共查询到20条相似文献,搜索用时 31 毫秒
1.
A new nonlinear equation for the dynamics of the spatial spectrum of a self-focusing monochromatic wave in a medium with cubic nonlinearity is derived in the nonparaxial approximation. The formation of optical beams with cross section on the order of a wavelength is considered. Backward self-reflection is found to be the fundamental cause for the limitation of optical self-focusing 相似文献
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Boardman A. D. Marinov K. Pushkarov D. I. Shivarova A. 《Optical and Quantum Electronics》2000,32(1):49-62
Spatial solitary waves carried by a TE mode in planar optical waveguides with Kerr-type of nonlinearity are investigated based on a modified nonlinear (1 + 1) Schrödinger equation. Looking for effects instigated by the spatial inhomogeneity of the nonlinear polarization, the nonzero divE-term is taken into account in the nonlinear guided wave equation together with the nonparaxial approach and vector model. It is shown that, at self-focusing of beams in a (1 + 1) geometry, the effect coming out from the divergence term predominates over modifications related to the nonparaxial vector model. This term is interpreted as nonlinearly induced diffraction which plays the role of an effective saturation. Analytical solutions supported by numerical results are found. 相似文献
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A spatial Fourier transform approach is proposed to investigate the effects of polarization changes and beam profile deformation of light during acousto-optic (AO) interaction in isotropic media. The behaviour of the total scattered optical fields inside the AO cell can be properly described by a vector wave equation of which the permittivity is perturbed by an acoustic wave propagating inside the medium. In the Bragg regime, using a spatial Fourier transform approach, two coupled differential equations can be derived from the wave equation to depict AO interaction in the spatial frequency domain. Analytic solutions, which comprise the effects of changing polarization, beam deformation and propagating diffraction, can be found from the coupled equations. Detailed numerical simulations, including Fourier transforming the incident light profile to calculate the spectra of the scattered light beams and, hence, their profiles in space using the inverse transform, are presented. 相似文献
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We have worked out some consequences of the optical nonlinearities due to laser induced changes in the order parameter of a liquid crystal. The change in the order parameter can be affected by laser induced suppression of the director fluctuations in liquid crystals and or changes in the tilt angle of smectic liquid crystals. Both the processes lead to well known nonlinear optical effects like self-focusing, self-divergence, self-phase modulation, wave mixing, and so on. In addition, we predict some new phenomena like self-iridescence and new types of optical spatial solitons. In the case of chiral liquid crystals in the short wavelength limit the laser beam induces a change in the twist and at the long wavelength edge of the Bragg band it leads to temporal oscillations in the twist and the transmitted intensity. In smectic liquid crystals interesting periodic structures in a standing laser wave are to be expected. 相似文献
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In this research, we apply two different techniques on nonlinear complex fractional nonlinear Schrödinger equation which is a very important model in fractional quantum mechanics. Nonlinear Schrödinger equation is one of the basic models in fibre optics and many other branches of science. We use the conformable fractional derivative to transfer the nonlinear real integer-order nonlinear Schrödinger equation to nonlinear complex fractional nonlinear Schrödinger equation. We apply new auxiliary equation method and novel \(\left( {G'}/{G}\right) \)-expansion method on nonlinear complex fractional Schrödinger equation to obtain new optical forms of solitary travelling wave solutions. We find many new optical solitary travelling wave solutions for this model. These solutions are obtained precisely and efficiency of the method can be demonstrated. 相似文献
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The filamentational instability of spatially broadband femtosecond optical pulses in air is investigated by means of a kinetic wave equation for spatially incoherent photons. An explicit expression for the spatial amplification rate is derived and analyzed. It is found that the spatial spectral broadening of the pulse can lead to stabilization of the filamentation instability. Thus optical smoothing techniques could optimize current applications of ultrashort laser pulses, such as atmospheric remote sensing. 相似文献
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By using the generally projective Riccati equation method, more new exact travelling wave solutions to extended
nonlinear Schrödinger equation (NLSE), which describes the
femtosecond pulse propagation in monomode optical fiber,
are found, which include bright soliton solution, dark soliton
solution, new solitary waves, periodic solutions, and rational
solutions. The finding of abundant solution structures for
extended NLSE helps to study the movement rule of femtosecond
pulse propagation in monomode optical fiber. 相似文献
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R. M. Gadiev A. N. Lachinov V. M. Kornilov R. B. Salikhov R. G. Rakhmeev A. R. Yusupov 《JETP Letters》2010,90(11):726-730
The scheme of an experiment has been proposed to observe nonadiabatic atomic transitions in the standingwave laser field and
splitting of atomic wave packets on the nodes of the standing wave induced by these transitions in a certain range of optical
detuning. The effect can be implemented in atomic-optical nanolithography for making spatial atomic structures with a period
much smaller than the optical wavelength. 相似文献
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A summary is presented of the principal types of completely integrable partial differential equations having soliton solutions. Each type is derived from an appropriate physical model of an electromagnetic wave problem, with the intention to show how known mathematical results apply to a coherent class of physical problems in electromagnetic waves. The non-linear Schrödinger (NS) equation appears when the induced non-linear dielectric polarization is expanded in a series of powers of the electric field, only the linear and third-order polarizations are retained, and the temporal spectrum of the wave is a narrow band far removed from any resonance of the medium. The sine-Gordon equation appears from a similar optical model of propagation in a dielectric consisting of identical 2-level atomic systems, but resonance occurs between the carrier frequency of the wave and the transition frequency of the atoms. The Boussinesq and Korteweg– de Vries equations appear at different levels of approximation to a potential wave on a transmission line having a non-linear capacitance such that the charge stored is a non-linear function of the line potential. In all cases the evolution variable is the propagation distance; the transverse variable is time, but in the case of the NS equation it may alternatively be a spatial coordinate, giving rise to the possibility of spatial solitons as well as temporal solitons for NS-type problems. Two examples are derived of non-integrable Hamiltonian systems having spatial solitary waves, namely the second-order cascade interaction and vector spatial solitary waves of the third-order interaction, and a brief survey of the analytical solutions for the plane waves and solitary waves of these two types is presented. Finally, the addition of a second spatial dimension to the non-linear transmission line problem leads to the Kadomtsev–Petviashvili equations, and a further approximation for weakly modulated travelling waves leads to the Davey–Stewartson equations. Both of these completely integrable systems support combined spatial–temporal solitons. 相似文献
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利用波动方程,研究了脉冲贝塞尔光束在自由空间传输时的空间诱导群速度色散(SIGVD)效应. 结果表明,三阶SIGVD能使脉冲贝塞尔光束的时域逐渐演化为艾里分布. 由于艾里-贝塞尔光弹是一种新奇的时、空都不扩展的局域波包, 能在光与物质相互作用的很多应用领域发挥作用.因此,本文提出了 通过色散管理技术补偿二阶SIGVD,利用三阶SIGVD在自由空间产生艾里-贝塞尔光弹的方案. 为分析这种光弹的时空传输特性,数值模拟了它在色散介质中的传输情况. 结果表明,这种光弹能在色散介质中保持空域不衍射、时域不色散的稳定传输. 相似文献
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A new form of the quasioptical equation is proposed to describe the propagation of an electromagnetic wave beam in a stationary smoothly inhomogeneous medium with spatial dispersion and dissipation. The proposed approach guarantees the positive definiteness of the absorbed power in the locally dissipative medium, which is a nontrivial property for inhomogeneous media with spatial dispersion. An efficient numerical scheme is constructed to solve the derived quasioptical equation. 相似文献
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We propose a method for recording an optical wave field that is based on diffraction of the optical wave field by two screens
that are complementary to each other. We show that the new method ensures the measurement of the phase of the wave field with
a high accuracy and spatial resolution. An optical scheme for implementing the diffraction method and an algorithm for reconstructing
the phase of the wave field from the measurement data are developed. We perform a computer simulation of the experiment on
recording the optical wave field based on the method proposed. 相似文献
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We show that in the context of paraxial optics, which can be analyzed through a wave equation similar to the non-relativistic Schrödinger equation of quantum mechanics but replacing time t by spatial coordinate z, the existence of a vector potential A⊥ mimicking the magnetic vector potential in quantum mechanics is allowed by specific gauge symmetries of the optical field in a medium with anisotropic refractive index. In this way, we use Feynman?s path integral to demonstrate an optical analogue of the quantum-mechanical Aharonov-Bohm effect, encouraging the search for another optical systems with analogies with more complex quantum field theories. 相似文献
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This paper predicts that grey spatial solitons can exist in
two-photon photorefractive materials. In steady state and under
appropriate external bias conditions, it obtains the grey spatial
soliton solutions of the optical wave evolution equation. The
intensity profile, phase distribution,and transverse velocity of
these grey solitons are discussed. 相似文献