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The Interaction of Peregrine Solitons
WU Zhen-Kun, ZHANG Yun-Zhe, HU Yi, WEN Feng, ZHANG Yi-Qi, ZHANG Yan-Peng
Chin. Phys. Lett. 2014, 31 (09):
090502
.
DOI: 10.1088/0256-307X/31/9/090502
We theoretically investigate the interaction of two in-phase and out-of-phase Peregrine solitons in a Kerr nonlinear medium, addressing both the cases of first- and second-order solitons. Upon adjusting the interval between the solitons, their interactions exhibit different properties. If the interval is sufficiently large, two Peregrine solitons will propagate individually and will not interact each other. However, if the interval is not very large, the Peregrine solitons will strongly interact and display varying behavior.
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Proton Spectroscopic Factors Deduced from Helium-3 Global Phenomenological and Microscopic Optical Model Potentials
Jenny LEE, PANG Dan-Yang, HAN Yin-Lu, M. B. Tsang
Chin. Phys. Lett. 2014, 31 (09):
092103
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DOI: 10.1088/0256-307X/31/9/092103
Global phenomenological GDP08 and microscopic helium-3 optical model potentials have been recently derived. We evaluate these two potential sets by comparing the elastic scattering data of 25 MeV 3He on 16O, 18O, 19F, 23Na, 24Mg, 25Mg, 26Mg, 27Al, 28Si, 30Si, 31P, 32S, 34S, 35Cl, 37Cl, and 39K isotopes. Using the deuteron angular distributions calculated with the distorted wave Born approximation model, we extract the ground-state proton spectroscopic factors from (3He, d) reactions on the same set of nuclei. The extracted proton spectroscopic factors are compared with the large-basis shell-model calculations.
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A Sensitivity Test of Extracting the Optical Potential Parameters for 6He+209Bi from the Transfer Reaction 208Pb(7Li,6He)209Bi
WU Zhen-Dong, YANG Lei, LIN Cheng-Jian, JIA Hui-Ming, YANG Feng, XU Xin-Xing, ZHANG Huan-Qiao, LIU Zu-Hua, BAO Peng-Fei, SUN Li-Jie, MA Nan-Ru, ZHENG Lei
Chin. Phys. Lett. 2014, 31 (09):
092401
.
DOI: 10.1088/0256-307X/31/9/092401
Recently, an indirect method has been proposed to study the optical model potential of exotic nuclear systems by fitting the transfer reaction angular distribution. The sensitivity test of this transfer method is performed with 208Pb(7Li,6He)209Bi as an example, by varying the potential parameters individually. The results indicate that, except for the ambiguity in the real potential depth V, other optical potential parameters of 6He+209Bi as well as the structural information of the reactions can be extracted reliably. Moreover, the radius parameter of the bound state, rbound, is an extraordinarily sensitive parameter, which should be taken care of in the calculation procedure. The present work provides a theoretical reference for the application of the transfer method.
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A 52-mJ Ho:YAG Master Oscillator and Power Amplifier with Kilohertz Pulse Repetition Frequency
QIAN Chuan-Peng, YAO Bao-Quan, DUAN Xiao-Ming, JU You-Lun, YU Kuai-Kuai, WANG Yue-Zhu
Chin. Phys. Lett. 2014, 31 (09):
094201
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DOI: 10.1088/0256-307X/31/9/094201
We report on a high energy, high repetition rate Ho:YAG master oscillator and power amplifier (MOPA), resonantly dual-end-pumped by Tm:YLF lasers at room temperature. At the pulse repetition frequency of 1 kHz, we demonstrate a maximum energy of 30 mJ per pulse with a 28.2 ns pulse width in a Ho:YAG oscillator system resonantly double-end-pumped by Tm:YLF lasers. A maximum energy of 52 mJ per pulse with a 30.5 ns pulse width is achieved in the Ho:YAG amplifier, corresponding to a peak power of approximately 1.7 MW. The output wavelength is at 2090.6 nm and 2096.9 nm, and a beam quality factor of M2~2.1 is achieved.
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A Mode-Locked Soliton Erbium-Doped Fiber Laser with a Single-Walled Carbon Nanotube Poly-Ethylene Oxide Film Saturable Absorber
R. Z. R. R. Rosdin, F. Ahmad, N. M. Ali, R. M. Nor, N. R. Zulkepely, S. W. Harun, H. Arof
Chin. Phys. Lett. 2014, 31 (09):
094202
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DOI: 10.1088/0256-307X/31/9/094202
We present a simple, compact and low-cost mode-locked erbium-doped fiber laser (EDFL) using single-walled carbon nanotubes (SWCNTs) embedded in a poly-ethylene oxide (PEO) thin film as a passive saturable absorber. The film is fabricated by using a prepared homogeneous SWCNT solution, which is mixed with a diluted PEO solution and cast onto a glass Petri dish to form, by evaporation, a thin film. The 50 μm-thick film is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate self-started stable soliton pulses operating at 1560.8 nm. The soliton pulse starts to lase at a pump power threshold of 12.3 mW with a repetition rate of 11.21 MHz, a pulse width of 1.02 ps, an average output power of 0.65 mW and a pulse energy of 57.98 pJ.
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Crack Arrest in Brittle Ceramics Subjected to Thermal Shock and Ablation
WANG Yan-Wei, YU He-Long, TANG Hong-Xiang, FENG Xue
Chin. Phys. Lett. 2014, 31 (09):
094601
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DOI: 10.1088/0256-307X/31/9/094601
Ceramics are suitable for high temperature applications, especially for aerospace materials. When serving in high temperature environments, ceramics usually have to deal with the challenge of both thermal shock and ablation. We report the crack arrest in brittle ceramics during thermal shock and ablation. In our experiment, the specimens of Al2O3 are subjected to oxygen-propane flame heating until the temperature arises up to 1046°C and then are cooled down in air. The crack occurs, however, it does not propagate when arrested by the microstructures (e.g., micro-bridges) of the crack tip. Such micro-bridge enhances the toughness of the brittle ceramics and prevents the crack propagation, which provides a hint for design of materials against the thermal shock.
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Placement Scheme of Numerous Laser Beams in the Context of Fiber-Based Laser Fusion
XU Teng, XU Li-Xin, WANG An-Ting, GU Chun, WANG Sheng-Bo, LIU Jing, WEI An-Kun
Chin. Phys. Lett. 2014, 31 (09):
095201
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DOI: 10.1088/0256-307X/31/9/095201
A simple scheme based on the uniform distribution for the placement of numerous laser beams in the context of fiber-based laser fusion is proposed. It is theoretically demonstrated that all modes of the geometrical factor can be eliminated if sufficient laser beams are uniformly distributed on the sphere. In the case of a finite number of laser beams, a quasi-uniform distribution of beams can be achieved based on the equal area subdivision algorithm. Numerical simulations indicate that with the increasing number of laser beams, the order of the dominant geometrical mode increases, and the irradiation nonuniformity decreases accordingly.
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Millimeter Propagation and High Confinement in Rhombus-Based Hybrid Plasmonic Waveguides
HU Ru, LANG Pei-Lin, ZHAO Yu-Fang, DUAN Gao-Yan, WANG Lu-Lu, DAI Jin, CHEN Zhao, YU Li, XIAO Jing-Hua
Chin. Phys. Lett. 2014, 31 (09):
095202
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DOI: 10.1088/0256-307X/31/9/095202
A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metal, is proposed and numerically analyzed by the finite-element method. Simulations show that the present waveguide can achieve the millimeter propagation distance (1244 μm) and deep subwavelength mode area (5.5×10?3 μm2), simultaneously. Compared with the previous hybrid waveguides based on cylinder nanowires or flat films, the rhombic corner angles enable our waveguide to achieve both longer propagation distance and smaller mode area. This is due to the enhanced coupling between the dielectric guided mode in nanowires and the surface plasmon polariton mode at rhombic surface. Furthermore, the extreme confinement near the rhombic corner angles can strengthen the light-matter interaction greatly and make the present waveguide useful in many applications, such as nonlinear photonics, high-quality nanolasers and nanophotonic waveguides.
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Analysis of Atomic Electronic Excitation in Nonequilibrium Air Plasmas
HE Xin, DANG Wei-Hua, JIA Hong-Hui, YIN Hong-Wei, ZHANG Hai-Liang, CHANG Sheng-Li, YANG Jun-Cai
Chin. Phys. Lett. 2014, 31 (09):
095204
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DOI: 10.1088/0256-307X/31/9/095204
Electronic excitation of atoms is studied in nonequilibrium air plasmas with the electronic temperature between 8000 K and 20000 K. By using the modified Saha–Boltzmann equation, our simplified method takes into account significant radiative processes and strong self-absorption of the vacuum ultraviolet lines. Calculations are carried out at three trajectory points of the Fire II flight experiment. Good agreement with the detailed collisional-radiative model is obtained, and the performance of this method in applications to highly nonequilibrium conditions is better than Park's quasi-steady-state model and Spradian-9.0. A short discussion on the influence of optical thickness of the vacuum ultraviolet radiation is also given. It costs about 2.9 ms on the average to solve one cell of the shock layer on a low cost computer, which shows that the present method is fast and efficient.
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States of Excitons and Linear Optical Spectra in Metallic Single-Walled Carbon Nanotubes
YU Gui-Li, LI Gui-Chen, JIA Yong-Lei, TANG Gang
Chin. Phys. Lett. 2014, 31 (09):
097102
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DOI: 10.1088/0256-307X/31/9/097102
Considering the exciton effect, the excitation energy and its binding energy of the metallic single-walled carbon nanotubes (SWNTs) are theoretically studied by using the simple tight-binding model, based on which the linear absorption spectra are also calculated. It is found that due to the trigonal warping effect, the excitation energies of the linear optical spectra all are split into two corresponding ones. Additionally, the splitting depends on both the chirality and the transition energy: (1) the splitting is maximal for the zigzag tubes, the splitting decreases with the increasing chiral angle; (2) the higher the transition energy is, the larger the splitting is. It is very interesting to find that the obtained results are in good agreement with the experimental results.
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Transport Behavior in Spinel Oxide MgTi2O4
ZHU Yuan-Yuan, WANG Rong-Juan, WANG Li, LIU Yong, XIONG Rui, SHI Jing, AN Li-Heng, SUN Duo-Hua
Chin. Phys. Lett. 2014, 31 (09):
097201
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DOI: 10.1088/0256-307X/31/9/097201
Spinel oxide MgTi2O4 is synthesized by the spark plasma sintering method. The temperature dependences of magnetic susceptibility and resistance are measured and investigated in detail. It is shown that the transition of MgTi2O4 occurs at the phase transition temperature Tt~258 K. The fits of resistance versus temperature curve demonstrate that MgTi2O4 displays metal behavior above Tt, while a dual conducting mechanism, the Mott-insulator-like variable range hopping and normal activated conduction, is suggested to be responsible for the transport behavior of MgTi2O4 below Tt.
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Effects of Pretreatment on the Electronic Properties of Plasma Enhanced Chemical Vapor Deposition Hetero-Epitaxial Graphene Devices
ZHANG Lian-Chang, SHI Zhi-Wen, YANG Rong, HUANG Jian
Chin. Phys. Lett. 2014, 31 (09):
097301
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DOI: 10.1088/0256-307X/31/9/097301
Quasi-monolayer graphene is successfully grown by the plasma enhanced chemical vapor deposition hetero-epitaxial method we reported previously. To measure its electrical properties, the prepared graphene is fabricated into Hall ball shaped devices by the routine micro-fabrication method. However, impurity molecules adsorbed onto the graphene surface will impose considerable doping effects on the one-atom-thick film material. Our experiment demonstrates that pretreatment of the device by heat radiation baking and electrical annealing can dramatically influence the doping state of the graphene and consequently modify the electrical properties. While graphene in the as-fabricated device is highly p-doped, as confirmed by the position of the Dirac point at far more than +60 V, baking treatment at temperatures around 180°C can significantly lower the doping level and reduce the conductivity. The following electrical annealing is much more efficient to desorb the extrinsic molecules, as confirmed by the in situ measurement, and as a result, further modify the doping state and electrical properties of the graphene, causing a considerable drop of the conductivity and a shifting of Dirac point from beyond +60 V to 0 V.
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Extraction of Channel Length Independent Series Resistance for Deeply Scaled Metal-Oxide-Semiconductor Field-Effect Transistors
MA Li-Juan, JI Xiao-Li, CHEN Yuan-Cong, XIA Hao-Guang, ZHU Chen-Xin, GUO Qiang, YAN Feng
Chin. Phys. Lett. 2014, 31 (09):
097302
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DOI: 10.1088/0256-307X/31/9/097302
The recently developed four Rsd extraction methods from a single device, involving the constant-mobility method, the direct Id–Vgs method, the conductance method and the Y-function method, are evaluated on 32 nm n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs). It is found that Rsd achieved from the constant-mobility method exhibits the channel length independent characteristics. The L-dependent Rsd extracted from the other three methods is proven to be associated with the gate-voltage-induced mobility degradation in the extraction procedures. Based on L-dependent behaviors of Rsd, a new method is proposed for accurate series resistance extraction on deeply scaled MOSFETs.
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Efficient Phosphorescent Organic Light Emitting Diodes Using F4TCNQ as the Indium-Tin-Oxide Modification Layer
JIAO Bo, ZHU Xiao-Bo, WU Zhao-Xin, YU Yue, HOU Xun
Chin. Phys. Lett. 2014, 31 (09):
097801
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DOI: 10.1088/0256-307X/31/9/097801
A phosphorescent organic light emitting diode by using tetrafluorotetracyanoquinodimethane (FTCNQ) as the indium-tin-oxide modification layer and 4,4'-bis(carbazol-9-yl)biphenyl (CBP) as the hole transporting layer is reported. CBP doped with a green phosphorescent dopant, tris(2-(p-tolyl)pyridine) iridium(III) (Ir(mppy)3) is used as the emission layer in this device, and the maximum current efficiency of 31.3 cd/A is achieved. Furthermore, low efficiency roll-off of 10.4% is observed with device luminance increasing from 100 cd/m2 (29.7 cd/A) to 10000 cd/m2 (26.5 cd/A). It is demonstrated that a charge-generation area is formed at F4TCNQ/CBP interface, which will benefit hole injection into the hole transporting layer. Moreover, use of the CBP hole transporting layer will benefit the low efficiency roll-off by broadening triplet exciton formation, as well as by avoiding accumulation of unbalanced carrier at the hole transporting layer/emission layer interface.
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An Ultra-Miniature Cell-Type Rb Atomic Clock Based on a Novel Waveguide Cavity
BAI Li-Na, CAO Yuan-Hong, LIU Lei-Ji, YANG Lin, ZHENG Xing-Shi, ZHOU Wei
Chin. Phys. Lett. 2014, 31 (09):
098402
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DOI: 10.1088/0256-307X/31/9/098402
We introduce a novel waveguide cavity for ultra-miniature cell-type Rb atomic clock. In the cavity, a coupling ring shaped to be a semi-circle imports an rf signal from electronics, a screw regulator acts as a medium coupler to transmit the microwave signal into the absorption cell, and both the parts serve as a filter to suppress useless components except 6.8 GHz. Furthermore, the waveguide cavity can be used to design a miniature Rb atomic clock, and spread it to a chip-scale atomic clock. We have completed the design of the smallest cell-type Rb atomic clock in the world based on this waveguide cavity. It has not only a small size but also obviously better key performances than those of other miniature Rb atomic clocks. This ultra-miniature cell-type Rb atomic clock aging is 4×10?13/d, which is obviously slower than that of other miniature Rb atomic clocks.
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44 articles
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