bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic electrical characteristics of organic light-emitting diodes
Authors: Zhang Xiu-Long  , Yang Sheng-Yi  , Lou Zhi-Dong  , Hou Yan-Bing  ,   北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京 100044
Published: December 2020

The charge carriers conduction mechanism of single-layer device ITO/Alq3(90 nm)/Al has been studied by impedance spectroscopy. According to the frequency-dependent response and its equivalent circuit model，the device can be interpreted in terms of the equivalent circuit model of a contact resistance Rs in series with a parallel combination of a capacitance Cp and a resistance Rp, and the values of Rp, Cp and Rs can be found from experimental data. Our experimental results confirmed that the charge carriers conduction mechanism of ITO/Alq3(90 nm)/Al is trap-charge limited current with exponential distribution, and the dielectric relaxation time of the material decreases dramatically with increasing applied bias voltages.
The electronic states in one-dimensional disordered system with long-range correlations
Authors: Xu Hui  , Deng Chao-Sheng  , Liu Xiao-Liang  , Ma Song-Shan  , Wu Xiao-Zan  ,   中南大学物理科学与技术学院，长沙 410083
Published: December 2020

We generated the long-range correlated random energy sequences with the power-law spectral density s(q)∝q-p in the one-dimensional Anderson disordered chain, and then investigated the localization length by using the transfer matrix method. The density of electronic states were also analyzed with the help of the negative eigenvalue theory. Then we made a comparison between the results and that of the system which does not have long-range correlations. Our results show that after introducing the long-range correlations in the one-dimensional Anderson disordered chain, the properties of electronic states change greatly, and when the correlation exponent p≥2.0, there exists a localization-delocalization transition at the energy band center. Accordingly, the density of electronic states changes obviously and presents six van Hove singul arities, and moreover, the energy band of the system also extends slightly, accompanying the above changes.
Fabrication of SOI material based on smart-cut technology
Authors: Shu Bin  , Zhang He-Ming  , Zhu Guo-Liang  , Fan Min  , Xuan Rong-Xi  ,   西安电子科技大学微电子学院，宽禁带半导体材料与器件教育部重点实验室，西安 710071
Published: December 2020

The process of the low-temperature-direct-bonding and smart-cut technologies is optimized, and the SOI material is fabricated at 550℃ under 2.1×10-2 Pa. The bonding strength of this structure is 153.7 kg/cm2, the total thickness variation and the defect density of the top monocrystalline silicon film are 8.5 nm and 90 cm-2, respectively. This method can produce a good insulator layer between active layers in the fabrication of the three-dimensional integrated circuits (3D ICs), avoiding the unfavorable effects of the high-temperature process on the device structure, material quality and performance of the active layers. At the same time, the high quality monocrystalline silicon layer can be available for producing subsequent active layers in the fabrication of the 3D ICs.
Phase transition and vortex noise spectrum in two-dimensional Josephson-junction array
Authors: Wu Bing-Guo  , Zhao Zhi-Gang  , You Yu-Xin  , Liu Mei  ,   东南大学物理系，南京 210096
Published: December 2020

Using the resistively shunted junction (RSJ) model，we calculate the temperature dependence of vorticities and fluctuations of vorticities in two-dimensional Josephson junction array (JJA). It is found that the phase transition is of the Berezinski-Kosterlitz-Thouless (KTB) type. We also study the temperature and driving current dependence of the noise power spectrum in the vicinity of phase transition. The calculated results are consistent with recent experimental reports, and the main characteristics of the noise power spectrum can be explained by the motion of vortices.
A numerical study on the aging of two-dimensional spin systems
Authors: Lei Xiao-Wei  , Zheng Bo  , Ying He-Ping  ,   (1)浙江大学浙江近代物理中心,杭州 310027; (2)重庆文理学院物理与信息工程系,重庆 402160；浙江大学浙江近代物理中心,杭州 310027
Published: December 2020

With a large-scale Monte Carlo simulation, the aging of the two-dimensional dynamic Ising and XY models is numerically studied. Starting from a disordered state, the systems are quenched to critical temperature Tc and then evolve according to dynamics of model A. By calculating the autocorrelation function A(t,t′) we observe the aging phenomenon for both spin systems. Then, relatively accurate values of the dynamic critical exponent λc and z are estimated. Especially, we confirm that for the two-dimensional XY model, there is a strong logarithmic correction to scaling in the dynamic relaxation starting from a completely disordered.
Effect of the secondary crystal field-effect and the exchange interaction on magnetic and magneto-optic properties of PrF3
Authors: Xia Tian  , Zhang Guo-Ying  , Zhang Xue-Long  , Xue Liu-Ping  ,   (1)上海理工大学医疗器械学院，上海 200093; (2)中国矿业大学理学院物理系，徐州 221008
Published: December 2020

In the PrF3 crystal, the lowest crystal field state of Pr3+ ion is a single state, which has no contribution to the susceptibility and the Verdet constant of the crystal in first-order effect. The secondary crystal field-effect admixes the state with other states and makes the state have a great contribution to the magnetic properties of PrF3 crystal. In this paper, the effect of secondary crystal field-effect on the magnetic and magnetio-optic properties of PrF3 crystal is presented. Furthermore, the effective field of exchange interaction between the ions is investigated, which has the form is Hin=(1.9-0.02556 T)×10-5M. By means of the effective field, the inverses of the magnetic susceptibility and Verdet constant of PrF3 crystal as functions of temperature are calculated, and the results are in good agreement with the measured ones. The results show that the crystal field's second-order contribution and exchange interaction between ions shouldn't be ignored.
Investigation of spectral properties and thermal stability of Er3+/Yb3+ co-doped TeO2-B2O3-SiO2 glasses
Authors: Zhang Xu-Dong  , Xu Tie-Feng  , Nie Qiu-Hua  , Dai Shi-Xun  , Shen Xiang  , Lu Long-Jun  , Zhang Xiang-Hua  ,   (1)法国雷恩1大学玻璃与陶瓷实验室,法国 雷恩 35042; (2)宁波大学信息科学与工程学院，宁波 315211
Published: December 2020

A series of Er3+/Yb3+ co-doped (85-x) TeO2-15B2O3-xSiO2 (TBS x=0,5,10,15,20 mol%) glasses have been prepared. The thermal stability, absorption and emission spectra, lifetime of Er3+: 4I13/2 level and infrared transmit spectra were measured and discussed. The emission spectra of Er3+:4I13/2→4I15/2 transition was analyzed using a peak-fit routine, and an equivalent four-level system was proposed to estimate the Stark splitting for the 4I15/2 and 4I13/2 levels of Er3+ ions. It was found that the thermal stability of these glasses was improved by introducing SiO2. The difference between the glass transition temperature (Tg) and the crystallization onset temperature (Tx), ΔT=Tx-Tg, have came to 178℃ when SiO2 was 20 mol%, indicating that they were suitable for fiber drawing. The fluorescence full width at half maximum (FWHM) and peak of emission cross-section (σpeake) of Er3+ ions in different glass hosts have been compared. The results indicate that these new TBS glasses are promising host material for broadband amplifiers.TeO2-B2O3-SiO2, thermal stability, G
The luminescent properties of YBO3:Eu3+ nanocrystal
Authors: Luo Wen-Xiong  , Huang Shi-Hua  , You Fang-Tian  , Peng Hong-Shang  ,   北京交通大学光电子技术研究所，发光与光信息技术教育部重点实验室，北京 100044
Published: December 2020

YBO3:Eu3+ nanoparticles have been prepared by hydrothermal method. The size and morphology of the nanoparticles were controlled by the reaction conditions. The luminescence of the nanoparticles has been investigated and compared to that of the bulk YBO3:Eu3+. In nano-sized materials, a large portion of doped rare earth ions located at the sites with micro-environments are affected by the surface. Such an influence could enhance the Judd-Ofelt Ω2 parameter, and hence increase the relative intensity of the Eu3+5D0→7F2 emission and improve the chromaticity of the red phosphor.
The optical properties of conical bubble sonoluminescence in glycol
Authors: He Shou-Jie  , Ha Jing  , Zhang Zi-Sheng  , Zhao Zeng-Chao  , Dong Li-Fang  , Wang Long  , Wang Zhi-Jun  ,   (1)河北大学物理科学与技术学院，保定 071002; (2)河北农业大学理学院，保定 071001; (3)中国科学院物理研究所，北京 100080
Published: December 2020

Using an improved conical bubble U tube, the optical properties of conical bubble sonoluminescence in glycol are measured. A strong single flash is observed and the width of light pulse reaches 150 us, which is much higher than that of the results obtained by other methods. The spectrum is a continuum ranging from ultraviolet to visible region, superposed with the spectral line of the 3P-3S transition of sodium around 589 nm. The blue satellite bands of Na-Ar has been measured on the sides of atomic spectral line; the red satellite band of Na-Ar and the 3S-4S atomic spectral line of Na are firstly measured in sonoluminescence.
Preparation of polycrystalline V0.97W0.03O2 thin films with ultra high TCR at room temperature
Authors: Li Jin-Hua  , Yuan Ning-Yi  , Xie Tai-Bin  , Dan Di-Di  ,   江苏工业学院信息科学系，功能材料实验室，常州 213016
Published: December 2020

The W doped vanadium oxide film was deposited on the SiO2 substrate by modified ion beam enhanced deposition (IBED) method. The V2O5 and WO3 mixed powders, atom ratio of W/V being 3/97, were pressed as the sputtering target. After annealed in Ar or N2 the polycrystalline IBED VO2 film doped with tungsten was obtained. The annealed IBED V0.97W0.03O2 film was orientated only to ［002］ of VO2 structure, and the latice parameter d was larger than that of VO2 crystal powder measured by X-ray diffraction. The results of resistance-temperature test showed that the phase transition temperature was decreased from 68℃ to 28℃. The thermal coefficient of resistance (TCR) was high up to 10 %/K at 300K. With the ionic radius of tungsten larger than the radius of vanadium, W6+ ion doping would induce a tension stress into the film. As a result, the transition temperature of the W-doped VO2 films was decreased to the room temperature, and the TCR was increased greatly.
Study of FN-DLC thin films: (Ⅰ) sp structure and chemical bond analysis
Authors: Xiao Jian-Rong  , Xu Hui  , Guo Ai-Min  , Wang Huan-You  ,   (1)中南大学材料科学与工程学院，长沙 410083; (2)中南大学物理科学与技术学院，长沙 410083; (3)中南大学物理科学与技术学院，长沙 410083；中南大学材料科学与工程学院，长沙 410083
Published: December 2020

Nitrogen doping of fluorinated diamond-like carbon (FN-DLC) thin films were prepared by radio frequency plasma enhanced chemical deposition (RF-PECVD) under different radio frequency power (RF-power) with CF4, CH4 and nitrogen as source gases. The sp hybrid structure and chemical bond structure of the films were characterized by Auger electron spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared absorption spectrometry, and the sp2/sp3 hybrid ratios were analyzed by fitting multi-peaks of Gauss an form. The results show that the thin films are a type of diamond-like carbon films. The sp2/sp3 hybrid ratios in the films deposited by different RF-power lie between 2.0 to 9.0. The sp2 structure in the films increases with the increasing RF-power. The chemical bond structure in the films are C—Fx(x=1,2),C—C, C=C and C≡N. The C—C bond increases with the increasing RF-power, while the C—F bond decreases. Higher RF-power is shown to reduce the F content in the films. The degree of cross-linking in the films is enhanced and the films become more stable with increasing RF-power.
A theory of polymer solubility parameter
Authors: Ji Qing  , Qiao Bao-Fu  , Zhao De-Lu  ,   中国科学院化学研究所高分子物理与化学国家重点实验室，北京 100080
Published: December 2020

Recently, our group introduced Gibbs distribution into Flory—Huggins polymer solution theory. It reasonably describes the polymer cohesion energy. In the present study, we applied the said theory to calculate the polymer solubility parameter and a more accurate value has been found. It indicates that the present theory is reliable and can be used to compute polymer solution parameters.
Application of fiber mode mixer in differential optical absorption spectroscopy
Authors: Si Fu-Qi  , Liu Jian-Guo  , Xie Pin-Hua  , Zhang Yu-Jun  , Li Ang  , Qin Min  , Li Yu-Jin  , Dou Ke  , Li Su-Wen  , Liu Wen-Qing  ,   中国科学院环境光学与技术重点实验室，中国科学院安徽光学精密机械研究所，合肥 230031
Published: December 2020

Differential optical spectroscopy (DOAS) has become an important method for determination of tropospheric trace gases, using the photomultiplier (PMT) as detector. The use of photodiode array (PDA) detectors enhances DOAS system considerably owing to PDA's higher sensitivity and advantage in multi-channel application. When the PMT is simply replaced by PDA, a difference between lamp spectrum and atmosphere spectrum, as will as unwanted standard deviation of residual noise as much as 1.4×10-3 appears after corrected for the pixel response. A fiber mode mixer, based on fiber disturb mode principle was developed and tested. This new device reduces the standard deviation to 3.4×10-4 in field experiments.
The mechanism of self-assembly of polystyrene submicrospheres at water-air interface
Authors: Wang Xiao-Dong  , Dong Peng  , Chen Sheng-Li  , Yi Gui-Yun  ,   中国石油大学重质油国家重点实验室，北京 102249
Published: December 2020

The mechanism of polystyrene submicrospheres assembling in aqueous suspension was studied systemically. During the evaporation of solvent, the PS spheres were transported to the water-air inter-surface, where these spheres self-assemble into colloidal crystal through the capillary force between the particles at water-air interface. The wettability of the PS spheres at the water-air interface changes from complete wetting to partial wetting and finally to non-wetting with the evaporation of water, so that the contact angle between the PS spheres and water increases gradually. The experiment showed that only after the contact angle reached a critical value θ′critical, could the PS sphere-assembly occur. The critical value θ′critical obtained from the Wenzel equation was greater than the measured value θcritical＝22° because the surface of the PS colloidal crystal was “regularly” coarse. The change of the PS spheres at water-air interface from the hydrophilic to hydrophobic is essential for the PS spheres to assemble into colloidal crystals.
Decentralized output feedback robust stabilization and impulse analysis of uncertain generalized large-scale composite system
Authors: Ma Yue-Chao  , Zhang Qing-Ling  ,   (1)东北大学系统科学研究所，沈阳 110004; (2)东北大学系统科学研究所，沈阳 110004；燕山大学理学院，秦皇岛 066004
Published: December 2020

This paper considers a class of uncertain generalized large-scale composite system and studies the decentralized stabilization problem for the system by employing Lyapunov method and using the matrix norm properties. We design a kind of decentralized output feedback robust controllers and obtain the norm bounds of system uncertainties which ensure robust stabilization for the system. Meanwhile, we　analyse the impulse control problem of uncertain generalized composite system and its isolated subsystems. We give the norm bounds of system uncertainties which ensure the closed loop system impulse free. Finally, we obtain the norm bounds of being asymptoticly stable and impulse free for the closed loop of uncertain generalized composite system and its isolated subsystems.
Dynamic behavior of complete synchronization of coupled chaotic oscillators
Authors: Bao Gang  , Narenmandula  , Tubuxin  , Eredencang  ,   内蒙古民族大学物理与机电学院,通辽 028043
Published: December 2020

The dynamic behavior of phase synchronization in coupled oscillators is investigated using Lyapunov exponents and correlation function. A strongest chaotic phase synchronization——complete synchronization was observed, in which the first two transverse Lyapunov exponents are made equal and the projective structures of oscillators become exactly the same.
Chaos anti-synchronization of a class of chaotic systems based on state observer design
Authors: Wang Xing-Yuan  , Wu Xiang-Jun  ,   大连理工大学电子与信息工程学院，大连 116024
Published: December 2020

We present a systematic design procedure to anti-synchronize a class of chaotic systems based on techniques from the state observer design and the pole placement technique. In contrast to the conventional anti-synchronization approaches, the proposed method is rather simple and convenient to realize anti-synchronization. Furthermore, the rate of achieving anti-synchronization is very fast. Numerical simulations show the effectiveness of the proposed scheme.
Bifurcations of safe basins and chaos in softening Duffing oscillator under harmonic and bounded noise excitation
Authors: Rong Hai-Wu  , Wang Xiang-Dong  , Xu Wei  , Fang Tong  ,   (1)佛山大学数学系，佛山 528000; (2)西北工业大学应用数学系，西安 710072
Published: December 2020

The erosion of the safe basins and related chaotic motions of a softening Duffing oscillator under harmonic and bounded random noise are studied. By the Melnikov method, the system's Melnikov integral is computed and the parametric threshold for the onset of chaos is obtained. Using the Monte-Carlo and Runge-Kutta method, the erosion of safe basins is also discussed. As an alternative definition, stochastic bifurcation may be defined as a sudden change in the character of stochastic safe basins when the bifurcation parameter of the system passes through a critical value. This definition applies equally well to either randomly perturbed motions or purely deterministic motions. It is found that random noise may destroy the integrity of the safe basins, bringing forward the stochastic bifurcation and making the threshold for onset of chaos vary to a large extent, which makes the system less safe and chaotic motion easier to occur.
Modulation principles and code design for multilevel optical data storage
Authors: Hu Hua  , Xiong Jian-Ping  , Xu Duan-Yi  , Qi Guo-Sheng  , Xiao Jia-Xi  , Hu Heng  ,   清华大学精密仪器与机械学系，光盘国家工程研究中心，北京  100084
Published: December 2020

Multilevel optical data storage is an important technology to improve the recording density of optical disc without changing the optical parameters. One approach is multilevel amplitude modulation, which uses the variance of signal amplitude of length-fixed recorded marks to record information. Another one is multilevel runlength-limited (RLL) modulation, which records information in both the signal amplitude and the length of recorded marks, thus can improve the recording density more effectively than the first way. Multilevel RLL coding is a key technology in multilevel RLL modulation optical recording. In this paper, a new 8-ary (1，3) RLL code is designed with state splitting algorithm. The recording density of this code is as high as 3.0 bits/symbol, and the encoder/decoder is simple and easy to implement. The proposed code can be used for future high density multilevel RLL modulation optical disc systems.
The vectorial properties of paraxial beams propagating in uniaxial left-handed materials
Authors: Cao Jing-Xiao  , Hu Wei  , Luo Hai-Lu  , Yang Xiang-Bo  ,   (1)华南师范大学传输光学实验室，广州 510006; (2)华南师范大学光子信息技术实验室，广州 510006;华南师范大学传输光学实验室，广州 510006; (3)华南师范大学激光生命科学研究所，广州 510631
Published: December 2020

The vectorial properties of paraxial beams propagating along the optical axis of uniaxial left-handed materials are studied. On the basis of a suitable plane-wave angular spectrum representation of the electromagnetic field, we obtain the analytical expressions of the optical field. The longitudinal component is expressible in terms of the firest correction of the transverse field. Moreover, the transverse field varies when either of the polarization and the distributing of the initial electromagnetic field is changed. But the longitudinal component is only dependent on the initial distributing of the field.
Entanglement evolution and Bell inequality violation of two atoms in Tavis-Cummings model with intrinsic decoherence
Authors: Guo De-Jun  , Shan Chuan-Jia  , Xia Yun-Jie  ,   (1)湖北师范学院物理系，黄石 435002; (2)曲阜师范大学物理工程学院，曲阜 273165
Published: December 2020

Considering the interaction between two two-level atoms and a single-model field, we find an exact solution of the Milburn equation for the system. We investigate the time evolution of the entanglement between the two atoms and the maximal violation of Bell-CHSH inequality. The influence of dipole-dipole interaction and detuning between the caving and the atom on the entanglement and Bell violation is discussed. The effect of dipole-dipole interaction between two atoms on the entanglement and Bell inequality violation is obvious; with the detuning increasing, the entanglement between two atoms and Bell inequality violation becomes larger and we find that the stationary value of the entanglement between two atoms only depends on the difference between the dipole-dipole coupling intensity and the detuning. The Bell inequality violation and the entanglement does not satisfy the monotonic relation, a large Bell inequality violation may correspond to a small amount of entanglement.
New even and odd nonlinear coherent states and their non-classical properties
Authors: Meng Xiang-Guo  , Wang Ji-Suo  ,   聊城大学物理系,聊城 252059
Published: December 2020

A new kind of even and odd nonlinear coherent states (EONLCS) is constructed. Using the numerical computation method, the non-classical properties such as squeezing, amplitude-squared squeezing, anti-bunching and phase probability distribution of the new EONLCS are investigated. The results show that, in the different ranges of the parameter |λ|, the new EONLCS exhibits amplitude-squared squeezing in the directions Y1 and Y2. The squeezing effect is shown in the direction X2 for new even nonlinear coherent states, and the anti-bunching effect is shown for new odd nonlinear coherent states. Moreover, we find that the new EONLCS exhibit different quntum interference properties by studying the probability distributions of the states.
Wigner function for the photon-added even and odd coherent state
Authors: Meng Xiang-Guo  , Wang Ji-Suo  , Liang Bao-Long  ,   聊城大学物理系,聊城 252059
Published: December 2020

Using the coherent state representation of the Wigner operator, the Wigner function for the photon-added even and odd coherent state (PAEOCS) is obtained. In terms of the variations of the Wigner function with the complex parameter α in the phase space, the non-classical properties of the PAEOCS are discussed. It is found that the PAEOCS always exhibits the non-classical properties, and the photon-added even (or odd) coherent state exhibits the non-classical properties more easily when m is odd (or even). By virtue of the marginal distributions of the Wigner function for the PAEOCS, we illuminate the physical meaning of the Wigner function. Finally, based on the intermidate coordinate-momentum presentation the quantum tomogram function for the PAEOCS is obtained.
Generation of twisted stigmatic beam and transfer of orbital angular momentum during the beam transformation
Authors: Gao Ming-Wei  , Gao Chun-Qing  , Lin Zhi-Feng  ,   北京理工大学光电工程系,北京 100081
Published: December 2020

The twisted stigmatic beam with orbital angular momentum generated by transforming the Hermite-Gaussian beam through a rotated cylindrical lens system was studied. By utilizing of method of mode decomposition, the theory of transformation was analyzed. The transfer of orbital angular momentum during beam transformation was analyzed using beam transforming matrix and Collins integral. It was found that the angular momentum transfer takes place at the first cylindrical lens and remains constant after that.
Fractional thermal loading and thermal lensing in end-pumped Tm,Ho:YLF lasers
Authors: Zhang Xin-Lu  , Wang Yue-Zhu  , Li Li  , Ju You-Lun  ,   (1)哈尔滨工程大学理学院,哈尔滨 150001; (2)哈尔滨工程大学理学院,哈尔滨 150001;哈尔滨工业大学可调谐激光国家重点实验室 ,哈尔滨 150001; (3)哈尔滨工业大学可调谐激光国家重点实验室 ,哈尔滨 150001
Published: December 2020

Based the energy transfer between ions and the transition between energy levels of diode-end-pumped Tm,Ho:YLF laser, and considering the energy transfer up-conversion and ground state re-absorption, the rate equations are set up. The analytical formula of fractional thermal loading is deduced from the rate-equations, and the results show that the fractional thermal loading critically depends on the pump-to-mode size ratio. The focal length of the thermal lens as a function of pump power is obtained in experiment. The experimental results are compared with theoretical results, which shows that the theoretical results are reasonable.
Pulse width measurement of ultra-broad-bandwidth Ti: sapphire oscillator using SPIDER technique
Authors: Wang Peng  , Zhao Huan  , Zhao Yan-Ying  , Wang Zhao-Hua  , Tian Jin-Rong  , Li De-Hua  , Wei Zhi-Yi  ,   中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080
Published: December 2020

The pulse width generated by an ultra-broad-bandwidth Ti: sapphire oscillator is measured using SPIDER technique. The measurement result is 7.86 fs, which is, as presently reported in China, the shortest pulse output directly from an oscillator in which only chirped mirrors was used to compensate for the laser dispersion. Layout of the oscillator and the SPIDER setup are introduced in details, and the spectral phase of the laser pulse obtained through calculation is discussed.
Theoretical investigation on the bistability of nonlinear Bragg gratings
Authors: Tian Jian-Feng  , Wu Zheng-Mao  , Xia Guang-Qiong  ,   西南大学物理科学与技术学院,重庆 400715
Published: December 2020

Based on the coupled mode theory, the bistability performance of nonlinear Bragg gratings is analyzed theoretically in terms of elliptic integration. The analytical expression describing the relation between the input intensity and the output intensity is presented. Consequently, the dependence of the bistability on the gratings inner parameters is investigated numerically. The results show that, the bistability performance of the nonlinear Bragg gratings depends not only on the product of the couple coefficient and the grating length but also on the couple coefficient and the gratings length respectively.
Energy transfer and upconversion luminescence of Tm3+/Yb3+ co-doped lanthanum-zinc-lead-tellurite glasses
Authors: Jin Zhe  , Nie Qiu-Hua  , Xu Tie-Feng  , Dai Shi-Xun  , Shen Xiang  , Zhang Xiang-Hua  ,   (1)雷恩第一大学玻璃与陶瓷实验室,法国雷恩 35042; (2)宁波大学信息科学与工程学院，宁波 315211
Published: December 2020

Tm3+/Yb3+ codoped lanthanum-zinc-lead-tellurite glasses were prepared. Infrared spectrum and upconversion luminescence spectra under 980 nm excitation were studied, and the upconversion luminescence mechanisms were discussed. Rate equations based on energy levels of Tm3+ and Yb3+ and the upconversion mechanisms were developed, and population density in different levels and coefficients of the energy transfer rate Cbi(i=0, 1,3) between Tm3+ and Yb3+ were obtained. The results indicated that, with increasing PbO content in the glass, the energy transfer between Yb3+:2F5/2 and Tm3+:3H4 was intensified, and upconversion luminescence intensity of blue emission was enhanced significantly.
Stability and vibration of an elastic helical rod with circular cross section
Authors: Liu Yan-Zhu  , Sheng Li-Wei  ,   上海交通大学工程力学系，上海 200030
Published: December 2020

The dynamical behavior of an elastic helical rod with circular cross section are discussed on the basis of Kirchhoff's theory. The dynamical equations of the rod described by the Euler's angles are established in the Frenet coordinates of the centerline. The helical state without twisting of the rod under the action of axial force and torque is discussed. The stability of the helical equilibrium is analyzed in the fields of statics and dynamics respectively. The difference and relationship between Lyapunov's and Euler's stability concepts of the rod equilibrium are discussed. We proved in the sense of first approximation that the Euler's stability conditions of the helical rod in the space domain are the necessary conditions of Lyapunov's stability in the time domain. The free frequency of three-dimensional flexural vibration of the helical rod is derived in analytical form as a function of the pitch angle of the helix and the wave number of the perturbed elastica.
Structure and growth behavior of low N-doped diamond film by microwave plasma assisted chemical vapor deposition
Authors: Liu Yan-Yan  , Bauer-Grosse E.  , Zhang Qing-Yu  ,   (1)Laboratoire de Science et Génie des Surfaces,Ecole des Mines,Nancy 54042,France; (2)大连理工大学三束材料改性国家重点实验室，大连 116024; (3)大连理工大学三束材料改性国家重点实验室，大连 116024;Laboratoire de Science et Génie des Surfaces,Ecole des Mines,Nancy 54042,France
Published: December 2020

采用微波等离子体化学气相沉积(MPCVD)技术，在甲烷和氢气的混合气体中，通过掺入微量氮气的方法，合成了掺氮金刚石薄膜.利用扫描电子显微镜、拉曼光谱和透射电子显微镜对薄膜的形貌和结构进行了表征.研究结果表明：处于基片中心位置的薄膜具有比较高的成核密度，成核密度高达4.8×108　cm-2，并且具有〈001〉的择优取向，晶粒呈立方金刚石特征，但沿{111}晶面生长时存在大量层错.处于基片边缘的薄膜成核密度较低，晶粒为6H型多型金刚石结构，而且多型金刚石的出现，导致金刚石孪晶关系的变化.此外，根据薄膜的生长速率，探讨了MPCVD过程中掺氮对薄膜生长行为的影响.
Two-step growth of ZnO films deposited by reactive radio-frequency magnetron sputtering on Si(001) substrate
Authors: Gu Jian-Feng  , Liu Zhi-Wen  , Liu Ming  , Fu Wei-Jia  , Ma Chun-Yu  , Zhang Qing-Yu  ,   大连理工大学三束材料改性国家重点实验室，大连 116024
Published: December 2020

Using reactive radio-frequency magnetron sputtering, ZnO films have been deposited on Si(001) substrate with a two-step growth method. The first step: depositing a ZnO buffer layer at low temperature and annealing at 800 ℃, the second step: growing the ZnO at the temperature of 750 ℃. In this paper, we discuss the dependence of the ZnO film growth on the etching time of Si chips and the deposition time of the buffer layer. It is found that different deposition time of the buffer layer results in the difference in the morphology of ZnO films. The difference can be related to the coverage of the buffer layer. When the buffer layer does not cover the substrate, the ZnO film has small grains similar to the film without buffer layer and quite large roughness and internal stress. When the substrate is completely covered by the buffer layer, a ZnO film can be obtained with large-sized grains, smooth surface and low internal stress. The growth behavior of the ZnO films is also related to the etching time of Si chip. With the increase of etching time, both the roughness of the ZnO films and the correlation length of the self-affine morphology decrease.
Propagation dynamics of Laue solitons in a resonant photonic crystal
Authors: Xue Chun-Hua  , Zhou Jun  , Qi Yi-Hong  ,   (1)江苏大学机械工程学院光信息科学与技术系，镇江  212013; (2)江苏大学机械工程学院光信息科学与技术系，镇江  212013;宁波大学理学院光学研究所，宁波  315211
Published: December 2020

When an incident pulse is input obliquely with certain orientation of the reciprocal lattice vector in a resonant photonic crystal, the so-called Laue diffraction will be created. In this paper, the propagation dynamics of Laue solitons is theoretically researched, and is verified through numerical method. The results show that the incident pulse will give rise to four diffracted modes due to the nonlinear diffraction, in which the propagation dynamics of Laue solitons within the structure is similar to that of the solitons in a normal resonant medium.
Spin current of a single quantum well
Authors: Li Hong  , Wang Wei-Lu  , Gong Pi-Feng  ,   (1)东华理工学院机电工程系,南昌 330027; (2)淮北煤炭师范学院物理系,淮北 235000
Published: December 2020

Using the method of density matrix, the rate equation of electron transport in mesoscopic systems are obtained from many-body Schrdinger equation. From those equations, we deduce expressions of spin current and charge current of single quantum well. It is found that there exists only spin current under certain conditions. Then we derive connection between the left current and the right one. The result shows that when the frequency of the rf field matches the Zeeman frequency of the electron in the quantum well, the spin current has a maximum value, which decreases with spin decoherence time.
Interactions between counter-propagating photovoltaic spatial solitons
Authors: Jiang De-Sheng  , She Wei-Long  ,   中山大学光电材料与技术国家重点实验室，广州  510275
Published: December 2020

We study the interactions between two counter-propagating photovoltaic spatial solitons with different frequencies. Numerical results show that these two solitons display different dynamic characteristics during spatial evolution, which also differ obviously from the case of co-propagation. These two solitons exhibit different induced focusing or defocusing behavior when they propagate coaxially, which is sensitive to the specimen length. When they propagate in parallel and closely overlapping, the induced focusing or defocusing effects are weakened and the soliton with higher frequency attracts the one with lower frequency markedly. And their evolutions are different from the case of co-propagation.
Time-integral theorems for Birkhoff systems
Authors: Ge Wei_Kuan  , Mei Feng_Xiang  ,   (1)北京理工大学力学系,北京 100081; (2)湖州师范学院物理系,湖州 313000
Published: December 2020

The purpose of this paper is to study the time-integral theorems for the Birkhoff systems. A time-integral identity of the systems is presented. The power-like equation, the Pfaff-Birkhoff integral variational principle and the Pfaff-Birkhoff-d′Alembert differential variational principle of the systems are deduced by using the time-integral identity.
Sub-harmonic resonances of the non-autonomous system with delayed position feedback control
Authors: Wang Hong_Po  , Li Jie  ,   长沙国防科学技术大学机电工程与自动化学院磁浮工程中心，长沙 410073
Published: December 2020

The response of the Maglev system with delayed position feedback control under the sub-harmonic excitation of the flexible guideway is investigated. The dynamical model is linearized at the equilibrium. Employing time delay as its bifurcation parameter, the condition under which the Hopf bifurcation may occur is investigated. Center manifold reduction is applied to get the Poincar normal form of the nonlinear system with guideway disturbance so that we can study the relation between periodic solution and system parameter. The sub-harmonic resonant periodic solution of the normal form is calculated based on the method of multiple scales, and we get the bifurcation equation of the free oscillation. The existence condition of the free oscillation in the solution is analyzed. Relationship between periodic solution and control and excitation parameters is also investigated. Finally numerical method is applied to study how system and excitation parameters affect the system response. It was shown that the critical time delay to keep the response of the system stable is less than that without perturbation. Time delay can not only suppress sub_harmonic resonance, but also control the appearance of the chaos. Control parameter can govern the emergence of the free oscillation and affect the amplitude of the forced oscillation. So carefully selecting the system parameters can restrain the oscillation effectively.
Top- and side-view method for measuring photorefractive spatial optical solitons
Authors: Wang Cheng  , Liu Jin-Song  , Zhang Guang-Yong  , Liu Shi-Xiong  , Zhang Hui-Lan  ,   华中科技大学激光技术国家重点实验室，武汉  430074
Published: December 2020

Basing on CCD technology and software processing, a new method, namely top- and side-view method, is presented for the observation of spatial optical solitons in photorefractive crystals. When a laser beam is propagating in a crystal, this method has an ability to show the horizontal and vertical outline of the beam at any location of the crystal very intuitively. By use of this method, we have experimentally observed the two-dimension bright photovoltaic solitons in a KNSBN crystal, and the measured results are qualitatively in agreement with the results of numerical simulation.
Ground-state structures and magnetisms of GenFe(n=1—8) clusters: The density functional investigations
Authors: Zhao Wen-Jie  , Yang　Zhi  , Yan Yu-Li  , Lei Xue-Ling  , Ge Gui-Xian  , Wang Qing-Lin  , Luo You-Hua  ,   (1)河南大学物理与信息光电子学院,开封 475001; (2)河南大学物理与信息光电子学院,开封 475001；华东理工大学理学院，上海 200237
Published: December 2020

The geometries, total energies, and frequencies of GenFe(n=1—8) clusters have been systematically investigated using density functional theory with the generalized gradient approximation, and the equilibrium geometries at different spin multiplicities as well as the ground-state structures have been determined. The calculated results indicate that the average binding energy of the GenFe clusters is obviously higher than that of the corresponding pure Gen clusters, which implies that the doping of Fe atom can enhance the stability of the germanium clusters. Except for Ge2 with triplet multiplicity, the ground-state structures of pure germanium clusters are spin singlet; however, the GenFe clusters are all triplet. We also systematically studied magnetic properties of GenFe clusters and found that the total magnetic moment of cluster stabilizes at about 2μB (except for Ge8Fe with total moment of 2.391μB), and the magnetic moment of Fe atom stabilizes around 2.5μB.
Electroluminescence of polymer doped small-molecules light-emitting diodes and the effects of doping trap
Authors: Nie Hai  , Zhang Bo  , Tang Xian-Zhong  ,   (1)电子科技大学微电子与固体电子学院，成都  610054; (2)电子科技大学微电子与固体电子学院，成都  610054;成都信息工程学院，成都  610225
Published: December 2020

Polymer doped small-molecule light-emitting diodes have been fabricated using a novel PTPD (poly-TPD) as the hole transport material and the highly fluorescent rubrene as the dopant. Electroluminescent characteristics are studied at different doped concentrations and different film thicknesses. The results indicate the presence of doping trap effect. It is assumed that the traps are limited at discrete levels. Based upon the double-carrier injection theory, an analytical model of J-V characteristics of doped device is deduced by solving the Poisson equation. Calculated data of this model are consistent with our experimental results.
Numerical study on parameters for a longitudinal pulsed discharge Ne-CuBr UV laser
Authors: Mao Bang-Ning  , Chen Gang  , Wang Yu-Bo  , Chen Li  , Pan Bai-Liang  ,   浙江大学物理系，杭州 310027
Published: December 2020

A kinetic model is developed to describe the Ne-CuBr UV laser action in a longitudinal pulsed discharge. The influence of main parameters on the laser output characteristics is numerically calculated. The dependence of laser intensity on the buffer gas pressure, the operation temperature and the tube radius is found out and the experimental results are explained quantitatively. The modelling results can provide a reference to improve the laser output characteristics.
Research on selective optical amplification of Brillouin spectrum of weak scattering signals in water
Authors: Gao Wei  , Lü Zhi-Wei  , He Wei-Ming  , Zhu Cheng-Yu  , Dong Yong-Kang  ,   (1)哈尔滨工业大学光电子技术研究所，哈尔滨 150001; (2)哈尔滨理工大学应用物理系，哈尔滨 150080
Published: December 2020

The principle of selective optical amplification of weak scattering signal in water based on Brillouin amplification is presented. Based on the theoretical model of Brillouin amplification with frequency detuning, the influences of linewidth and frequency detuning of Stokes seed beam on Brillouin amplification are analyzed. The dependence of seed amplification factor on water temperature and seed power density are investigated. The theoretical calculations coincide with experimental results. Researches show that, taking the same frequency detuning into account, amplification factor of a spectrally broadened seed beam is higher than that of a narrow-linewidth signal beam. When 20℃ CS2 is used as amplifier medium, Stokes seed signals produced by different-temperature seawater are efficiently amplified. At the same pump power density, the amplification factor decreases with increasing signal power density. The amplification factor exceeds 102 for signal energy of 5μJ.
High-gain degenerated optical parametric chirped-pulse amplification in periodically poled LiTaO3
Authors: Jiang Yong-Liang  , Zhao Bao-Zhen  , Liang Xiao-Yan  , Leng Yu-Xin  , Li Ru-Xin  , Xu Zhi-Zhan  , Hu Xiao-Peng  , Zhu Shi-Ning  ,   (1)南京大学固体微结构国家重点实验室，南京 210093; (2)中国科学院上海光学精密机械研究所强场激光物理国家重点实验室，上海 201800
Published: December 2020

The gain curve in periodically poled LiTaO3 crystal (PPLT) was calculated for type 0 (e+e→e) quasi-phase matching (QPM). A high-gain amplifier centered at 1064nm based on degenerated optical parametric chirped-pulse amplification was built. The gain of ～106 and ～10.3% conversion efficiency were achieved with low pump energy of several hundreds of μJ. The experimental results are consistent with the simulation.
Momentum transfer at quantum-vacuum level inside an anisotropic magnetoelectric medium
Authors: Shen Jian-Qi  , Zhuang Fei  ,   (1)杭州师范学院理学院，凝聚态物理研究所,杭州 310012; (2)浙江大学光及电磁波研究中心，紫金港校区(东五楼)，杭州 310058；浙江大学-瑞典皇家工学院光子学联合研究中心,紫金港校区，杭州 310058
Published: December 2020

The breaking of universal symmetry of electromagnetic field distribution in an anisotropic magnetoelectric material will give rise to nonzero vacuum momentum. This may lead to the transfer of momentum between the anisotropic quantum vacuum and the magnetoelectric material. Very recently, Feigel considered the quantum vacuum contribution to the momentum transfer effect ［Phys. Rev. Lett. 92 (2004) 020404］. An alternative approach is proposed based on the eigenvector equation of electromagnetic field to calculate the total mechanical contribution of all anisotropic quantum-vacuum modes to the material momentum. It is suggested that the said macroscopic mechanical effect of quantum vacuum on the anisotropic material can be detected by current technology (e.g. fiber optical sensor), which can measure nanoscale velocity. Physical mechanism of such quantum vacuum effects and potential applications are discussed.
Multi-wavelength dispersion compensator based on fiber gratings with low crosstalk
Authors: Tan Zhong-Wei  , Cao Ji-Hong  , Chen Yong  , Liu Yan  , Ning Ti-Gang  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所，北京  100044
Published: December 2020

A novel method is proposed to suppress the crosstalk of the DWDM system with dispersion compensated by fiber gratings, combining the merits of both concatenated narrowband fiber gratings and sampled fiber gratings. Random time delay is induced only between the adjacent channels to improve the characteristics of fiber gratings' linear crosstalk, with the cross modulation effects and the four wave mixing effects being suppressed simultaneously. Using this method，we can realize the low crosstalk multi-wavelength dispersion compensators based on fiber gratings.
The theoretical study and numerical simulation of self-similar transmission of high energy wave-breaking　free ultra-short pulse
Authors: Lei Ting  , Tu Cheng-Hou  , Li En-Bang  , Li Yong-Nan  , Guo Wen-Gang  , Wei Dai  , Zhu Hui  , Lü Fu-Yun  ,   (1)南开大学物理科学学院，天津 300071; (2)天津大学精密仪器与光电子工程学院，天津 300072
Published: December 2020

The approximation of the phase introduced by self-phase modulation (SPM) is reasonably calculated and the spectrum broadening factor is given basing on nonlinear Schrdinger equation. The spectrum of propagating pulses is broadened seriously by SPM in the fiber with normal group velocity dispersion (GVD) when gain (G) exists. And the spectra broadening of the central part of pulses is quite different from that of the wings of the pulses. The self-similar evolution of Gaussian pulses is described. The temporal shape of the wings of the pulses being covered by the central part gradually is discovered. A theoretical explanation of self-similar pulses propagation is given which verified by the numerical simulation for the self-similar evolution of three kinds of pulses.
The time-window of pulse injection seeding for effective spectra linewidth narrowing of gain-switched DFB laser diodes
Authors: Wang An-Bang  , Wang Yun-Cai  , Guo Wen-Ge  , Zhang Shou-Gang  ,   (1)太原理工大学理学院物理系，太原  030024; (2)中国科学院国家授时中心，西安  710600
Published: December 2020

Spectral linewidth narrowing of gain-switched distributed feedback laser diode with pulse injection seeding is related to injection time, as indicated by experiment and theoretical analysis. The experimental and numerical simulation results show that in an approximately 100 ps time-window before the generation of optical pulse, the spectral linewidth can be narrowed dramatically by injecting pulse seeding, and that spectral linewidth decreases with increasing intensity of injection pulse. Near transform-limit low-chirp ultrashort optical pulses can be obtained with optical pulse injection seeding. A spectral linewidth reduction from 0.46 to 0.08 nm was obtained and the time-bandwidth product of 2.46 lowered down to 0.70 correspondingly in the experiment.
Characteristics of hopping conductivity in one-dimensional binary disordered system with off-diagonal correlations
Authors: Ma Song-Shan  , Xu Hui  , Liu Xiao-Liang  , Wang Huan-You  ,   (1)中南大学物理科学与技术学院,长沙 410083; (2)中南大学物理科学与技术学院,长沙 410083;中南大学材料科学与工程学院,长沙 410083
Published: December 2020

Based on a tight-binding disordered model describing a single electron band, we establish a model of electronic transport in one-dimensional binary disordered systems with off-diagonal correlations, and derive the dc conductance formula. By calculating the dc conductivity, the function of disorder and off-diagonal correlations in electronic transport are analyzed, and the relationships between electric field and conductivity and between temperature and conductivity are studied. The results indicate that the conductivity of the systems decreases with the increase of the degree of lattices energy disorder, and off-diagonal correlations lead to delocalization and enhance the electrical conductivity of system. The model also quantitatively explains the temperature and electric field dependence of the conductivity of systems, that is, the dc conductivity of the systems increases with the increasing of temperature and electric field.
Relation between breakdown voltage and current collapse in GaN FP-HEMTs
Authors: Guo Liang-Liang  , Feng Qian  , Ma Xiang-Bai  , Hao Yue  , Liu Jie  ,   西安电子科技大学微电子研究所,宽禁带半导体材料与器件教育部重点实验室,西安 710071
Published: December 2020

Passivation is generally used to suppress the current collapse, however, it also cause the decrease in breakdown voltage. By incorporating a field plate, the breakdown voltage was enhances from 46 to 148V as tested using the drain current inject technology (DCIT), which indicates that the field plate can increase the breakdown voltage remarkablely. Then, comparisons between the degrees of current collapse in the conventional HEMTs, the HEMTs after passivation and FP-HEMTs indicate that the field plate performs better in suppressing current collapse than passivation. It is conclusded that adopting the field plate structure is a good solution to the problem of incresing the breakdown voltage and at the same time suppressing the current collapse in GaN HEMTs.
A novel AlGaInP thin-film light emitting diode with omni directional reflector
Authors: Zhang Jian-Ming  , Zou De-Shu  , Liu Si-Nan  , Xu Chen  , Shen Guang-Di  ,   北京工业大学北京市光电子技术实验室,北京 100022
Published: December 2020

A novel AlGaInP thin-film light emitting diode (LED) with omni directional reflector structure was proposed, the corresponding fabrication process was developed. This reflector is realized by the combination of a low-refractive-index dielectric layer and a high reflectivity metal layer. The AlGaInP LED layers with dielectric-metal reflector is invertedly bonded to the GaAs submount by using 80Au-20Sn (wt%) alloy as a solder (Reflector-Submount, RS-LED), and then GaAs substrate is removed. The light that would otherwise be absorbed by the GaAs substrate is reflected by the high reflectivity dielectric-metal reflector. The optical and electrical characteristics of the RS-LED are presented and compared with the conventional AlGaInP absorbing substrate (AS) LED and AlGaInP absorbing substrate LED with distributed Bragg reflectors (DBR). A great improvement in the brightness and efficiency is observed. It is shown that the light output and lumen efficiency from the RS-LED at forward current 20mA exceed those of AS-LED by about a factor of 2.2 and 1.2, respectively, and ～2× the light output of AS-LED (DBR) and ～1.5× the lumen efficiency of AS-LED　(DBR) were achieved. 194.3mcd luminous intensity from the RS-LED (at 20mA, peak wavelength 627nm) could be obtained under 20mA injection, which is 2.8 and 1.6 times higher in luminous intensity than the AS-LED (at 20mA, peak wavelength 624nm) and AS-LED(DBR) (at 20mA, peak wavelength 623nm), respectively.