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1.
Polymethyl methacrylate (PMMA) is one of the most commonly used optical materials. However, the application of it in the area of optical communication is strongly limited by the intrinsic absorption loss of carbon-hydrogen stretching vibration. In this paper, we present a method to solve the problem by adopting the hollow-core fibers with cobweb cladding structure. The fibers use a single dielectric material and may solve the problem of structural support. Thus the feasibility of the “OmniGuide” fibers is improved, while a series of advantages of the “OmniGuide” hollow-core fiber are retained. It is promising that a fiber with low transmission loss, high bandwidth, large-core, and low costs can be designed and fabricated using PMMA. At the same time, a very broad range of the wavelengths (from visible to near infrared region, for instance, wavelengths at 0.65-1.12 μm, and even 1.30 μm, 1.54 μm and their neighbors) may be adopted for signal wavelength. 相似文献
2.
Long-period fibre gratings inside standard single-mode optical communication fibres are successfully fabricated with infrared femtosecond laser pulses. The refractive index perturbations are well confined within the fibre core by choosing the proper laser focusing parameters and translation speed of the fibre during the direct laser writing process. With the self-focusing effect considered and at a constant average irradiation dose of 1.62 × 10^3 J/(cm^2μm), the threshold intensity for fabricating long-period gratings with infrared femtosecond laser pulses is determined to be 5.13 × 10^13 W/cm2. 相似文献
3.
Zhigang Yin Nuofu Chen Shulin Song Jun Zhong Kurash Ibrahim 《Solid State Communications》2005,135(7):430-433
Nickel-doped ZnO (Zn1−xNixO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni has a chemical valence of 2+. According to the magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn0.86Ni0.14O. We studied the electronic structure of Zn0.86Ni0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at ∼2 eV below the Fermi energy EF, which is of Ni 3d origin. No emission was found at EF, suggesting the insulating nature of the film. 相似文献
4.
F. A. Gianturco J. A. Rodriguez-Ruiz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,31(3):149-159
The many-body correlation forces, which act between the impinging electron and the bound electrons of the two heaviest rare gas atoms, are treated here using a newly developed correlation-polarisation potential that originates from the calculation of correlation energies in electronic bound-states of atoms and molecules. The new formulation of such forces, already tested by us for the lighter atomic targets, is particularly effective for the present systems and can be implemented very easily even for heavy atomic targets. The calculations reported in this paper show clearly that very good accord is obtained with more sophisticated theoretical treatments and with several experimental data on integral cross sections, momentum transfer cross sections and angular distributions.Von Humboldt — Prize Awardee 1992 相似文献
5.
Electronically elastic, electron scattering cross sections are calculated for molecules in particular rotational states in order to establish the sensitivity of the scattering pattern to the quantum state. For the examples of diatomic molecules and symmetric tops considered here, the scattering pattern provides a unique fingerprint of the quantum state if one measures the scattered intensity for different orientations of the scattering vectors. The structure in the scattered intensity reflects the anisotropy of the square of the rotational wavefunction. Even for low angular momentum states which have diffuse rotational wavefunctions, very large differences in intensity are the result at certain scattering angles for states whose quantum numbers differ even by only one unit. 相似文献
6.
Hisashi Shima Fumiyoshi Takano Hidenobu Muramatsu Masashi Yamazaki Hiroyuki Akinaga Akinori Kogure 《固体物理学:研究快报》2008,2(3):99-101
Kelvin probe force microscopy (KFM) and conductive atomic force microscopy (C‐AFM) together with micro X‐ray photoelectron spectroscopy (XPS) were performed for the stacking structure comprising of the transition metal oxide Co–O and metal electrode, which exhibits large reproducible resistance switching. The application of the external voltage by the C‐AFM cantilever decreases the resistance of Co–O, which well accords with the non‐polar forming process observed in the Pt/Co–O/Pt trilayer, known as the candidate of resistance random access memory (ReRAM). Furthermore, the KFM and micro XPS experimentally revealed that the local reductive reaction of Co–O possibly nucleates the defect related energy levels which dominates the current conduction in the low resistance state. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
A. Gopalan J. Bömmels S. Götte A. Landwehr K. Franz M.-W. Ruf H. Hotop K. Bartschat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):17-29
A novel electron scattering apparatus for high resolution studies of angle-differential elastic and inelastic electron scattering
from atoms and molecules in the gas phase is described and its performance characterized. It combines a laser photoelectron
source, a triply differentially pumped collimated supersonic beam target (half angle 0.015 rad, background to beam density
ratio < 0.01), and several electron multipliers for simultaneous detection of elastically scattered electrons and metastable atoms (or
molecules) due to inelastic scattering. In detailed test measurements of the yield for the production of metastable He*(23S1) atoms around its threshold, the dependence of the overall energy width on various experimental parameters has been investigated.
So far a resolution down to 7 meV (FWHM) has been obtained. Under such conditions we have investigated the profile of the
He- (1
s
2
s
2
2
S
1/2
) resonance at the scattering angles 22
°
, 45
°
, and 90
°
. From a consistent fit of the measured profiles by resonant scattering theory we determine a new value for the resonance
energy ( E
r
= 19.365(1) eV) and an accurate resonance width ( Γ = 11.2(5) meV). These results are consistent with the previously recommended values.
Received 23 July 2002 Published online 29 October 2002
RID="a"
ID="a"e-mail: hotop@physik.uni-kl.de
RID="b"
ID="b"Permanent address: Department of Physics and Astronomy, Drake University, Des Moines, IA 50311, USA. 相似文献
8.
S. Y. Yousif Al-Mulla 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):11-14
Differential cross sections for the elastic scattering of electrons from the
ground states of
copper for the configuration 3d10 4s and the excitation state 2D
with the configuration 3d9 4s2
have been calculated. Local density approximations to the exchange and
correlation potentials
have been used in these calculations, and it is confirmed that Hara exchange
coupled with a
Hedin-Lundqvist electron-gas-type correlation potential joined to an
adiabatic polarization
potential gives good predictions for differential cross sections.
A comparison of the calculated results with other experimental and
theoretical data are presented and discussed. 相似文献
9.
M. Gupta K. L. Baluja 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):475-483
Electron-H2S collision process is studied using the R-matrix method. Nine low-lying states of H2S molecule are considered in the R-matrix formalism to obtain elastic integral, differential, momentum transfer and excitation cross sections for this scattering
system. We have represented our target states using configuration interaction (CI) wavefunctions. We obtained adequate representation
of vertical spectrum of the target states included in the scattering calculations. The cross sections are compared with the
experiment and other theoretical results. We have obtained good agreement for elastic and momentum transfer cross sections
with experiment for entire energy range considered. The differential cross sections are in excellent agreement with experiment
in the range 3–15 eV. A prominent feature of this calculation is the detection of a shape resonance in 2B2 symmetry which decays via dissociative electron attachment (DEA). Born correction is applied for the elastic and dipole allowed
transition to account for higher partial waves excluded in the R-matrix calculation. The electron energy range is 0.025–15 eV. 相似文献
10.
Experimental Investigation of High Power Erbium-Ytterbium Co-doped Double Clad Fibre Laser 下载免费PDF全文
All-fibre high power erbium-ytterbium co-doped double clad fibre lasers are proposed and demonstrated. By using different back-cavity mirrors, the different double clad fibre lasers are constructed. It is experimentally found that the output behaviour of laser can be controlled by a back-cavity mirror. The lower the reflectivity of the back-cavity mirror, the higher the output power and the high the slop efficiency. The maximum output power is about 1.6 W and the slop efficiency is 27.6%. 相似文献