bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic theory of a novel THZ gyrotron with three-mirror quasi-optical cavity
Authors: Li Wen-Ping  , Zhang Ya-Xin  , Liu Sheng-Gang  , Liu Da-Gang  ,   电子科技大学物理电子学院，成都  610054
Published: December 2020

Based on the linear theory of gyrotron, and using the Laplace transformation and residue theorem, the kinetic theory of a novel gyrotron with three-mirror quasi-optical cavity is developed within the framework of the linearized Vlasov-Maxwell equations. The beam-wave interaction power, frequency shift and starting current have been derived and numerically calculated. The results indicate that this novel gyrotron has high interaction power when operating at high cyclotron harmonics, and has potential application in THZ band.
The transfer ionization mechanism in the low charge state ion-atom collisions
Authors: Liu Yu-Wen  , Chen Xi-Meng  , Shao Jian-Xiong  , Ding Bao-Wei  , Fu Hong-Bin  , Cui Ying  , Zhang Hong-Qiang  , Lu Yan-Xia  , Gao Zhi-Min  , Du Juan  , Chen Lin  , Sun Guang-Zhi  , Yin Yong-Zhi  , Yu De-Yang  , Cai Xiao-Hong  ,   兰州大学核科学与技术学院,兰州  730000
Published: December 2020

In this work, the ionizations involving the charge transfer and single capture processes in low charge state ion-atom collisions in low-to-medium energy region, are investigated by the position sensitive and time-of-flight techniques. For a given charge state of the incoming projectiles, the dependence of the ratio RTS of the transfer ionization to the single capture changing with the projectile velocity is obtained, and the conclusion that the ionized electron in the transfer ionization process comes from the outermost sub-shell of the target atom is confirmed by comparing our theoretical results with the experimental data.
A novel left-handed material with wire array in a ferrite-filled TE10 rectangular waveguide
Authors: Chu Qing-Xin  , Gong Jian-Qiang  ,   (1)华南理工大学电子与信息学院，广州  510640; (2)西安电子科技大学电子工程学院，西安  710071
Published: December 2020

A novel left-handed material is proposed, which is composed of a metallic wire array in an X-band TE10 rectangular waveguide filled with ferrite. The proposed structure is analyzed by using the transfer function matrix technique and with the full wave simulation tool Ansoft HFSS. The results show that there exist left-handed passband and backward wave propagation phenomenon for the proposed structure in the frequency band in which the effective permeability for the ferrite transversely magnetized is smaller than zero, and the frequency band can be tuned by adjusting the externally imposed magnetic field and the ferrimagnet's magnetization, so we believe such a structure should provide medium-loss and tunable left-handed passband.
Saturable absorption of Yb3+/Na+ codoped CaF2 crystals at 1050nm
Authors: Chai Lu  , Yan Shi  , Xue Ying-Hong  , Liu Qing-Wen  , Ge Wen-Qi  , 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

The saturable absorption of Yb3+/Na+ codoped CaF2 crystals at 1050nm has been demonstrated by comparative experiments by inserting the novel Yb3+,Na+:CaF2 crystal with different doping concentrations into a Yb:YAG laser in stable continuous wave operation, which is the cause for the crystals working as the gain material to tend to self-Q-switching at 1050nm. The results show that the dominative element is Yb3+ rather than Na+ for saturable absorption action of the crystals. However, the effect of Q-switching by codoping Na+ into the CaF2 crystals can be greatly improved so that the Yb3+,Na+:CaF2 crystals with optimum concentration and doping ratio can be used as a Q-switching element at 1050nm.
Improving the stability of the Ti: sapphire oscillator
Authors: Cao Shi-Ying  , Zhang Zhi-Gang  , Chai Lu  , Wang Qing-Yue  ,   (1)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; (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；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

Stability of the pulse intensity and timing jitter of the Ti: sapphire oscillator is analyzed in this paper. The stability, central wavelength and bandwidth of the pulse train from the Ti: sapphire oscillator with and without water cooling plate were experimentally compared. The results show that by introducing a water cooling plate, the stability of the Ti: sapphire oscillator can be improved.
Study on variations of stimulated Brillouin scattering parameters of mixed media with mixing ratio
Authors: Hasi Wu-Li-Ji  , Lü Zhi-Wei  , Liu Shu-Jie  , He Wei-Ming  , Zhao Xiao-Yan  , Zhang Wei  ,   (1)哈尔滨工业大学光电子技术研究所，哈尔滨  150001; (2)哈尔滨工业大学空间光学工程研究中心，哈尔滨  150001；哈尔滨工业大学光电子技术研究所，哈尔滨  150001
Published: December 2020

From the relation between the refractive index, viscosity, density, sound velocity and mixing ratio of mixed medium, we deduce the variation of SBS parameters, namely the Brillouin linewidth, phonon lifetime and gain coefficient, with mixing ratio. For the HT-70/FC-72 mixture, the variations of Brillouin linewidth, phonon lifetime and gain coefficient with mixing ratio are numerically simulated, and the variations of absorption coefficient and optic breakdown threshold with mixing ratio are measured in experiment. The results show that the SBS parameters exhibit a monotonic variation with mixing ratio without extrema. The use of mixed medium not only diversifies SBS medium but also optimizes the SBS system.
Optimized design of phase plates for shaping partially coherent beams based on the adaptive genetic algorithm
Authors: Li Jian-Long  , Lü Bai-Da  ,   四川大学激光物理与化学研究所，成都  610064
Published: December 2020

Based on the adaptive genetic algorithm，the optimized design of phase plates for shaping partially coherent beams is performed. Taking the Gaussian Schell-mode beam as an example，the analytical expression for the far-field intensity is derived and the phase plate capable of transforming GSM beams to flat-topped ones is optimized. The effect of spatial coherence on the beam shaping is illustrated by a numerial example. Comparison of the results with the previous work shows the advantages of the adaptive genetic algorithm in shaping partially coherenct beams.
Study on the optical and electrical properties of plasma for the deposition of microcrystalline silicon
Authors: Zhang Fa-Rong  , Zhang Xiao-Dan  , Amanatides E.  , Mataras D.  , Zhao Jing  , Zhao Ying  ,   (1)南开大学光电子薄膜器件与技术研究所；天津市光电子薄膜器件与技术重点实验室；光电信息技术科学教育部重点实验室(南开大学)，天津  300071; (2)天津新华职工大学，天津  300040; (3)希腊帕特雷大学等离子体技术实验室，帕特雷，希腊  26500
Published: December 2020

Optical emission spectroscopy and Fourier transform power and impedance analysis have been used to investigate the effects of substrate bias and glow discharge on the plasma optical and electrical properties for the deposition of microcrystalline silicon. Results show that the Hα emission intensity distribution has the same tendency under bias AC，floating and -DC +AC, and their mean sheath lengths are almost located at the same position of the electrode gap. Compared to the above three bias states，Hα emission intensity increases sharply and double layers appear under +DC+AC bias and grounded conditions. Increasing of glow discharge power leads to the rise of Hα emission intensity，both the resistance and reactance decrease，and the plasma becomes more capacitive.
Second harmonic generation by the Kelvin-Helmholtz instability for two-dimensional incompressible fluid
Authors: Wang Li-Feng  , Ye Wen-Hua  , Li Ying-Jun  ,   (1)北京应用物理与计算数学研究所，北京  100088；浙江大学物理系，杭州  310028; (2)中国矿业大学(北京)，北京  100083
Published: December 2020

A model of second harmonic generation by Kelvin-Helmholtz (KH) instability is presented. Weakly nonlinear theoretical results of the growth of the second harmonic agree well with the results of the LARED-S code. Nonlinear threshold of the KH instability for the single mode perturbation is determined by two-dimensional simulation.
Prevention of misfit dislocations by using nano pillar crystal array substrates
Authors: Zhou Nai-Gen  , Zhou Lang  ,   南昌大学材料科学与工程学院，高等研究院，南昌  330031
Published: December 2020

Three-dimensional molecular dynamics simulations of epitaxial growth of aluminum film on substrates of nano pillar crystal array have been carried out. The embedded atom method (EAM) potential was employed for computing atomic interaction in aluminum. The results show that，the nano pillar crystal array substrate can release the misfit strain in the epitaxial film without forming any misfit dislocations，achieving a high quality epitaxial crystal film. However，two conditions must be met: 1) the cross sectional size of pillar crystal should be larger than the critical size of thermal stability，which is 19nm for aluminum at 700K；2) the height-space interval ratio of pillar crystals should be higher than 076. The latter ensures that the epitaxial layers on the neighboring pillar crystals can bridge with each other，and form a continuous film free of misfit dislocations.
Staging effects on the structural and energetic properties of fast ionic conductor LixTiS2
Authors: Song Qing-Gong  , Jiang En-Yong  , Kang Jian-Hai  ,   (1)天津大学理学院现代材料物理研究所，天津市低维材料物理与制备技术重点实验室，天津  300072; (2)天津大学理学院现代材料物理研究所，天津市低维材料物理与制备技术重点实验室，天津  300072；中国民航大学理学院，天津  300300; (3)中国民航大学理学院，天津  300300
Published: December 2020

A series of cell models for stage-2 ordered LixTiS2(x=1/8，1/6，1/4，1/3，3/8，1/2)system were constructed according to concentration-wave theory. Geometry optimizations and total energy computations were carried out for the stage-2 ordered systems and stage-1 ordered LixTiS2(x=0，1/4，1/3，1/2，2/3，3/4，1)system by plane-wave pseudopotential method. The results of stage-2 ordered systems were compared with that of stage-1 ordered systems. It turns out that there is a similar increment tendency in lattice parameters c(d) of stage-2 cell and 2c0(d) of stage-1 cell. Furthermore，there are extra expansions of c1(d)，i.e. the space between two sandwiches with intercalated ions in stage-2 system，compared with c0(d)，i.e. the space between two sandwiches in stage-1 system，and the corresponding c2(d)，i.e. the space between two sandwiches without intercalated ions in stage-2 system, is compressed. The extrc expansion of c1(d) is complementary to the compression of c2(d) to a certain extent. Staging has remarkable effect on the atomic structure of TiS2 sandwiches. The formation energy of stage-2 ordered Li1/2TiS2 is distinctly higher than that of stage-1 ordered Li1/2TiS2，indicating that the latter is more stable than the former，which is well in accordance with the experimental results reported. The lower formation energy of stage-2 ordered Li1/4TiS2，compared with stage-1 ordered Li1/4TiS2，predicts a new ordered structure.
Characteristics of acoustic phonon transport and thermal conductance in quasi-one-dimensional quantum waveguides with semi-circular-arc cavity
Authors: Yao Ling-Jiang  , Wang Ling-Ling  ,   湖南大学物理与微电子科学学院，长沙  410082
Published: December 2020

By using the scattering matrix method，the transmission coefficient and thermal conductance of acoustic phonon through a quantum waveguide with semi-circular-arc cavity under both stress-free and hard-wall boundary conditions at low temperatures are studied. The results show that the transmission spectra and thermal conductance exhibit different characteristics under two different boundary conditions. Under the stress-free boundary condition，the universal quantum thermal conductance can be observed regardless of the geometry details in the limit T→0. The quantized plateau is observed only on assuming that the quantum wire is perfect (uniform). For quantum structures with semi-circular-arc cavity，the plateau is destroyed due to the additional scattering induced by the nonuniform waveguide widths to the phonon. When the hard-wall boundary condition is applied，the universal quantum thermal conductance disappears. The thermal conductance increases with the increase of temperature. Moreover，it is found that both the transmission coefficient and thermal conductance can be adjusted by changing the radius of the semi-circular-arc cavity.
Spectroscopic ellipsometer (SE) studies of a novel cyanine dye in Langmuir-Blodgett films
Authors: Zeng Hao  , Gao Feng  , Ma Shi-Hong  ,   复旦大学物理学系，上海  200433
Published: December 2020

The optical properties of the HQ Langmuir-Blodgett films (Y-type) have been studied in the range of ultraviolet-visible light (λ=2755—8266nm) by using the spectroscopic ellipsometer. The high absorption of the LB films in different frequency ranges have been discussed. We have also carried out the theoretical computation and numerical value fitting by using the Lorentz oscillator model for the films and the fitting results were in agreement with the experiment data.
Study on thermal conductivity of hydrogenated amorphous silicon films
Authors: Li Shi-Bin  , Wu Zhi-Ming  , Yuan Kai  , Liao Nai-Man  , Li Wei  , Jiang Ya-Dong  ,   电子科技大学光电信息学院电子薄膜与集成器件国家重点实验室，成都  610054
Published: December 2020

The thermal conductivity of hydrogenated amorphous silicon (a-Si：H) film was measured using platinum metal as heating resistance. The films are prepared by plasma enhanced chemical vapor deposition (PECVD) and the thickness of them is in the range of 300—370nm. The dependence of thermal conductivity of the films on substrate temperature was studied. The influence of substrate temperature on the growth rate of a-Si：H films was obtained by spectra ellipsometer (SE). Fourier-transform infrared spectrometer (FTIR) was used to characterize the infrared spectra of films deposited on KBr substrate. The thermal absorption duc to vibrational mode of Si-H bond decrease the thermal conductivity of the films. Kinetic theory was used to analyze the result that the thermal conductivity of the films increases with the increasing of mean temperature. The effects of phonon propagation and free electrons displacement on thermal conductivity was also compared.
Nearfield acoustic holography based on wave superposition algorithm for cyclostationary sound filed
Authors: Zhang Hai-Bin  , Jiang Wei-Kang  , Wan Quan  ,   上海交通大学机械系统与振动国家重点实验室,上海  200240
Published: December 2020

The seriously modulated radiation sound waves, as a kind of special nonstationary signal in the engineering, can be considered as cyclostationary. The modulating feature can not be understood clearly via the reconstructed sound field by conventional nearfield acoustic holography (NAH). A cyclostationary NAH (CYNAH) technique based on wave superposition algorithm (WSA) is suggested for reconstructing the cyclostationary sound field, which can be applied to the cyclostationary acoustic sources with complicated profiles. The information of modulating wave can be understood by the reconstructed hologram of cyclic spectrum density (CSD), in which the distribution of modulating wave is visualized and the location of modulating wave can be determined. The simulation and the experiment verified that the modulating characteristic can be understood by CYNAH based on WSA. The main advantages of WSA, including the high calculation accuracy and calculation efficiency due to the exclusion of uniqueness and singularity problems inherent in the boundary element method, are retained in the presented CYNAH procedure.
Effect of side groups on the electronic transport properties of molecular devices
Authors: Xia Cai-Juan  , Fang Chang-Feng  , Hu Gui-Chao  , Li Dong-Mei  , Liu De-Sheng  , Xie Shi-Jie  , Zhao Ming-Wen  ,   (1)山东大学物理与微电子学院；山东大学晶体材料国家重点实验室，济南  250100; (2)山东大学物理与微电子学院；山东大学晶体材料国家重点实验室，济南  250100；山东济宁学院物理系，曲阜  273100
Published: December 2020

Basing on ab initio methods and nonequilibrium Green's function(NEGF) theory, we have investigated the electronic transport properties of 4-4′-dimercaptodibenzene molecular which have been functionalized with different side groups. Numerical results show that the same side group on different site does not strongly affect the resonances responsible for current flow through the molecular. But different side groups on the same site will have a stronger effect on the energetics of the molecular device than on the orbitals responsible for current transport. So functionalization has a significant effect on the interactions within the molecular, and the molecular with NO2 side group exhibit local minima associated with twisted conformations of the molecular device which can induce the molecular memory effect.
First principle study on the electron life span of degenerate anatase phase TiO2 semi-conductor with high concentration of oxygen vacancies
Authors: Hou Qing-Yu  , Zhang Yue  , Zhang Tao  ,   北京航空航天大学材料科学与工程学院，北京  100083
Published: December 2020

Plane wave ultrasoft pseudopotential technique based on the density functional theory was used to study the effect of high concentration of oxygen vacancies on the electron life span. Using first-principle theory, the structure of anatase TiO2 was optimized, then the state density was calculated. The result showed that at a constant temperature and with high oxygen vacancy concentration, the life span of electrons in anatase TiO2 declines with the increase of the O vacancy concentration, while the electron concentration has no effect on the electron lifes pan. Meanwhile, the Mott phase transformation takes place when the concentration of oxygen vacancies in anatase TiO2 is high.
Role of contacts in the conherent transport
Authors: Zhang Li  , Yu Ya-Bin  , Cai Meng-Qiu  , Liu Yi-Xing  , Quan Jun  ,   湖南大学物理与微电子科学学院,长沙  410082
Published: December 2020

In order to study the role of contacts in the coherent transport of mesoscopic structure systems, a 2D-1D-2D model of nano-sized single-barrier system is considered, which includes a single-barrier structure conductor with two reservoirs. Basing on the scattering-matrix method and the Thomas-Fermi approximation, we have calculated the transmission probability and the distribution of internal potential when a dc voltage is applied to the system. The results show that: (1) the contacts can produce significant effects on the transmission probability; (2) the behaviors of conductance and the distribution of internal potential differ from the usual transport conductance give by the Kirchhoff's laws. Therefore we conclude that since contacts and the mesocopic systems are quantum coherent, the role of contacts is important for in-depth investigation of the transport in mesoscopic systems.
Transport of electrons through an asymmetric T-shaped quantum waveguide in a magnetic field
Authors: Tang Li-Ming  , Wang Ling-Ling  , Wang Ning  , Yan Min  ,   湖南大学物理与微电子科学学院，长沙  410082
Published: December 2020

We investigate transport properties of electrons through an asymmetric T-shaped magnetic quantum structure by the mode-mathcing technique and solution of the single electron Schrdinger equation. The results show that the changes of structural factors and magnetic field affect the electron scattering behavior and result in various patterns of electron transmission. When different magnetic configurations and structural factors are used, the transmission exhibits various patterns such as wide valley, sharp peak, resonant reflection, resonant transmission, and so on. Our results show that one may control the transmission property to design interferential quantum devices by adjusting magnetic configurations and or structural parameters.
Optimizing polymorphous silicon back surface field of a-Si(n)/c-Si(p) heterojunction solar cells by simulation
Authors: Zhao Lei  , Zhou Chun-Lan  , Li Hai-Ling  , Diao Hong-Wei  , Wang Wen-Jing  ,   中国科学院电工研究所太阳电池技术研究室，北京  100080
Published: December 2020

Back surface field (BSF) effect of polymorphous silicon with different band gaps on a-Si(n)/c-Si(p) heterojunction solar cell was simulated and analyzed by utilizing AFORS-HET software. It was predicted that the polymorphous silicon capable of producing the optimal BSF effect is the microcrystalline silicon with band gap of 16 eV，the doped concentration of 1018cm-3 and the thickness about 5nm. Such microcrystalline silicon BSF is easy to realize in practice. It makes the efficiency of solar cell much higher than that using the conventional Al BSF with the same doping concentration.
Numerical simulation of radial segregation patterns of binary granular systems in a rotating horizontal drum
Authors: Zhao Yong-Zhi  , Cheng Yi  ,   (1)清华大学化学工程系,北京  100084; (2)浙江大学化学工程与生物工程学系化工机械研究所,杭州  310027
Published: December 2020

A 3D three-equation linear spring-dashpot model considering the normal contact force, the tangential contact force, and the rolling friction torque, and the corresponding programs for granular dynamics were developed. The flow and the segregation of the S-type binary granular mixtures in a thin rotating horizontal drum were simulated by using the new model. The influences of the rotation speed and the load of the drum on the pattern formation were discussed. The simulation results show that the pattern formation of the S-type binary granular mixtures in the rotating drum can be predicted accurately. As the rotation speed is high, the moon pattern appears,in which the small particles concentrate in a central core and the large particles distribute in the periphery. As the rotation speed is lowered, the petal pattern is found in thin drums, and the number of petals increases as the rotation speed decreases. The process of pattern formations was obtained by the simulation. As the petal pattern forms, the wavy flow of granules in the drum appears. Finally, the necessary condition and mechanisms of the pattern formation in the thin drums are discussed in the paper.
Study of the LC resonance giant magneto-impedance effect
Authors: Pan Hai-Lin  , Cheng Jin-Ke  , Zhao Zhen-Jie  , He Jia-Kang  , Ruan Jian-Zhong  , Yang Xie-Long  , Yuan Wang-Zhi  ,   华东师范大学物理系，上海  200062
Published: December 2020

CoP/Insulator/BeCu composite wire incorporating a capacitor was prepared by chemical deposition. This new type of composite wire functions as an LC resonance circuit element by itself, in which large LC resonance giant magneto-impedance (LCR-GMI) effect was observed when the driving frequency approached to the LC resonance frequency. The properties of LCR-GMI in the composite wire with a length of 95 cm were investigated. Its LCR-GMI ratio and field sensitivity are 4875% and 046%/A·m-1 at the resonance frequency of 29 MHz, respectively, which are higher than those of the ordinary composite wire. When the carrier frequency deviates from the resonance frequency, LCR-GMI ratio decreases obviously, showing distinct selectivity of frequency. Meanwhile, we proposed an equivalent circuit model based on the characteristics of the LC resonance composite wire, and simulated the experimental curves. The simulation results agreed well with the experimental data. Using the equivalent circuit model, we analyzed the physical mechanisms of LCR-GMI and the influence of wire length on the LCR-GMI effect.
Elastomechanical study of interface coupling in magnetoelectric bilayers
Authors: Cao Hong-Xia  , Zhang Ning  ,   南京师范大学磁电子学实验室, 南京  210097
Published: December 2020

A theoretical model is introduced to derive the ME voltage coefficients of bilayer in free state according to the constitutive equations of magnetostrictive and piezoelectric phases. Using this model, the ME voltage coefficients of La07Sr03MnO3(LSMO)-PZT and Tb1-xDyxFe2-y (TDF)-PZT bilayers have been calculated and analyzed using the corresponding material parameters of individual phases. The results show that the ME voltage coefficient increases to a maximum at a given volume fraction of piezoelectric phase. With increasing interface coupling parameter k, an approximately linear increase of the maximum ME voltage coefficient have been observed. The maximum ME voltage coefficient for TDF-PZT bilayer reaches 19Vcm-1Oe-1, while for LSMO-PZT bilayer, the maximum value is only 165mVcm-1Oe-1. The theoretical results of ME voltage coefficients versus bias magnetic field for LSMO-PZT bilayer have been found to agree well with the measured data when k=02. Analysis shows that large magnetostriction, appropriate volume fraction and adequate interface coupling are key facters for obtaining excellent ME performance.
Investigation of the charge-transfer spectra of Ce4+-doped Ca2SnO4 with one-dimensional structure
Authors: Fu Shi-Liu  , Chai Fei  , Chen Jie  , Zhang Han-Yan  ,   汕头大学物理系,汕头  515063
Published: December 2020

Ca2Sn1-xCexO4 and Ca2-ySrySn1-xCexO4 with one-dimensional structures were prepared by the solid-state reaction method. The X-ray photoelectron spectra of Ce4+-doped Ca2SnO4 showed the existence of two oxidation states of O2- ions with binding energy peaks at 5277 eV and 5293 eV. The former corresponds to the terminal O2- ions in the SnO6 octahedra while the latter corresponds to the equatorial O2- ions of the octahedra. The luminescence from Sr2CeO4 and Ca2Sn1-xCexO4 phosphors with one-dimensional structures originates from a ligand-to-metal Ce4+ charge transfer (CT) and it is generally accepted that there exist two excitation peaks in the ultraviolet excitation band. However, it was found from the Ca2-ySrySn1-xCexO4 sample that the excitation band of Ca2Sn1-xCexO4 was actually comprised of three excitation peaks which were centered at about 31000, 34500 and 37400cm-1. When Sr2+ ions were doped in Ca2Sn1-xCexO4, three excitation components peaking at about 31200, 34700 and 38400cm-1 were observed apparently, whose locations exhibited a blue shift as compared with those of Ca2Sn1-xCexO4. However, the substitution of Ca2+ by Sr2+ had no influence on the shape of the emission spectrum. The excitation spectrum of Sr2CeO4 can also be deconvoluted into three Gassian components which are centered at about 29300, 33400 and 37000cm-1, respectively.
Study of photoluminescence and energy transfer properties of an organic dye salt doped thin films
Authors: Xu Deng  , Ye Li-Hua  , Cui Yi-Ping  , Xi Jun  , Li Li  , Wang Qiong  ,   东南大学电子科学与工程学院先进光子学中心,南京  210096
Published: December 2020

The photoluminescence and energy transfer properties based on an organic salt trans-4-［p-(N-ethyl-N-(hydroxylethyl)amino)phenylstyryl］-N-(hydroxyethyl)pyridinium iodide (ASPI) doped PVK thin film were investigated by steady-state and time-resolved fluorescent spectra. We observed that the emission intensity and the fluorescent lifetime of PVK reduced with increasing ASPI doping concentration due to the Forster energy transfer from PVK to ASPI, which is strongly correlated with an efficient spectral overlap between ASPI absorption and PVK emission. We also added some Alq3 into the doping system as energy carriers in order to increase the energy transfer efficiency from PVK to ASPI at low concentration, or there will be an evident decrease in photoemission efficiency due to the concentration quenching at high concentration. The dynamical process of energy transfer is discussed.
Numerical simulation of ozone generation in oxygenic plasmas
Authors: Ouyang Jian-Ming  , Shao Fu-Qiu  , Lin Ming-Dong  ,   国防科学技术大学理学院，长沙  410073
Published: December 2020

The generation processes of ozone in oxygen plasmas and atmospheric plasmas were numerically simulated in this paper. It is concluded that the generation of ozone is closely correlated with free oxygen atoms, and the maximum number density of ozone is correlated with the initial electron number density. The best discharge interval is the time when the number density of oxygen atoms is maximal.
The geometric structure of Friedmann universe in the discrete spacetime and its properties
Authors: Chen Guang  ,   东华大学信息学院，上海  201620
Published: December 2020

The geometric structure of Friedmann universe in the discrete space time is researched. It is proved that the dust matter which forms the Friedmann universe is not distributed on the Friedmann spacetime points. The geodesic motion equations of test particles are derived, and the effects of clock and frequency shift are revealed.
A new method of calculating the unitary evolution matrix ds(t) of the spin-s operators and its applications
Authors: Hu Ming-Liang  , Xi Xiao-Qiang  ,   西安邮电学院应用数理系，西安  710061
Published: December 2020

We propose a method for calculating the unitary evolution matrix of the arbitrary spin-s operators rigorously. This is an indirect method, which differs from the method of group theory or the method of direct calculation. The kernel of our method is to use the identity of two systems in their expressions, namely the Hamiltonian Hs=Sx of spin-s particle and the Hamiltonian of the Heisenberg XX open chain with interaction J=n(N-n). Because of this identity, the calculation of the unitary evolution matrix of the spin-s operators is substituted by the calculation of the state evolution matrix in Heisenberg XX open chain. As examples, the unitary evolution matrix of s=3/2, s=2 and s=5/2 are calculated by using our method. Since the evolution of the state |sm〉 under the operator e-itSx corresponds to the rotation of the initial state |sm〉 around the x-axis by an angle β＝t, and the evolution matrix element dsm′m(t)=〈sm′|e-itSx|sm〉 is just the projection of the finial state e-itSx|sm〉 on the initial state |sm′〉, the evolution matrix at t=π corresponds the perfect transmission of quantum state in the Heisenberg XX open chain.
Effects of time period modulation of the noise correlation intensity on stochastic resonance of the single-mode laser
Authors: Chen De-Yi  , Wang Zhong-Long  ,   三峡大学理学院物理系，宜昌  443002
Published: December 2020

By means of the linear approximation, we investigate the power spectrum and signal-to-noise ratio of the laser intensity for the gain-noise model of the single-mode laser with the noise correlation intensity λ modulated by the time period. Effects of the noise intensity D and Q, the noise correlation intensity λ, the period modulation frequency Ωλ and the input signal frequency Ω on the signal-to-noise ratio R are discussed. Some novel phenomena are found.
Criteria for synchronization with error bound of forced oscillators with parameters mismatch
Authors: Wang Jian-Gen  , Cai Jian-Ping  , Ma Mi-Hua  , Feng Jiu-Chao  ,   (1)华南理工大学电子与信息学院，广州  510640; (2)漳州师范学院数学系，漳州  363000; (3)中山大学应用力学与工程系，广州  510275；漳州师范学院数学系，漳州  363000
Published: December 2020

Some algebraic criteria for synchronization with error bound of forced oscillators with different external forces are derived by Lyapunov direct method and Sylvester's criterion. Using algebraic inequalities, the synchronization error bound can be estimated. By controlling the estimated synchronization error bound, the real synchronization error bound can be controlled to be smaller than a prescribed precision of the synchronization. The Duffing-Van der Pol forced oscillator used as a numerical example verifies the effectiveness of the method.
The law of the underwater explosion bubble motion near free surface
Authors: Zhang A-Man  , Yao Xiong-Liang  ,   哈尔滨工程大学船舶工程学院，哈尔滨  150001
Published: December 2020

The numerical model of underwater explosion bubble coupling with free surface is created based on boundary integral method and the corresponding program is exploited to get the calculated result which presents satisfactory precision with experiment data. From the basic phenomenon of the interaction between bubble and free surface, the dynamic behavior of bubble near free surface is studied systematically employing the exploited program including the ring rebound of bubble near free surface and spike of free surface as well as the relation between distance parameter buoyancy parameter strength parameter and Bjerknes effect near free surface to summarize relative laws that the dynamic behavior near free surface has close relation with these characteristic parameters. In the process of study, scope of applicability of Blake rule on the basis of Kelvin_impulse theory is discussed and the reason for inactivation of Blake rule is interpreted to present references to research on dynamic behavior of underwater explosion bubble near free surface.
Analysis of temperature and deformation fields in an optical coating sample
Authors: Liu Ming-Qiang  , Li Bin-Cheng  ,   (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  100039
Published: December 2020

By solving thermal conduction and thermo-elastic equations with an integral-transform method, a theory to describe the three-dimensional temperature and deformation distributions in an optical coating sample irradiated by a pulsed or square-wave modulated laser is developed for both transient and steady state cases. The theoretical simulations are compared with corresponding results of the finite-element method in time and space domains and good agreements are obtained. In addition, the influences of heating-beam radius and modulation frequency on the temperature and deformation distributions are discussed. Applications of the theoretical model to absorptance and deformation measurements of optical coatings are discussed.
The potential energy function and thermodynamic properties of AuZn and AuAl for the ground states and low-lying excited states
Authors: Li Quan  , Zhu Zheng-He  ,   (1)四川大学原子分子物理研究所，成都  610065; (2)四川师范大学化学与材料科学学院，成都  610066
Published: December 2020

The structure and potential energy function of the ground states and low-lying excited states for AuZn and AuAl molecule are studied using B3LYP method. Their analytic potential energy functions are in good agreement with the Murrell-Sorbie function，and the ground states is X2Σ and X1Σ for AuZn and AuAl molecule，respectively. The adiabatic excitation energies of a4Σ for AuZn，and a3Σ for AuAl molecule is 43529 and 19991kJ/mol，respectively.The electronic and vibration energy or electronic and vibration entropy of the gas molecules are assumed to be the corresponding values of their solid states. The relationships of thermodynamic properties of formation reaction and temperature have been calculated based on this approximation.
THz spectra of hypoxanthine and inosine
Authors: Ma Xiao-Jing  , Zhao Hong-Wei  , Dai Bin  , Liu Gui-Feng  ,   (1)石河子大学化学化工学院，石河子  832003; (2)中国科学院上海应用物理研究所，上海  201800; (3)中国科学院上海应用物理研究所，上海  201800；石河子大学化学化工学院，石河子  832003
Published: December 2020

Far-infrared absorption spectra and refractive indices of hypoxanthine and inosine have been measured by terahertz time-domain spectroscopy (THz-TDS) in the frequency range of 03—16THz at room temperature. The experimental results show that there is a distinct difference between the THz absorption spectra of hypoxanthine and inosine，which suggests that THz-TDS is highly sensitive to molecular structures and the components. Hartree-Fork calculation was used to optimize and simulate the THz spectra obtained by measurement. The low frequency vibrational mode at 14THz of inosine is attributed to the swing and torsion between purine and pentose rings according to the theoretical calculation. There is a linear relationship between the absorption intensity and the concentration of sample，which is consistent with Lambert-Beer's Law. Quantitative analysis of the components of mixtures of hypoxanthine and inosine was carried out by linear regression with non-negative constraint and the relative error was less than 7%. The sources of error were also discussed.
Study of isotope effect in 3He(4He)-H2 collisions
Authors: Shen Guang-Xian  , Wang Rong-Kai  , Linghu Rong-Feng  , Yang Xiang-Dong  ,   (1)贵州师范大学理学院，贵阳  550001; (2)贵州师范大学理学院，贵阳  550001；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

Close-coupling equation is applied to the 3He(4He)-H2 system，and the rotational excitation cross sections for incidence energy of 05eV are calculated.By analyzing the differences between these partial wave cross sections and differential cross sections，the change of the partial wave cross sections and differential cross sections with increase of quantum number，as well as with the change of the mass of isotope atom are found out. Based on the calculation，the effect of isotopic substitution on atom-diatom collision is discussed.
Fully differential cross sections for 102eV electron-impact ionization of helium in non-coplanar geometry
Authors: Sun Shi-Yan  , Jia Xiang-Fu  , Shi Wen-Qiang  , Li Xiong-Wei  ,   山西师范大学物信学院，现代物理研究所，临汾  041004
Published: December 2020

DS3C model is applied to study single ionization of helium by 102eV electron impact. Fully differential cross sections are calculated at different scattering angles of θ1 (8°，10°，15°，20°) for the perpendicular plane geometry. The results of 3C and CCC model were compared with experimental data, which sho ws that DS3C model can give a successful description of the (e，2e) process for noncoplanar geometry qualitatively，indicating the existence of strong dynamic correlations effect between the three particles in the final channel for noncoplanar geometry.
Study on the Doppler shift and the spectrum widening of the scattered echoes from the 2-D rough sea surface
Authors: Guo Li-Xin  , Wang Rui  , Wang Yun-Hua  , Wu Zhen-Sen  ,   (1)西安电子科技大学理学院，西安  710071; (2)中国海洋大学海洋遥感研究所，青岛  266003
Published: December 2020

Based on the 2-D ocean-like surface of linear model and the first-order small slope approximation，the characteristic of Doppler shift for different order Doppler spectra of scattered echoes is investigated and the formula of Doppler shift is derived. Comparing with the conventional formula of Doppler shift，the influence of the wind speed and the orbit motion of the sea wave in large scale is considered in our result. By employing the two-scale model of rough surface and physical mechanism of Doppler shift，a formula of the spectrum widening for the scattered field from the oceanic surface is also presented. The numerical results evaluated by the formulae in this study are compared with the simulated and the measured data，the dependence of the Doppler shift and the spectrum widening on the parameters，such as the wind speed，the frequency of the incident wave and the incident angle, etc. are discussed. It is found that the formulae obtained in this research can be used to predict the Doppler shift and the spectrum widening.
Study on the propagation properties of Lorentz beam
Authors: Zhou Guo-Quan  ,   浙江林学院理学院，临安  311300
Published: December 2020

Based on the second-order moment theory of beam propagation，the properties of Lorentz beam have been investigated. The expressions of the beam waists，the transverse divergence angle and the beam propagation factor have been presented. The transverse beam waist only depends on the corresponding beam parameter. However，the transverse divergence angle and the beam propagation factor are both determined by the two transverse beam parameters. The curves of the beam propagation factor versus the two transverse beam parameters are also given. The numerical results show that variational laws of the beam propagation factor in the x-and y-directions versus the two transverse beam parameters are apparently different，while the variational rule of the integrated beam propagation factor versus the two transverse beam parameters is the composite manifestation of the above cases. In the paraxial case，the beam propagation factor trends to a constant value of 141. With the beam waist being the same，therefore，the divergence of Lorentz beam is 1.41 times that of the Gaussian beam in the paraxial case. Accordingly，Lorentz beam is an appropriate model to describe certain laser sources with high divergence.
Enhanced transmission through metal-film hole arrays and the surface plasmon resonance
Authors: Zhou Ren-Long  , Chen Xiao-Shuang  , Zeng Yong  , Zhang Jian-Biao  , Chen Hong-Bo  , Wang Shao-Wei  , Lu Wei  , Li Hong-Jian  , Xia Hui  , Wang Ling-Ling  ,   (1)湖南大学物理与微电子科学学院，长沙  410082; (2)湖南科技大学物理学院，湘潭  411201；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; (3)中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083; (4)中南大学物理科学与技术学院，长沙  410082
Published: December 2020

In this paper，we show that the enhanced transmission and the surface plasmon distribution through a thin gold film with a periodic array of subwavelength holes with the finite-difference time-domain (FDTD) method. The transmission spectra exhibit two different surface plasmon resonance features: the localized waveguide resonance and the well-recognized photonic crystal resonance. For the localized waveguide resonance，the tangential electric field component Ey is seen to be concentrated entirely in the rectangular air hole region. And for the photonic crystal resonance，the tangential electric field components Ey is nonzero only on the two sides of the rectangular hole region. With the aid of the SP，light can form a strong focal spot at the bottom of the metal.
Study of characteristics of acoustic-optic Q-switched double-clad fiber laser with different cavity configurations
Authors: Zhao Hong-Ming  , Lou Qi-Hong  , Zhou Jun  , Dong Jing-Xing  , Wei Yun-Rong  , Wang Zhi-Jiang  ,   (1)上海光学精密机械研究所，上海  201800; (2)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  100039
Published: December 2020

The characteristics of acoustic-optic double-clad fiber laser end-pumped by diode laser are reported for different pumping constructions. The comparison and discussions of average power, pulse width and stability of Q-switched pulses under the forward pump and back ward pump conditions are presented. In experiment, the output of Q-switched pulses with 60% slope efficiency of average power, 52ns pulse width and 03mJ single pulse were obtained at the repetition rate of 10kHz. Finally, the rate equations with different pump configurations are deduced to analyze the Q-switched pulse, and the theoretical results agree with well experimental results.
Theoretical analysis and characterization of injection current distribution and influences on optical near-field modes in gain-guided vertical-cavity surface-emitting lasers
Authors: Cai Lu-Gang  , Wu Jian  ,   北京航空航天大学理学院物理系，北京  100083
Published: December 2020

Three-dimensional analytical model for analyzing injection current vectors in gain-guided vertical-cavity surface-emitting lasers was developed based on the theory of steady-state electric field. Our calculation covered the spatial distribution of injected current density and its correlation with parameters of the top electric contact ring. The results showed that there exists a region between the two contacts where the radial carrier distribution has a maximum at the center. As the optical power is proportional to the injected current, to obtain fundamental mode or uniform light intensity output with low threshold, the active region should be set to overlap with the boundary layer where the uniform carrier distribution just occurs. The carrier distributions for top-and bottom-emitting configurations with various ring parameters as well as the influences on the near-field modes were discussed.
Effect of spontaneously generated coherence on absorption and dispersion in probe laser
Authors: Yan Xiang-An  , Song Jian-Ping  , Yin Bao-Yin  , Jiang Wen-Juan  , Zhen Huai-Bin  , Zhang Yan-Peng  ,   (1)西安交通大学电子物理与器件教育部重点实验室，西安  710049; (2)西安交通大学电子物理与器件教育部重点实验室，西安  710049；陕西师范大学物理学与信息技术学院，西安  710062; (3)西安交通大学电子物理与器件教育部重点实验室，西安  710049；西安工程大学理学院，西安  710048
Published: December 2020

A theoretical investigation is carried into the effect of spontaneously generated coherence on absorption and dispersion in probe laser of Y-type atom system. It is found that the electromagnetically induce transparency window in the system narrows gradually as the spontaneously generated coherence intensifies. Moreover, the anomalous dispersion appears and the absorption changes from negative value to positive valve at resonance. At the same time, the absorption is zero or negative near resonance when the relative strength of the coupling field and pump field are different, and the atomic medium shows positive absorption when the two fields are exattly or nearly equal and close.
The influence of pump power on pulse shape control by Brillouin amplification of two Brillouin amplifiers
Authors: Yang Jun  , Ruan Shuang-Chen  , Zhang Min  ,   深圳大学电子科学与技术学院,深圳  518060
Published: December 2020

A reshaping Brillouin amplifier is combined with the main Brillouin amplifier in the conventional stimulated Brillouin scattering (SBS) phase conjugation mirror (PCM), which can control the SBS pulse shape, the main amplifier controls the pulse shape roughly, while the reshaping amplifier can control it finely. Effect of pump on pulse shape is studied, and the dependence of the pulse shape on the distance between the two amplifiers is achieved at various pump intensities. Results show that the pump intensity determines the amplifying efficiency of the seed, and that it is an important parameter to control the pulse shape.
Mode and band analysis of finite dielectric photonic crystals
Authors: Yin Hai-Rong  , Gong Yu-Bin  , Wei Yan-Yu  , Yue Ling-Na  , Lu Zhi-Gang  , Gong Hua-Rong  , Huang Min-Zhi  , Wang Wen-Xiang  ,   电子科技大学物理电子学院,成都  610054
Published: December 2020

In this article, dielectric photonic crystals (PhC) with finite dimensions and exposed in air is analyzed for its potential value in traveling wave tubes (TWTs). The modes existing in finite dielectric PhC are EH and HE, and also E if the finite PhC is two-dimensiond. The E1 mode is the E polarization in infinite dielectric PhC. Calculation shows that only the existence of gaps of pass-bands is necessary for PhC in TWTs, while the complete photonic crystal band gaps are superfluous.
Electron field emission of nanocrystalline Si prepared by laser crystallization
Authors: Zhou Jiang  , Wei De-Yuan  , Xu Jun  , Li Wei  , Song Feng-Qi  , Wan Jian-Guo  , Xu Ling  , Ma Zhong-Yuan  ,   南京大学物理系,固体微结构物理国家重点实验室,南京  210093
Published: December 2020

The electron field emission characteristics of nanocrystalline Si thin films prepared by KrF excimer laser crystallization of ultrathin amorphous Si films and subsequent thermal annealing is reported. Stable and reproducible field emissionbehavior can be observed for the crystallized Si films. The turn-on electric field is reduced from 17V/μm for the as-deposited sample to 85V/μm for the crystallized one, and the emission current density can reach as high as 01mA/cm2 The improvement in field emission characteristics is attributed to both the change of film surface and the formation of high-density nanocrystalline Si, which induces the enhancement of internal local electric field.
The lattice dynamics of BaVS3 compound
Authors: Miao Ren-De  , Tian Miao  , Huang Gui-Qin  ,   (1)南京师范大学物理科学与技术学院，南京  210097; (2)南京师范大学物理科学与技术学院，南京  210097；解放军理工大学理学院，南京  211101
Published: December 2020

The lattice dynamics of hexagonal perovskite BaVS3 compound is studied by first-principles calculations based on the ab initio pseudopotential and plane wave basis. Phonon spectra throughout the Brillouin zone are obtained using the density-functional perturbation method within the framework of linear response theory. The calculated frequencies of the Raman active modes are compared with the experimental measurements. For E22g and A1g modes, our calculated values are in good agreement with the experiment. But for E32g mode, the value of the calculated frequency differs significantly from the experiment. After further calculation using the frozen-in phonon method, we suggest that this difference is caused by the large anharmonicity of E32g mode. The most prominent feature of the phonon spectrum is that there appears the imaginary frequency for E12u mode, which involves the planar vibration of the vanadium atoms. The appearance of imaginary frequency for E12u mode indicates the planar instability of hexagonal BaVS3 crystal structure. We believe that this soft mode is responsible for the observed hexagonal-orthorhombic phase transition.