002; (3)平顶山学院电气工程学院,平顶山  467002; (4)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 equations for a nonholonomic system of unilateral non-Chetaev's type in the event space are studied. The differential equations of motion for the system are established. The definition and the criteria of Mei symmetry, loose Mei symmetry and strict Mei symmetry for the system are respectively given. The existence condition and the expression of Mei conserved quantity deduced directly from Mei symmetry are obtained. An example is given to illustrate the application of the results.
Exact wave function of the coupled harmonic oscillator with time-dependent mass and frequency
Authors: Ling Rui-Liang  , Feng Jin-Fu  ,   常熟理工学院物理系,常熟  215500
Published: December 2020

Using the coordinate and momentum transformation theory and the trial function methed, the exact wave function of the coupled harmonic oscillator with time-dependent mass and frequency is derived.
Deriving operator identities by two-mode coherent-entangled state representation
Authors: Zhou Nan-Run  , Gong Li-Hua  , Jia Fang  ,   (1)江西师范大学物理与通信电子学院，南昌  330022; (2)南昌大学电子信息工程系，南昌  330031
Published: December 2020

On the basis of the new introduced two-mode coherent entangled state representation and the technique of integration within an ordered product of operators, we derived some operator identities of the operator functions about the quadrature of two-mode optical field, such as （X1+X2）/21/2 and （μX1+νX2）/λ, which should be helpful to further studying the high order squeezing properties of optical field and to constructing some generalized-squeezed states.
Adaptive continuous variable quantum key distribution based on channel estimation
Authors: Zhu Chang-Hua  , Chen Nan  , Pei Chang-Xing  , Quan Dong-Xiao  , Yi Yun-Hui  ,   西安电子科技大学综合业务网理论及关键技术国家重点实验室，西安  710071
Published: December 2020

In order to obtain steady key rate for a continuous variable quantum key distribution system, Alice should adaptively adjust the intensity of optical pulses she sents. In this paper, an optical fiber channel is taken as the additive bosonic quantum Gaussian channel. It is proven that a Gaussian channel transforms Gaussian states into Gaussian states. The maximum-likelihood method is used to estimate the channel parameters after balanced homodyne detection. Then, Alice can change the intensity of optical pulses adaptively according to the estimated noise level, thereby a steady key rate can be obtained.
Conformal invariance and conserved quantities of Mei symmetry for general holonomic systems
Authors: Cai Jian-Le  ,   杭州师范大学理学院，杭州  310018
Published: December 2020

Conformal invariance and conserved quantities of Mei symmetry for general holonomic systems are studied thoroughly. By introducing a single-parameter infinitesimal transformation group and its infinitesimal transformation vector of generators, definitions of the conformal invariance of Mei symmetry for the system are provided. Conditions that the conformal invariance should satisfy are derived using the Euler operator, and their determining equations are then presented. Moreover, the relationship between conformal invariance and the three symmetries, i.e., Noether symmetry, Lie symmetry and Mei symmetry, are discussed. The system’s corresponding conserved quantities are obtained, according to the structure equation satisfied by the gauge function. Finally, an example is provided to illustrate how the given result can be applied.
An optimization scheme for generating of Chebyshev optical chaotic sequence
Authors: Liu Hui-Shi  , Xin Xiang-Jun  , Yin Xiao-Li  , Yu Chong-Xiu  , Zhang Qi  ,   (1)北京邮电大学电子工程学院,北京  100876; (2)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

The methods of generating spread-spectrum sequences with Mach-Zehnder interferometer are studied, also the principle and the scheme of a reported Chebyshev chaotic sequence generator is analyzed. To eliminate the limitation caused by the size of optical elements, a new scheme using the properties of cosine function is put forward. By using voltage to adjust the refractive index of the arms of Mach-Zehnder interferometer, a wavelength adaptive generator can be realized, with which different Chebyshev optical chaotic sequences with different input wavelengths could be obtained.
Circuit implementation and synchronization of an improved system with invariable Lyapunov exponent spectrum
Authors: Li Chun-Biao  , Chen Su  , Zhu Huan-Qiang  ,   (1)江苏经贸职业技术学院江苏省食品安全工程技术研究开发中心,南京  210007; (2)南京理工大学电子工程与光电技术学院,南京  210094; (3)南京理工大学电子工程与光电技术学院,南京  210094；江苏经贸职业技术学院工程技术系,南京  210007；江苏经贸职业技术学院江苏省食品安全工程技术研究开发中心,南京  210007
Published: December 2020

By differentiating the parameters of a newly proposed chaotic system with invariable Lyapunov exponent spectrum, an improved chaotic system is reported in this paper. The system has three important properties which can be summarized as: invariable Lyapunov exponent spectrum for two parameters, existence of the global linear amplitude adjuster and the phase reversal parameter. Simulation analysis by Lyapunov exponent spectrum and bifurcation diagram combined with theoretical reasoning and theory proving, the dynamical characteristics of the system are investigated and expounded. An analog electronic circuit is designed to implement the improved system, and then the chaotic behavior is verified by physics experiments. Finally, the synchronization of the new chaotic system is realized by using the single variable coupling feedback, and meanwhile the circuit of synchronization is presented and the synchronization condition is verified.
Investigation on mixed traffic system with automatic cruise control
Authors: Chen Shi-Dong  , Kong Ling-Jiang  , Liu Mu-Ren  , Zheng Rong-Sen  , Zhu Liu-Hua  ,   (1)广西师范大学物理与电子工程学院,桂林  541004; (2)玉林师范学院物理与信息科学系,玉林  537000
Published: December 2020

Based on the principle of automatic driving, the mixed traffic flow model of vehicles with different lengths and maximum velocities on one-lane highway is proposed. We obtained the fundamental diagrams of traffic flow model under different parameters via numerical simulation. Moreover, with the help of mean-field theory, the analytical results are given. The theoretical results are in agreement with those from numerical simulations.
An improved cellular automaton model simulation of pedestrian counter flow with variety velocities
Authors: Zhou Jin-Wang  , Chen Xiu-Li  , Kong Ling-Jiang  , Liu Mu-Ren  , Tan Hui-Li  , Zhou Jian-Huai  ,   广西师范大学物理与电子工程学院，桂林  541004
Published: December 2020

Taking into account three basic pedestrian behaviors, namely the position-exchange, lateral-move and step back, we proposed an improved cellular automaton model to simulated pedestrian counter flow with different velocities in subterranean channel. We compared cellular automaton model with Weng's model. By computer simulation, the improved model is proved to be more efficient. Moreover, pedestrians in the system tend to have higher mean velocity and lower occupancy density.