bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of continuous wave pumping waveguide to generate terahertz laser
Authors: Zhang Hui-Yun  , Liu Meng  , Zhang Yu-Ping  , Shen Duan-Long  , Wu Zhi-Xin  , Yin Yi-Heng  , Li De-Hua  ,   Qingdao Key Laboratory of Terahertz Technology, College of Science, Shandong University of Science and Technology, Qingdao 266510, China
Published: December 2020

This paper, based on the rate equation theory, astablishes a model for optical pump waveguides to generate terahertz laser. By analyzing and solving the rate equation, the expressions of pump absorption coefficient, terahertz small-signal gain coefficient and terahertz output power are obtained. The calculation shows that the THz power increases first and reduces gradually with the increase of pressure of the working material, and it will increase with the increase of pumping power and the decrease of the output mirror reflectivity. The best working pressure increases with the rise of the pumping power. The number of particles in the excited state and the THz flux increase in the waveguide radial direction from the center, while the small-signal gain coefficient shows the opposite trend. Pump saturation, weak pump absorption and excited state terahertz absorption are the primary cause limiting the increase of the laser conversion efficiency. Results based on this model are in good agreement with the data from the relevant literature.
Time-dependent density functional theory studies of dynamics of hydroxy by proton impact
Authors: Wang Zhi-Ping  , Zhu Yun  , Wu Ya-Min  , Zhang Xiu-Mei  ,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

Using the time-dependent density functional theory and non-adiabatic coupling in molecular dynamics, the reaction dynamics of collisions between energetic proton and hydroxy is studied. The variations in kinetic energy of proton and hydroxy and the motions of electron of hydroxyl and ion before and after collisions are investigated. It is found that when a proton is incident in the direction perpendicular to the molecular axis, it that has lose kinetic energy rebounds, and captures electrons from hydroxy, while the hydroxy that has lost part of electrons gains kinetic energy, and thus translates toward the calculating boundary in the manner of contracting vibration. The larger the kinetic energy of incident proton, the more the number of electrons captured from hydroxy is. Therefore the bond length of hydroxy lengthens, oscillation strengthens, and vibrational frequency decreases. In addition, it is found that the incident direction of proton has a great influence on the dynamic behavior of excitation in a collision process. Considering the case where the proton is incident from different directions, the results show that the larger the kinetic energy of incident proton, the more the lost energy is, and the lost energy is linearly related to the initial kinetic energy of incident proton. For hydroxy, when the incident kinetic energy of proton is less than 25 eV, the kinetic energy gained by the proton is linearly related to the initial kinetic energy, but unrelated to incident direction, while when the initial kinetic energy of incident proton is larger than 25 eV, the increment in kinetic energy of hydroxyl is much larger in the case where the proton is incident along the axis of hydroxyl molecule than in the case where the proton is incident in the direction perpendicular to the axis of the hydroxyl molecule.
Improving the single atom probability by using the blue-detuned laser-assisted-collisions between the cold atoms trapped in the for-off-resonance trap
Authors: Diao Wen-Ting  , He Jun  , Liu Bei  , Wang Jie-Ying  , Wang Jun-Min  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices (Shanxi University), and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
Published: December 2020

Using the light-assisted-collisions (LAC) and the feedback controlling loop on a quadrupole magnetic field, we have realized high probability of single atoms in the far-off-resonance trap (FORT). We analyzed the principle of LAC irradiated by a red-detuning laser or by a blue-detuning laser. And we also experimentally proved that using the red-detuned laser (the blue-detuned laser) we can realize 50% (80%) of single atom probability in the FORT. Using the feedback controlling loop, we realized 95% of single atom probability in the FORT, which opens a way for a two-dimensional FORT array. When the number of atom was zero, we decreased the gradient of the quadrupole magnetic field to quickly load atoms, and when we had more than one atom in the FORT, we switched on the blue-detuned laser to irradiate the atoms to play LAC. We measured the second-order coherence degree of the fluorescence photons emitted by the atom trapped in the FORT by using HBT scheme and found it was g(2)(τ=0)=0.08.
Dispersion characteristics of dielectric loaded metal grating
Authors: Cao Miao-Miao  , Liu Wen-Xin  , Wang Yong  , Li Ke  ,   Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

A novel type of slow-wave structure for Smith-Purcell device called dielectric loaded metal grating, is proposed in this article. The “hot” dispersion align of the structure is obtained by using the eigen-function method and single-mode approximation. The first-and second-order growth rate of beam-wave interaction are obtained at the synchronization point. The effects of grating groove width and depth on dispersion characteristic are analyzed, and the influences of electron beam parameters and distance between electron beam and grating surface on growth rate characteristic are also studied. The results show that dielectric-loaded metal grating can effectively weaken the structure dispersion, and that with the increases of relative dielectric permittivity, groove width and depth, the dispersion curve becomes flatter and moves toward low frequency. When the electron beam voltage or current changes, the first-order growth rate curve can only roughly describe the change trend, while the second-order growth rate can accurately show the change values. The simulation of the structure is performed by using two-dimensional particle-in-cell code MAGIC, and the simulation results accord well with the theoretical results.
Nonlocal surface dark solitons and their stability analysis
Authors: Gao Xing-Hui  , Tang Dong  , Zhang Cheng-Yun  , Zheng Hui  , Lu Da-Quan  , Hu Wei  ,   College of Mechanical and Electric Engineering, Guangzhou University, Guangzhou 510006, China;,   Guangdong Key Laboratory of Micro-Nano Photonic Materials and Devices, South China Normal University, Guangzhou 510631, China
Published: December 2020

Due to their future applications in optical communication, nonlocal dark solitons in bulk medium and surface bright solitons have received much attention recently. However, nonlocal surface dark solitons have not been investigated till now. In this paper, 1+1 dimensional nonlocal fundamental and second-order surface dark solitons have been found numerically at the interface between thermal nonlinear medium and linear medium. The relation between the wave shape of nonlocal surface dark soliton and propagation constant and nonlocality degree is investigated. Moreover, the stability of them is analyzed theoretically. The numerical simulation results show that 1+1 dimensional nonlocal fundamental surface dark Solitons are always stable in the domain of their existence, while second-order surface dark solitons are oscillatorily unstable and the width of unstable domain depends more greatly on propagation constant than nonlocality degree of nonlocal nonlinear medium. The figure showing the propagation, with the initial input of noise added, confirms the correctness of stability analysis results.
Simultaneous measurement of temperature and bending-curvature using a single local micro-structured longperiod fiber grating
Authors: Cao Ye  , Pei Yong-Wei  , Tong Zheng-Rong  ,   Key Laboratory of Film Electronics and Communication Devices, School of Computer and Communication Engineering, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

A local micro-structured long-period fiber grating (LMSLPFG) is proposed and investigated experimentally. The LMSLPFG is fabricated by using hydrofluoric acid (HF) to partially etch a standard long-period fiber grating (LPFG), thereby forming a local defect in the cladding. The theoretical analysis and experimental results show that partially etching will change the effective refractive index modulation in the cladding mode, which equivalently introduces a phase shift into the part of defect and manifests, in the spectrogram, as openning a transmission window between the stopbands, forming two transmission stopbands and one transmission passband. On this basis we study the temperatures and bending characteristics of the two stopbands and one passband. The results show that the temperature sensitivities of the two stopbands and one passband are all approximately 0.05 nm/℃; the bending sensitivity of the passband (2.61 nm/m-1) is less than those of two stopbands (4.71 nm/m-1). Thus by using the sensitive matrix, we can simultaneously measure the curvature and temperature, with only one grating used.
Phase transition in liquid due to zero-net-mass-flux jet and its numerical simulation using lattice Boltzmann method
Authors: Ren Sheng  , Zhang Jia-Zhong  , Zhang Ya-Miao  , Wei Ding  ,   School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

The phase transition in liquid due to the excitation of zero-net-mass-flux jet is simulated using the lattice Boltzmann method. First, the scheme for inlet/outlet boundary of the specific zero-net-mass-flux jet is derived. Then, with the model proposed by Shan and Doolen for single component and multiphase flow, the process of a single bubble formation in a liquid-filled square cavity is simulated, with the excitation of zero-net-mass-flux jet taken into consideration. Further, the investigation of the effects of three significant parameters, ε/T, T and vout/vin, on phase transition in the square cavity is carried out. The results show that the number of vapor nodes increases rapidly in the early stage of phase transition, and then achieves a constant after a long term fluctuation. In some sense, the previously mentioned parameters except T reflect the rapid change of jet velocity when the stages of inflow and outflow are transformed into each other. Thus the evolution of phase transition in liquid can be affected by the parameters ε/T and vout/vin mainly, but by parameter T negligibly. When ε/T is small, the single bubble resulting from phase transition is separated from the boundary. On the contrary, when ε/T is large, the corresponding single bubble attaches to the bottom boundary, and the process of phase transition is accelerated. Moreover, with vout/vin increases, the domain filled by vapor phase in the square cavity, decreases slightly. In summary, this study reveals the details of phase transition process in liquid subjected to the zero-net-mass-flux jet.
Nonlinear dynamic analysis of nano-resonator driven by optical gradient force
Authors: Liu Yan  , Zhang Wen-Ming  , Zhong Zuo-Yang  , Peng Zhi-Ke  , Meng Guang  ,   State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China
Published: December 2020

Optical gradient force, as a novel type of actuation force for nano-resonators, has recently attracted a lot of attention. In this paper, the inherent nonlinear characteristics of the optical gradient force are analyzed. A nonlinear dynamic model of the ring and spoke resonant system driven by optical gradient force is proposed. The influences of optical input power and geometric parameters on the nonlinear dynamic responses of the system are investigated. The results show that the optical gradient force can cause stiffness to soften. The amplitude increases and the resonance frequency shifts as the input optical power increases. Moreover, the amplitude and resonance frequency of the nano-resonator decrease as the initial gap of the rings increases. Therefore, the resonance frequency can be adjusted by changing the optical input power. This work can be useful for the further design and performance prediction of nano-resonators driven by the optical gradient force.
Enhanced performance of organic light-emitting diodes by using PTB7 as anode modification layer
Authors: Huang Di  , Xu Zheng  , Zhao Su-Ling  ,   Key Laboratory of Luminescence and Optical Information of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China;,   Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3, 4-b]thiophenediyl]] (PTB7) is used as an anode modification layer to fabricate organic light-emitting diode (OLED) with the configuration of ITO/PTB7 (with different concentrations)/NPB(40 nm)/Alq3(60 nm)/LiF(1 nm)/Al, and the effect of PTB7 concentration on the performance of device is investigated. The best concentration of PTB7 is 0.25 mg/mL, while the best device turn-on voltage is 4.3 V. For the best device, its maximum luminance is 45800 cd/m2 at a driving voltage of 14.6 V, its maximum current efficiency is 9.1 cd/A, its turn-on voltage is reduced by 1.9 V and the maximum luminance is increased by 78.5% compared with that of the device without PTB7. The improvement of its performance is ascribed to the fact that the hole injection and transport ability are improved by the layer of PTB7.
Research on equivalent circuit of multi-gap output cavity for sheet beam extended-interaction klystron
Authors: Chen Shu-Yuan  , Ruan Cun-Jun  , Wang Yong  ,   Key Laboratory of High Power Micriwave Sources and Technology, Institute of Electronics Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Sheet beam extended interaction klystron, which has both the advantages of sheet beam klystron and extended-interaction klystron (EIK), has become a key technique for developing high power microwave and millimeter-wave vacuum electron devices. An equivalent circuit of the five-gap output cavity for sheet beam EIK is proposed in this paper. The mode, resonant frequency, and the cavity impedance can be calculated by using the method of equivalent circuit efficiently. The bandwidth could be estimated by the curve of cavity impedance versus frequency. The influences of coupling coefficient (k) and external Q (Qe) on mode frequency interval and bandwidth are discussed. In order to test and verify the method of equivalent circuit, the 3D-PIC simulation of output cavity is conducted. The bandwidths under different values of external Q are calculated in two ways. The results accord well with each other. It is confirmed that the method of equivalent circuit for sheet beam EIK is accurate and credible. This is useful for the design of the whole tube.
Focusing bistatic forward-looking synthetic aperture radar based on modified hyperbolic approximating
Authors: Ma Chao  , Gu Hong  , Su Wei-Min  , Li Chuan-Zhong  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The conventional monostatic synthetic aperture radar (SAR) shows a limitation if a forward-looking geometry is used. However, bistatic forward-looking SAR gives a good solution, providing a high resolution image in the flight path direction. Due to the fact that the range history of bistatic SAR is a double square root, classical imaging algorithm cannot be applied to the bistatic SAR directly. Also it is difficult to deduce imaging algorithm from double square root directly. The hyperbolic approximating method can transform double square root into single one, when being used in forward-looking geometry, and the high order term error is obvious and cannot be ignored. In this paper, we propose a modified hyperbolic approximating method, which makes a cubic term approximation and improves the precision, then we apply the new method to bistatic forward-looking SAR and deduce the bistatic point spectrum. Based on the spectrum, a modified range Doppler algorithm is proposed for focusing bistatic forward-looking SAR. Finally, numerical simulation is used to compare the original hyperbolic approximating method with the modified one for veridating the proposed algorithm and processing approach.
Trapping of multiple particles by space speckle field and infrared microscopy
Authors: Zhang Zhi-Gang  , Liu Feng-Rui  , Zhang Qing-Chuan  , Cheng Teng  , Wu Xiao-Ping  ,   CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
Published: December 2020

Optical tweezer technology is widely used in trapping and manipulating micro-and nano-sized particles, mainly including the trapping of transparent particles in water and the trapping of absorbing particles in air. In this paper, a frosted glass diffuser is irradiated by laser beam, and a subjective speckle field is generated in the image plane of a lens after the laser has transmitted the lens. The speckle field is spatially distributed, and contains multiple bright spots and dark spots. A large number of dark spots surrounded by bright spots are spatial energy traps, and can be used to trap a large number of absorbing particles. The sizes and densities of trapped particles are about 2–8 μm and 1–2 g/cm3. In addition, an infrared microscope is used to record the infrared images of the particles trapped by the speckle field, and the infrared images show that the temperature of trapped particles rises by absorbing the light energy, which verifies that the mechanism of trapping absorbing particles by speckle field is photophoretic force.
Study of boron-doped zinc oxide film serving as front contact with high haze used in amorphous silicon thin film solar cells
Authors: Wang Li  , Zhang Xiao-Dan  , Yang Xu  , Wei Chang-Chun  , Zhang De-Kun  , Wang Guang-Cai  , Sun Jian  , Zhao Ying  ,   Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300071, China
Published: December 2020

Boron-doped zinc oxide (BZO) deposited by metal organic chemical vapor deposition (MOCVD) method is used as front contact in amorphous silicon thin film solar cells. Asahi-U type SnO2:F is used as the reference front contact for comparison. When the a-Si:H intrinsic layer thickness is changing changed, the performance of a-Si:H solar cells shows different evolution trends. These different results can be understood from the shadowing effect during the growth of intrinsic silicon material, which is caused by the as-grown pyramid texture in the surface of BZO substrate. In order to reduce this negative effect on the performance of solar cells, the deposition temperature of the a-Si:H intrinsic layer is optimized, to thereby improving improve the open circuit voltage and fill factor. The conversion efficiency of a-Si:H solar cells can reach up to 7.34%, with the thickness of absorber layer being only around 200 nm. and only Al back reflector is being used.
Numerical simulations of the lightning attachment points on airplane based on the fractal theory
Authors: Sun Ke-Yan  , Zhao Xiao-Ying  , Zhang Gong-Lei  , Zang Hong-Ming  ,   School of Electronic and Information Engineering Beihang University, Beijing 100191, China
Published: December 2020

Determination of the aircraft lightning attachment points which can provide the basis for the design of aircraft lightning protection, is a prerequisite for the division of lightning strike zones and the lightning test of aircraft components. In this paper, a novel numerical simulation method based on fractal theory is presented to simulate lightning attachment points on airplane. Firstly, the discharge gap distance, lightning starting coordinates, aircraft attitudes, discharge times and other parameters are determined according to the relevant provisions about aircraft lightning attachment point test in standard SAE-ARP5416. Then, according to the fractal theory, the dielectric breakdown model is used to simulate the fractal growth of the lightning leaders, which accords with physical mechanisms and geometric characteristics of nature lightning. Finally, considering the case where the aircraft itself triggers the bi-directional leader, we obtain the distribution of aircraft lightning attachment points. Because the probability distribution of lightning attachment points on aircraft F-4 obtained through the simulating is almost in line with those obtained through actual aircraft flight test and laboratory test, the proposed method is verified. The proposed method provides a potential way of simulating the lightning attachment points on aircraft. And this method can be used as the foundation of the aircraft lightning protection design and future related research work.
Ultraviolet surface plasmon polariton propagation for ZnO semiconductor-insulator-metal waveguides
Authors: Hu Meng-Zhu  , Zhou Si-Yang  , Han Qin  , Sun Hua  , Zhou Li-Ping  , Zeng Chun-Mei  , Wu Zhao-Feng  , Wu Xue-Mei  ,   Jiangsu Key Laboratory of Thin Films, School of Physical Science and Technology, SooChow University, Suzhou 215006, China;,   Institute of Modern Optical Technologies, Suzhou 215006, China
Published: December 2020

Ultraviolet surface plasmon polariton propagation for ZnO semiconductor-insulator-metal waveguide is investigated by means of the finite-element method. The field distribution, effective refractivity, propagation distance, and mode area of the hybrid mode supported by the waveguides were detailed analyzed, which are dependent on the dielectric constant and geometrical parameters. In order to achieve low propagation loss and subwavelength field confinement, several materials are calculated. Our investigation indicated that air and aluminum are better, which act as the insulator and metal respectively, and the effective mode area of such a waveguide can be as small as λ2/100. The results can help the development of nano-sized light sources which can enhance the sensitivity for bio-detection devices and diagnostic equipments.
Approximate analytic solution of solitary-like waves in a class of quantum plasma
Authors: Han Xiang-Lin  , Chen Xian-Feng  , Mo Jia-Qi  ,   Departmentt of Mathematics, Huzhou Teachers College, Huzhou 313000, China;,   Department of Mathematics, Shanghai Jiaotong University, Shanghai 200240, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241001, China
Published: December 2020

The quantum plasma system in a class of environment is discussed. A nonlinear dynamic disturbed equation is studied. Using the revised generalized functional variational iteration method, the solitary-like wave approximate analytic solution of corresponding system is obtained.
Analysis of measurement device independent quantum key distribution with an asymmetric channel transmittance efficiency
Authors: Dong Chen  , Zhao Shang-Hong  , Zhao Wei-Hu  , Shi Lei  , Zhao Gu-Hao  ,   School of Information and Navigation, Air Force Engineering University, Xi’an 710077, China;,   Department of information security, Xi’an Communication College, Xi’an 710006, China
Published: December 2020

Measurement-device-independent quantum key distribution is immune from all the detection attacks, thus when it is combined with the decoy state method, the final key is unconditional secure. In this paper, the performance of three-intensity decoy state measurement-device-independent quantum key distribution at an asymmetric channel transmittance efficiency is considered and compared with each other at the symmetric choice scenario. Simulation result shows that the key rate at the symmetric scenario can tolerate 62 dB channel loss, otherwise when the distance ratio changes, the tolerated channel loss will decrease to 37 dB and 19 dB. A method to choose the optimal intensity is proposed for asymmetric channel transmittance regardless of distance ratio, which can be easily adapted to practical experimental settings.
Curved surface effect and characteristic emission of silicon nanostructures
Authors: Huang Wei-Qi  , Huang Zhong-Mei  , Miao Xin-Jian  , Yin Jun  , Zhou Nian-Jie  , Liu Shi-Rong  , Qin Chao-Jian  ,   Institute of Nanophotonic Physics, College of Physics, Guizhou University, Guiyang 550025, China;,   State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003, China
Published: December 2020

Some bonds on the curved surface (CS) of silicon nanostructures can produce localized electron states in the band gap. Calculated results show that different curvature can form the characteristic electron states for some special bonding on nanosilicon surface, which are related to a series peaks in photoluminescience (PL), such as LN, LO1 and LO2 lines in PL spectra due to SiN, Si=O and SiOSi bonds on the curved surface, respectively. In the same way, SiYb bond on the curved surface of Si nanostructures can manipulate the emission wavelength into the window of optical communication by the CS effect, which is marked as LYb line near 1550 nm in the electroluminescience (EL).
Coherent emitting of multiple sub-beams for small target detection
Authors: Lian Tian-Hong  , Wang Shi-Yu  , Cai De-Fang  , Li Bing-Bin  , Guo Zhen  ,   School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071, China
Published: December 2020

A method for multiple sub-beams coherently emitting is put forward to improve the ability of laser to detect small targets in a long distance. The laser beam is split into many sub-beams with equal power parallelly emitted to the target in a certain arrangement. The sub-beams produce interference pattern on the target plane due to the fact that they are from the same laser source and have good coherence. Calculated results show that an interference peak is produced. Ideally, the maximum intensity would be N times as large as the intensity of the single beam emitted directly, where N is the number of the sub-beams. The detection is realized by using the interference peaks, and it will benefit especially to the detection of small targets. Beams divergence should be reduced to let a greater power to the target. In order to control the light intensity instability and the spot distortion, the jitters of the emitting mirrors must be controlled as well. Results show that a position accuracy of 0.1λ and an angle accuracy of 0.2θ are needed to have a stable and ideal interference peak, where λ is the wavelength and θ is the divergence angle of the beam.
Improvement of the filtering performance of a heterostructure photonic crystal ring resonator using PSO algorithm
Authors: Chen Ying  , Wang Wen-Yue  , Yu Na  ,   Department of Automation Equipment, College of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China;,   Hebei Province Key Laboratory of Test/Measurment Technology and Instrument, Qinhuangdao 066004, China;,   Institute of information Science and Engineering, Yanshan University, Qinhuangdao 066004, China
Published: December 2020

To improve the filtering performance of a heterostructure photonic crystal ring resonator filter, the filtering structural parameters were optimized globally by using particle swarm optimization (PSO) algorithm. By taking the square lattice photonic crystal ring resonator filter structure as the optimized object, according to the position-velocity updating formula of the PSO method, the radius of scattering rods, coupling rods, and internal rods at the photonic crystal defect were optimized globally. From the theoretical analysis and numerical simulation results, it can be seen that after the filter structural parameters were optimized, single narrowband filtering can be achieved. At the same time, its normalized transmission rate is increased from 53% to 97%, indicating the effectiveness of the optimization algorithm, which provides a basis for the application in photoelectric device.
Study of prism surface plasmon resonance effect based on dielectric-aided layer
Authors: Zhang Qian-Yun  , Zeng Jie  , Li Ji-Feng  , Zhou Ya-Bin  , Zhang Xian-Hui  , Cao Hai-Dong  ,   State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Published: December 2020

A prism surface plasmon resonance (SPR) incentive model based on the dielectric-aided layer structure is studied. The model consists of four structure layers: prism-dielectric-aided layer-gold-environmental media. According to the thin film optics and waveguide theory, the excited mechanism and modulation characteristic of SPR effect are explored based on resonance composite film composed of dielectric-aided layer and gold film. Numerical simulation is conducted on the relation of layer thickness, film dispersion characteristics and resonance energy transfer by the finite difference time domain method. Thereby, the wavelength modulation prism dielectric-aided layer SPR excitation system is also developed. Results show that with the same refractive index of liquid, the SPR resonance spectrum of dielectric-aided layer incentive model shifts to the longer wavelength region and the resonant halfwave width is wider than the spectrum of common Kretschmann incentive model based on prism-gold-environmental media. With increasing refractive index, the SPR resonance spectrum redshifts, and its sensitity is 75% higher than the common incentive model. The designed model can effectively improve the sensitivity of the prism surface plasmon resonance effect, and in the areas such as high sensitivity detection, new types of optical filter, the modulator and other fields the SPR technology may provide a theoretical and practical basis.
Study on the periodic error in ptychographic iterative engine imaging
Authors: He Xiao-Liang  , Liu Cheng  , Wang Ji-Cheng  , Wang Yue-Ke  , Gao Shu-Mei  , Zhu Jian-Qiang  ,   Department of Photoelectric Information Science and Engineering, Jiangnan University, Wuxi 214122, China;,   Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

Based on the analysis of the periodic error in the reconstructed image of the ptychographic iterative engine (PIE), the cause in mathematics for this kind of error is found out, and then a method is proposed to eliminate it. By replacing the 2D periodic scanning of fixed step interval in common PIE imaging with the 2D raster scanning of changing step interval, the periodical error in the reconstructed images can be dramatically reduced, and then the accuracy of the PIE imaging is remarkably improved. Both the theoretical investigation and numerical simulations are presented.
Study on band gap properties of two-dimensional 8-fold quasi-periodic phononic crystals
Authors: Chen A-Li  , Liang Tong-Li  , Wang Yue-Sheng  ,   Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

For the two-dimensional (2D) 8-fold solid-fluid quasi-periodic photonic nanocrystal (QPNC) (steel-water system), the transmission spectra of the systems with different sizes are obtained by experimentation. At the same time, combined with the supercell method, the finite element method (FEM) is used to calculate the dispersion curves and transmission spectrum of the system. The transmission spectra obtained by means of these two methods are in good agreement with each other, but the band gaps appearing in the transmission spectrum calculated using the FEM are clearer than those obtained via experimentation. The dispersion curves of the 2D 8-fold solid-fluid QPNC can be well studied by using the supercell which only contains its center puzzle.
Influence of H2 introduction on wide-spectrum Mg and Ga co-doped ZnO transparent conductive thin films
Authors: Tian Cong-Sheng  , Chen Xin-Liang  , Liu Jie-Ming  , Zhang De-Kun  , Wei Chang-Chun  , Zhao Ying  , Zhang Xiao-Dan  ,   Institute of Photo-Electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071, China; Tianjin Key laboratory of Photo-Electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071, China; Key laboratory of Opto-Electronic Information Science and Technology, Ministry of Education, Nankai University, Tianjin 300071, China
Published: December 2020

To meet the demands of high efficient silicon thin film solar cells, transparent conductive hydrogenated Mg and Ga co-doped ZnO (HMGZO) thin films were deposited via pulsed direct current (DC) magnetron sputtering on glass substrates at a substrate temperature of 553 K. The micro-structural, morphological, electrical, and optical properties of HMGZO thin films were investigated at various H2 flow rates. Experimental results show that all the HMGZO thin films are polycrystalline with a hexagonal wurtzite structure exhibiting a preferred (002) crystal plane orientation. Appropriate H2 flow rate increases grain size and also enhances the RMS roughness. The deposition rate of HMGZO films decreases with the increase of H2 flow rate due to the decrease of sputtering yield. Resistivity of HMGZO thin films decreases rapidly from 117 to 7.2×10-3 Ω·cm with increasing H2 flow rate from 0 to 4.0 sccm. With further increasing H2 flow rate (4.0–16.0 sccm), the resistivity increases slightly due to the reduced carrier concentration and excessive H atoms as impurity. Optical transmittance of all the HMGZO thin films is higher than 87.7% in the wavelength range from 320 to 1100 nm. Burstein-Moss band-filling determined by carrier concentrations and the incorporation of Mg atoms together contribute to the band-gap (Eg) widening phenomenon. The band gap Eg varies from ～ 3.49–3.70 eV and the maximum Eg of 3.70 eV is obtained at a H2 flow rate of 16.0 sccm.
Electronic properties and modulation of structurally bent BN nanoribbon
Authors: Feng Xiao-Qin  , Jia Jian-Ming  , Chen Gui-Bin  ,   School of Physics and Electronic Electrical Engineering, Huaiyin Normal University, Huaian 223300, China
Published: December 2020

Boron nitride nanoribbon (BNNR) is a one-dimensional single layer nano-material with finite width and infinite length. Bent BNNR will show some unique electronic properties because of the rotation of Pz orbit. The software DMOL3 of Material Studio, based on the first principles, can be used to calculate the energy band, and the band gap will change with the bending angle; in the armchair BN nanoribbons the change is more obvious. Band gaps of zigzag BN nanoribbons may change more than those in armchair BN nanoribbons do if the external electric field is also added on the bent BN nanoribbons. When the electric field is increased to a certain value, nanoribbons will transit from semiconductor to metal, and it is important that the corresponding critical electric field value depends on the bending angle. The modulation of electric field on the band gap is also related with the size of nanoribbons; the wider the nanoribbon, the easier the modulation, and the smaller the critical electric field.
Investigation of the saturation characteristic and lifetime of the novel AlGaInP lightemitting diodes
Authors: Ma Li  , Shen Guang-Di  , Chen Yi-Xin  , Jiang Wen-Jing  , Guo Wei-Ling  , Xu Chen  , Gao Zhi-Yuan  ,   Key Laboratory of Opto-electronics Technology of Ministry of Education, Beijing University of Technology, Beijing 100124, China
Published: December 2020

Absorption of substrates, small angle for total reflection, and heat generated by photon blocking of electrode, all can lead to saturation and performance degradation of AlGaInP light emitting diodes(LEDs). In this paper, a novel LED composed of compound current spreading layer, compound DBR reflectors, and current blocking layer, is proposed, the saturation characteristic and lifetime are also tested. Simulation results show that there is only tiny invalid photocurrent through the electrode in the novel LEDs. Experimental results indicate that the novel LEDs have higher extraction efficiency and better saturation characteristics. Saturation current of the novel LEDs is as high as 110 mA, and the light intensity is enhanced by treble at saturation current as compared to the conventional LEDs. The accelerated aging test shows that the lifetime of the novel LEDs is as long as 17.8×104 hours, which means the novel LEDs have high reliability and can be used with high current.
Effect of anisotropic surface tension on deep cellular crystal growth in directional solidification
Authors: Chen Ming-Wen  , Chen Yi-Chen  , Zhang Wen-Long  , Liu Xiu-Min  , Wang Zi-Dong  ,   School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China;,   School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

An asymptotic solution of the concentration and interface morphology for a deep cellular crystal in directional solidification is obtained by using the matched asymptotic expansion method and multiple variable expansion method, and the effect of anisotropic surface tension on deep cellular crystal growth is studied. Results show that the anisotropic surface tension has a significant effect on the concentration and interface shape of deep cellular crystal growth in directional solidification. As the anisotropic surface tension parameter increases, the concentration near the front part of deep cellular crystal decays and the interface shrinks; when as the concentration near the root increases and the curvature of the interface near the root increases or the curvature radius decreases; and the amplitude of the deep cellular crystal increases. The concentration and interface shape of the deep cellular crystal in directional solidification can be calculated with the results obtained in this paper.
The adhesion of two cylindrical colloids to a tubular membrane
Authors: Niu Yu-Quan  , Zheng Bin  , Cui Chun-Hong  , Wei Wei  , Zhang Cai-Xia  , Meng Qing-Tian  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

The adhesion of two cylindrical colloids to a tubular membrane is investigated theoretically in terms of the full treatment of Helfrich model. By analyzing the free energy of the system, it is found that this adhesion can produce both shallow wrapping with relatively small wrapping angle and deep wrapping with big wrapping angle. A second-order adhesion transition from the desorbed to weakly adhered state is found, and a first-order phase transition where the cylindrical colloids undergo an abrupt transition from weakly adhered to strongly adhered state can be obtained as well. Different relative positions between rigid cylinders and membrane tube will affect the phase transition and structure of the system.
Influences of drivers attributions on signalized intersection traffic
Authors: Mei Chao-Qun  ,   Institute of Statistics, Capital University of Economic Trade, Beijing 100070, China
Published: December 2020

A cellular automaton model is proposed to study the traffic at signalized intersection. The driving behaviors induced by drivers attribution (gender, driving experience, character, etc.) are numerically analyzed. Simulation results show that the rusty driving skills or tension driving, impatient driving and so on can lead to the transition from free flow to congestion more easily, and these behaviors are the important cause for low travel efficiency at the intersection; the signal cycle is the main factor influencing traffic flux and travel time fairness.
Effective field theory approach to the weakly interacting bose gas
Authors: Xu Yan  , Fan Wei  , Ji Yan-Jun  , Song Ren-Gang  , Chen Bing  , Zhao Zhen-Hua  , Chen Da  ,   College of Science, Shandong University of Science and Technology, Qingdao 266590, China
Published: December 2020

In this paper we study the theory of nonrelativistic weakly interacting Bose gas from the point of view of effective field theory. Firstly, the nonrenormalizability of the theory is briefly discussed. Then, starting from the effective Lagrangian, the lowest order contributions of Feynman diagrams are calculated for the parameters in the effective Lagrangian. These illustrate the running coupling constant phenomenon. After that, the differential align of the parameters in the effective Lagrangian is obtained. We show that the intrinsic energy scale of this effective theory can be removed, while it is not possible to do so for relativistic Bose gas. Our results can help to study the critical behavior of weakly interacting Bose gas.
Compound attractors between different chaotic systems
Authors: Ai Xing-Xing  , Sun Ke-Hui  , He Shao-Bo  ,   School of Physics and Electronics, Central South University, Changsha 410083, China;,   School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
Published: December 2020

To obtain compound attractors between different chaotic systems, based on theoretical analysis, numerical simulation, and circuit simulation methods, compound attractors between different 2-scroll systems, between different multi-scroll chaotic systems, between 2-scroll system and 2-wing system and between multi-scroll system and multi-wing system, are designed via switching control. Dynamical characteristics of the system are analyzed by observing the attractor phase diagram, the largest Lyapunov exponent and the Poincaré section. A circuit for a compound multiple scroll-multiple wing chaotic attractor is designed and simulated. Numerical simulation and circuit simulation are consistent with each other. It shows that the method of obtaining compound attractors between different chaotic systems via switching control is correct.
Analysis and prediction of complex dynamical characteristics of short-term traffic flow
Authors: Zhang Hong-Bin  , Sun Xiao-Duan  , He Yu-Long  ,   Beijing Key Laboratory of Traffic Engineering, Beijing University of Technology, Beijing 100124, China;,   School of Automobile Engineering, Dezhou University, Dezhou 253023, China
Published: December 2020

In order to reveal the internal dynamic property of short-term traffic flow, the nonlinear analysis method is used to identify the chaotic property of traffic flow which is the basis for the prediction of the traffic flow time series. Traffic flow time series is reconstructed in phase-space based on chaos theory. The embedding dimension and delay time are first calculated via the C-C method. The correlative dimension of attractor is then calculated with the Grassberger-Procaccia method. The largest Lyapunov exponent of traffic flow set is calculated on the basis of the improved small data set method to verify the presence of the chaos in traffic flow time series. A novel multi-step adaptive prediction method is proposed to solve the problem of adjusting the filter parameters of the chaos local adaptive prediction method during traffic flow multi-step prediction. The traffic flow time series are found to have chaotic properties in different statistical scales of 2, 4, and 5 min and show that the improved small data set method can accurately evaluate the chaotic property for traffic flow time series, and that the multi-step adaptive prediction method is capable of effectively predicting its fluctuation, which provides a useful reference for traffic guidance and control.
Theoretical and experimental study on self-accelerating Bessel-like Hermite-Gaussian beams
Authors: Zhao Juan-Ying  , Deng Dong-Mei  , Zhang Ze  , Liu Jing-Jiao  , Jiang Dong-Sheng  ,   School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China;,   Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou 510631, China;,   Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Phase modulation is an important method of designing accelerating optical beams. In this paper, we present new self-accelerating non-diffracting Bessel-like Hermite-Gaussian beams based on our previous research on Bessel-like beams. The evolutions of the beams along different trajectories are studied numerically and experimentally. These beams are designed by modulating the phase of the initial Hermite-Gaussian beams. With the split-step beam propagation method, we show numerically that (0,1), (1,0), (1,1) and (1,2) modes of the Bessel-like Hermite-Gaussian beams can propagate along different predesigned trajectories. With the computer-generated hologram and spatial light modulator, we observe the propagating behaviors of the Bessel-like Hermite-Gaussian beams along different trajectories, including parabolic, hyperbolic, hyperbolic secant and 3D trajectories. Experimental results show good agreement with the theoretical prediction. It is also demonstrated that the peculiar profile of Bessel-like Hermite-Gaussian beams exhibits nondiffracting and self-healing properties propagating along the tunable trajectories. These beams generalize the concept of Bessel-like beams, suggesting that more exotic optical beams can be obtained.
Hundred-watt-level supercontinuum generation in seven-core photonic crystal fiber
Authors: Chen Hong-Wei  , Wei Hui-Feng  , Liu Tong  , Zhou Xuan-Feng  , Li Jiang  , Tong Wei-Jun  , Chen Zi-Lun  , Chen Sheng-Ping  , Hou Jing  , Lu Qi-Sheng  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China;,   State Key Laboratory of Optical Fiber and Cable Manufacture Technology, Yangtze Optical Fiber and Cable Company Ltd. R&D Center, Wuhan 430073, China
Published: December 2020

A 104.2 W supercontinuum spanning from 750 nm to beyond 1700 nm is generated by pumping a piece of home-made seven-core photonic crystal fiber with a 141.6 W picosecond fiber laser. The evolution of the output spectrum is investigated in detail with the increase of the picosecond laser power. The feasibilities of broadening the spectral range and scaling the output power for the supercontinuum source based on the seven-core photonic crystal fiber are analyzed and discussed. The research results will make a contribution to the further development of high-power supercontinuum source.
Tissue lesion induced by a spherical cavity transducer
Authors: Geng Hao  , Fan Ting-Bo  , Zhang Zhe  , Tu Juan  , Guo Xia-Sheng  , Li Fa-Qi  , Zhang Dong  ,   Key Laboratory of Modern Acoustics (Nanjing University), Ministry of Education, Institute of Acoustics, Nanjing 210093, China;,   Institute for Medical Equipment Testing of Jiangsu Province, Nanjing 210012, China;,   Chongqing Medical University, Chongqing 400016, China;,   State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

Spherical cavity transducer can generate high acoustic pressure in a narrow focal region at a sub-wavelength level, which suggests a great potential application in high intensity focused ultrasound (HIFU) treatment. In this paper, tissue lesion induced by a spherical cavity transducer is investigated based on the nonlinear acoustics theory and bio-heat transfer theory. A 430 kHz spherical cavity transducer with a diameter of 240 mm is used to generate tissue lesion for liver tissues. The result shows that the tissue lesion with a size less than a wavelength can be formed under the 2 s HIFU exposure at a acoustic pressure of 53 kPa. The numerical simulations coincide well with the experimental measurements, and the optimization of the design of the spherical cavity transducer is also discussed. This work demonstrates that the spherical cavity transducer can be used in the accurate HIFU tumor treatment.