共查询到20条相似文献,搜索用时 32 毫秒
1.
O. V. Zhuravleva A. V. Ivanov D. S. Isaev V. D. Kurnosov K. V. Kurnosov V. I. Romantsevich R. V. Chernov 《Journal of Applied Spectroscopy》2005,72(5):757-762
It is shown that superluminescent diodes rank below laser diodes in energy characteristics, but they have a wider emission
spectrum and lower noise level. The amplitude-frequency and noise characteristics of the laser diode correlate with each other,
whereas there is no such correlation for the superluminescent diode. The photon density distribution along the active area
is more homogeneous for the laser diode than for the superluminescent one.
Presented at the 5th International Scientific-Technical Conference “Quantum Electronics,” November 22–25, 2004, Minsk, Belarus.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 689–693. September–October, 2005. 相似文献
2.
M. Pleimling W. Selke 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(3):385-391
The effect of imperfections on surface critical properties is studied for Ising models with nearest-neighbour ferromagnetic
couplings on simple cubic lattices. In particular, results of Monte Carlo simulations for flat, perfect surfaces are compared
to those for flat surfaces with random, “weak” or “strong”, interactions between neighbouring spins in the surface layer,
and for surfaces with steps of monoatomic height. Surface critical exponents at the ordinary transition, in particular ,are found to be robust against these perturbations.
Received: 7 October 1997 / Accepted: 19 November 1997 相似文献
3.
We approach the quantification theory of the wave–particle duality restricting ourselves to a qubit entangled with its environment.
We use the notion of the conditional expectation value and conditional variance to provide an alternative derivation of the
well-known “strong” inequality for the which-way knowledge and quantum-erasure visibility. 相似文献
4.
A. Lucchesini S. Gozzini C. Gabbanini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):223-226
By using a spectrometer having as source a commercial etherostructure Al
x
Ga1 − x
As diode laser operating in “free-running mode”, line shape parameters of some water vapor ro-vibrational overtones at 820–830
nm have been measured at room temperature. These weak absorption lines have been detected by using the wavelength modulation
spectroscopy technique with second-harmonic detection. The broadening and shifting coefficients have been obtained by fitting
the collected second-harmonic absorption features while varying the pressure of different foreign gases. 相似文献
5.
The dependence of the current on emitter size is obtained for a high-current planar diode with a discrete emitting surface.
It is shown that if the distance between the emitters appreciably exceeds their size, the dependence of the current on the
ratio of the emitter size to the diode gap is a power dependence with an exponent of 3/2. The voltage dependence of the current
obeys the “three-halves” law up to higher voltages than that for a planar diode with a homogeneous emitting surface.
Zh. Tekh. Fiz. 69, 97–101 (June 1999) 相似文献
6.
Frieder Kleefeld 《Czechoslovak Journal of Physics》2005,55(9):1123-1134
On the basis of a new method for the derivation of the effective action the nonperturbative concept of “ dynamical generation”
is explained. A non-trivial, non-Hermitian and PT-symmetric solution for Wightman's scalar field theory in four dimensions
is dynamically generated, rehabilitating Symanzik's precarious φ4-theory with a negative quartic coupling constant as a candidate for an asymptotically free theory of strong interactions.
Finally it is shown making use of the dynamical generation that a Symanzik-like field theory with scalar confinement for the
theory of strong interactions can be even suggested by experiment.
Presented at the 3rd International Workshop “Pseudo-Hermitian Hamiltonians in Quantum Physics”, Istanbul, Turkey, June 20–22,
2005. 相似文献
7.
V. L. Frolov V. O. Papoport G. P. Komrakov A. S. Belov G. A. Markov M. Parrot J. L. Rauch E. V. Mishin 《Radiophysics and Quantum Electronics》2008,51(11):825-833
We report on the French DEMETER and American DMSP satellite measurements of largescale field-aligned plasma-density perturbations
(ducts) induced in the topside ionosphere by the ionospheric F
2-layer pumping by means of high-power HF radio waves from the “Sura” heating facility. Characteristics of such plasma perturbations
and conditions of their formation are determined.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 915–924, November 2008. 相似文献
8.
V. Yu. Osipov 《Technical Physics》1998,43(9):1075-1082
Focusing of a high-power laser beam, whose initial wave front is deformed by spherical aberration and astigmatism, in a medium
with refractive-index nonlinearity is investigated by the computer experiment method. It was found that the extended formations
which arise near the focus are no longer diffraction catastrophes, since they are structurally unstable. It is shown that
weak disturbances of the shape of the initial wave front produce extremely strong distortions of the optical field in the
focusing region. As the wave propagates in the z direction, spatial chaos in the distribution of the optical field develops in the region of focusing (from 137 to 142 mm).
Optical turbulence arises in the focusing region as a result of self-diffraction of light by self-induced nonuniformities
of the refractive index of the medium. After the region with the smallest cross section of the formation near the focus, the
three-dimensional optical field has the form of chaotically dispersing “splashes” and extended “filamentary ejecta.”
Zh. Tekh. Fiz. 68, 74–83 (September 1998) 相似文献
9.
The scattering of an atom in the field of counterpropagating light waves is studied under conditions such that the state of
the atom is a superposition of the ground and excited states. For the case in which this superposition is created by the field
of a traveling wave, the momentum distribution function of the atom after scattering by a standing wave is found analytically
in the approximation of a short interaction time, when the atom’s motion can be neglected. Longer interactions of the atom
with the field are studied numerically. We also consider the case of counterpropagating light waves consisting of Gaussian
or supergaussian pulses.
Zh. éksp. Teor. Fiz. 113, 563–572 (February 1998) 相似文献
10.
It is shown for doped and compensated germanium that the appearance of negative magnetoresistance under the conditions of
Mott hopping conductivity may be due to the presence of a nonuniform spatial distribution of the electron density, the temperature
at which the effect appears apparently being determined by the temperature at which the electron gas condenses into electron
“lakes.” A “dead zone” effect was also observed in weak magnetic fields, the threshold field increasing with the nonuniformity
of the electron distribution.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 3, 187–191 (10 February 1996) 相似文献
11.
M. Fifirig A. Cionga 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):33-39
We study the “coherent phase control” between the three-photon ionization by a fundamental laser field and the one-photon
ionization by its third harmonic for a hydrogen atom in its ground state. The relative phase δ of the harmonic field with
respect to the fundamental laser radiation “modulates” the interference between the two ionization channels, which is important
near the crossing points between the ionization rates of the two individual processes. Numerical results for the total ionization
rate and for the angular distribution of the photoelectrons as a function of the phase δ are presented for frequencies located
in the vicinity of the atomic resonances corresponding to the absorption of two laser photons.
Received 31 August 2000 and Received in final form 6 February 2001 相似文献
12.
It is a model theoretical work of the applied character in which: “Outside the framework of the dipole approximation (with
an accuracy of about v/c) the effective interaction force between stripped uranium nuclei in the presence pulsed field of two laser waves extending
towards each other is theoretically studied. It is shown that the effective interaction force between uranium nuclei, can
become an attractive force on certain time intervals in the presence of the pulsed laser field. As a result the pulsed laser
field can slow down backward motion of nuclei in 7 times.” 相似文献
13.
An analysis is made of a two-electron system of two adjacent quantum dots (QD) with a two-dimensional parabolic lateral confining
potential, and of two coupled or double, spatially separated QDs (a “horizontal” and a “vertical” QD molecule), and of their
behavior in an external transverse magnetic field. The ground-state energies and energy spectra of the system have been determined
by various methods (Heitler-London, molecular-orbital, variational approach, and numerical diagonalization of Hamiltonian),
with inclusion of electron-electron interaction, and for a broad range of confining-potential steepness, QD-center spacing
(interlayer distance), and external magnetic field.
Fiz. Tverd. Tela (St. Petersburg) 40, 2127–2133 (November 1998) 相似文献
14.
The stimulated radiation pressure acting on an atom nonadiabatically interacting with the field of counterpropagating frequency-modulated
waves is shown to reach high values typical for the rapid adiabatic passage of the instantaneous frequency of the field of
the counterpropagating waves through resonance with an atomic transition. Under the appropriate choice of interaction parameters,
the radiation pressure changes insignificantly in a wide range of atomic velocities.
Original Russian Text ? V.I. Romanenko, L.P. Yatsenko, 2007, published in Pis’ma v Zhurnal éksperimental’noĭ i Teoreticheskoĭ
Fiziki, 2007, Vol. 86, No. 12, pp. 868–872. 相似文献
15.
A. I. Akhiezer A. A. Isaev S. V. Peletminskii A. P. Rekalo A. A. Yatsenko 《Journal of Experimental and Theoretical Physics》1997,85(1):1-12
This paper discusses how an electromagnetic field consisting of a superposition of a constant magnetic field and a field of
laser type can affect nuclear beta decay. In general it is not assumed that the intensities of the two types of fields are
small compared to the characteristic field H
cr*=β
1
H
cr, where H
cr=m
2
c
3/eℏ and the quantity β
1 depends on the energy liberated in the decay and the configuration of the electromagnetic field. For nonrelativistic decays
the quantity β
1 is found to be of the same order as the maximum kinetic energy of an electron referenced to its rest energy β
1∼I≪1. It is assumed that the frequency of the wave field satisfies ℏω/mc
2⩽I. The behavior of the probability for the process is studied over a wide range of the fundamental parameters that characterize
the fields. Corresponding asymptotic expressions are derived in the “weak”-and “strong”-field regimes. Also discussed are
so-called interference corrections to the unperturbed decay probability, which cannot in principle be studied by the methods
of perturbation theory. It is shown that the times and distances that are important in generating these contributions exceed
the parameters of the unperturbed processes, just as in the case of a plane-wave field previously investigated in detail by
Nikishov and Ritus. However, in contrast to the case of a pure wave field, when a system is simultaneously subjected to a
constant magnetic field and a wave field, the degree to which these characteristic regions are enlarged can depend not only
on the intensities of the electromagnetic fields but also on their rates of change, even in the limit in which the wave field
is slowly varying.
Zh. éksp. Teor. Fiz. 111, 3–24 (January 1997) 相似文献
16.
We discuss the validity of the perturbation technique (i.e., power-series expansion in terms of the high-frequency field amplitude)
applied for solving the kinetic equation. The case where the validity conditions of this method are formally violated for
a “strongly localized” distribution function is considered. It is shown that in this case, the asymptotic expressions for
the distribution-function moments remain correct not only in the linear, but also in quadratic approximation with respect
to the field.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 5, pp. 406–413, May 2005. 相似文献
17.
E. V. Ponizovskaya A. M. Bratkovsky 《Applied Physics A: Materials Science & Processing》2009,95(4):1137-1142
Negative index materials (NIM) enable subwavelength resolution and are promising for applications in integrated optical systems,
since the mode volume is small. Most promising NIM systems essentially use noble metals (Ag, Au) with material losses much
lower than in other metals, but still rather hefty, like in metal–dielectric–metal “fishnets”. Therefore, we perform extensive
finite-difference time-domain modeling of NIM “fishnets” in combination with gain medium, InGaAsP multiple quantum wells in
the present work. The signal recovery is weak, which is related to weak overlap between the radiation field and the gain medium.
The signal modulation speed may be very large, in a picosecond range. 相似文献
18.
A theory of coherent interaction between a sequence of ultrashort laser pulses and planar, thin-film microcavities in the
form of Fabry-Perot resonators containing resonating atoms has been developed. The dynamics of transmission of single laser
pulses has been analyzed numerically. Analytic solutions of the problem of four-wave mixing of optical fields separated in
time have been obtained in the small-area approximation. The dynamic efficiency of conversion of incident waves to the coherent
response field (photon echo) generated in a microcavity can be higher than in the case of a bulk resonant structure. Specific
features of photon echo generation in a microcavity for arbitrary “areas” of laser pump pulses are discussed.
Zh. éksp. Teor. Fiz. 114, 1578–1594 (November 1998) 相似文献
19.
N. S. Ginzburg V. Yu. Zaslavskii I. V. Zotova A. M. Malkin N. Yu. Peskov A. S. Sergeev 《Technical Physics》2011,56(2):155-163
Combination of various modifications of Bragg structures makes it possible to control electromagnetic fluxes in the interaction
space, thus ensuring spatial coherence of radiation for high superdimensionality in two transverse coordinates required, which
is for the operation of free electron lasers with distributed feedback in the submillimeter range. We propose that coupling
between traveling and quasi-critical waves in the input Bragg mirror be used for mode selection in the “narrow” transverse
coordinate directed along the normal to the conductors forming a planar waveguide. A traditional Bragg structure coupling
copropagating and counterpropagating wave flows can be used as the output mirror. 相似文献
20.
Spectral lines of Yb lasing in 1.03–1.05 μm region structured by 50–200 μm spots were found at focusing a pulsed LiF:F2+ color center laser of 0.5–5.0 GW/cm2 intensity on highly doped Yb:YAG or Yb:glass plates in a resonator. Small spots at the spectrograph located ≈ 1 m apart from
the resonator indicated a “sub-diffraction” directivity of Yb generation, 1–2 orders better than the diffraction limit 10−3–10−2 rad determined by the pumped volume dimensions. Observed features of Yb emission are explained assuming off-axis oscillations
in Yb laser on phase-synchronized photons due to a strong spatial-angular selection of radiation in the resonator. Propagation
of near diffraction free beams at angles to the axis built at the spectrograph slit for every 10–15 ns pulse of Yb generation
a magnified “image” of a structure of generating channels in the active medium. This image projection brought a corresponding
structure of spots in Yb spectra. It was found that channels may be formed due to a high-frequency spatial modulation (micrometers
scale) of the refractive index profile in samples caused by the oscillating amplitude of thermoelastic stresses in the pumped
medium. Obtained data demonstrate a possibility to study (with high spatial and temporal resolution) non-equilibrium stales
of materials in small volumes using laser radiation emerging from these objects. This study results evidence for the novel
concept of the spatial distribution of electromagnetic field of a photon: not in the form of a “travelling” wave but in the
form of a wave with maxima and nodes located at fixed positions along the photon propagation direction. 相似文献