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1.
A model to describe the magnetic properties of Fe/Cr/Fe films with nanometer-thick layers of Fe and Cr is proposed. The model rests on the assumption that there exists a magnetic order of the linearly polarized spin-density wave type in a chromium interlayer with thicknesses even less than its wavelength. This only assumption proved to be enough to describe the following characteristics, experimentally observed, of the magnetic properties of the multilayer Fe/Cr films: the existence of short and long periods, dependences of their magnetic properties on the chromium layer thickness, noncollinear orientation of the magnetizations of neighboring iron layers, the existence of the magnetization curves beyond the hysteresis loops of magnetization. 相似文献
2.
V. P. Gapontsev S. M. Matitsin A. A. Isineev V. B. Kravchenko 《Optics & Laser Technology》1982,14(4):189-196
In this paper results of experimental investigations into erbium glass lasers and their likely applications are discussed. Regularities of the inversion energy accumulation, also as channels of energy losses, are covered in detail. Different erbium lasers, both flashtube and neodymium laser-pumped, are compared. Parameters of some erbium laser glasses are presented, including the new LGS-E7, which requires a smaller pumping energy density (less than 100–200 J cm-2). Test data from experimental models are summarized. 相似文献
3.
A. M. Tkachuk I. K. Razumova A. A. Mirzaeva A. V. Malyshev V. P. Gapontsev 《Optics and Spectroscopy》2002,92(1):67-82
Formation of the inverse population of working levels of 3-μm laser transition in LiY1−x
ErxF4 (x=0.003–1) crystals under CW InGaAs laser-diode pumping (0.967–0.982 μm) was investigated. Dependences of population of the
4
I
11/2 and 4
I
13/2 levels on the dopant concentration and pump power were studied theoretically and experimentally. Relative changes in populations
of the studied levels were experimentally monitored by measuring the steady-state spectra of IR crystal luminescence in the
wavelength range corresponding to 4
I
11/2→4
I
13/2 (2.7–2.8 μm), 4
I
11/2→4
I
15/2 (0.96–1.04 μm), and 4
I
13/2→4
I
15/2 (1.45–1.65 μm) transitions. Theoretical and experimental estimates of the rates of intracenter and intercenter relaxation
processes (migration, self-quenching, and up-conversion) with allowance for statistics of coupling of impurity centers in
the system were used to determine the energy-transfer mechanisms, elucidate the predominant mechanisms, and obtain microparameters
and concentration dependences of the energy-transfer rates and nonlinear coupling. Dependences of the steady-state population
of the levels of laser transition 4
I
11/2→4
I
13/2 on the dopant concentration and pumping power density were calculated within the context of rate balance equations for the
scheme with the five lowest excited states of erbium. Good agreement between theory and experiment was obtained.
__________
Translated from Optika i Spektroskopiya, Vol. 92, No. 1, 2002, pp. 73–88.
Original Russian Text Copyright ? 2002 by Tkachuk, Razumova, Mirzaeva, Malyshev, Gapontsev. 相似文献
4.
de Matos CJ Popov SV Rulkov AB Taylor JR Broeng J Hansen TP Gapontsev VP 《Physical review letters》2004,93(10):103901
Air-cored, photonic band-gap crystal fibers exhibiting low nonlinearity and anomalous chromatic dispersion in spectral ranges inaccessible to conventional fibers can be used in the realization of all-fiber-format pulse compressors with unprecedented peak powers and wavelength diversity. Linear compression of inherently chirped and prestretched pulses by factors ranging from 20 to 80 around 1.0 and 1.5 microm have allowed generation of pulses as short as 163 fs. The results show that totally integrated femtosecond fiber laser sources can be realized throughout the visible and near-infrared and point to the possibility of megawatt peak and tens of watt average in-fiber power levels. 相似文献
5.
Effect of poly (lactic acid)‐graft‐glycidyl methacrylate as a compatibilizer on properties of poly (lactic acid)/banana fiber biocomposites 下载免费PDF全文
The main aim of this study was to synthesis of poly (lactic acid) (PLA)‐graft‐glycidyl methacrylate (GMA) as well as its influence on the properties of PLA/banana fiber biocomposites. PLA‐graft‐GMA graft copolymer (GC) was synthesized by melt blending PLA with GMA using benzoyl peroxide and dicumyl peroxide as initiators. Graft copolymerization was confirmed by FTIR and 1H‐NMR spectroscopic studies. PLA/silane treated banana fiber (SiB) biocomposites with various GC concentrations were prepared by melt blending followed by injection molding techniques. The influence of GC content on the mechanical, thermal and moisture resistance properties of the composite was investigated. The addition of 15 wt% GC content in the biocomposite provided optimum tensile and flexural strength, which is attributed to the greater compatibility between fiber and PLA matrix. The thermal properties of biocomposites have been evaluated using thermogravimetric analysis which provided evidence of improved interfacial adhesion between SiB and PLA by the addition of GC. Additionally, GC enhanced the moisture absorption resistance of biocomposites. These results indicated that GC is indeed a good candidate as a compatibilizing agent to improve the compatibility in PLA/fiber biocomposites. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
N. B. Bakulina M. I. Kurkin S. A. Gudin A. V. Gapontsev 《Physics of the Solid State》2010,52(2):328-334
The possibility of appearing jumps in the magnetization curves of Fe/Cr multilayers has been predicted under the assumption
that magnetic ordering in chromium interlayers has the form of a linearly polarized spin-density wave. This possibility has
been analyz ed for an Fe/Cr/Fe three4ayer film with a conventional quality of Fe/Cr interfaces, which does not ensure a change
in the ferromagnetic and antiferromagnetic orientations of the magnetizations of neighboring iron layers with a variation
in the thickness of the chromium interlayer by one atomic layer (short oscillation period). The model used suggests that the
wave vector of the spin-density wave is responsible for the experime ntally observed long period of these oscillations. Relationships
have been derived for the range of thicknesses of chromium interlayers in which the appearance of the predicted effect can
be expected, and the magnitude of the effect has been evaluated. 相似文献
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9.
Supercontinuum self-Q-switched ytterbium fiber laser. 总被引:18,自引:0,他引:18
We have discovered a new mechanism for passive Q switching of fiber lasers. 10-kW peak power pulses with ~2-ns pulse widths are reported from a diode-pumped ytterbium-doped fiber laser. The laser generates a high-brightness Raman-dominated supercontinuum spectrum covering the complete window of transparency of silica fiber in the infrared from 1.06 to 2.3 mum. 相似文献
10.
The magnetic properties of Li x CoO2 for x = 0.94, 0.75, 0.66, and 0.51 are investigated within the method combining the generalized gradient approximation with dynamical mean field theory (GGA + DMFT). A delicate interplay between Hund’s exchange energy and t 2g ?e g crystal field splitting is found to be responsible for the high-spin to low-spin state transition for Co4+ ions. The GGA + DMFT calculations show that the Co4+ ions at a small doping level adopt the high-spin state, while delithiation leads to an increase in the crystal field splitting and low-spin state becomes preferable. The Co3+ ions are found to stay in the low-spin configuration for any x values. 相似文献