bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of electronic transport property of semiconductors by three-dimensional modulated free carrier absorption technique
Authors: Zhang Xi-Ren  , Li Bin-Cheng  , Liu Xian-Ming  ,   (1)中国科学院光电技术研究所,成都  610209; (2)中国科学院光电技术研究所,成都  610209；中国科学院研究生院，北京  100049
Published: December 2020

A three-dimensional model for the modulated free carrier absorption (MFCA) is developed to measure the electronic transport properties (the carrier lifetime, the carrier diffusivity, and the front surface recombination velocity) of semiconductor wafers. The dependence of MFCA amplitude and phase on the electronic transport properties at different pump-probe-beam separation and different modulation frequencies is investigated. It is found that the sensitivities of MFCA signal to individual transport parameters increase with increasing two-beam separation. An experiment with a silicon wafer is performed and the carrier lifetime, carrier diffusivity, and front surface recombination velocity are determined simultaneously and unambiguously by fitting the observed values of the MFCA amplitude and phase as functions of the separation between the pump and probe laser spots, measured at several modulation frequencies covering an appropriate range.
Positron annihilation study of Mo dispersion in MoO3/Al2O3 catalysts
Authors: Zhang Hong-Jun  , Wang Dong  , Chen Zhi-Quan  , Wang Shao-Jie  , Xu You-Ming  , Luo Xi-Hui  ,   (1)武汉大学物理科学与技术学院，武汉  430072; (2)中国石化抚顺石油化工研究院，抚顺  113001
Published: December 2020

A series of MoO3/Al2O3 catalysts was prepared by the impregnation method. The positron annihilation lifetime spectra(PALS)and coincidence Doppler broadening (CDB) spectra of the samples were measured to study the pore structure and dispersion of MoO3. The PALS result shows that there are two types of pores with different size in the Al2O3 support. After MoO3 was loaded in the support, Mo species are mainly dispersed inside the large pores of the support, and thus decrease the volume of the large pores. The CDB spectrum shows significant change while MoO3 loading is just 3%. This indicates that the Mo species are dispersed into the pores, and cause the change of the electron momentum distribution seen by positrons. As the MoO3 loading exceeds 18%, the size of the large pores is decreased to the similar size of the small pores, and the positron annihilation parameters show nearly no change with further Mo loading, which indicates saturation of the dispersion of Mo species.
Theoretical study on the reaction mechanism of the reaction of FC(O)O with NO
Authors: Zhao Jiang  , Cui Lei  , Zeng Xiang-Hua  , Xu Xiu-Lian  ,   (1)宿迁学院基础部，宿迁  223800; (2)扬州大学物理科学与技术学院,扬州  225002
Published: December 2020

Density functional theory was used to study the mechanism of the reaction of FC(O)O with NO. The geometric configurations of reactants, intermediates, transition states and products were optimized by B3LYP method at 6-311G(d,p) level. The energies of stationary points along the pathway were calculated at CCSD(T) level. Intermediates and transition states were confirmed by the results of vibrational analysis. From the results of the reaction mechanism of the reaction of FC(O)O with NO, one can see that the reaction of FC(O)O+NO has four pathways and several steps. Comparing the four pathways’activation energies, one can find that the pathway FC(O)O+NO→M3→TS6→M5→FNO+CO2 is the main reaction pathway and FNO radical and CO2 are the main products, which is in good agreement with the result reported in the literature.
Numerical simulation of acceleration and radiation of surface electrons in the interaction of intense laser pulses with a solid target
Authors: Dong Xiao-Gang  , Sheng Zheng-Ming  , Chen Min  , Zhang Jie
Published: December 2020

The movement and radiation of fast electrons emitting along the surface of a target irradiated by intense laser pulses has been investigated theoretically and numerically by use of the classical theory of Thomson scattering by free electrons in static field. The results indicate that the surface electrons are oscillating in the quasistatic field and the laser field at the beginning. The electrons will be accelerated when their oscillation frequency comes close to the laser frequency, and the attosecond pulse trains and high harmonic are emitted along the surface by surface electrons. The temporal and spatial characteristics of the acceleration and radiation of electrons in different initial states has been compared. The frequency characteristic of the coherent radiation of electron beams are also investigated.
Dynamics of dipolar spinor condensates in the external magnetic field
Authors: Li Ju-Ping  , Tan Lei  , Zang Xiao-Fei  , Yang Ke
Published: December 2020

The equilibrium populations and the coherent off-equilibrium spin mixing with dipole-dipole interaction dynamics in an external magnetic field are investigated. By adjusting the external magnetic field, spin-exchange interaction and the aspect ratio of the potential well we can control the tunneling of the hyperfine components, the oscillation of the populations and the relative phases.
Stochastic resonance for dichotomous noise in a second derivative linear system
Authors: Guo Li-Min  , Xu Wei  , Ruan Chun-Lei  , Zhao Yan
Published: December 2020

We investigated the stochastic resonance for dichotomous noise in a second derivative linear system, measured the average to get the amplitude gain of the output signal, and studied its relationship with the frequency of the system, the frequency of the signal, the strength and correlation time of noises. The amplitude gain of the output signal shows a nonmonotonic dependence on these factors, and the parameter of the dichotomous noise effects the peak value of stochastic resonance.
Implementation of full adder based on chaos computing
Authors: Yang Xue-Mei  , Luo Hong  , Li Li-Xiang  , Luo Qun  , Peng Hai-Peng
Published: December 2020

Chaos computing is a new scheme which can construct fundamental logical gates by using one chaotic unit. In this paper, we propose a new method to implement full adder based on chaos computing. By setting different thresholds and judgment conditions, the full adder is implemented by using only one chaotic unit. This method reduces the complexness of the structure of full adders and provides certain flexibility compared with the traditional method. At last, the Logistic mapping is taken as an example to show how to implement a full adder by using one chaotic unit.
Polarization measurement using polarization interference imaging spectrometer
Authors: Jian Xiao-Hua  , Zhang Chun-Min  , Zhu Bao-Hui  , Zhao Bao-Chang  , Du Juan
Published: December 2020

It is a common method to use the interferential characteristics of light to detect the object in the polarization interference imaging spectrometer system，but the polarized characteristics are usually ignored. In this paper, an advanced way, which combines the basic theories of polarization interference imaging spectroscopy and polarization measurement technology, is studied and used to detect the polarization parameters (e.g. degree of polarization, azimuth angle of polarization), and the error is analyzed, which proves that the system is very stable and precise in theory. Now the polarization interference imaging spectrometer can be used not only as cameras and interferometers but also as polaristrobometers, because the polarized characteristics of the light are made good use of to analyse and distinguish the object in a new way.
Structure and analytic potential energy function of N2O isomer
Authors: Wu Dong-Lan  , Cheng Xin-Lu  , Yang Xiang-Dong  , Xie An-Dong  , Wang Hui-Jun
Published: December 2020

The equilibrium geometry of N2O, NO and N2 molecules have been calculated on the computational levels of density functional theory. The Murrell-Sorbie analytic potential energy function of NO and N2 molecules have been derived through the least-square fitting to ab initio data. Similarly, the harmonic frequency has been calculated and the analytic potential energy function of linear molecule N2O isomer is derived by many-body expansion theory for the first time.
Application of wavelet-Galerkin time domain method in the composite scattering of target and lossy ground
Authors: Dai Shao-Yu  , Wu Zhen-Sen
Published: December 2020

This paper employs the wavelet-Galerkin time domain (WGTD) technique to study composite scattering of arbitrarily target and a lossy ground, and the incidence is realized through three-wave technology. The far-field radiated by the surface currents is calculated using the reciprocity theorem instead of the more complicated Sommerfeld integration. Numerical radar cross section demonstrate the validity and precision of WGTD. Compared to finite difference time domain method, the WGTD method has the advantages of smaller memory and higher efficiency.
Electron acceleration by a focused laser pulse in static electric field
Authors: Huang Shi-Hua  , Wu Feng-Min
Published: December 2020

The model given by Singh for vacuum laser acceleration in a static magnetic field is revisited by using the fifth order corrected laser field equations of a focused laser beam in which the diffraction effect and the longitudinal electric field of a focused laser beam are considered. However, the static magnetic field is replaced with a static electric field in our model. Simulation shows that the electrons can gain much more net energy in this model than that without the added field. Due to the added static electric field, the electrons can be drawn out of deceleration phase from one acceleration stage and directly enter to next acceleration stage.
A multicasting method based on four-wave mixing in highly nonlinear fibers
Authors: Miao Xiang-Rui  , Gao Shi-Ming  , Gao Ying
Published: December 2020

Multicasting is an important function of wavelength-routing optical communication networks. An all-optical multicasting is presented and experimentally demonstrated based on four-wave mixing (FWM) in highly nonlinear fibers. An input signal with data information together with a pump are injected into a highly nonlinear fiber and two idlers with new frequencies can be generated through two degenerate FWM processes, which carry the same data information as the input signal. The single input signal is copied to two channels and the pump can also be modulated by this data. The advantage of this scheme consists in the simple configuration, where only a single pump is needed and no other injected lights are required, the uniform powers and tunable wavelengths of the multicasting signals, and the capacity to further increase multicasting channel number.
Study of fiber Bragg grating characteristics under local transverse force
Authors: Cai Lu-Lu  , Yin Wen-Wen  , Wu Fei
Published: December 2020

Fiber Bragg grating under local transverse force was studied theoretically and experimentally. Based on the transfer matrix method, the consequential changes in reflected spectrum under local transverse force are analyzed, the corresponding mathematical model is established, and the mathematical expressions are deduced. When fiber Bragg grating is pressed by local transverse force, the reflection spectra are independent of the applied length. The wavelength of split point is periodical and linearly proportinal to the applied force. And the reflectivity of split point is approximately hyperbolically tangential versus the applied position.
Low pass effect of surface defect metal based on laser ultrasonic
Authors: Wang Jing-Shi  , Xu Xiao-Dong  , Liu Xiao-Jun  , Xu Gang-Can
Published: December 2020

The travelling properties of laser-generated surface acoustic wave with broad bandwidth, which propagated on a sample with surface defects, have been investigated in theory. The numerical results of theoretical models with different defects indicate that the surface defects worked as low-pass filter for the travelling surface acoustic waves. The cut-off frequency of low-pass filter is linearly related to the depth of the defect, and decreased against the increasing depth of the defect. The amplitude of the travelling surface acoustic wave is seriously attenuated with increasing width of surface defect. The numerical results provide a theoretical basis for quantitative detection of the surface defects.
Microstructure and mechanical properties of AlN/BN nanostructured multilayers
Authors: Yu Li-Hua  , Dong Shi-Run  , Xu Jun-Hua
Published: December 2020

Monolithic AlN，BN films and AlN/BN multilayers were prepared by reactive magnetic sputtering. The films were characterized by X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation. Results showed that the w-AlN phase and amorphous BN films structure exist in AlN and BN monolithic films. The crystal structure of BN layers in the multilayers depends on the thickness of BN layers. When the thickness of BN is less than 0.55nm, BN layers grew epitaxially with AlN under the influence of the “template effect" of w-AlN layers and form the same structure as AlN. When the thickness of BN is larger than 0.74nm, BN layers are amorphous. The hardness of AlN/BN multilayers also depends on the thickness of BN layers. When the thickness of BN is 1—2 molecular mono_layers, the superhardness enhancement of the multilayer is observed. The superhardness effect disappears when the thickness of BN is larger than 0.74nm. The critical thickness of BN layers marking the change from the crystalline to the amorphous structure has been calculated. The hardening mechanism of AlN/BN multilayers has been discussed. The main reason of the superhardness enhancement of the multilayer is the stress and modulus difference between the layers of BN and AlN.
Thermal stimulated current in sandwiched Al2O3 single crystal samples
Authors: Li Sheng-Tao  , Cheng Peng-Fei  , Li Jian-Ying
Published: December 2020

Thermal stimulated current in Al2O3 single crystal and sandwiched Al2O3 single crystal-Bi2O3-Al2O3 single crystal samples was measured during the heating， soaking and cooling processes. It was found that the thermal stimulated current can be detected in sandwiched samples， while no current was observed in the Al2O3 single crystal sample. With the increase of heating rate， the thermal stimulated current measured during cooling decreases， which implies that the thermal stimulated current is induced by defect ions. The calculation of active energy shows that there are two kinds of defect ions involved in producing the thermal stimulated current.
First-principle calculation of electronic structure of the wurtzite CdxZn1-xO
Authors: Zhao Dong-Qiu  , Diao Xian-Feng  , Wang Gui-Li  , Qiu Guo-Li  , Huang Xiao-Wei  , Li Yun-Cai
Published: December 2020

The electronic structures of pure and Cd-doped wurtzite ZnO have been investigated by using first-principle ultrasoft pseudopotential approach of the plane wave. The calculation indicates that the band gap of ZnO is reduced by Cd doping. With increasing Cd-doping concentration, the lower energy states of Zn 4s orbital can take part in hybridization, so that the conduction band of minimum determined by the antibonding Zn 4s states can shift to the lower energy, and the energy of antibonding pd states which control the valence band of maximum becomes higher.
First-principle study of the effect of boron (nitrogen)-doping on adsorbing characteristics of aluminum on single-walled carbon nanotubes
Authors: Wang Kun-Peng  , Shi Chun-Sheng  , Zhao Nai-Qin  , Du Xi-Wen
Published: December 2020

The geometrical structures of adsorbed aluminum atoms on different sites of undoped and boron (nitrogen)-doped single-walled carbon nanotubes (SWCNTs) were optimized using plane wave pseudopotential method with generalized gradient approximation based upon the density functional theory. The band structures，density of states，electron density difference，Mulliken population， adsorption energies of both undoped and boron (nitrogen)-doped SWCNTs were calculated theoretically. The results revealed that boron-doping enhances the adsorption energy Ea of Al on metallic (5，5) CNTs and semiconducting (8，0) CNTs by forming an electron-deficient structure filled with the electrons offered by Al atom. Meanwhile the results also suggest that nitrogen-doping increases Ea of Al on SWCNTs by forming electron-rich half-filled donor structure around Fermi level filled with the electrons of Al atom. Boron- and nitrogen-doping enhance the adsorption energy Ea by forming ionic-bond-type and covalent-bond-type bonds， respectively. The doping effect may also be beneficial to strengthening contact of interfaces between Al matrix and CNTs.
Synthesis， electronic structure and optical properties of MBiO2Cl (M=Ca，Sr，Ba)
Authors: Li Hui-Liang  , Yuan Jun-Lin  , Wang Xiao-Jun  , Zhao Jing-Tai  , Zhang Zhi-Jun  , Yang Xin-Xin
Published: December 2020

The absorption， electronic structure and luminescence spectrum of three Sillen bismuth oxyhalides， CaBiO2Cl， SrBiO2Cl and BaBiO2Cl， are reported and analyzed. The calculated electronic structure by the density functional theory shows that both SrBiO2Cl and BaBiO2Cl are semiconductors with direct band gap， which are consistent with the results of ultraviolet (UV)-vis diffuse reflectance experiment. The X-ray and UV excited luminescent spectra show a broad emission band extending from 400 to 550nm at room temperature. The light yield of BaBiO2Cl powders is about 1.4 times that of Bi4Ge3O12 (BGO) powders at room temperature under X-ray excitation， and BaBiO2Cl powders have shorter decay times of 100ns (22%)， 300ns (41%) and 600ns (37%)， compared with those of the BGO powders. The luminescence properties show a correlation between Bi—O(Cl) distance and radius of M2+ ions. Considering that the density of BaBiO2Cl is 6.98g/cm3， it may be a potential practical scintillator.
A nonlinear elastic analysis of static stress and lateral pressure coefficient for granular Couette systems
Authors: Zheng He-Peng  , Jiang Yi-Min
Published: December 2020

Whether or not the classical theory of elasticity is valid for static granular matter is a basic question of granular physics. We present in this work stress distributions inside hollow cylindrical (Couette geometry) specimens， calculated with the nonlinear elastic equations recently reported in literature. Most of these results can be experimentally measured， and are useful for clarifying the basic question by testing the applicability of the nonlinear elastic equations to granular matter. Moreover they can also be used for analyzing the lateral pressure coefficient of interest in soil engineering.
Theoretical study on structural properties for rare earth intermetallic compounds RFe2Zn20-xInx
Authors: Chen Yi  , Shen Jiang  ,   北京科技大学应用物理研究所,北京  100083
Published: December 2020

The rare earth intermetallic compounds, RFe2Zn20 （R　represents rare earth）, have become one of hot spots in research field due to their excellent magnetic properties with lower concentration of rare earth atoms. The addition of quaternary could influence the structural properties. The crystal structures of ternary RFe2Zn20 and site preferences of quaternary RFe2Zn20-xInx compounds are investigated by using interatomic potentials based on the lattice inversion technique. The calculated results show that the lattice constants and cell volumes of RFe2Zn20 decline linearly with atomic weight of rare earth increasing and the linear relation is independent of whether the quaternary element is added into the compounds. The In atoms substituted for Zn atoms preferentially occupy 16c site and then 96g site, without 48f site. The sequence of site preference is coincident with the measurements and the analyses from interatomic potentials.
Influence of Nb doping on oxidation resistance of γ-TiAl:A first principles study
Authors: Li Hong  , Wang Shao-Qing  , Ye Heng-Qiang  ,   中国科学院金属研究所，沈阳材料科学国家（联合）实验室，沈阳  110016
Published: December 2020

Nb doping is proved to be the most promising way of enhancing the oxidation resistance of TiAl alloys， yet the intrinsic mechanism is still unclear. To understand the effect of Nb doping, a first principles study of several point defects in γ-TiAl during oxidation is performed. Besides the determination of the stable defect structures it is revealed that （1） the formation energy of Nb doping increases with Nb content increasing， at the cost of degradation of the phase stability， which is a hindrance to the oxidation resistance; （2） the abilities of interstitial oxygen and titanium vacancy formation are lowered by Nb addition， thus oxygen diffusion and vacancy formation are reduced correspondingly， which enhances the oxidation resistance of the alloy; （3） the effect of Nb doping on the formation energy of point defect is rather localized， therefore the influence of Nb doping is correlated with its distribution and content in γ-TiAl.
Formalism of the transfer matrix and its application to Ⅲ/Ⅴ semicondutor quantum well systems
Authors: Li Long-Long  , Xu Wen  , Zeng Zhi  ,   中国科学院固体物理研究所材料物理重点实验室，合肥  230031
Published: December 2020

A formalism of transfer matrix method is presented and used to solve a one-dimensional time-independent Schrdinger equation based on a simple one-band effective mass model and the envelope function approximation. The accuracy of this method is proved by comparing the numerical solution and analytical solution for a GaAs-based type Ⅰ single quantum well system， and its applicability is demonstrated by experimental photoluminescence results of the InAs/GaSb-based type Ⅱ and broken-gap quantum well structures. The formalism is extended to calculating the subband energies and corresponding wavefunctions in the GaAs/GaAlAs-based type Ⅰ coupled multiple quantum well systems, showing that the formalism is universal and practical.
Calculation of quantum efficiency of alkali halide photocathode materials in the extreme ultraviolet region
Authors: Li Min  , Ni Qi-Liang  , Chen Bo  ,   (1)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033; (2)中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室，长春  130033；中国科学院研究生院，北京  100049
Published: December 2020

In order to meet the requirement of microchannel plate position-sensitive photon counting detector in the extreme ultraviolet region, the quantum efficiency of alkali halide photocathode was studied. Based on the fact that the photoemission from photocathode is formed by secondary electrons, the theoretical model of secondary electron emission for alkali halide photocathode was presented， and the formula of secondary electron yield was obtained. For photon energy ranging from 30 to 250 eV, the effect of the thickness of photocathode and the incidence angle on the secondary electron yield was calculated and analyzed，the result showed that when the thickness was higher than 100 nm and the grazing angle was larger than the critical angle of photocathode material, high secondary electron yield was obtained. Finally, according to the derived formula, the spectrum response of the secondary electron yield for twenty alkali halides was analyzed， and the result showed that the position of the peak yield was in accordance with the resonant absorption of photocathode materials.
Effect of solvent refractive index on Raman cross-section of β-carotene
Authors: Li Zhan-Long  , Ouyang Shun-Li  , Cao Biao  , Zhou Mi  , Li Zuo-Wei  , Gao Shu-Qin  ,   吉林大学物理学院，长春  130023
Published: December 2020

The Raman cross-sections of β-carotene C=C double bond （1520 cm－1） and C—C single bond（1155 cm－1） vibration mode have been measured using cyclohexane as internal standard. The result shows that the Raman cross-section of β-carotene increases with the increase of refractive indexes of solvents. The difference of β-carotene Raman cross-section in different refractive indexes of solvents was explained by the dispersion and resonance Raman theory.
Stereodynamics study of the reactions of He+H+2 and its isotopic variants
Authors: Kong Hao  , Liu Xin-Guo  , Xu Wen-Wu  , Liang Jing-Juan  , Zhang Qing-Gang  ,   山东师范大学物理与电子科学学院，济南  250014
Published: December 2020

The stereodynamics in the chemical reaction He+H+2 and its isotopic variants at the collision energy of 145 kJ/mol have been studied by using the quasi-classical trajectory （QCT） method on AQUILANTI surface. The correlated k-j′， k-k′-j′ angular distributions, and the product rotational alignment are discussed in detail. The calculations indicate that the stereodynamics of the reactions of He+HH+→HeH++H, He+HD+→HeH++D and He+HT+→HeH++T are sensitive to the mass factor and the repulsive energy of diatomic molecule.
A theoretical study on final channel screening and exchange effects in large energy loss geometry
Authors: Yang Huan  , Zhang Sui-Meng  , Wu Xing-Ju  ,   (1)皖西学院基础实验中心，六安  237012；皖西学院数理系，原子与分子物理研究所，六安  237012; (2)皖西学院数理系，原子与分子物理研究所，六安  237012
Published: December 2020

The triple differential cross sections for electron impact ionization of helium in the special geometry of coplanar large energy loss are calculated by using the BBK model and the modified BBK model. The calculated results are compared with the experimental results of Catoire and the present experimental results of Stevenson. The previous theoretical deduction is proved and the exchange effects are analyzed and discussed.
Positron study of carbon-Fe3O4 coaxial nanofibers
Authors: Xiong Tao  , Gao Chuan-Bo  , Chen Xiang-Lei  , Zhou Xian-Yi  , Weng Hui-Min  , Cao Fang-Yu  , Ye Bang-Jiao  , Han Rong-Dian  , Du Huai-Jiang  ,   (1)中国科学技术大学材料科学与工程系，合肥  230026; (2)中国科学技术大学近代物理系，合肥  230026
Published: December 2020

This paper presents the positron study on carbon-Fe3O4 coaxial nanofibers, which is one kind of new promising functional materials. According to the positron annihilation lifetime spectra and the coincidence Doppler broadening spectra, we find in this material that positrons annihilate partly in monovacancies of Fe3O4, partly in microcavities of Fe3O4 and partly in shelled carbon nanotubes. We also estimate the annihilation proportion in each part, which reveals the nanofibers’ microstructure to a certain extent.
Evolution and axial distribution of Ar clusters in supersonic jets
Authors: Liu Meng  , Lu Jian-Feng  , Han Ji-Feng  , Li Jia  , Luo Xiao-Bing  , Miu Jing-Wei  , Shi Mian-Gong  , Yang Chao-Wen  ,   四川大学物理科学与技术学院，辐射物理及技术教育部重点实验室,成都  610064
Published: December 2020

For Ar clusters produced by specifical jet, the Rayleigh scattering was employed to investigate the cluster formation process and to measure the cluster size along nozzle axis under different background gas pressures. The developing process of cluster and the axial distribution of cluster size were observed at pressures from 20 to 60 atm experimentally. The relationship between the cluster size and the pressure and axial distance from the jet nozzle was obtained. It was found that the largest clusters were formed at distance 5 mm from the nozzle.
Density functional theory study on TinLa（n=1—7） clusters
Authors: Qi Kai-Tian  , Yang Chuan-Lu  , Li Bing  , Zhang Yan  , Sheng Yong  ,   (1)鲁东大学物理与电子工程学院,烟台  264025; (2)四川大学材料科学与工程学院,成都  610065
Published: December 2020

The geometrical structures of Tin and TinLa（n=1—7） clusters are optimized by using density functional theory（B3LYP） and LANL2DZ basis sets, and the vibrational frequency and electronic properties are calculated. The effect of La atom on the pure Tin clusters is discussed by analyzing the changes of average bond length, binding energy, HOMO-LUMO gaps, and magnetic moments between TinLa and Tin clusters. Furthermore, the reason of the changes caused by La atom is also studied.
Suppression of small-scale self focusing of high power laser using moving beam
Authors: Cheng Wen-Yong  , Zhang Xiao-Min  , Su Jing-Qin  , Zhao Sheng-Zhi  , Dong Jun  , Li Ping  , Zhou Li-Dan  ,   (1)山东大学信息科学与工程学院，济南  250100; (2)中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900；山东大学信息科学与工程学院，济南  250100
Published: December 2020

The concept of “moving beam” in near field is proposed. It is found that the device of smoothing by spectral dispersion （SSD） can generate “moving beam” in the near field. The mechanism and the condition for generating “moving beam”， the motion characteristics of the “moving beam”， and the suppression of small-scale self focusing are analyzed theoretically. The numerical simulations agree with the theoretical analyses.
Frequency response of fourth-order acoustic low-pass filtering fiber-optic hydrophones
Authors: Wang Ze-Feng  , Hu Yong-Ming  , Meng Zhou  , Luo Hong  , Ni Ming  ,   国防科技大学光电科学与工程学院，长沙  410073
Published: December 2020

Response properties of the fourth-order acoustic low-pass filtering fiber-optic hydrophones are investigated theoretically and experimentally. A mechanical acoustic resistance， which is used to describe the system’s mechanical loss， is introduced into the previous lumped parameters model of the hydrophone， and an improved acoustic equivalent circuit is given. Phase frequency response is an important parameter for the hydrophone array applications. It has great effect on beamforming， which affects the abilities of locating， discerning， and tracking targets. Therefore， the phase response peroperties is studied with the amplitude response peroperties. Some results， which are instructive for designing of acoustic low-pass filtering hydrophone， are obtained by numerical simulation. The measured rsponse curves are in good agreement with the simulation results， which verifies the correctness of the theory and the model. The fourth-order acoustic low-pass filtering fiber-optic hydrophones are useful for improvement of the anti-aliasing ability of modern sonar arrays.
Penumbral imaging of Kα radiation source
Authors: Wang Jian  , Zhao Zong-Qing  , Cai Da-Feng  , Huang Wen-Zhong  , He Ying-Ling  , Gu Yu-Qiu  ,   (1)内江师范学院物理与电子信息工程学院，内江  641112; (2)中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900；内江师范学院物理与电子信息工程学院，内江  641112
Published: December 2020

At the SILEX-Ⅰlaser facility， penumbral imaging technique was used to record a Kα source in two dimensions. Due to the fact that the source was produced via the interaction between ultrashort-ultraintensity laser and ‘Velvet’ target， we can obtain high quality Kα source images. More details about the source spatial distributions can be deduced from the two-dimensional imaging than that from the one-dimensional imaging such as knife edge imaging.
Self-similar transformation and quasi-unit cell construction of quasi-periodic structure with twelve-fold rotational symmetry
Authors: Liao Long-Guang  , Fu Hong  , Fu Xiu-Jun  ,   华南理工大学理学院物理系，广州  510640
Published: December 2020

The structural properties of a quasicrystal model with twelve-fold rotational symmetry are studied. We correct the errors in the self-similar transformation of the square-rhombus-hexagon tiling model proposed by Socolar. Based on the Stampfli-Ghler square-rhombus-triangle tiling model， the quasi-unit cell is successfully constructed， which can describe the dodecagonal quasiperiodic structure by the covering theory.
Calculation of Raman shifts of Si（1-x）Gex and amorphous silicon using Keating model
Authors: Duan Bao-Xing  , Yang Yin-Tang  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

The Raman shifts of Si—Si， Ge—Ge and Si—Ge in Si（1-x）Gex alloys are calculated by Keating model. The calculated Raman shifts are 40275，41339 and 38815 cm-1 when the concentrations of Ge are 01， 05 and 09 respectively. These results are consistent with the reported experimental results， which indicates the validity of the Keating model for obtaining the Raman frequency of strained materials by changing the elastic coefficients of stretching and compression and bond-bending interaction. The single-phonon scattering peak at 477029 cm-1 in amorphous silicon is obtained for the first time by Keating model, which is in agreement with the result of 4800 cm-1 from the literature, indicating that the atoms of amorphous silicon as a whole are stretched compared with that of crystalline silicon.
First-principles calculation on interaction between a semiconducting single-walled carbon nanotube and its graphite substrate
Authors: Wang Liang  , Zhang Zhao-Hui  ,   北京大学物理学院，人工微结构与介观物理国家重点实验室，北京  100871
Published: December 2020

The interaction between a semiconducting single-walled carbon nanotube and its graphite substrate was studied by calculation based on the density functional theory. Between two contact configurations of the system energy minimum, a series of metastable contact configurations of the carbon nanotube on the graphite were optimized, and the atomic structures of these contact configurations and the related energy bands of the system were determined. It is found that the interaction makes the contacted graphite surface concave and the band gap of the carbon nanotube narrow, which may be significant to the carbon-based nanodevice strategy.
Theoretical analysis of cascade levels forming in SrTiO3
Authors: Zhang Rui-Zhi  , Wang Chun-Lei  , Li Ji-Chao  , Mei Liang-Mo  ,   山东大学物理学院，济南  250100
Published: December 2020

The possibility of forming cascading energy levels in SrTiO3 by doping Bi and Cu as an example is analyzed by using the density-functional-theory based first principles calculations of the electronic structure. The results show that both Bi doping and Cu doping can introduce a defect level in the forbidden band，and Co-doping of Bi and Cu can introduce two defect levels in the forbidden band. Electrons at the top of valence band can transit to the bottom of conduction band through a cascade transition process. Using the nonradiative transition model，we point out that the probability of electronic transition from the valence band to the conduction band through a cascade transition is much higher than that of direct transition from the valence band to the conduction band. The cascade transitions can effectively increase the carrier concentration in the conduction band.
Preparation of Mg and Al co-doped ZnO thin films with tunable band gap
Authors: Gao Li  , Zhang Jian-Min  ,   陕西师范大学物理学与信息技术学院，西安  710062
Published: December 2020

Al （Al2O3，2wt%） doped ZnO thin films （ZAO） with tunable band gap，alloyed with different Mg contents （1wt%，3wt% and 5wt%），were prepared by radio frequency magnetron sputtering on glass substrates and annealed at 500℃ in air. The optical and electrical properties of the films were measured by X-ray diffractometer，four-point probe method，Hall-effect configuration，and UV-VIS spectrophotometer. The results show that the Mg co-doped ZAO thin films have a wurtzite structure with （002） preferred orientation. Compared with ZAO film，the optical transmission of Mg co-doped ZAO thin films in the ultraviolet region increases and the average optical transmissions in the visible region is greater than 85%，except the 5wt% Mg doped films. The band gaps of ZAO and Mg co-doped ZAO thin films can be modulated from 344 eV to 351 eV by increasing the Mg content from 1wt% to 5wt%. For 1wt%，3wt% and 5wt% Mg doping，the Mg co-doped ZAO thin films have the resistivity of 12×10-3，37×10-3 and 85×10-3 Ω·cm，respectively. Stokes shifts of 20，14 and 50 meV were observed for doping of 1wt%，3wt%，and 5wt% Mg contents. We find that a large Mg doping content will degrade the crystal quality of Mg co-doped ZAO thin films，decrease the optical transmissions in the visible region and decrease the carrier mobility in the films. Therefore，the resistivity of Mg co-doped ZAO thin films increases with the Mg doping content.
Electric-field-induced magnetization in 1-3 type multiferroic nanocomposite thin film
Authors: Zhong Chong-Gui  , Jiang Qing  , Fang Jing-Huai  , Jiang Xue-Fan  , Luo Li-Jin  ,   (1)常熟理工学院江苏省新型功能材料重点建设实验室，常熟  215500; (2)南通大学理学院，南通  226007; (3)南通大学理学院，南通  226007；苏州大学物理科学与技术学院，苏州  215006; (4)苏州大学物理科学与技术学院，苏州  215006
Published: December 2020

Considering the electrostrictive，magnetostrictive effects in the ferroelectric （FE） phase and ferromagnetic （FM） phase and the elastic stress arising from FE/FM and film/substrate interfaces，using the Landau-Devonshire thermodynamic theory，we investigate the magnetoelectric coupling effect in epitaxial 1-3 type multiferroic nanocomposite thin films. We renormalize the dielectric and magnetic coeffcients twice and obtain the quasi-intrinsic magnetoelectric coupling in Landau free energy function of this multiferroic system. Then，the electrical-field-induced magnetization and polarization for films of different thickness in 1-3 type BaTiO3-CoFe2O4 nanocomposite system are analyzed. Our results show that the relaxation of the in-plane compressive stress of the thin film makes magnetization and polarization both decrease with the increasing film thickness，and an applied electric field can result in the reversal of magnetization in step with the switching of the electric polarization due to the out-of-plane elastic coupling between the interface of the FE and FM phases. Our results agree well with the experimental results.
Study of ultrafast carrier dynamics in amorphous Ge2Sb2Te5 film by femtosecond-resolved reflectivity spectroscopy
Authors: Zuo Fang-Yuan  , Wang Yang  , Wu Yi-Qun  , Lai Tian-Shu  ,   (1)中国科学院上海光学精密机械研究所强激光材料重点实验室，上海  201800; (2)中山大学物理科学与工程技术学院，光电材料与技术国家重点实验室，广州  510275
Published: December 2020

Ultrafast dynamics and its excitation-energy-density dependence of photoexcited carriers in amorphous Ge2Sb2Te5 film were studied at room temperature by femtosecond-time-resolved pump-probe reflectivity spectroscopy. It was found that the reflectivity reduced down to a minimum in 05 ps after pump excitation, and then started to increase sharply up to a new maximum value larger than the initial reflectivity in several picoseconds. Furthermore, the decreased and increased amplitudes of the reflectivity with respect to its initial value as well as its rising rate from the minimum to the maximum both increased with the increasing excitation energy density. The sharp rising process of the reflectivity was explained quantitatively based on the model of Auger recombination of high density plasma and Auger-recombination-induced heating of cyrstal lattice, which shows that the heating effect induced by Auger recombination in high density plasma should be the main mechanism of ultra-short laser pulse-induced phase change.
Single mode vertical-cavity surface emitting laser with surface plasmon nanostructure
Authors: Song Guo-Feng  , Zhang Yu  , Guo Bao-Shan  , Wang Wei-Min  ,   中国科学院半导体研究所纳米光电子实验室，北京  100083
Published: December 2020

The vertical-cavity surface-emitting laser（VCSEL） has proved to be a low cost light source with attractive properties such as surface emission, circular and low divergence output beam, and simple integration in two-dimensional array. Many new applications such as in spectroscopy, optical storage, short distance fiber optic interconnects, and in longer distance communication, are continuously arising. Many of these applications require stable and single-mode high output power. Several methods that affect the transverse guiding and/or introduce mode selective loss or gain have been developed. In this study, a method for improving the single mode output power by using metal surface plasmons nanostructure is proposed. Theoretical calculation shows that the outpout power is improved about 50% compared to the result of standard VCSELs.
Calculation of the overlap factor and correction of near-field signal of the off-axis lidar based on the Gaussian mode of laser beam
Authors: Liu Qiao-Jun  , Yang Lin  , Wang Jie-Yu  , Zuo Hao-Yi  , Luo Shi-Rong  , Andrew Yuk Sun Cheng  ,   (1)四川大学物理系,成都  610064; (2)四川大学物理系,成都  610064；澳门科技大学,澳门
Published: December 2020

Based on the geometrical analysis, the near-field overlapping area shape of an off-axis laser lidar, which is formed by the telescope field of view and the laser distribution, is divided into three types, and the analytical formula for calculating the overlapping factor of off-axis lidar is given. According to the formula and the Gaussian distribution of the laser mode, the curve of the overlapping factor with the altitude of the Mie scattering lidar in our Laboratory is obtained. Using the curve, the lidar return signal under different weather conditions in Chengdu is corrected, based on which the return signal is retrieved by the Klett inversion method, and the curves of the atmospheric extinction coefficient varying with the altitude are obtained. The results show that the atmospheric extinction coefficient obtained by the correction method in the study is accordant with the practical weather condition.
Study of the partition functions of SiO2 molecules
Authors: Wu Dong-Lan  , Wan Hui-Jun  , Xie An-Dong  , Cheng Xin-Lu  , Yang Xiang-Dong  ,   (1)井冈山大学数理学院,吉安  343009; (2)井冈山大学数理学院,吉安  343009；四川大学原子与分子物理研究所,成都  610065; (3)四川大学原子与分子物理研究所,成都  610065
Published: December 2020

The total internal partition functions are calculated for 16O28Si16O at temperatures from 20—6000 K. In deducing the rotational partition sums Qrot, the centrifugal distortion corrections are taken into account. The method used for calculating the vibrational partition sums Qvib is the harmonic oscillator approximation. The temperature range is divided into five regions and the calculated total internal partition functions are fitted to a fourth-order polynomial in T, and the coefficients are evaluated in the five temperature regions. This permits rapid and accurate calculation of the total internal partition functions in the temperature range from 20—6000 K.
Research on CRIT property in ring-in-ring structure resonator
Authors: Wang Nan  , Zhang Yun-Dong  , Wang Jin-Fang  , Tian He  , Wang Hao  , Zhang Xue-Nan  , Zhang Jing  , Yuan Ping  ,   哈尔滨工业大学光电子技术研究所,哈尔滨  150080
Published: December 2020

Considering the insertion loss of coupler， we theoretically analyzed the CRIT effect of the ring-in-ring structure resonator. In the process of the theoretical analysis， the transmission coefficient and effective phase shift were deduced using iterative approach， and then the dispersion was obtained， including the effect of the insertion loss. The analysis shows the effective phase shift， group velocity and bandwidth of the whole system can be controlled by the insertion loss， the multiples between the lengths of rings and the number of rings. The control of dispersion in ring-in-ring structure is important for applications of this structure in rotating sensor， optical delay line， optical buffer and filtering.
Effect of interface on microstructure and soft magnetic properties of Fe65Co35 thin films
Authors: Li Yan-Bo  , Liu Xi  , Li Zheng-Hua  , Fu Yu  , Kamzin A. S.  , Wei Fu-Lin  , Yang Zheng  ,   (1)俄罗斯科学院约飞物理-技术研究所,圣·彼德堡  194021,俄罗斯; (2)兰州大学磁学与磁性材料教育部重点实验室，磁性材料研究所,兰州  730000
Published: December 2020

Bilayer films with Fe65Co35 main layer/underlayer structure were successfully prepared by magnetron sputtering on different underlayers （Co93Fe7 and Fe）. X-ray diffraction （XRD） analysis and magnetic measurements show that Fe65Co35 thin films deposited on different underlayers have different textures. Moreover, the soft magnetic properties of Fe65Co35 thin films with （200） texture are better than that of Fe65Co35 thin films with （110） texture. Investigation of several typical samples by conversion electron Mssbauer spectrum （CEMS） reveals that the vector of magnetization of Fe65Co35 thin films have a little deviation from the film plane, and the deviation from the film plane of Fe65Co35 thin films with （110） texture are bigger than that of Fe65Co35 thin films with （200） texture. Further study exhibits that this phenomenon is caused by the interface anisotropy induced by magnetoelastic anisotropy at the interface between Fe65Co35 thin film and underlayer.
Three-dimensional four-wing generalized augmented Lü system
Authors: Qiao Xiao-Hua  , Bao Bo-Cheng  ,   江苏技术师范学院电气信息工程学院，常州  213001
Published: December 2020

The augmented Lü system is a three-dimensional chaotic system, which can generate a false 4-wing attractor with only two control parameters. By using the method of anti-control chaos, a new three-dimensional chaotic system, named as generalized augmented Lü system, is proposed by the introducing a simple linear state controller into the augmented Lü system. The new system implements a real 4-wing attractor with compound structure and contains two mirrored symmetrical sub-system. By either of theoretical analyses, numerical simulations and circuit experiments, the existence of 4-wing chaotic attractor evolved from the generalized augmented Lü system is verified. It is also elaborated that the generalized augmented Lü system having more abundant dynamical behaviors than the augmented Lü system.
Electric field-controlled permeability and impedance in a heterotypic composite of ferroelectrics/magnet with high permeability
Authors: Gao Jian-Sen  , Zhang Ning  ,   (1)南京师范大学物理科学与技术学院，南京  210097; (2)宿迁学院基础教学部,宿迁  223800
Published: December 2020

Using the product effect of electrostrain and piezopermeability, a novel and heterotypic composite of magnet/ferroelectrics has been developed and its electromagnetic coupling has been investigated. Under a constant electric field of 5 kV/cm, about 40% electric-field-induced changes of inductance and impedance have been observed over a wide range of frequency for the composites. The electric-field dependent inductance and impedance show a joint behavior of ferromagnetic and ferroelectric relaxation. Analysis shows that all the behaviors observed can be ascribed to the electric field-controlled variation of the internal stress in the composite.
Excitation processes of up-conversion green emission for Er3+ and Yb3+ codoped tellurite glass
Authors: Dong Li-Qiang  , Huang Shi-Hua  , Wen Hong-Yu  , Yang Yan-Min  , Wang Da-Wei  , Duan Xiao-Xia  ,   (1)北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京  100044; (2)北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京  100044；防化研究院，北京  102205; (3)防化研究院，北京  102205; (4)河北大学物理科学与技术学院，保定  071002
Published: December 2020

This paper analyzed the build-up characteristics of Er3+ 4S3/2 and the relationships between Er3+ 4S3/2，4I11/2 and Yb3+ 2F5/2 according to the energy structure for green up-conversion emission and relative transition rating function model for Er3+-Yb3+ codoped tellurite glass. Through fitting the build-up and decay curves by the model the relative parameters for rating equation model were determined，and the relative value between energy transfer and excited state absorption when population of 4S3/2 energy tend to be stable was calculated，also the dynamic processes in green up-conversion emission of Er3+-Yb3+ codoped tellurite glass were analyzed.
Design and fabrication of multilayer antireflection coating for optoelectronic devices by plasma enhanced chemical vapor deposition
Authors: Yuan He  , Sun Chang-Zheng  , Xu Jian-Ming  , Wu Qing  , Xiong Bing  , Luo Yi  ,   State Key Laboratory of Integrated Optoelectronics, Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

The design and fabrication of multilayer antireflection (AR) coating based on plasma enhanced chemical vapor deposition (PECVD) is studied for its applications in optoelectronic devices. Deposition conditions for obtaining SiO2/SiNx thin films with large refractive index difference is determined through systematic study of factors influencing the refractive index of deposited SiNx. Four-layer SiO2/SiNx AR coating is designed to exhibit a reflectivity of less than 10-4 over 70 nm bandwidth. Reflectivity of the thin film structure at the center wavelength of 1550 nm remains less than 5×10-4 when the thickness deviation of any single layer is within ±5 nm from the designed value. Based on the simulation results, SiO2/SiNx multilayer AR coating is deposited on the end facet of a Fabry-Perot laser. By analyzing the output spectra of the laser, the residual reflectivity of the AR coating is determined to be on the order of 10-4 over the wavelength range of 1535—1565 nm.