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981.
F. Martinez-Pinon J. A. Alvarez-Chavez D. Jaramillo-Vigueras L. de la Cruz-May H. L. Offerhaus 《Laser Physics》2008,18(11):1340-1343
Results on high radiance Yb3+-doped fiber lasers with novel double innerclad structures (double-D clad and four hole) and polarized output at ≈1090 nm are presented. We have demonstrated >40% of the total output power being polarized, making the fiber laser suitable for LIDAR and second-harmonic generation (SHG) applications. It also showed a 10-nm tuning range with low (less than 10 mW) average power variations. The narrow linewidth source was pumped with a low cost, low brightness laser diode, and exhibited a relatively low slope efficiency, which gives room for improvement by using a 976-nm pump source where Yb3+ has a narrower linewidth and at least five times higher absorption. 相似文献
982.
We solve the general problem of mixing of electromagnetic and scalar or pseudoscalar fields coupled by axion-type interactions
L
int = g
ϕ
ϕε
μναβ
F
μν
F
αβ
. The problem depends on several dimensionful scales, including the magnitude and direction of background magnetic field,
the pseudoscalar mass, plasma frequency, propagation frequency, wave number, and finally the pseudoscalar coupling. We apply
the results to the first consistent calculations of the mixing of light propagating in a background magnetic field of varying
directions, which show a great variety of fascinating resonant and polarization effects.
相似文献
983.
Direct Numerical Simulation (DNS) of decaying isotropic 3D magnetohydrodynamic (MHD) turbulence based on the 10243-modes in a periodic box is used to study the statistical properties of turbulence. In this paper, the presence of intermittency in MHD turbulence is investigated through the analysis of the Probability Distribution Function (PDF) for Elsässer fields and total energy fluctuations. We observe that the PDFs of the Elsässer fields fluctuations display a strong non-Gaussian behavior at small scale, which can be ascribed to multifractality feature, while the PDFs of the total energy fluctuations have the same shape over all observed scales and are monofractal. The PDFs have stretched exponential tail and satisfy the function P(|δX|) ~ exp(?A|δX| μ ). Numerically, we extract the exponent μ and find that it is constant for monofractal behavior as the length scale varies. To check the notion of self-similarity in the respective fluctuation, we apply the compensated structure functions. 相似文献
984.
Sumana Chakraborty Yew Kam Ho 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):59-65
This work presents an investigation on the doubly excited 1S
e
autoionizing states of screened helium atom lying below the n = 4 threshold of the He+ ion. The potential generated in this system is represented by a Yukawa type potential. We have employed complex-coordinate
rotation method, as it is a powerful scheme to study high lying resonances. Hylleraas type wave function is used to consider
the correlation effect between all the charged particles. Our resonance parameters for the resonances lying below the He+ (n = 2) threshold agree well with those of the existing calculations by using the stabilization method. Resonances associated
with higher thresholds are new calculations. All the present results are well converged with basis length N = 444. 相似文献
985.
We have studied the tunneling conductance in ferromagnet/insulator/p-wave superconductor junctions, taking into account the
rough interface scattering effect. We find that there exist zero-bias conductance peaks and single-minimum structure in tunneling
spectroscopy. As the exchange energy increases, the Andreev reflection is always suppressed and the differential conductance
decreases. The differential conductance depends on the barrier strength and the roughness at the interface.
Supported by the Natural Science Foundation of Jiangsu Higher Education Institutions, China (Grant No. 06KJB140009) 相似文献
986.
We review recent structural studies that we have undertaken aimed at elucidating the fundamental properties of metal-organic
framework materials and their interactions with hydrogen. We have shown that exposing coordinatively unsaturated metal centers
can greatly enhance the hydrogen binding energy and that they result in a significant increase of the surface packing density
of adsorbed hydrogen molecules on materials’ surface. We will review some of the structural aspects of these materials, especially
the adsorbed hydrogen molecule surface packing density in one type of metal-organic framework, MOF-74, which can be packed
even denser than that in solid hydrogen.
相似文献
987.
The phase diagram of the coupled sine circle map system exhibits a variety of interesting phenomena including spreading regions
with spatiotemporal intermittency, non-spreading regions with spatial intermittency, and coherent structures termed solitons.
A spreading to non-spreading transition is seen in the system. A cellular automaton version of the coupled system maps the
spreading to non-spreading transition to a transition from a probabilistic to a deterministic cellular automaton. The solitonic
sector of the system shows spatiotemporal intermittency with soliton creation, propagation and absorption. A probabilistic
cellular automaton mapping is set up for this sector which can identify each one of these phenomena.
相似文献
988.
Maleic anhydride was grafted by long-chain alcohols (1-hexadecanol, 1-octadecanol) to amphiphilic mono-L cis-butene dicarboxylates (L = hexadecyl, octadecyl), i.e., MAH, MAO, respectively. Subsequently, corresponding amphiphilic cerium
complexes with these two mono-L cis-butene dicarboxylate ligands (Ce(L')3, L'= MAH, MAO) were synthesized and behaved as the precursors to prepare CeO2 nanoparticles for both of which can form nanosized micelle-like aggregates by special self-assembly in the wet chemical process.
The nanoparticles were further characterized by Fourier transform-infrared spectroscopy (FTIR), Diffuse reflectance ultraviolet-visible
spectra (DRUVS), scanning electron microscope (SEM), transmission electron microscope (TEM), and x-ray diffraction (XRD).
Both the CeO2 nanoparticles are in a cubic fluorite structure and present regular and well-dispersion club-like morphology with average
particle size in the range of 40–70 nm. Besides, the strong ultraviolet–visible absorption for these CeO2 nanoparticles can be found at the long-wavelength ultraviolet to visible region of 200–500 nm. 相似文献
989.
Xinzheng Zhang Jingmin Zhang Li Chen Jun Xu Liping You Dapeng Yu 《Applied Physics A: Materials Science & Processing》2008,92(3):669-672
In order to well understand the growth mechanism of the diverse morphology of the ZnO nanostructures, in situ analysis of
the formation of different ZnO nanostructures, such as nanowires, nanocombs, and nanosheets, has been conducted in an environmental
scanning electron microscope (ESEM). It is found that both nanocombs and nanosheets grew in two-stage heating processes on
parent nanowires. The difference is that the nanocombs were synthesized in extremely high pressure of zinc vapor via a self-catalyzed
vapor-liquid-solid process, while the ZnO nanosheets were grown in relatively low pressure of zinc vapor. All the growth processes
were revealed in real time imaging. It is demonstrated that the change in the growth environments can influence the thickness
of the ZnO polycrystalline surface of the zinc powder, which alters the pressure of the zinc vapor and in turn determines
the morphology of the final nanostructures. 相似文献
990.
Jiří Herec 《Czechoslovak Journal of Physics》2004,54(12):1473-1481
In this paper the quantum-statistical properties of light beams propagating in a directional nonlinear coupler are investigated.
This device is composed of a pair of linearly coupled nonlinear waveguides operating by means of degenerate parametric downconversion.
The possibility of generation of nonclassical states of light in single and compound modes, using the short-length approximation,
is discussed. Influence of linear and nonlinear mismatches for generation of nonclassical light is taken into account.
This work was supported by Project LN00A015, Research Project No. CEZ: J14/98 and the COST project OC P11.003 of the Czech
Ministry of Education. 相似文献