bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma electrolytic deposition on aluminum tubes
Authors: Gu Wei-Chao  , Lü Guo-Hua  , Chen Huan  , Chen Guang-Liang  , Feng Wen-Ran  , Zhang Gu-Ling  , Yang Si-Ze  ,   中国科学院物理研究所，北京 100080
Published: December 2020

Plasma electrolytic oxidation (PEO), also called micro-arc oxidation or anode spark deposition, is a novel technique to produce hard ceramic coatings on metals, such as aluminum, titanium, magnesium and their alloys (called by a joint name of valve metals). Up to now, almost all the researchers focused attention on the PEO process for samples of regular shapes such as cubes, discs or rods, and no one paid attention to the irregular samples such as tubes. In this work, the PEO behavior of aluminum tubes was investigated. The potential difference, which had a liner relation with the coating thickness inside the tube, was measured. A central axial accessorial electrode was used to eliminate the effect of potential decay inside tubes, which was effective for obtaining axially uniform coating on the inner surface of the tube.
Investigations of lattice distortion and spin-Hamiltonian parameters for V3+ in Al2O3 crystal
Authors: Wei Qun  , Yang Zi-Yuan  , Wang Can-Jun  , Xu Qi-Ming  ,   (1)宝鸡文理学院物理系,宝鸡 721007; (2)西安建筑科技大学材料科学与工程学院,西安 710055; (3)西安建筑科技大学材料科学与工程学院,西安 710055;宝鸡文理学院物理系,宝鸡 721007
Published: December 2020

In order to study the local structure distortion and spin-Hamiltonian parameters of Al2O3:V3+ crystal, a new model has been proposed. On the basis of it, the relationship between the crystal structure parameters and spin-Hamiltonian (SH) parameters is established using Newman crystal-field superposition model. the lattice distortion and SH parameters of Al2O3:V3+ crystal, taking into account the slight magnetic interactions, including spin-spin, spin-other-orbit and orbit-orbit interactions, have been studied using the complete diagonalization method. The calculated results are in good agreement with experimental ones. It is found that the distance between upper and lower ligand oxygen plane increases by 0.0060 nm when V3+ is doped into Al2O3 crystal. Based on the local structure distortion model, at the same time, the microscopic origins of the SH parameters have been investigated for 3d2 ions in trigonal-symmetry crystal field. The results show that the SH parameters are mainly depend on spin triplets, and the contributions to SH parameters from slight magnetic interactions are related to spin triplets only.
Performance improvement of polymer light-emitting diodes based on fluorene copolymer with cesium fluoride/aluminum cathode
Authors: Tian Ren-Yu  , Yang Ren-Qiang  , Peng Jun-Biao  , Cao Yong  ,   (1)华南理工大学高分子光电材料与器件研究所,广州 510640; (2)华南理工大学高分子光电材料与器件研究所,广州 510640;华南理工大学特种功能材料及其制备新技术教育部重点实验室,广州 510640; (3)华南理工大学物理科学与技术学院,广州 510640
Published: December 2020

Polymer light-emitting diodes with saturated red emission were fabricated using the copolymer, poly　［2,7-(9,9-dioctyl)fluorene-co-5,5′-(4,7-diselenophenyl)-2,2′-yl-2,1,3-benzothiadiazole］ (PFO-SeBT). Special attention was paid to polymer/electrode interface modification. The highest electroluminescence external quantum efficiency of 1.79%, which was more than twice that of devices with low work function metal cathode Ba/Al, was achieved by incorporation of CsF/Al cathode with carefully optimized thickness of CsF, and insertion of PVK layer in the PFO-SeBT1/anode interface. Efficient improvement of electron injection of CsF/Al cathode and blocking effect of PVK to electrons were proposed to be responsible for the improved performances of the device.
Dispersion feature in arbitrary direction of surface acoustic wave applied to property characterization of ultra-large-scale integrated circuit interconnect films
Authors: Xiao Xia  , You Xue-Yi  , Yao Su-Ying  ,   (1)天津大学电子信息工程学院,天津 300072; (2)天津大学环境科学与工程学院,天津 300072
Published: December 2020

The ultrasonic surface acoustic wave (SAW) technique is becoming attractive for accurate and nondestructive property determination for thin low-k films employed in the modern ultra-large-scale integrated circuit (ULSI). In this paper, the dispersive characteristics of SAW propagating along arbitrary directions on the layered films deposited on Si(100) were studied in detail. The computation time was reduced greatly by appling coodinate transformation. The calculation of 9×9 Christoffel matrix was simplified to 6×6 matrix for one film layer structure, and from 15×15 matrix to 10×10 matrix for two-layered structure. This work will benefit the on-line test of low-k film properties during ULSI fabrication. Furthermore, the limitation on the propagating direction of SAW can be eliminated in the measurement.
Suppression of meandering spiral waves in the excitable media due to a perturbation with stochastic phase
Authors: Ma Jun  , Jin Wu-Yin  , Li Yan-Long  , Chen Yong  ,   (1)兰州大学理论物理研究所,兰州 730000; (2)兰州理工大学机电工程学院,兰州 730050; (3)兰州理工大学物理系,兰州 730050;兰州大学理论物理研究所,兰州 730000
Published: December 2020

A new scheme is proposed to suppress the meandering spiral waves in the excitable media, which is described with two-dimensional variables. An external electronic signal with stochastic phase is imposed on a local area; few grids of the system are perturbed, for example, 4×4 and/or 5×5 grid nodes among all the 256×256 nodes, so that a new target wave may occur and competition between the newly generated target wave and the intrinsic meandering spiral waves develops dynamically. The numerical simulation results confirm that it is effective to suppress the meandering spiral wave in the Barkley model. Compared with a simple periodical driving in a local area, it shows some advantages such as shorter transient period to kill the spiral wave, and it is robust to spatiotempaoral noise. A new target wave could come into being and will kill the meandering spiral wave even in the anisotropic media,of which the diffusion coefficient is a function of space, when the intensity of the spatiotemporal noise is not too strong.
Study on the colorimetric properties of the LED projection sources
Authors: Zhao Xing  , Fang Zhi_Liang  , Mu Guo_Guang  ,   南开大学现代光学研究所光电信息技术科学教育部重点实验室，天津 300071
Published: December 2020

The colorimetric properties of the conventional arc lamp and LED are calculated and analyzed by using the colorimetry theory. Comparing to the conventional arc lamp used as projection light source, LED illuminator has higher efficiency of the spectral power and better ability of color display. It can reach sRGB standard widely used by digital projectors. The single-color LED driven by temporal pulses will produce high-brightness projection display with saturate colors. Therefore, LED can take place of conventional arc lamp to satisfy the colorimetric requirement of the projection display.
The relation between crystal structure and infrared optical properties of ErF3 film
Authors: Su Wei_Tao  , Li Bin  , Liu Ding_Quan  , Zhang Feng_Shan  ,   中国科学院上海技术物理研究所光学薄膜与材料实验室，上海 200083
Published: December 2020

In this article, thermal evaporation technology was employed to deposit erbium fluoride films on germanium(111) substrates. XRD diffraction pattern shows that films turn from amorphous to crystalline with the increase of substrate temperature. Correspondingly, the morphology and infrared optical properties change obviously. The infrared transmission spectrum of the partially crystalline film is homologous to the totally amorphous film but not the crystalline films. Crystal lattice parameters calculation indicates that there is great compression thermal stress in the erbium fluoride film deposited at high deposition temperature. The refractive indices and extinction coefficients of the films were calculated by fitting the infrared transmission spectrum using Lorentz oscillator model. The refractive index and extinction coefficients at 10μm for the amorphous erbium fluoride film are n=1.38 and k=0.01, and for crystalline films are n=1.32 and k=0.006, respectively.
MRCI potential curves and analytical potential energy functions of the low-lying excited states (1∏，3∏) of ZnHg
Authors: Gao Feng  , Yang Chuan_Lu  , Zhang Xiao_Yan  ,   鲁东大学物理与电子工程学院，烟台 264025
Published: December 2020

The multireference configuration interaction (MRCI) electronic energy calculations with effective core potentials have been carried out for two low-lying excited states (1∏,3∏) of ZnHg dimer. Potential energy curves (PECs) are generated. The PECs are fitted to analytical potential energy functions (APEFs) using the Murrel-Sorbie potential function. The computational equilibrium interatomic distances and dissociation energies are compared with the theoretical values available in the literature. Some important spectroscopic parameters are calculated. Based on the PECs, the vibrational levels of the two states　are predicted by solving Schrdinger equation of nuclear motion.
Theoretical studies of nonlinear optical properties of a novel double-conjugated-segment molecule
Authors: Huang Xiao-Ming  , Tao Li-Min  , Guo Ya-Hui  , Gao Yun  , Wang Chuan-Kui  ,   (1)菏泽学院物理系，菏泽 274015; (2)山东师范大学物理与电子科学学院，济南 250014
Published: December 2020

One-photon and two-photon absorption properties of a double-conjugated-segment molecule (BSBAB) composed of two single-conjugated-segment molecules are studied by using density functional theory at ab initio level. The optimized geometrical structure shows that the two single-conjugated-segment parts in molecule BSBAB retain their own coplanarity and are nearly perpendicular to each other, which seems to indicate that the molecule BSBAB contains optical characteristics of both parts. The molecule BSBAB is found to have three two-photon absorption peaks in lowest energy region which are contributed respectively the two single-conjugated-segment parts respectively and the coupling between them. This also demonstrates that the molecule BSBAB is a broadband strong two-photon absorption chromophore. The response theory approach at Hatree-Fock level is used to prove the convergence of results given by the state summation method with truncated approximation. The charge-transfer process between the charge-transfer states is visualized. The theoretical results are in good agreement with the measurements.
Evolution of atom and field linear entropies
Authors: Zhao Jie  , Guo Hong  ,   (1)华中师范大学物理科学与技术学院，武汉 430079; (2)华中师范大学物理科学与技术学院，武汉 430079;长江大学物理科学与技术学院，荆州 434001
Published: December 2020

The atom and field linear entropies of a two-level atom interacting with gray-body field are investigated. The effect of the atomic initial state, detuning, intensity of the incident field, absorptivity of the cavity and temperature of the system on the atom and field linear entropies are dicussed.
Probing the spectrum evolution of femtosecond pulse filament in argon gas with a hollow fiber
Authors: Cao Shi-Ying  , Zhang Zhi-Gang  , Chai Lu  , Wang Qing-Yue  , Yang Jian-Jun  , Zhu Xiao-Nong  ,   (1)南开大学现代光学研究所，光电信息技术科学教育部重点实验室，天津 300071; (2)天津大学精密仪器与光电子工程学院超快激光研究室，信息技术科学教育部重点实验室，天津 300072; (3)天津大学精密仪器与光电子工程学院超快激光研究室，信息技术科学教育部重点实验室，天津 300072;北京大学信息科学技术学院，量子信息与测量教育部重点实验室，北京 100871
Published: December 2020

Spectrum evolution in the filament was experimentally demonstrated with a 420μm diameter, 18cm length hollow fiber. The experimental results show that the spectrum evolution in filamentation result from the different pulse duration along the filamentation. In our experiment, at a particular position of the filament, the pulse can be compressed to 24.8fs from 50fs of the incident pulse.
Generation of background-free pulses at 1064nm accurately synchronized with femtosecond laser pulses at 794nm
Authors: Zhai Hui  , Xu Shi-Xiang  , Xu Zhi-Xiong  , Cai Hua  , Yang Xuan  , Wu Kun  , Zeng He-Ping  ,   华东师范大学光谱学与波谱学教育部重点实验室,上海 200062
Published: December 2020

This paper reports on generation of background-free pulses at 1064nm accurately synchronized with femtosecond pulses at 794 nm, by the use of a continuous-wave He-Ne laser seeded non-collinear optical parametric amplification (NOPA) pumped by frequency-doubled Ti:sapphire femtosecond laser at 396nm. Experimental results showed that the 1064 nm light pulses can be used as the pump seed for optical parametric chirped pulse amplification to realize an all-optical synchronization between pump and signal beams. Background-free pulses at 1064 nm could also be generated by using a NOPA with continuous-wave seed from the intracavity 632.8 nm light of an appropriate He-Ne cavity. The spectral and spatial chirp properties of the idler pulses were quite similar in both cases according to our measurements. The generated idler pulses in the intracavity seed case have single pulse energy 10 times that of the external cavity case.
First-principles investigation on alloying effect of Nb and Mo in γ-TiAl
Authors: Dang Hong-Li  , Wang Chong-Yu  , Yu Tao  ,   (1)钢铁研究总院功能材料所,北京 100081; (2)钢铁研究总院功能材料所,北京 100081;清华大学物理系,北京 100084;中国科学院国际材料物理中心,沈阳 110016
Published: December 2020

The site substitution behavior of the 4d transition elements and the alloying effect of Nb and Mo have been studied using the first-principles discrete variational (DV) and DMol method within the framework of the density-functional theory. The transfer energy calculation indicates that Y, Zr, Nb, and Mo show the tendency to occupy Ti sites while Tc, Ru, Rh, and Pb have the tendency to occupy Al sites in γ-TiAl. In addition, the alloying effect of Nb and Mo on the electronic structure of γ-TiAl is also studied. It was found that Nb and Mo give rise to strong interaction and charge transfer with the neighboring host atoms of TiAl, resulting in a strong solution strengthening effect.
Temperature-dependent absorption spectra investigation of shallow levels in HgCdTe grown by liquid phase epitaxy
Authors: Yue Fang-Yu  , Shao Jun  , Wei Yan-Feng  , Lü Xiang  , Huang Wei  , Yang Jian-Rong  , Chu Jun-Hao  ,   (1)中国科学院上海技术物理研究所红外物理国家重点实验室,上海 200083; (2)中国科学院上海技术物理研究所红外物理国家重点实验室,上海 200083;华东师范大学ECNU-SITP联合实验室,上海 200062; (3)中国科学院上海技术物理研究所先进材料与器件研究中心,上海 200083
Published: December 2020

Temperature-dependent absorption spectra in temperature range of 11—300K are recorded for a series of unintentionally doped HgCdTe grown by liquid phase epitaxy. The abnormal energy shift of about 7—20meV of absorption edge in the low temperature range (<70K) has been analyzed. The results suggest this the phenomenon to be caused by the Hg vacancies and the abnormal red-shift is related to the composition and the carrier density of the materials. The Hg vacancy level is estimated to be at 20meV above the valence band, which is well consistent with the results of Hg vacancy acceptor level calculated by the empirical expression. The results may provide a preliminary explanation that the bandgap obtained by the conventional transmission spectroscopy is slightly higher than the cutoff energy of the photocurrent response in practical device applications.
Perturbation of Lie symmetries and a type of generalized Hojman adiabatic invariants for variable mass systems with unilateral holonomic constraints
Authors: Jing Hong-Xing  , Li Yuan-Cheng  , Xia Li-Li  ,   中国石油大学(华东)物理科学与技术学院，东营  257061
Published: December 2020

In this paper, the perturbation problem of Lie symmetries and adiabatic invariants for variable mass systems with unilateral holonomic constraints are studied. Firstly, a type of generalized Hojman conserved quantity under general infinitesimal transformation is obtained. Then, based on the definition of high-order adiabatic invariants of a mechanical system, the perburbation of Lie symmetries for variable mass systems with unilateral holonomic constraints under small disturbance is discussed and a type of generalized Hojman adiabatic invariants are given. At last, an example to illustrate the application of the results is given.
Solving solitary wave solutions of nonlinear evolution equations with the homotopy analysis method
Authors: Yang Hong-Juan  , Shi Yu-Ren  , Duan Wen-Shan  , Lü Ke-Pu  ,   (1)西北师范大学物理与电子工程学院，兰州  730070; (2)西北师范大学物理与电子工程学院，兰州  730070; 兰州大学理论物理研究所，兰州  730000
Published: December 2020

We solved the Burgers equation by using the homotopy analysis method (HAM) and obtained its approximate kink solitary wave solutions. The solutions agree very well with the exact solutions. The results indicate that the HAM is valid for finding the solitary wave solutions of a class of nonlinear evolution equations. We also made some efforts to extend the HAM. As an example, we got the bell-like solitary wave solutions of KP equation by this approach. Our extended method can be used to find the approximate solitary wave solutions for more nonlinear evolution equations in an easy way.
The self-consistent theory of the electron distribution and electro-magnetic field of a relativistic hollow electron beam in ion-channel
Authors: Wang Zhen-Yu  , Tang Chang-Jian  ,   四川大学物理科学与技术学院,成都 610064
Published: December 2020

The effect of space-charge and relativistic self magnetic-field on the self-consistent equilibrium of the system with a relativistic hollow electron beam and ion-channel is studied. The distribution function and the relationship between location and energy of electron beam are derived by use of kinetic theory. The self-consistent field in ion-channel has also been established. It is clearly shown that the self-consistent equilibrium of the system exists. The relation of location of beam and radius of ion-channel was presented using numerical calculation. The distribution of electro-magnetic field in ion-channel is also given. The theory which is used in apparatus design is afforded by the research.
Two kinds of hexagon emission patterns with different spatio-temporal symmetry in dielectric barrier discharge
Authors: Dong Li-Fang  , Liu Shu-Hua  , Wang Hong-Fang  , Fan Wei-Li  , Gao Rui-Ling  , Hao Ya-Juan  ,   河北大学物理科学与技术学院,保定 071002
Published: December 2020

Two kinds of emission hexagonal patterns with different spatio-temporal symmetry are observed in lower and higher applied voltage range respectively by using a dielectric barrier discharge device with water electrodes. The spatial wavelength and filament diameter of the hexagon in higher applied voltage range are larger than that in lower voltage range. The hexagon in higher applied voltage range has a brighter background，while no background exists in the hexagon in lower applied voltage range. The spatio-temporal dynamics of the two kinds of hexagon patterns is investigated. It is found that the hexagonal pattern in lower voltage range is an interlacing of two rectangular sublattices, which have a time sequence inversion behavior. The filaments in the hexagon in higher voltage range discharge simultaneously. The influence of the wall charges on the spatio-temporal dynamics of the emission patterns is discussed.
Local structures of Si/Gen/Si(001) hetero-structure films studied by grazing incidence fluorescence X-ray absorption fine structure
Authors: Pan Zhi-Yun  , Sun Zhi-Hu  , Xie Zhi  , Yan Wen-Sheng  , Wei Shi-Qiang  ,   中国科学技术大学国家同步辐射实验室,合肥 230029
Published: December 2020

The local structures around Ge atoms in the Si/Gen/Si(001) hetero-structure films (consisting of 1, 2, 4 and 8 monolayers) prepared by molecular beam epitaxy at 400℃ have been investigated by grazing incidence fluorescence X-ray absorption fine structure (XAFS). The results show that for the Si/Ge1/Si(001) or Si/Ge2/Si(001) hetero-structure film, the Ge atoms are dominantly surrounded by Si atoms as the nearest neighbor. For the Si/Ge4/Si(001) hetero-structure film, the coordination environment around Ge atoms is close to that of Si0.70Ge0.30 alloy. Even for the Si/Ge8/Si(001) hetero-structure film, the fraction of Ge-Ge coordination pair in the first shell is only 55%. This suggests that under the growth temperature of 400℃, the Ge atoms have a strong ability to migrate into the Si capping layer. With the thickness of Ge layer increasing from 1 to 2, 4 and 8ML, the amount of migrated Ge atoms increases from about 0.5 to 1.5, 2.0 and 3.0 nominal　ML. We consider that the migration of Ge atoms during the growth of the Si cap is mainly attributed to the surface segregation of Ge atoms, which leads to the decrease in surface energy as well as strain energy in the Ge layer.
Luminescence properties of Yb3+/Na+ codoped CaF2 crystal and laser operation with low threshold
Authors: Chai Lu  , Yan Shi  , Xue Ying-Hong  , Liu Qing-Wen  , Wang Qing-Yue  , Su Liang-Bi  , Xu Xiao-Dong  , Zhao Guang-Jun  , Xu Jun  ,   (1)天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津 300072; (2)中国科学院上海光学精密机械研究所，上海 201800
Published: December 2020

Basing on measuring the luminescence spectra at room temperature pumped by 975nm light, the action mechanism of Na+ in the novel Yb3+,Na+:CaF2 crystal was systemically investigated. The relation between the concentration of doping Na+ and the laser operation threshold was analyzed. The optimum match concentration for Yb3+,Na+:CaF2 with low laser threshold was obtained. In the experiment, the lowest laser operation threshold at only 70mW of absorbing pumped power for 2%Yb3+, 3%Na+:CaF2 crystal is realized, which is in good agreement with the analysis of luminescence properties.
Realization of femtosecond-resolved near-field optical system and its application
Authors: Li Zhi  , Zhang Jia-Sen  , Yang Jing  , Gong Qi-Huang  ,   北京大学物理系,人工微结构和介观物理国家重点实验室，北京 100871
Published: December 2020

By combining femtosecond laser with the scanning near-field optical microscope (SNOM), we have successfully realized the femtosecond-resolved near-field optical system. Through high frequency acousto-optic modulation and difference frequency lock-in detection, the signal-to-noise ratio was greatly improved and the background signals of the pump and probe light were removed. Therefore, we can measure a femtosecond-resolved weak transmission change in the collection mode SNOM. Spatial resolution of 80nm and temporal resolution better than 200fs were achieved simultaneously. Using this system, we studied the relaxation processes of hot electrons in gold nanostrucures and the difference in relaxation dynamics was observed at different sample positions.
A new method for soluing the problem of electron oscillation between coupled quantum wells
Authors: Zhang Guo-Feng  ,   北京航空航天大学理学院物理系，北京 100083
Published: December 2020

The oscillation of electron between two quantum wells has been studied by exactly solving the time-dependent Schrdinger equation(Acta Phys. Sin. 52 1862). The oscillation behaviour for a general case was given and the case for ω=0 was specially discussed. In this paper, we obtained the same solution more simply for the ω＝0 case using a new method.
Stochastic resonance in a single-mode laser with modulated noise and biased amplitude modulation
Authors: Jin Guo-Xiang  , Cao Li  , Zhang Liang-Ying  ,   (1)华中科技大学激光技术国家重点实验室，武汉 430074; (2)武汉工程大学计算机科学与工程学院，武汉 430073; (3)襄樊学院物理系，襄樊 441053
Published: December 2020

By adopting the gain-noise model of the single-mode laser in which the pump noise is subject to amplitude modulation wave and the action of biased signal, we use the linear approximation to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity, which is driven by two colour noises correlated in the form of an exponential function. The result shows that the SNR shows stochastic resonance with the variation of the noise intensity, the self-correlation time of the pump noise, the parameter of the laser system, the carrier frequency and the signal frequency of the amplitude modulation wave.
Chaotification control of buck converter via time-delayed feedback
Authors: Yang Ru  , Zhang Bo  ,   (1)华南理工大学电力学院，广州 510640; (2)华南理工大学电力学院，广州 510640;广州大学物理与电子工程学院，广州 510400
Published: December 2020

Chaotification is an inverse process of chaos control. This paper addresses the mechanism of chaotification of buck converter. A new chaotification model of buck converter is established. Then the chaotification rule of buck converter is discussed. The fact that using time-delay feedback at the input can realize chaotification in buck converter is proved. The ranges of control parameters are determined using nonlinear dynamics stability theory. Computer simulation is made to verify the proposed method and analyze the influence of different control parameters. The theoretical results are verified by experimental measurements.
Real stabilization method for single particle resonances
Authors: Zhang Li  , Zhou Shan-Gui  , Meng Jie  , Zhao En-Guang  ,   (1)北京大学物理学院，北京 100871; (2)北京大学物理学院，北京 100871;中国科学院理论物理研究所，北京 100080;兰州重离子加速器国家实验室原子核理论中心，兰州 730000; (3)中国科学院理论物理研究所，北京 100080;兰州重离子加速器国家实验室原子核理论中心，兰州 730000
Published: December 2020

We calculate the single-particle resonances in a one-dimensional model potential and isotropic three-dimensional harmonic and Woods-Saxon potentials using the real stabilization method in coordinate space. The results of the real stabilization method are in good agreement with those from the scattering phase shift method and the analytical continuation in the coupling constant method.
Study of the dipole characteristic of terahertz wave emitted from photoconductor switches
Authors: Jia Wan-Li  , Shi Wei  , Ji Wei-Li  , Ma De-Ming  ,   (1)西安理工大学理学院应用物理系，西安 710048; (2)西安理工大学理学院应用物理系，西安 710048;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

In this paper，different methods are used to simulate the dipole characteristic of terahertz (THz) wave emitted from low-temperature grown GaAs (LT-GaAs) and Semi-insulting GaAs (SI-GaAs) photoconductive semiconductor switches. The results indicate that the main cause of the dipole characteristic of THz wave emitted from LT-GaAs is the lifetime of optical-generated carriers being shorted than the generation time. For SI-GaAs photoconductive semiconductor switches with lifetime of optical-generated carriers longer than 100ps，the dipole characteristic of THz waveforms is mainly caused by intra-valley scattering and space charge field screening under different experimental conditions (different bias field and different optical pulse energy).
Proton and neutron 1S0 superfluidity in asymmetric nuclear matter
Authors: Zuo Wei  , Lu Guang-Cheng  ,   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

The proton and neutron 1S0 pairing gaps and their isospin dependence in isospin asymmetric nuclear matter have been studied by the isospin dependent Brueckner-Hartree-Fock approach and the BCS theory. We have focused on investigating and discussing the effect of three-body force. The calculated results indicate that as the isospin asymmetry increases，the density range of the 1S0 neutron superfluidity is narrowed slightly and the maximum value of the neutron pairing gap increases，while the density domain for the proton superfluidity enlarges rapidly and the peak value of the proton gap decreases remarkably. The three-body force turns out to affect only weakly the neutron 1S0 superfluidity and its isospin dependence，i.e.，it leads to a small reduction of the neutron 1S0 paring gap. However, the three-body force not only reduces largely the strength of the proton 1S0 gaps at high densities in highly asymmetric nuclear matter but also suppresses strongly the density domain for the proton 1S0 superfluidity phase.
Magnetic quadrupole M2 2s2 1S0—2s2p3P2(Z=10—103) trangsions for Be-like ions
Authors: Ouyang Yong-Zhong  , Yi You-Gen  , Zhu Zheng-He  , Zheng Zhi-Jian  ,   (1)四川大学原子与分子工程研究所，成都 610065; (2)中国工程物理研究院激光聚变研究中心，绵阳 621900; (3)中南大学物理科学与技术学院，长沙 410083; (4)中南大学物理科学与技术学院，长沙 410083;四川大学原子与分子工程研究所，成都 610065;中国工程物理研究院激光聚变研究中心，绵阳 621900
Published: December 2020

A full relativistic multi-configuration Dirac-Fock theory with quantum electrodynamical (QED) effect and Breit corrections is used to calculate the magnetic quadrupole M2 2s21S0—2s2p3P2(Z=10—103) transition energy level, transition probabilities and oscillator strengths for Be-like ions for the first time. The results with Breit and QED corrections included are in good agreements with current experimental data and other theoretical values. The results show that the magnetic quadrupole transition probabilities of highly ionized atoms are comparable with those of neutral atomic allowed transitions and cannot be ignored in the laser plasma of high temperatures in ICF and MCF fusions. The effect of the magnetic quadrupole transition of highly ionsized atoms should be considered in the calculation of dielectronic recombination process, opacity, free path and so on.
Analytical method of the diffraction characteristic of ruled grating based on profile fitting function
Authors: Bayanheshig  , Zhu Hong-Chun  ,   (1)中国科学院长春光学精密机械与物理研究所，长春 130033; (2)中国科学院长春光学精密机械与物理研究所，长春 130033;中国科学院研究生院，北京 100049
Published: December 2020

The diamond stylus extrudes the metal film and causes coupled elastic-plastic deformation which shapes the profile of the ruled grating. The grating profile function which is hard to get would influenced accurate analysis of the diffraction characteristic. An analytical method of the diffraction characteristic of the mechanically ruled grating is presented based on the profile fitting function. The problem of excessive departure between the measured and theoretical value of the diffraction efficiency of high density ruled grating is solved by this method. We take a 1200l/mm UV grating，the grating profile is scanned in the principal section and then the profile curve function is got. The reason why the diffraction efficiency wasn't high is found by calculation. And then the diffraction efficiency increased about 20% by improving the technology.
Evolution of emmitted light intensity in two-photon pumping random lasers
Authors: Wang Ke-Jia  , Liu Jin-Song  , Lü Jian-Tao  ,   华中科技大学光电子科学与工程学院，激光技术国家重点实验室，武汉 430074
Published: December 2020

Based on the diffusive equation of incoherent-feedback random lasers，whose gain is modified by adding a saturation factor，the evolution of the emitted light intensity in two-photon pumping random lasers varying with time is studied by use of finite difference method. Numerical results show how the intensity of emitted light varies from the spontaneous radiation，which undergoes amplification at small-signal gain，to the steady output due to the saturation effect. It is noted that the nonlinear effect，e.g. saturation of gain，in such laser system can be achieved under low intensity conditions due to the disorder of media. Our results give a theoretical support to obtaining the steady output of the two-photon pumping random lasers.
Photoacoustic imaging of blood vessels based on modified simultaneous iterative reconstruction technique
Authors: Xiang Liang-Zhong  , Xing Da  , Gu Huai-Min  , Yang Di-Wu  , Yang Si-Hua  , Zeng Lü-Ming  ,   华南师范大学激光生命科学研究所暨激光生命科学教育部重点实验室，广州 510631
Published: December 2020

Photoacoustics as a potential and noninvasive medical imaging technology，it combines the advantages of ultrasound imaging and optical imaging to provide high ultrasonic resolution and high optical contrast tissue images. A reconstruction algorithm named the modified simultaneous iterative reconstruction technique (MSIRT) using in limited-view data in photoacoustic imaging was studied. The simulation and experiments result demonstrated that MSIRT has good performance in photoacoustic imaging for limited-view data at angles 90°，135° and 180°. It works much better than traditional algebraic reconstruction algorithm in rectification of the measurement and the speed of convergence. A circular scan with a single-element transducer system was used to obtain photoacoustic signals through 180° in the experiment. This technique provides a high contrast and high resolution (about 60μm) photoacoustic imaging of blood vessels of a chicken embryo based on MSIRT. It greatly reduced the data acquisition time. This method could be potentially used to realtime monitoring of cerebral blood flow and the vascular damage during photodynamic therapy.
An auto-compensating and efficient differential phase shift quantum key distribution system
Authors: Lin Yi-Man  , Liang Rui-Sheng  , Lu Yi-Qun  , Lu Hong  , Guo Bang-Hong  , Liu Song-Hao  ,   (1)佛山科学技术学院光电子与物理学系，佛山 528000; (2)华南师范大学信息光电子科技学院光子信息技术广东省高校重点实验室，广州 510631; (3)华南师范大学信息光电子科技学院光子信息技术广东省高校重点实验室，广州 510631;佛山科学技术学院光电子与物理学系，佛山 528000
Published: December 2020

We present an improved differential phase shift quantum key distribution schemewhich features auto-compensation，high efficiency，and excellent practicality. Alice modulates continuous laser using an intensity modulator based on polarization to generate coherent pulse train. Bob employs a Fraday-Michelson interferometer instead of a traditional M-Z interferometer，which automatically compensates for the polarization mode dispersion caused by the changes of environment and improves the stability of the interference visibility. The present scheme not only has a simpler configuration，but also offers a higher key creation efficiency than traditional schemes. Furthermore，it enhances the security of the system. With the proposed experimental setup，a stable quantum key distribution was performed over 80km fiber with a quantum bit-error rate of less than 4%.
Theoretical investigation of properties of soliton in hot dusty plasma with non-thermal ions
Authors: Wang  Hong-Yan  , Duan Wen-Shan  ,   (1)西北师范大学 物理与电子工程学院, 兰州 730070; (2)西北师范大学 物理与电子工程学院, 兰州 730070;四川理工学院物理系，自贡 643000
Published: December 2020

In this paper, the properties of soliton structures in a hot, unmagnetized dusty plasma which consists of a negatively charged hot dust fluid with variable dust charge, non-thermal distribution of ions and Boltzmann distribution of electrons have been studied. A modified KdV (mKdV) equation which describes the dust acoustic waves in this system is derived by the reductive perturbation method. The effects of dusty plasma parameters on the dust-acoustic solitary waves is studied theoretically. It is found that the soliton structures is determined by the dusty plasma parameters. Furthermore, the soliton only exists in certain regions where these parameters are specially chosen.
Effect of pressure on the glass transition and crystallization dynamics of Zr46.75Ti8.25Cu7.5Ni10Be27.5 bulk amorphous alloy
Authors: Wang Xiu-Ying  , Chen Ying  , Zhang Ning-Yu  , Zhao Li-Ping  , Pang Yan-Tao  , Wang Wen-Kui  ,   (1)山东建筑大学理学院，济南 250101; (2)燕山大学材料科学与工程学院，秦皇岛 066004
Published: December 2020

The glass transition and crystallization behavior of Zr46.75Ti8.25Cu7.5Ni10Be27.5 bulk amorphous alloy are investigated by X-ray diffraction and differential scanning calorimetry under high temperature and high pressure. The results show that the free volume and enthalpy and crystallization activation energy decrease with increasing pressure.
Nanoindentation investigation of the hardness and Young’s modulus of porous silicon depending on microstructure
Authors: Yang Hai-Bo  , Hu Ming  , Zhang Wei  , Zhang Xu-Rui  , Li De-Jun  , Wang Ming-Xia  ,   (1)天津大学电子信息工程学院，天津 300072; (2)天津师范大学物理与电子信息学院,天津 300074
Published: December 2020

In this paper, porous silicon (PS) was prepared by electrochemical etching method, its two-dimensional microstructure was observed by field emission scanning electron microscope (FESEM) and the three-dimensional topological image of PS was captured by Nano-Profilometry (NP), thus the reason for the difference of PS microstructures was discussed and the effect of microstructure on its mechanical property was investigated. Using MTS Nano Indenter XP, the relationship between hardness and Youngs modulus and the indentation displacement was studied and the mechanical property of PS with various porosities was compared. The experimental result showed that the porosity of PS prepared under various etching current densities (40,60,80 and 100mA/cm2) ranges from 60%—80%, which is increasing with the rising etching current density. The thickness of PS prepared under 20% HF is approximately 40—50μm; the average value of hardness and Youngs modulus of PS ranges from 0.478GPa—1.171GPa and 10.912GPa—17.15GPa， respectively； and the values decrease with the etching current density rising, and decrease or keep constant with the displacement increasing in the range of nano_hardness and micro_hardness, respectively. The impact on PS mechanical property of its surface condition, thickness, microstructure and environment was analyzed and the relationship between PS mechanical property and microstructure was obtained.
Fabrication of nonpolar ZnO film on γ-LiAlO2 substrate and its photo-luminescence properties
Authors: Zhou Jian-Hua  , Zhou Sheng-Ming  , Huang Tao-Hua  , Lin Hui  , Li Shu-Zhi  , Zou Jun  , Wang Jun  , Zhang Rong  ,   (1)南京大学物理系，南京 210093; (2)中国科学院上海光学精密机械研究所，上海 201800; (3)中国科学院上海光学精密机械研究所，上海 201800;中国科学院研究生院，北京 100049
Published: December 2020

Nonpolar a-plane (1120) ZnO films were successfully grown on (302) γ-LiAlO2 substrate by pulsed laser deposition. When the temperature of the substrate was 350℃, the film was mix-oriented(a and c) with a wide distribution of crystal grain size, and the c-plane ZnO was dominant. When the temperature of the substrate was 500℃, pure (1120) ZnO film was formed，with the FWHM of ZnO (1120) rocking curve ～0.65° and the grain size distribution narrowed. Its in-plane anisotropy was demonstrated by polarized transmission spectrum. The FWHM of the peak of near band emission in the PL spectra was found to be only 105meV for the sample with substrate temperature of 650℃，indicating the large size and uniform distribution of crystal grains which was also confirmed by AFM.
Experimental study of residual stress of galvanized passive film based on XRD
Authors: Kong De-Jun  , Zhang Yong-Kang  , Chen Zhi-Gang  , Lu Jin-Zhong  , Feng Ai-Xin  , Ren Xu-Dong  , Ge Tao  ,   (1)江苏大学机械工程学院，镇江 212013; (2)江苏工业学院机械工程系,常州 213016; (3)江苏工业学院机械工程系,常州 213016;江苏大学机械工程学院，镇江 212013
Published: December 2020

Residual stresses of galvanized passive film were measured by X-ray diffraction (XRD), at the same time, the residual stress distribution of galvanized passive film in the thickness direction was measured with electro-analysis polishing method, and the effect of residual stress on bonding strength of the film were analyzed. The experimental results show that residual stress of galvanized passive film is always compressive, which decreases as the residual stresses on the substrate surface increases. Residual stress of galvanized passive film in the thickness direction of 2—10μm is -274.5—-428.3MPa, and the residual stress distribution of galvanized passive film in the thickness direction has a gradient. Interfacial bonding strength of galvanized passive film/substrate is inversely proportional to the residual stress, and the decrease of the film stress improves the bonding strength.
Stability of lubricant perfluoropolyether films
Authors: Li Xin  , Hu Yuan-Zhong  , Wang Hui  , Chen Hui  ,   清华大学摩擦学国家重点实验室，北京 100084
Published: December 2020

Molecular dynamics simulations based on a coarse-grained, bead-spring model are adopted to investigate the stability of both nonfunctional and functional perfluoropolyether (PFPE) on solid substrates. For nonfunctional PFPE, the surface morphology changes little with time. The film is stable. For functional PFPE, part of lubricant molecules show local dewetting which causes the increase of surface roughness with time. The film is unstable. Besides, the changes in surface morphology with different endbeads are compared, which indicate that the endbead-endbead interaction is the principal reason for the film instability and the endbead-substrate interaction has little effect on the film stability.
Research of breakdown characteristic of InP composite channel HEMT
Authors: Li Xiao  , Zhang Hai-Ying  , Yin Jun-Jian  , Liu　Liang  , Xu　Jing-Bo  , Li Ming  , Ye Tian-Chun  , Gong Min  ,   (1)四川大学物理科学与技术学院，成都 610064; (2)四川大学物理科学与技术学院，成都 610064;中国科学院微电子研究所，北京 100029; (3)中国科学院微电子研究所，北京 100029
Published: December 2020

Density gradient quantum model has been used to analyse the breakdown characteristic of InP-based composite channel HEMT(high electron mobility transistor). The collision ionization in composite channel and quantum effect has been taken into consideration. We payed great attention to the relationship of on-state breakdown voltage with respect to the thickness of In0.7Ga0.3As channel, and promoted a method to enhance the on-state breakdown voltage. A commercial 2D-device simulation program. Sentaurus has been used to simulate the on-state breakdown voltage of the device. A comparison has been made between the result of simulated and measured data. The result shows that with the reduction of the thickness of In0.7Ga0.3As channel, on-state breakdown voltage of the device will be enhanced greatly without reducing saturation current, which has a significant meaning for promoting the power performance of InP-based HEMT.
Modified Kosterlitz-Thouless transition model for the temperature dependence of the resistivity of anisotropic superconductors
Authors: Ji Gao-Feng  , Liu Sheng-Li  ,   (1)江苏工业学院信息科学系，常州 213164; (2)南京邮电大学数理学院，南京 210003
Published: December 2020

Based on the Kosterlitz-Thouless (KT) phase transition model of two-dimensional systems, by introducing the thermal activation energy and the mean height of the pinning landscape into the correlation length, a modified KT transition model has been proposed to study the temperature dependence of the resistivity transition in anisotropic superconductors. This modified KT transition model is consistent with the Coulomb-Gas (CG) scaling law and the Halperin-Nelson relation. And it is applied to study the scaling behavior of the resistivity transition of Tl2Ba2CaCu2Ox (Tl-2212) thin film under various intensities of magnetic field. The calculated mean height of the pinning landscape from the resistivity curve depends on the temperature linearly, which supports the proposed model.
Investigation on pumping dynamics and pulsed energy storage performance of Yb ions
Authors: Yu Hai-Wu  , Xu Mei-Jian  , Duan Wen-Tao  , Sui Zhan  ,   中国工程物理研究院激光聚变研究中心，绵阳 621900
Published: December 2020

Based on the energy structure of quasi-three-level Yb-ion, the pumping and lasing rate equations are set up. The pumping dynamics of Yb-ion is investigated analytically and numerically, which includes the pumping excitation efficiency, the minimum pumping intensity, and the stored energy extraction efficiency. The laser performances of three typical Yb-doped laser materials are compared, i.e., Yb:S-FAP, Yb:YAG and Yb:FP-glass. Based on the criterion of amplified spontaneous emission (ASE), the design principles of pulsed energy-storage Yb lasers are investigated specifically, which includes the optimum thickness and doping concentration of the gain medium. Finally, based on our model, the baseline parameters are presented for a 100J-class diode-pumped solid-state laser based on either Yb:S-FAP or Yb:YAG. This paper would be helpful for designing the pulsed energy-storage Yb-based DPSS lasers.
Effect of nitrogen pressure on structure and optical band gap of copper nitride thin films
Authors: Xiao Jian-Rong  , Xu Hui  , Li Yan-Feng  , Li Ming-Jun  ,   (1)中南大学物理科学与技术学院,长沙 410083; (2)中南大学物理科学与技术学院,长沙 410083;桂林工学院数理系，桂林 541004
Published: December 2020

Copper nitride (Cu3N) thin films were deposited on glass substrates by reactive radio frequency magnetron sputtering under different radio frequency power (P) and nitrogen partial pressure r(r=N2/［N2+Ar］). The thickness, crystalline structure and surface morphology of films were characterized by profilometer, X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The optical transmission spectrum was obtained by an ultraviolet-visible (UV-VIS) spectrophotometer and the optical band gap (Eg) was calculated. The results suggest that the films' deposition rate increases with P and r. The surface of the films reveals a compact structure, and the grain size of Cu3N is about 30nm. Meanwhile, with increasing r, the grain size and optical band gap of Cu3N increase, of which Eg ranges from 1.47 to 1.82eV, and the films' growth prefers the (111) direction at low r and the (100) direction at high r.
Blue-upconversion in thulium and ytterbium codoped tellurite-gallium glasses pumped by laser diodes
Authors: Zhao Chun  , Zhang Qin-Yuan  , Chen Dong-Dan  , Jiang Zhong-Hong  ,   (1)特种功能材料及其制备新技术教育部重点实验室，华南理工大学光通信材料研究所，广州 510641; (2)特种功能材料及其制备新技术教育部重点实验室，华南理工大学光通信材料研究所，广州 510641;华南理工大学物理科学与技术学院，广州 510641
Published: December 2020

This paper reports on upconversion properties of Tm3+/Yb3+ co-doped TeO2-Ga2O3-R2O (R=Li, Na, K) glasses pumped by 808 and 977 nm laser diodes (LD). An intense upconversion emission centered at 476-nm (blue) along with a weak emission at 650 nm (red) has been observed when pumped by 977 nm LD, assigned to the transitions of 1G4→3H6 and 1G4→3H4 and/or 3F2，3→3H6 of Tm3+, respectively. The 476-nm upconversion intensity has a nearly cubic dependence on incident pump laser power, indicating a three-photon process. However, a quadratic dependence of the 476-nm upconversion intensity on the incident pump laser power has been observed when pumped by 808 nm LD, due to two-photon absorption process. It is noticed that the intensity of the blue-upconversion emission increases signifieantly with increasing radius of alkali metal of samples when pumped by 977 nm LD, while no obvious change has been observed when pumped by 808 nm LD.
2.0 μm emission properties and energy transfer of Tm3+/Ho3+-codoped tellurite glass
Authors: Chen Gan-Xin  , Zhang Qin-Yuan  , Yang Gang-Feng  , Yang Zhong-Min  , Jiang Zhong-Hong  ,   华南理工大学特种功能材料及制备新技术教育部重点实验室，华南理工大学光通讯材料研究所,广州 510641
Published: December 2020

This paper reports on spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped ZnO-WO3-TeO2 glass upon excitation of 808nm diode laser. The J-O strength parameters， spontaneous emission probability and radiative lifetime of Ho3+ were calculated using Judd-Ofelt theory. The absorption cross-section and stimulated emission cross-section were also investigated. Our result indicates that the highest gain of 2.0 μm emission, which comes from 5I7 to 5I8 transition of Ho3+, might be achieved from the glass at the rare-earth ion concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. It is found that coefficients of the forward Tm3+→Ho3+ energy transfer is about 18 times that for the backward Tm3+←Ho3+ energy transfer. The calculated fluorescence lifetime of the 5I7 level of Ho3+ is 3.9 ms and the emission cross section of the 5I7→5I8 transition of Ho3+ exhibits a maximum of 9.15×10-21 cm2 at 2027 nm. We also found that Tm3+/Ho3+-codoped tellurite glass is a promising host material for potential 2.0 μm laser by comparing the quantum efficiencies, the values of σe×τm and gain coefficients of fluoride and heavy metal oxide glasses respectively.
Fluorescence of Er, Yb: YAG glass-ceramics
Authors: Zhang Yue-Pin  , Xia Hai-Ping  , Zhang Xin-Min  , Wang Jin-Hao  , Zhang Jian-Li  , Jiang Chun  ,   (1)宁波大学光电子功能材料研究所,宁波 315211; (2)上海交通大学电子信息学院，上海 200030
Published: December 2020

The Er3+, Yb3+-doped CaO-Y2O3-Al2O3-SiO2 glasses were prepared by melting, and then annealed. The emission spectra and upconversion spectra of glass-ceramics have been investigated. The upconversion luminescence mechanisms of Er3+ in YAG glass-ceramics were analyzed. The results show that the Er,Yb:YAG glass-ceramics are obtained after annealing of the glasses. A broad emission spectrum of width 200nm in the wavelength range of 1450—1650nm was obtained in Er,Yb:YAG glass-ceramics at room temperature. The full width at half-maximum (FWHM) of the 4I13/2→4I15/2 transition is ～180nm. This may be as a result of the luminescence of the Er3+ ions in YAG crystal phase and the remnant Er3+ ions in glass phase acting together. The upconversion luminescence intensity increases because the phonon energy of YAG crystallite is lower than that of aluminosilicate glass. The infrared to green or to red upconversion luminescence intensities for the glass-ceramics are evaluated to be nearly 7 or 3 times as high as that of aluminosilicate glasses, respectively. The relative intensities of green and red upconversion emission changed because the microscopic environment around Er3+ and Yb3+ ions changed upon heat treatment.