共查询到20条相似文献,搜索用时 15 毫秒
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We report on the formation of spatial optical solitons in photorefractive media using picosecond laser pulses. Solitons are
generated with laser pulses in the visible and infrared wavelength region using photorefractive strontium barium niobate.
The dynamics of the soliton formation and the region of existence is studied in detail. 相似文献
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Asymmetry of the scattering amplitude of atoms in the field of short counterpropagating light pulses
Rectification in bipotential scattering of a beam of atoms in the field of short pulses of traveling and standing waves is
studied: As a result of the coherence induced by the traveling-wave pulse, the momentum transferred to the atomic beam during
scattering by the standing wave is nonzero. The magnitude and sign of the asymmetry in the scattering amplitude are oscillatory
functions of the duration of the traveling-wave pulse and the detuning of the frequency of the field from atomic resonance.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 920–923 (25 June 1996) 相似文献
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Supercontinuum generated in all-normal dispersion photonic crystal fibers with picosecond pump pulses 下载免费PDF全文
The supercontinuum (SC) generation in all-normal dispersion (ANDi) photonic-crystal fiber (PCF) pumped by high power picosecond pulses are investigated in this paper. Our results show that an octave SC may be achieved by pumping the ANDi PCF with picosecond pump pulses. However, the PCF length required may have to be lengthened to several tens of centimeters, which is much longer than that with femtosecond pump pulses. The relatively long PCF gives rise to much higher Raman gain and stronger Raman frequency shift compared to those with femtosecond pump pulses, which in turn not only cause a distorted temporal waveform and an un-flattened spectrum, but also severely degrade the coherence of the generated SC. 相似文献
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M. W. Evans 《Foundations of Physics Letters》1995,8(4):359-364
It has been argued theoretically that the recently proposed vacuum fieldB
(3)
is not accompanied by a real electric fieldE
(3)
. Experimental evidence for this interence is available in the data reported by Deschampset al. [10], using microwave magnetization of an electron plasma set up in helium gas. Faraday induction due toB
(3)
does not occur in the inert gas and is not observed experimentally in the absence of free electrons. WheneverB
(3)
interacts with free electrons, however, Faraday induction occurs through a pulse of induced magnetization (i.e., induced orbital electronic angular momentum). 相似文献
10.
H. Al-Obaidi R.J. Dewhurst D. Jacoby G.A. Oldershaw S.A. Ramsden 《Optics Communications》1975,14(2):219-222
The relaxation time τR of the saturable dye used to mode-lock a Nd: YAG laser has been changed using different dyes or dye solvent mixtures and the laser bandwidth Δω changed by the insertion of an etalon. The pulse duration τp was approximately transform-limited for τR<2π/Δω but increased to about twice this value when 2π/Δω<τp<τR. No significant increase in pulse duration was observed for τR?2π/Δω but multiple pulses were generated within each round-trip-transit-time. 相似文献
11.
Gely F. Zharkov 《Central European Journal of Physics》2005,3(1):77-103
Self-consistent solutions of the nonlinear Ginzburg-Landau (GL) equations are investigated numerically for a superconducting
(SC) cylinder, placed in an axial magnetic field, with a single vortex on the axis (m=1). Two modes, which show the original state of the cylinder, SC or normal (s
0 andn
0), are studied. The field increase (FI) and the field decrease (FD) regimes are studied. The critical fields destroying the
SC state withm=1 are found in both regimes. It is shown that in a cylinder of radiusR and GL-parameter ϰ, there exist a number of solutions depending only on the radial co-ordinater corresponding to different states such as M,e, d, p,i, n,
,n
*, and the state diagram on the plane of the variables (ϰ,R) is described. The critical fields corresponding to intrastate transitions and the onset of hysteresis are obtained. The
critical fieldH
0(R) dividing the paramagnetic and diamagnetic states of the cylinder withm=1 is determined. The limiting fields of supercooling or superheating of the normal state at which the restoration of the
SC state occurs are established. It is shown, that (in both casesm=1,0) there exist two critical parameters,
and
, which divide bulk SC into three groups (with
and
), in accordance with the behavior in a magnetic field. The parameters
and
mark the boundary for the existence of a supercooled normal
-state in FD-regime and a superheated SC M-state in FI-regime respectively. It is shown, that the value
, which was claimed in a number of papers as related to type-I superconductors, is illusory.
We regret to inform that Professor Gely Zharkov passed away on 9th July 2004. 相似文献
12.
K. Wolfrum J. Löbau A. Laubereau 《Applied Physics A: Materials Science & Processing》1994,59(6):605-610
We studied the vibrational Sum-Frequency (SF) spectra of long chain fatty alcohols and amines physisorbed at liquid/air interfaces and of OctadecylTrichlorSilan (OTS) chemisorbed on glass/air interfaces in situ, i. e., in normal laboratory environment. The intense, band-width-limited IR pulses generated by our laser system are tunable from 2600 to 4000 cm–1 with a constant pulse duration of 3 ps and a band width of 5 cm–1 (FWHM) over the entire tuning range, thus covering the CH-, NH-, and OH-stretching regions.Using suitable polarization geometries, information on the molecular orientation is obtained from the amplitudes of the symmetric and degenerate methyl-stretching modes. Opposite phase of adjacent vibrational modes can lead to destructive interference in the SF signal, as analyzed theoretically. This interference effect is observed experimentally for the first time, due to the superior spectral resolution and signal-to-noise ratio of our spectra. 相似文献
13.
Regression relations between the first main component, slope of the SBC curve towards the wavelength axis, and the degree
of mineralization of peat soils are established from experimental data. Errors in determination of peat soil productivity
are estimated using different spectral indices. For practical use it is recommended to measure the spectral brightness coefficients
of peat soils in the 0.50–0.75 μm range.
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 102–106, January–February, 1998. 相似文献
14.
The neutrino-electron scattering in a dense degenerate magnetized plasma under the conditions μ
2 > 2eB ≫ μE is investigated. The volume density of the neutrino energy and momentum losses due to this process are calculated. The results
we have obtained demonstrate that plasma in the presence of an external magnetic field is more transparent for neutrino than
for non-magnetized plasma. It is shown that neutrino scattering under conditions considered does not lead to the neutrino
force acting on plasma. 相似文献
15.
Magnetic field measurements above type-II superconductor films in a remanent magnetization state have been used to determine
two dimensional surface current distributions. Using the Biot-Savart law for the surface current density, integral equations
(of 2-D convolution type) for two components of current have been obtained. These equations have been solved by employing
Tikhonov's method of generalized discrepancy, and the surface current pattern in superconductors as well as the magnetic field
distribution on the film surface have been obtained. Current peculiarities related to various kinds of inhomogeneities, specific
character of the film form, and a laser pulse effect have been observed. In particular, it was discovered that a laser pulse
can signficantly redistribute the film currents without changing the total number of current vortices in the film. 相似文献
16.
S. A. Zibrov Ya. O. Dudin A. G. Radnaev V. V. Vassiliev V. L. Velichansky D. V. Brazhnikov A. V. Taĭchenachev V. I. Yudin 《JETP Letters》2007,85(9):417-421
The resonance of the intersection of sublevels in a probe laser field resonant to the cyclic transition corresponding to the D 2 87Rb line has been investigated in a zero magnetic field. The strong effect of an additional laser field acting on the adjacent transition has been revealed. In a cell without the buffer gas and antirelaxation coating, the amplitude of the probe-field absorption resonance can increase by more than an order of magnitude in the presence of a counterpropagating wave. The effect is observed at the laser frequency tuned to the cross resonance, when the counterpropagating waves simultaneously act on moving atoms at the cyclic and open transitions with the common lower level. The theoretical analysis of the effect of the additional field on the electromagnetically induced absorption resonance is in agreement with the experimental data. 相似文献
17.
The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d
h
(i)
of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients d
h
(1)
and d′
h
(3)
, were measured, d
h
(1)
=(244±3) pC/N and d′
h
(3)
=(92±1) pC/N. The hydrostatic piezoelectric coefficient d
h
(3)
for orthogonal axis system was calculated to be d
h
(3)
=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d
h
(1)
equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has
been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d
h
)
mean
corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d
h
)
mean
=136 pC/N. 相似文献
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Tomasz Błachowicz 《Central European Journal of Physics》2005,3(2):147-162
This paper explains the Random Field Ising Model simulations of a two-dimensional ferromagnetic/antiferromagnetic interface,
influenced by the exchange-bias interaction. Exchange-biased shifts, coercivity fields, the number of unreversed spins as
well as the numerical errors are provided. These were tested for different structure dimensions and boundary conditions in
order to find limitations of the method. The algorithm developed is simple, very effective, and provides deeper insight into
the nature of the exchange-bias phenomenon. 相似文献