bluuebunny/crossref_metadata_2025 huggingface dataset:
External electric field effect on exciton binding energy in InGaAsP/InP quantum wells
Authors: Wang Wen-Juan  , Wang Hai-Long  , Gong Qian  , Song Zhi-Tang  , Wang Hui  , Feng Song-Lin  ,   Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165, China;,   State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China;,   Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201203, China
Published: December 2020

Exciton binding energies in InGaAsP/InP quantum well with different contents of In are calculated through variational method in the effective mass approximation. The variation of exciton binding energy as a function of well width, In content, and applied external electric field is studied. It is shown that the exciton binding energy is a non-monotonic function of well width. It increases first until reaching a maximum, and then decreases as the well width increases farther. In addition, with the increase of In content, the well width should increase to reach the maximum value of exciton binding energy. It is also found that the external electric field has little effect on binding energy, but when the electric field is large enough, it will destroy the excitonic effect. These results may provide some theoretical basis for the design and control of InGaAsP/InP optical devices.
Design and study on the dual-band radome with FSS operation at Ku-/Ka-band
Authors: Wang Xiu-Zhi  , Gao Jin-Song  , Xu Nian-Xi  ,   Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   Universty of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In order to meet the multi-band and integration requirements of the communication apparatus, the coupling and resonance mechanism can be exploited to design a frequency selective surface (FSS), with two pass-bands at Ku-band and Ka-band, which is composed of three metallic layers and fabricated on a flat substrate equivalent to a solid wall radome or an A-sandwiched radome. According to the physical structure of the FSS, an equivalent circuit model is established to analyze the filtering mechanism, and the transmission characteristics of the radomes with FSS are obtained by using a full-wave analysis software. The first pass-band at Ku-band with miniaturization property can be achieved by coupling the electric and magnetic field of the three surfaces, while the second pass-band at Ka-band can be achieved by the resonance of the square loop slots embedded in the capacitive surfaces. The transmissions of the solid wall radome and A-sandwiched radome with FSS are 89% and 94.7% at Ku-band, and 88.2% and 93.7% at Ka-band, respectively. When the incident angle is varied from normal to 60°, the frequency response characteristics of the two pass-bands are stable. Finally, the experimental results of the prototype with a solid substrate measured in free-space environment are in good agreement with the simulated values. The proposed radome structure with FSS, which is based on the coupling and resonance mechanism, can achieve two stable pass-bands at Ku-/Ka-band. This may provide some theoretical and experimental assistance for the study of the multi-band and wide band spacing FSS.
High-temperature piezoelectirc thin films of 0.20BiInO3-0.80PbTiO3 deposited by pulsed laser deposition（Retracted Article)
Authors: Wang Wei  , Tang Jia-Wei  , Wang Le-Tian  , Chen Xiao-Bing  ,   College of Physical Science and Technonolgy, Yangzhou University, Yangzhou 225002, China
Published: December 2020

High-temperature piezoelectric thin films of 0.20BiInO3-0.80PbTiO3 (20BI-PT) were prepared via pulsed laser deposition and investigated by comparison with 0.15BiInO3-0.85PbTiO3(15BI-PT). XRD patterns show that (100) peak of 20BI-PT has been split, indicating a higher tetragnality than in 15BI-PT. FESEM images reveal some triangular grains corresponding to [111]-oriented grains in 20BI-PT. The remanent polarization (Pr) and coercive field (Ec) of 20BI-PT are ～ 28 C/cm2 and ～120 kV/cm, respectively. It is shown that the transverse piezoelectric coefficient e31, f keeps almost the same in 20BI-PT and 15BI-PT. The temperature dependence of dielectric permittivity in 20BI-PT reveals a higher Curie temperature (590 ℃) than that in 15BI-PT and no apparent frequency dependence is detected. Rayleigh analyses are performed to identify the extrinsic contributions to dielectric nonlinearity for different x. It is seen that x=0.15 exhibits greater extrinsic contributions to dielectric nonlinearity than the other compositions.
Raman spectra studies on (Ba,Sr)TiO3 ceramics under dc electric fields
Authors: Zhang Qi-Wei  , Zhai Ji-Wei  , Yue Zhen-Xing  ,   School of Rare Earth, Inner Mongolia University of Science and Technology, Baotou 014010, China;,   Functional Materials Research Laboratory, Tongji University, Shanghai 200092, China;,   State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084, China
Published: December 2020

BaxSr1-xTiO3 (0.40≤x≤0.70) ceramics have been prepared by the conventional solid-state reaction method. The changes of vibration modes in the pure BaxSr1-xTiO3 system have been investigated for an in-situ electric field by Raman spectra, and the transition from the cubic phase to tetragonal phases were obviously observed near the Curie temperature (Tc). Detailed results indicate that the A1(TO3) and E(TO4) modes correspond to the vibrations of O-Ti-O bond along a-axis in the ab plane, which are strongly related to the lattice structure of ABO3. With increasing electric field, the intensity of A1(TO3)/E(TO4) ratio is increased, suggesting that more and more paraelectric states are transformed into ferroelectric states, thus leading to the deformation of lattice, which results in the decrease of dielectric constant and the increase of tunability. The electric-induced-structure phase transitions responsible for the nonlinear dielectric properties are also discussed.
Stady on a high efficient Denisov-type launcher for high-power gyrotron oscillators
Authors: Wang Hu  , Shen Wen-Yuan  , Geng Zhi-Hui  , Xu Shou-Xi  , Wang Bin  , Du Chao-Hai  , Liu Pu-Kun  ,   Key Laboratory of High Power Microwave Sources and Technologies, Chinese Academy of Sciences; Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China;,   College of Electronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China;,   School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
Published: December 2020

In this paper, a high-efficiency Denisov-type launcher, a hardcore of quasi-optical mode converters in high-power gyrotron oscillators, is investigated. Based on integral expression of Bessel functions and geometric optics, the propagation of EM wave in circular waveguides, the syntheses of amplitude and phase of nine modes are analyzed in detail. A generalized method for designing the launcher with a dimpled waveguide wall operating in different modes is demonstrated. This method shows how to select a set of appropriate coupled modes to synthesize the Gaussian-like distribution on the inner wall of the launcher. A program is developed and its accuracy is confirmed by a high-power gyrotron at 140 GHz, in TE28,8 mode theoretically. Numerical calculations show a good agreement with reported results.
Comparison between memory characteristics of MONOS memory with LaON/SiO2 or HfON/SiO2 as dual-tunnel layer
Authors: He Mei-Lin  , Xu Jing-Ping  , Chen Jian-Xiong  , Liu Lu  ,   School of optical and electronic information, Huazhong University of Science & Technology, Wuhan 430074, China
Published: December 2020

Memory characteristics of MONOS memory with LaON/SiO2 or HfON/SiO2 as dual-tunnel layer were comparatively investigated. Experimental results show that the MONOS memory with LaON/SiO2 as dual-tunnel layer exhibits large memory window, high program/erase (P/E) speed, good endurance and retention properties. The basic mechanism lies in the large dielectric constant of LaON which increases the injection efficiency of carriers during programming/erasing, the smaller Oxygen diffusion coefficient in LaON which leads to the reduction of interface traps and thus the leakage of stored charges through trap-assisted tunneling during retention. Moreover, strong La-N, Hf-N and O-N bonds are formed at/near the interface due to Nitrogen incorporation, which effectively decreases the damages of the P/E cycle stress to the interface, and thus achieves excellent endurance. In addition, impacts of annealing temperatures on characteristics of MONOS memory were investigated. It is demonstrated that the memory annealed at 800 ℃ has better memory properties than that annealed at 700 ℃, which is attributed to the fact that the 800 ℃ NO annealing can incorporate more N into LaON (HfON), and well release strains, thus reducing defects in these dielectrics.
Bifurcation and attractor of two-dimensional sinusoidal discrete map
Authors: Bi Chuang  , Zhang Qian  , Xiang Yong  , Wang Jing-Mei  ,   State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China;,   School of Energy Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
Published: December 2020

A new two-dimensional sinusoidal discrete map is achieved by nonlinearly coupling a sinusoidal map and with a cubic map. The fixed points and the corresponding eigenvalues are obtained based on this two-dimensional sinusoidal discrete map, and the stability of the system is analyzed to study the complex nonlinear dynamic behavior of the system and the evolutions of their attractors. The research results indicate that there are complex nonlinear physical phenomena in this two-dimensional sinusoidal discrete map, such as symmetry breaking bifurcation, Hopf bifurcation, period doubling bifurcation, periodic oscillation fast-slow effect, etc. Furthermore, bifurcation mode coexisting, fast-slow periodic oscillations and the evolutions of the attractors of the system are analyzed by using the bifurcation diagram, the Lyapunov exponent diagram and the phase portraits when the control parameters of the system are varied, and the correctness of the theoretical analysis is verified based on numerical simulations.
Optimal Newman-Watts networks and synchronization of Ergodic network
Authors: Wang Li-Li  , Qiao Cheng-Gong  , Tang Guo-Ning  ,   College of Physical Science and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

Synchronization in Newman-Watts (NW) networks is studied in a Hindmarsh-Rose neuron dynamical system. The topological structures of some optimal synchronization networks are given. Numerical simulation results show that the synchronizability of the NW network is mainly determined by the distribution of coupling points in coupling space. The network with even distribution of coupling points generally has the strongest synchronizability. For a given number of edges there may exist some optimal synchronization networks with different topological structures. Optimal synchronization network has the strongest synchronizability, homogeneous degree distribution and better symmetry. However, its symmetry is not necessarily best. In general, optimal synchronization network is an irregular network. However, in the minor cases, the regular network may be an optimal synchronization network. A new type of network, the ergodic network, is introduced in this paper, and it has strong synchronizability as well as the characteristics of the optimal synchronization network.
Modeling of bicycle flow based on dynamic floor field and cellular automata
Authors: Yang Xiao-Fang  , Mao Wei  , Fu Qiang  ,   Department of Transportation Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;,   College of Surveying and Geo-informatics, Tongji University, Shanghai 200092, China
Published: December 2020

In this paper, dynamic floor field is introduced to investigate the characteristics of bicycle flow. To embody the features of bicycles and riders, the repulsive force among the riders and the velocity effect are taken into consideration in this new model. A new concept called lane-changing cost is proposed to study the effect of driving styles, and a new lane-changing rule is proposed based on the traffic environment comparison. The simulation results show that 1) the model can accurately describe the bicycle flow, and the obtained statistics accords with empirical data; 2) the capacity of the road of per unit width deceases as road-width increases; 3) aggressive driving style substantially increases the lane-changing times, which reduces the capacity of the road.
Up-conversion luminescence and temperature characteristics of Tm3+, Yb3+ co-doped CaWO4 polycrystal material
Authors: Zheng Long-Jiang  , Li Ya-Xin  , Liu Hai-Long  , Xu Wei  , Zhang Zhi-Guo  ,   Key Laboratory of Measurement Technology and Instrumentation of Hebei Province, Yanshan University, Qinhuangdao 066004, China;,   Laboratory of Sono-and Photo-Heranostic Technologies, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Tm3+, Yb3+ co-doped CaWO4 polycrystals are synthesized via the high temperature solid state method. Under excitation of a 980 nm laser, the up-conversion fluorescences based on the transitions 1G4→3H6, 1G4→3H4, 3H2→3H6 and 3H3→3H6 in the visible light region are successfully obtained. The effect of the concentration change of Yb3+ on the luminous intensity of Tm3+ is discussed. Meanwhile, the temperature properties of the red up-conversion fluorescences centered at 689 nm and 705 nm are studied in a tem-perature range between 313 and 773 K according to the fluorescence intensity ratio method. It is found that the temperature can be monitored by detecting the red up-converion fluorescences of Tm3+, Yb3+ co-doped CaWO4 polycrystals. The maximal sensitivity of temperature measurement can be achieved to be 5.7×10-4 K-1 at 458 K.
Nuclear test criterion by inert gas xenon
Authors: Wu Huai-Long  , Gong Jian  , Li Wei  , Wang Qian  , Zhang Chang-Fan  , Xiong Zong-Hua  , Chu Cheng-Sheng  , Tian Dong-Feng  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

It is an important approach to preventing nuclear proliferation that comprehensive nuclear test ban treaty is reached. How to judge whether a nuclear test has happened is a key point. In this paper we investigate a method to distinguish between a nuclear test and leakage from civilian nuclear reactor by measuring inert gas xenon nuclides 133mXe, 133Xe, 135Xe, and 131mXe. The distinction between the nuclear test and the reactor leakage is found by analyzing the variation of nuclide quantity with time in a complex decay chain. Two suspicious events in North Korea are measured and analyzed. In order to verify the theoretical results, an experiment of imitating plutonium irradiated by thermal neutron is designed.
First-principles study of the native defects in InI crystal
Authors: Zhang Wei  , Xu Zhao-Peng  , Wang Hai-Yan  , Chen Fei-Hong  , He Chang  ,   Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, College of Information Science and Engineering, Yanshan University, Qinhuangdao 066004, China;,   Key Laboratory of Applied Chemistry of Hebei Province, College of Environmental Science and Engineering, Yanshan University, Qinhuangdao 066004, China;,   Parks College of Engineering, Aviation and Technology, Electrical and Computer Engineering Department, Saint Louis University, Saint Louis 63103, U.S.A
Published: December 2020

The structures of six possible native point defects (I and In vacancies, I and In antisites, I and In interstitials) that maybe exist in the orthorhombic indium iodide (InI) crystal are optimized and investigated by the first-principles calculations based on density functional theory. The levels of difficulty in forming defects in their growth processes are obtained by calculating the defect energy levels; the position of each kind of energy level of native point defect and its effect on carrier transport are analyzed via calculating the density of states. The results show that the dominant low-energy defect of In interstitial induces a recombination center and a deep hole trap: the former shortens the lifetime of the minority carriers and the latter captures the holes from the valence band, thereby reducing the mobility-lifetime product of the hole. The calculation results provide a theoretical guidance for improving the mobility-lifetime product of carriers in InI crystal and also are helpful in obtaining the excellent materials for detecting the nuclear radiation of InI crystal.
Characteristics of neutral atom deposition under channel effect in a laser standing wave field
Authors: Zhang Wen-Tao  , Zhu Bao-Hua  , Wang Jie-Jun  , Xiong Xian-Ming  , Huang Ya-Qin  ,   School of Electronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

Based on semi-classical theory, a model of the interaction between neutral atoms and the laser standing wave field is established in this paper. The trajectories and the deposition characteristics are analyzed under channel effect, and the values of full width at half maximum of nano-grating are 0.532, 12.16 and 96.70 nm when the divergence angle, spherical and chromatic aberration are discussed, respectively. The simulation results show that the contrast of the stripe decreases with the increasing of divergence angle of the atomic beam. Also, the contrasts of the stripe are 85.2:1 and 5.33:1 when the divergence angles equal 0.1 and 0.3 mrad. When divergence angle increases over 0.5 mrad, the splitting of the stripe takes place, leading to the degradation of the deposition.
Infrared laser scattering characteristics of machining surfaces
Authors: Zhu Yuan-Qing  , Qu Xing-Hua  , Zhang Fu-Min  , Tao Hui-Rong  ,   State Key Laboratory of Precision Measuring Technology and Instruments, Institute of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

In order to study the scattering characteristics of practical machining surfaces under the infrared laser irradiation, an experiment device is designed to measure the semispherical scattering characteristics of machining surfaces. The measuring system consists of a laser power meter with a resolution of 10 nW, a laser device of 1550 nm wavelength, and two precisely rotating platforms. The distributions of scattering power from the specimen surfaces with micro V-groove structures and different surface roughness values are measured under the irradiation of 1550 nm infrared laser. After the measured results are converted into the bidirectional reflectance distributional function, the effects of incident azimuthal angle, incident angle, and surface roughness on the scattering characteristics of surface of such a kind are comparatively analyzed, and the cause for the formation of special scattering field is also analyzed. The experimental results indicate that the surface texture, incident angle and surface roughness all affect the scattering property in a regular manner. The results contribute to the study of surface scattering characteristics and the application of laser technology to surfaces with V-groove structures.
Study of phase transition of HoVO4 under high pressure by Raman scattering and ab initio calculations
Authors: Chen Yuan-Zheng  , Li Shuo  , Li Liang  , Men Zhi-Wei  , Li Zhan-Long  , Sun Cheng-Lin  , Li Zuo-Wei  , Zhou Mi  ,   State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China;,   College of Physics, Jilin University, Changchun 130012, China
Published: December 2020

The aim of this work is to confirm that the HoVO4 has a zircon-to-scheelite phase transition as reported in ScVO4 and YVO4. Firstly, we prepare HoVO4 samples used in the experiments by solid state reaction of appropriate quantities of pre-dried Ho2O3 and V2O5. And the Raman spectra of HoVO4 are measured in a pressure range from ambient pressure to 21.25 GPa at room temperature by using a diamond anvil cell. The discontinuities on Raman mode shifts and the occurrence of new Raman bands provide strong evidence for a phase transition at 9.3 GPa. Secondly, ab initio calculations are performed and the results reveal a zircon-type (I41/amd) to scheelite-type (I41/a) structure in this phase transition. The results are compared with those previously reported for the relevant ScVO4 and YVO4 with a common zircon-to-scheelite phase transition, mainly duo to volume collapses. The results in this work may improve our understanding of the high phase and structure of HoVO4 and benefit the application of this material.
Field emission properties from a carbon nanotube array with parallel grid
Authors: Lei Da  , Menggen Qi-Qi-Ge  , Zhang He-Liang  , Zhi Ying-Biao  ,   Ordos College of Inner Mongolia University, Ordos 017000, China
Published: December 2020

One of the models for the carbon nanotube array with parallel grids is proposed. The actual electric field at the top of the carbon nanotubes and the field enhancement factor are calculated analytically with the image charge method and floated sphere model. The effects of the geometrical parameters of the device and the contact resistance on actual electric field, field enhancement factor at the top of carbon nanotubes, and the field emission current from the gated carbon nanotubes are investigated. The calculation results show that the carbon nanotube array has the best density for field emission when the intertube distance is twice the height of carbon nanotube. The actual electric field and the field emission current from gated carbon nanotube are greatly reduced by the contact resistance. When the contact resistance is larger than 800 kΩ, the emission current from carbon nanotube tends to be zero and the field emission properties are improved via modulating gate voltage.
Algorithm for calculating the Lyapunov exponents of switching system and its application
Authors: Li Qing-Du  , Guo Jian-Li  ,   Key Laboratory of Industrial Internet of Things and Networked Control of Ministry of Education, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
Published: December 2020

Lyapunov characteristic exponent is significant for analyzing nonlinear dynamics. However, most algorithms are not applicable for the switching system. According to the traditional Jacobi method, in this paper we propose a new algorithm which can be used to compute n Lyapunov exponents for an n-dimensional switching system. We first study the geometric dynamics of two adjacent trajectories near the switching manifold, and obtain a compensation Jacobi matrix caused by switching. Then with QR-decomposition of this matrix, we compensate for the diagonal vector of R to realize the Lyapunov exponent expansion. Finally, we use the algorithm in a two-dimensional double-scrolls system, the Glass network and a spacecraft power system, and show its correctness and effectiveness by comparing the results with the Poincaré-map method.
Application of equiprobable symbolization sample entropy to electroencephalography analysis
Authors: Huang Xiao-Lin  , Huo Cheng-Yu  , Si Jun-Feng  , Liu Hong-Xing  ,   Institute of Biomedical Electronic Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing 210023, China;,   School of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500, China
Published: December 2020

Sample entropy or approximate entropy, a complexity measure that quantifies the new information generation rate and is applicable to short time series, has been widely applied to physiological signal analysis since it was proposed. However, on one hand, sample entropy is easily affected by non-stationary sudden noise, because the tolerance during calculation is set to be proportional to standard deviation; on the other hand, it is not independent of the probability distribution, so that it does not purely characterize the new information generation rate. To solve these two problems, a new improved method named equiprobable symbolization sample entropy is proposed in this paper. Through equiprobable symbolization, the effects of both non-stationary sudden noises and probability distribution are eliminated. Besides, since equiprobable symbolization is usually non-uniform, it further breaks through the linear constrains in classic sample entropy. The method is proved to be rational by simulating three typical noises that have different time correlations and new information generation rates. Then the method is applied to electroencephalography (EEG) analysis. Results show that the method can successfully discriminate two different attention levels based on EEG with duration as short as 1.25 s and without removing any artificial artifacts. Therefore, the method is of great significance for EEG biofeedback, in which strong real-time abilities are usually required.
A new method of measuring absolute distance by using optical frequency comb
Authors: Wu Han-Zhong  , Cao Shi-Ying  , Zhang Fu-Min  , Xing Shu-Jian  , Qu Xing-Hua  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China;,   Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100013, China
Published: December 2020

High-accuracy ranging system is of significance both in future space-based sciences and in large-scale manufacture. Based on the light intensity, a method of measuring absolute distance in a long range by using the optical frequency comb is demonstrated. The temporal coherence of the pulses emitted from the optical comb is analyzed. The measurement principle is introduced. The peak position of the interference fringe is analyzed, which can contribute to the distance measurement, and numerical simulations are also developed correspondingly. The experimental results show that the absolute distance measurement can be realized. This method can be used to measure a large-scale distance.
Design and analysis for the front imaging optical system of the spatiotemporal mixed modulated Fourier transform imaging spectrometer
Authors: Wang Wen-Cong  , Liang Jing-Qiu  , Liang Zhong-Zhu  , Lü Jin-Guang  , Qin Yu-Xin  , Tian Chao  , Wang Wei-Biao  ,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In order to satisfy the application requirements of the large flux and the high stability for the infrared imaging spectrometer, we propose a new type of static no-slit spatiotemporally mixed modulated Fourier transform imaging spectrometer based on the multi-level micro-mirrors. The working process and the generation manner of optical path difference of the system are analyzed. The front imaging system, as an important component of the imaging spectrometer, determines the distribution of the optical path difference, and its performance directly affects the image quality of target object. According to the generation manner of optical path difference of the system, the front imaging system for the telecentric structure in the image space is analyzed and designed. The athermalization design research is carried out by means of the passive optical elimination thermal difference. The result shows that the modulation transfer function curve of each field reaches the diffraction limit in a temperature range of -20-60 ℃. The front imaging optical system has a good imaging quality in the total step height of the multi-step micro-mirrors. At different temperatures, the maximum incident angle on the image surface is less than 0.02° for the principal ray of each field.
Propagation properties of Gaussian beam in gradient negative index of refraction material
Authors: Zhou Jian-Hua  , Li Dong-Hua  , Zeng Yang-Su  , Zhu Hong-Peng  ,   Institute of Laser Technology and Information, Department of Information Engineering, Shaoyang University, Shaoyang 422000, China
Published: December 2020

We apply the ABCD formalism to a gradient negative index medium (NIM) and investigate the propagation and transformation properties of Gaussian beams in this medium. First, we derive the ABCD formalism in a positive gradient NIM and obtain the propagation model. Spatial soliton and the spatial breather propagation in this medium are revealed. Our research suggests that the gradient coefficient has a significant effect on the focusing ability of slab. When the gradient coefficient increases, the quasi-lense effect becomes more prominent and notable. As a result, the focusing ability improves and the beam waist in the focal point shrinks. Second, when Gaussian beams propagate in the negative gradient NIM, the beam waist enlarges as the distance increases. There is neither spatial soliton phenomenon nor breather transmission phenomenon, which is completely different from the propagation characteristics in the positive gradient NIM.
Digital holographic microscope employing dual-Lloyd’s mirror
Authors: Yuan Fei  , Yuan Cao-Jin  , Nie Shou-Ping  , Zhu Zhu-Qing  , Ma Qing-Yu  , Li Ying  , Zhu Wen-Yan  , Feng Shao-Tong  ,   Key Laboratory for Opto-electronic Technology of Jiangsu Province, Nanjing Normal University, Nanjing 210023, China
Published: December 2020

We propose a digital holographic microscopy (DHM) setup employing a configuration with two Lloyd's mirrors, which is based on self-referencing and dual-wavelength optical phase unwrapping. We use two Lloyd's mirrors to fold the beam which does not exhibit sample structure and acts as the reference beam, returning onto itself to form a dual-wavelength hologram. Two wrapped phase images for every wavelength are reconstructed by angular spectrum method. Then the wrapped phase image and the three-dimensional profile image are acquired by dual-wavelength optical unwrapping method. In the experiment, we use two lasers of different wavelengths of 532 and 632 nm to record a hologram. Numerical methods are subsequently applied to reconstruct the hologram to enable direct access to both phase and amplitude information. The quantitative experimental results with dual-wavelength DHM involve a deviation less than 5% from the calibration values. The validity of this method is demonstrated.
Terahertz bandpass filter using double-layer reformative complementary frequency selective surface structures
Authors: Lan Feng  , Gao Xi  , Qi Li-Mei  ,   School of Physical Electronics, University of Electronic Science and Technology, Chengdu 610054, China;,   School of Information and Communication, Guilin University of Electronic Technology, Guilin 541004, China;,   College of Physics and Engineering, Qufu Normal University, Qufu 273165, China
Published: December 2020

The simulation and experimental study of a bandpass frequency selective surface filter in terahertz (THz) range using double-layer modified complementary structures are conducted in this paper. The modified four-split complementary electric inductive capacitive (CELC) structure is introduced as the resonant cell of the filter. The primary design objective is to improve the filtering performances of double-layer complementary metamaterial structures built on intensified thickening quartz substrate. The bandpass filter centered at 0.28 THz is simulated, fabricated and measured. Experimental results from 0.1 to 0.6 THz measured by THz time-domain spectroscopy are in excellent agreement with simulation. The reformative CELC bandpass filter has the advantages of a low cost, low loss, steepness of skirts, out-of-band rejection, and etalon resonance rejection.
Gyrator transform of generalized sinh-Gaussian beam and generation of dark hollow light beam with vortex
Authors: Zhu Kai-Cheng  , Tang Hui-Qin  , Zheng Xiao-Juan  , Tang Ying  ,   Key Laboratory for Super-microstructure and Ultrafast Process of Hunan Province, School of Physics and Electronics, Central South University, Changsha 410083, China
Published: December 2020

Starting from the Gyrator trnasform formula, the closed-form filed distribution of generalized sinh-Gaussian beam passing through such a transform system is derived, and the intensity distribution and the corresponding phase distribution associated with the transforming generalized sinh-Gaussian beams are analyzed. Based on the numerical method, the distributions are graphically drawn and it is found that, for appropriate beam parameters and by carefully adjusting the transform angle of Gyrator transform, the dark hollow beam with topological charge index being unity can be realized with sinh-Gaussian beam carrying an edge dislocation. And the influences of the beam parameters and the transform angle on the formation of perfect dark hollow beams are analyzed. However, it is impossible to obtain dark hollow beam with Gyrator transforming cosh-Gaussian beam.
Plasma inside and outside keyhole during 10 kW level fiber laser welding
Authors: Li Shi-Chun  , Chen Gen-Yu  , Zhou Cong  , Chen Xiao-Feng  , Zhou Yu  ,   State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China
Published: December 2020

In order to understand in depth plasma behavior during ultra-high power fiber laser deep penetration welding, the plasma inside and outside the keyhole is observed, and the spectrum of fiber laser-induced plasma is measured and analyzed. Based on the measured data of plasma, the electron temperature and electron density, ionization degree and pressure are calculated, and the characteristics of plasma parameters at different values of keyhole depth and outside the keyhole are investigated. The results indicate that the distribution of plasma inside the keyhole is uneven, and the vapor plume is much bigger outside the keyhole. The spectrum of plasma show that the fiber laser-induced plasma is weakly ionized and radiates a few spectral lines. The further calculation results also confirm that the plasma induced by fiber laser is in a weakly ionized state. However, the electron density of plasma still stays in a high level, and the transient pressure of plasma is up to hundreds of times as large as atmospheric pressure.
Quantitative analysis of laser induced breakdown spectroscopy of Pb in navel orange based on multivariate calibration
Authors: Chen Tian-Bing  , Yao Ming-Yin  , Liu Mu-Hua  , Lin Yong-Zeng  , Li Wen-Bing  , Zheng Mei-Lan  , Zhou Hua-Mao  ,   Key Laboratory of Optics-Electrics Application of Biomaterials of Jiangxi Province, College of Engineering, Jiangxi Agricultural University, Nanchang 330045, China
Published: December 2020

The detection accuracy of laser induced breakdown spectroscopy (LIBS) is affected by system parameters, ambient gas, matrix effect, sample morphology, calibration methods etc. Heavy metals in Gannan navel orange are determined by LIBS in our laboratory. The experimental parameters are optimized. In this work, multivariate linear regression model is used to predict the concentration of Pb element in navel oranges. The real concentration of Pb is quantitatively determined by atomic absorb spectroscopy (AAS). The concentration is set as dependent variable, while the intensity of Pb I 405.78 nm, the intensity sum of Ca Ⅱ 393.37 nm and Ca Ⅱ 396.84 nm, and the integrated intensity in a range of 405.03-405.96 nm are taken as independent variable. The calibration results indicate that the maximum relative error between the predicted Pb concentration from the multiple linear regression model and the measured one by the AAS is 12.99%, and the average relative error of the samples is 4.87%. And the fitting degree of the results of two methods is 0.995. The result shows that the multivariate calibration method can utilize the information about the spectra and reduce the influence of the matrix effect. The multivariate linear regression model is proved to be feasible in improving the prediction accuracy of LIBS.
Sampling methods of power spectral density method simulating atmospheric turbulence phase screen
Authors: Cai Dong-Mei  , Wang Kun  , Jia Peng  , Wang Dong  , Liu Jian-Xia  ,   Institute of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China;,   Institute of Information Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

Based on power spectral density method, the uniform sampling leading to the leakage of low frequency in atmosphere phase screens is analyzed. A new method - non-uniform sampling is proposed. The non-uniform sampling is modeled. The covered sampling frequency regions and the powers of single sampling region by the two sampling methods are discussed and compared. The new method proves to be effective and feasible. For the Kolmogorov spectrum of atmospheric turbulence, the numerical simulation phase screens are generated by the two sampling methods. The simulation results show that the random phase screens generated by the non-uniform sampling method under the condition of increasing neither sampling number nor computation burden, possesses rich high and low frequency information.
Underwater acoustic synchronization telemetry research based on binary offset carrier modulated signal with zero correlation window
Authors: Sun Zong-Xin  , Yu Yang  , Zhou Feng  , Liu Song-Zuo  , Qiao Gang  ,   Key Laboratory of Underwater Acoustic Science and Technology, Harbin Engineering University, Harbin 150001, China;College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Aiming at the problem that synchronized correlation of linear frequency synchronization of m sequence possesses self noise and there are strong side lobes in a code range besides main lobe, in this paper we propose a new underwater acoustic synchronization scheme based on binary offset carrier (BOC) modulated signal with no interference windows which employs the property that the sum of aperiodic auto correlation function is 0 to realize no interference window between the range of one code and zero inference window and utilizes BOC (1, 1) to modulate signal with sub-carrier to mitigate side lobes in one code range besides main lobe. The schemes are designed for both single and couple channel signal, and the validity of underwater acoustic synchronization, channel measurement and estimation are testified through simulation and experiments.
Acoustic field reconstruction using source strength density acoustic radiation modes
Authors: Nie Yong-Fa  , Zhu Hai-Chao  ,   National Key Laboratory on Ship Vibration and Noise, Institute of Noise and Vibration, Naval University of Engineering, Wuhan 430033, China
Published: December 2020

To use a small number of acoustic pressure measurement data to reconstruct the radiated acoustic field of the complicated structure, a theory of source strength density acoustic radiation modes is proposed and a formula of acoustic field reconstruction is developed. In the space defined on the surface of the structure, functional form of the acoustic radiation power expression in which parameter is source strength density is constructed. In terms of the functional a linear self-adjoint and positive radiation operator is defined whose eigenfunctions are source strength density acoustic radiation modes. And then it is proved that source strength density acoustic radiation modes possess space filter characteristic through analyzing the source strength density radiation modes of rectangular plate and cylinder with hemisphere ends. The formula of acoustic field reconstruction with the space filter nature is obtained. The sphere simulations and plate experiment validate the feasibility and robustness of the proposed acoustic field reconstruction method. The acoustic field reconstruction method based on the proposed radiation modes is simple, has high accuracy that can be obtained by using only a few measurement data, so this method is especially applicable for low frequency acoustic field reconstruction of the complicated structure.
Accelerating dissipative particle dynamics with graphic processing unit
Authors: Lin Chen-Sen  , Chen Shuo  , Li Qi-Liang  , Yang Zhi-Gang  ,   School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China;,   Shanghai Automotive Wind Tunnel Center, Tongji University, Shanghai 201804, China
Published: December 2020

In this paper, the graphic processing unit (GPU) parallel computing of dissipative particle dynamics (DPD) based on compute unified device architecture is carried out. Some issues involved, such as thread mapping, parallel cell-list array updating, generating pseudo-random number on GPU, memory access optimization and loading balancing are discussed in detail. Furthermore, Poiseuille flow and suddenly contracting and expanding flow are simulated to verify the correctness of GPU parallel computing. The results of GPU parallel computing of DPD show that the speedup ratio is about 20 times compared with central processing unit serial computing.
Opto-electronic properties of the single-walled carbon nanotube film and melamine formaldehyde resin composite
Authors: Li Zhen-Wu  ,   School of Jiang Zhen Mechanical and Electrical Engineering, Heze University, Heze 274015, China
Published: December 2020

The single-walled carbon nanotube (SWCNT) can strongly absorb light, particularly in the near infrared region, and can convert it into thermal energy, while the SWCNT also has a great capacity of converting thermal energy into electrical energy. In this paper, by means of vacuum filtering, SWCNT film is prepared by SWCNT arrays generated by the chemical vapor deposition. A simple experimental device of SWCNT is designed and the conversion from the infrared light to voltage output is successfully achieved. The SWCNT/melamine formaldehyde resin composite film is prepared by the functional steps. The experimental results show that the composite material can produce an output voltage of opposite sign, which indicates that the SWCNT and melamine formaldehyde resin composite material have good application prospect in the field of photo-electrical applications.
Surface and interface phonon-polaritons in four layer systems consisting of polar ternary mixed crystals
Authors: Bao Jin  , Yan Cui-Ling  , Yan Zu-Wei  ,   College of Sciences, Inner Mongolia Agricultural University, Hohhot 010018, China
Published: December 2020

Surface and interface phonon-polaritons in a four-layer (vacuum/polar binary crystal slab/polar ternary mixed crystal slab/polar binary crystal substrate) system are investigated with the modified random-element-isodisplacement model and the Born-Huang approximation, based on the Maxwell's equations with the usual boundary conditions. The numerical results of the surface and interface phonon-polariton frequencies as functions of the wave-vector, composition x, and thickness of slab in the two four-layer systems, i.e., AlxGa1-xAs/GaAs and ZnxCd1-xSe/ZnSe, are obtained and discussed. It is shown that there are seven branches of surface and interface phonon-polariton modes in the heterostructure systems, and that the frequencies of the surface and interface modes vary non-linearly with the composition and thickness of slab. The “one mode” and “two mode” behaviors of the ternary mixed crystals are also shown in the dispersion curves.
Refractive index homogeneity of large scale potassium dihydrogen phosphate crystal
Authors: Zhu Sheng-Jun  , Wang Sheng-Lai  , Liu Lin  , Wang Duan-Liang  , Li Wei-Dong  , Huang Ping-Ping  , Xu Xin-Guang  ,   State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
Published: December 2020

By using a traditional temperature reduction method, a large scale potassium dihydrogen phosphate (KDP) crystal is prepared. The refractive indices of different parts of this as-grown crystal are measured at 12 wavelengths between 0.253 and 1.530 um by using the new generation measuring instrument with an accuracy of 10-6. The measurement results show that refractive indices are inhomogenous in different parts of the large scale KDP crystal. The refractive index of the selected part close to the recovery area of crystal is smaller than that of selected part far from the recovery area. The deviation is on the order of 10-5-10-4. The refractive index inhomogeneity is related to the difference in crystalline quality among different parts in large KDP crystal. Furthermore, our measured data are compared with those in the literature published previously and the difference between them is analyzed. Meanwhile, by using root mean square method, numerical fitting to Sellmeier equation is conducted.
Surface-enhanced Raman scattering of gold/graphene oxide composite materials fabricated by interface self-assembling
Authors: Tang Jian  , Liu Ai-Ping  , Li Pei-Gang  , Shen Jing-Qin  , Tang Wei-Hua  ,   Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China;,   State Key Laboratory of Information Photonics and Optical Communication, School of Science, Beijing University Posts and Telecommunications, Beijing 100876, China
Published: December 2020

The colloidal gold nanoparticles (AuNP) are synthesized by the classic Frens' method, and the sandwich-structured AuNP/graphene oxide/AuNP (AuNP/GO/AuNP) composite materials are constructed on the phosphorus doped diamond-like carbon film by the interface self-assembling. The surface enhanced Raman scattering behaviors of the AuNP/GO/AuNP composites are investigated by using the rhodamine B (RhB) as the probe molecules. Our results indicate that the Raman intensity of RhB obtained from the AuNP/GO/AuNP composites shows a 16.5-fold increase over that from the AuNP monolayer due to the coupled effect of chemical enhancement of GO and localized electromagnetic field enhancement of plasmonic gold. The designed composite materials with metal/GO/metal sandwich configuration exhibit great potential applications in biochemical analysis, environmental monitoring, disease controlling, and food safety.
Optical properties of silver hollow square embedded disk nanostructures
Authors: Sun Song-Song  , Wang Hong-Yan  ,   School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

In this paper, we calculate the extinction spectra and the distribution of electric near-field of the nanoparticles which are embedded a disk in a hollow square structure through using the discrete dipole approximation method, and compare our results with extinction spectra and the distribution of electric near-field of the single hollow square nanostructure. The research results show that a new resonant mode, which is located in the traditional excitation wavelength range of surface enhanced raman scattering, can be produced due to the coupling interaction. Then, we can use this mode to meet the shortage of the hollow square nanostructure fabricated by nanoskiving. In addition, the surface plasmon resonance peak can be tuned by changing the shape parameters of the silver nanoparticle. These results can be used in Raman scattering, molecular biological, and chemical detection.