共查询到13条相似文献,搜索用时 0 毫秒
1.
B. B. Sevruk 《Journal of Applied Spectroscopy》2005,72(3):382-390
With the developed method of numerical simulation, the dynamics of formation of the spatial structure of interacting wave
fields in the process of generation of the sum-frequency radiation was investigated. Radial intensity profiles and angular
spectra of diffracting light beams with varied restriction and focusing parameters at different stages of energy exchange
in the KTP crystal have been calculated. It is shown that with weak focusing, a self-channeling wave structure of soliton
type with angular divergence of the second-harmonic component at the level close to the diffraction limit is formed in the
field of the wide Bessel-Gauss pumping beam. Moreover, in the far-field zone complete spatial separation of the light fluxes
corresponding to the fundamental and second harmonics occurs. Comparison of the efficiencies of conversion on pumping by Gauss
and Bessel-Gauss light beams is made.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 358–365, May–June, 2005. 相似文献
2.
N. B. Gubar 《Journal of Applied Spectroscopy》1997,64(6):863-865
In the present article the effect of compression of Gaussian pulses during their opposing propagation in a medium with inertial
cubic nonlinearity is considered. Using methods of computer simulation, conditions are found that determine the optimum regime
of compression. It is shown that after single passage through the medium the compression degree is equal to two.
B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 840–842, November–December, 1997. 相似文献
3.
B. B. Sevruk 《Journal of Applied Spectroscopy》2003,70(4):513-521
A method for numerical simulation of stimulated Raman scattering of cylindrical wave beams in a nonlinear medium has been developed. The features of the spatial structure formation of interacting wave fields in the regime of conservation of azimuthal angular distributions of amplitudes have been investigated. The radial intensity profiles of diffracting light beams in the near-field zone and their angular spectra in the far-field zone corresponding to different stages of energy exchange in the process of amplification from the noise in the barium nitrate crystal have been calculated. It has been shown that in the field of Bessel beams waveguide structures of the soliton type with a peak intensity of the self-channeling Stokes component significantly exceeding the initial pumping intensity are formed. A comparison of the conversion efficiencies under pumping by Gaussian and Bessel light beams has been made. 相似文献
4.
The possibility is demonstrated that the self-focusing of an elliptically polarized beam in a medium featuring a spatially disperse cubic nonlinearity can give rise to several radially symmetric ring-shaped regions of the same sense of rotation (right or left) of the electric-field vector in the cross-section of the beam. The formation dynamics and propagation features of such electric field structures are studied for various parameters of the incident radiation and nonlinear medium. 相似文献
5.
Based on the modification of the radial pulsation equation
of an individual bubble, an effective medium method (EMM) is presented for
studying propagation of linear and nonlinear longitudinal acoustic waves
in viscoelastic medium permeated with air bubbles. A classical theory
developed previously by Gaunaurd (Gaunaurd GC and \"{U}berall H, {\em J.
Acoust. Soc. Am}., 1978; 63: 1699--1711) is employed to verify the EMM under linear approximation
by comparing the dynamic (i.e. frequency-dependent) effective parameters,
and an excellent agreement is obtained. The propagation of longitudinal
waves is hereby studied in detail. The results illustrate that the nonlinear
pulsation of bubbles serves as the source of second harmonic wave and the
sound energy has the tendency to be transferred to second harmonic wave.
Therefore the sound attenuation and acoustic nonlinearity of the
viscoelastic matrix are remarkably enhanced due to the system's resonance
induced by the existence of bubbles. 相似文献
6.
基于瑞利衍射公式,研究了被光阑衍射的具有振幅调制和相位畸变光束的远场光谱变化规律。结果表明,有振幅调制和相位畸变光束在远场也会出现光谱异变现象和光谱开关效应,光阑截断参数、光束的相位畸变参数、振幅调制参数、光强调制参数对远场光谱的跃迁量和光谱开关产生影响。通过数值计算结果分析讨论了光阑截断参数及光束各参数影响远场光谱的规律。 相似文献
7.
本文在理论上首次发现有源耦合腔激光器的自启动锁模和时域调制特性,并对其进行了全面的分析和计算.对有源耦合腔激光器的自启动锁模机制和时域调制特性给予详尽的数值计算结果和清晰的物理图象解释,提出在有源耦合腔锁模激光器中可用连续泵浦源代替锁模泵浦源,而且有产生更短的光脉冲可能性. 相似文献
8.
9.
附加克尔介质Jaynes—Cummings模型场的位相特性 总被引:2,自引:1,他引:2
运用Pegg-Barnett厄米位相公式,研究了附加克尔(Kerr)介质Jaynes-Cummings(J-C)模型场的位相特性.具体讨论了场的位相概率分布、厄米位相算符的期待值以及位相的涨落,通过与标准J-C模型作比较,讨论了克尔介质与模场的非线性相互作用对场位相特性的影响. 相似文献
10.
Optical schemes of lasers that ensure the formation of giant pulses from narrowband, freeoscillation priming radiation with a change in the Qfactor and simultaneous increase in the gain coefficient and in the coefficient of filling a resonator with an active substance are developed. The results of experimental investigations of the parameters of singlepulse radiation of ruby lasers with electrooptical switching of a linear composite resonator are given. 相似文献
11.
R. D. Benguria M. C. Depassier M. Loss 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):331-334
We establish rigorous upper and lower bounds for the speed of pulled fronts with a cut-off. For all reaction terms of KPP
type a simple analytic upper bound is given. The lower bounds however depend on details of the reaction term. For a small
cut-off parameter the two leading order terms in the asymptotic expansion of the upper and lower bounds coincide and correspond
to the Brunet-Derrida formula. For large cut-off parameters the bounds do not coincide and permit a simple estimation of the
speed of the front. 相似文献
12.
13.
J. H. Li 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):467-473
We theoretically study the features of the spontaneous emission
spectra in a coherently driven cold four-level atomic system with
a cyclic configuration. It is shown that a few interesting
phenomena such as spectral-line narrowing, spectral-line
enhancement, and spectral-line suppression can be realized in our
system. Interestingly enough, the spectral-line enhancement and
suppression can be controlled just by appropriately modulating the
phase, the frequency, and the intensity of an external coherent
magnetic field, respectively. This investigation may find
applications in high-precision spectroscopy.
An erratum to this article is available at . 相似文献