Optical properties of ytterbium-doped tandem-pumped fiber oscillatorOptical properties of ytterbium-doped tandem-pumped fiber oscillatorOptical properties of ytterbium-doped tandem-pumped fiber oscillator

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-rim fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.     

Spectroscopic properties of Δ baryons

The resonance state of the ? baryon, which exists in four isospin( I = 3/2) states, has been studied using the hypercentral constituent quark model(hCQM) with a simple linear potential with added first order correction.The calculated data ranges for 1S-5S, 1P-5P, 1D-4D and 1F-2F are given, with possible spin-parity assignments for all the states. The magnetic moments have also been obtained for all four configurations. The Nπ decay channel width has been calculated for a few states. The linear nature of the data has been verified through Regge trajectories.     

Magneto-optical properties of terbium glass

Dispersion of the Verdet Constant of Tb-glass is investigated.The cause of thisdispersion is dicussed by a comparison with the dispersion of refractive index.Relationship be-tween the Verdet constant and Tb~(3 ) concentration is summaried and can be used to estimatethe Verdet constant of Tb~(3 )-materials.     

Atomistic properties of γ uranium

The properties of the body-centered cubic γ phase of uranium (U) are calculated using atomistic simulations. First, a modified embedded-atom method interatomic potential is developed for the high temperature body-centered cubic (γ) phase of U. This phase is stable only at high temperatures and is thus relatively inaccessible to first principles calculations and room temperature experiments. Using this potential, equilibrium volume and elastic constants are calculated at 0 K and found to be in close agreement with previous first principles calculations. Further, the melting point, heat capacity, enthalpy of fusion, thermal expansion and volume change upon melting are calculated and found to be in reasonable agreement with experiment. The low temperature mechanical instability of γ U is correctly predicted and investigated as a function of pressure. The mechanical instability is suppressed at pressures greater than 17.2 GPa. The vacancy formation energy is analyzed as a function of pressure and shows a linear trend, allowing for the calculation of the extrapolated zero pressure vacancy formation energy. Finally, the self-defect formation energy is analyzed as a function of temperature. This is the first atomistic calculation of γ U properties above 0 K with interatomic potentials.     

Anisotropic properties of TaS2

The anisotropic properties of 1T- and 2H-TaS2 axe investigated by the density functional theory within the framework of full-potential linearized augmented plane wave method. The band structures of 1T- and 2H-TaS2 exhibit anisotropic properties and the calculated electronic specific-heat coefficient γ of 2H-TaS2 accords well with the existing experimental value. The anisotropic frequency-dependent dielectric functions including the effect of the Drude term are analysed, where the ε^xx（ω） spectra corresponding to the electric field E perpendicular to the z axis show excellent agreement with the measured results except for the ε1^xx（ω） of 1T-TaS2 below the energy level of 2.6 eV which is due to the lack of the enough CDW information for reference in our calculation. Furthermore, based on the values of optical effective mass ratio P of 1T and 2H phases it is found that the anisotropy in 2H-TaS2 is stronger than that in 1T-TaS2.     

Theoretical investigation of nonlinear properties of electrooptical chromophores

Organic electrooptical (EO) chromophores are now gaining more attention because the property of organic photorefrative (PR) materials could be controlled by doped EO chromophores. In this paper, nonlinear optical (NLO) properties of a new group of organic electrooptical chromophores, synthesized recently in our laboratory, were elucidated theoretically with the quantum chemical density functional theory (DFT) and the intermediate neglect of differential overlap Hamilton and the configuration interaction (INDO/CI), as well as semiemperical Austin Model 1 (AM1) methods. The electronic transition intensity, dipole moment and the second- order polarizability were obtained. The results show this group of chrormophores possess appropriate optical absorption property and good electrooptical property and optical activity. The second-order polarizabilities βare as large as the order of 10-29 to 10-28 ESU, indicating the promising applications in the future. The physical mechanism of NLO is discussed by means of molecular orbital and electronic charge distribution.     

Design and properties of binary axilens

A novel optical element, axilens, proposed by Davidson et al., for achieving extended focal length is introduced. We propose a method to design the binary axilens which has high diffraction efficiency. Using computer numerical simulation, we designed 4 axilenses each has different parameters. In this paper we present our results and make comparison with that in ref. [1]. The properties of binary axilens such as the focal depth, the lateral resolution and the intensity distribution along axis is discussed.     

Optical absorption properties of Ge-Sb-Te films

The optical properties of monolayer Ge2Sb2Te5 thin films with three different thicknesses prepared by dc magnetron sputtering method at the range of 400-800 nm were studied. The optical absorption coefficients and the optical energy gap (Eg) were calculated, The results gave values for the absorption coefficients in the range of (1.3-7.5)×105 cm-1 which were in the high absorption wavelength region of     

Design and properties of binary axilens

A novel optical element, axilens, proposed by Davidson et al., for achieving extended focal length is introduced. We propose a method to design the binary axilens which has high diffraction efficiency. Using computer numerical simulation, we designed 4 axilenses each has different parameters. In this paper we present our results and make comparison with that in ref. [1]. The properties of binary axilens such as the focal depth, the lateral resolution and the intensity distribution along axis is discussed.     

The NUBASE2012 evaluation of nuclear properties

This paper presents the Nubase2012 evaluation that contains the recommended values for nuclear and decay properties of nuclides in their ground and excited isomeric(T1/2>100 ns) states.All nuclides for which some experimental information is known are considered.NUBASE2012 covers all up to date experimental data published in primary(journal articles) and secondary(mainly laboratory reports and conference proceedings) references,together with the corresponding bibliographical information.During the development of NUBASE2012,the data available in the "Evaluated Nuclear Structure Data File"(Ensdf) database were consalted,and critically assessed of their validity and completeness.Furthermore,a large amount of new and somewhat older experimental results that were missing in Ensdf were compiled,evaluated and included in NUBASE2012.The atomic mass values were taken from the "Atomic Mass Evaluation"(AME2012,second and third parts of the present issue).In cases where no experimental data were available for a particular nuclide,trends in the behavior of specific properties in neighboring nuclei(TNN) were examined.This approach allowed to estimate,whenever possible,values for a range of properties,and are labeled in NUBASE2012 as "non-experimental"(lagged "#").Evaluation procedures and policies that were used during the development of this database are presented,together with a detailed table of recommended values and their uncertainties.     

Magnetic properties of TiZr alloys

Magnetic susceptibility measurements of TiZr alloys are reported. Zirconium, by alloying, acts on the Néel temperature giving rise to a complicated magnetic phase diagram. The main mechanism in the T_N shift is the change of the Fermi level. The experimental dependence between T_N and X₀ is in good agreement with the theoretical dependence obtained on the Fedders-Martin model by taking into account the effect of nonmagnetic impurity on the Fermi level.     

Decay properties of N ≃ Z nuclei

This review focusses on recent results obtained by using fusion-evaporation reactions for the production of N ≃ Z nuclei, the on-line mass separator of GSI for the preparation of the radioactive samples, and charged-particle and γ-ray detectors for performing decay spectroscopy. The experimental results on prompt and β-delayed disintegration modes are discussed in comparison with theoretical model predictions. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: e.roeckl@gsi.de     

Optical properties of Hg1−xCdxTe

Optical properties of Hg_1−xCd_xTe are summarized in this study. Based on Penn-like models, the Moss relation and the Wemple and DiDomenico approach, calculations of energy gap, plasmon energy, Fermi energy, oscillator strength and electronic polarizability have been made. Comparisons are made with the data available in the literature. Details of the dependency of the properties on composition are presented.     

Nonlinear optical properties of polyaniline composite materials

The nonlinear optical properties of polyaniline composite materials (PANI/Au) were studied using the single-beam Z-scan technique.These molecules exhibited a strong reverse saturable absorption and an interesting optical limiting performance with a nanosecond Nd:YAG laser pulses at 532 nm.     

Propagation properties of Airy–Gaussian beams

The propagation of the Airy–Gaussian beams is studied in strongly nonlocal nonlinear media analytically and numerically. The linear momentum of the analytical Airy–Gaussian beam solution of the Snyder–Mitchell model is not conservational, which is the reason that results in the disagreement between the analytical Airy–Gaussian beam solution and the numerical simulations of the nonlocal nonlinear Schr?dinger equation in the case of strong nonlocality. The quasi-Airy–Gaussian soliton in the Gaussian-shaped response material can be obtained when the parameter χ ₀ is large enough, and the patterns of Airy–Gaussian beams are variable periodically in liquid crystal material during propagation.     

Photocurrent properties of high-sensitivity GaN ultraviolet photodetectors

GaN epilayers were grown on sapphire substrates by metal-organic chemical vapour deposition. Metal-semiconductor-metal photoconductive detectors were fabricated using this material. The photocurrent properties of the detectors were measured and analysed. The spectrum response shows a high sensitivity in the wavelength region from 330 to 360nm, with a peak at 358um and a sharp cutoff near 360nm. The maximum responsivities at 358nm were 700A/W (2V) and 7000A/W (30V). The relationship between responsivity and bias indicates that the responsivity increases linearly with bias until 30V. The influence of the spacing between two electrodes on the detector responsivity was also studied.     

Spectroscopic properties of neodymium-doped tellurite glass fiber

Nd~(3+)-doped tellurite glass and a single mode tellurite glass fiber with a core diameter of 8 μm were prepared in this work. The 1.33-μm emission from the ~4F_(3/2)→~4I_(13/2) transition of Nd~(3+) with a spectral bandwidth of 55 nm in tellurite glass fiber is observed. The lifetime of 164 μs of ~4F_(3/2) level and quantum efficiency of about 100% are obtained.     

Mechanical properties of kaolinite ‘macro-crystals’

The mechanical properties of a rare sample of kaolinite macroscopic crystals were evaluated using instrumented indentation. The crystals were also characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy before and after heat treatment at 1100°C. The results are explained in terms of the fracture process occurring in the layered structure of kaolinite, and of the effect of roughness on the hardness and elastic modulus. Data analysis using One-way ANOVA (p?<?0.05) showed that the values of hardness and elastic modulus obtained are statistically homogeneous. Before heat treatment, the sample was composed essentially of kaolinite, with hardness of 42?MPa and elastic modulus equal to 1.3?GPa. After calcination at 1100°C, the sample keeps its layered habit and consists of amorphous metakaolinite. The hardness increases to 360?MPa and the elastic modulus increases to 6.9?GPa.